This PDF file contains the front matter associated with SPIE Proceedings Volume 11780, including the Title Page, Copyright information, and Table of Contents.

In this paper, we illustrate a discrete Fourier processor based on dual optical frequency combs (OFCs). The simulation verified the DFT calculation with the frequency coverage of 0.2 GHz to 3 GHz and the resolution is 200 MHz. Meanwhile, demodulation of standard OFDM signal in time domain is simulated. This scheme avoids the problem of "electronic bottleneck" in current all-electronic processors. It is superior to the existing photon-assisted Fourier transform schemes in flexibility and accuracy, and has the characteristics of low power consumption, high throughput and high precision.

Raman backscattering happens when a laser pulse is launched and travels along the optic fiber from which the temperature can be calculated along the fiber based on OTDR technology. Wellbore temperature data under different working schemes can be obtained with the fiber optic run into well via different methods, enabling the temperature anomaly construction between the geothermal temperature and the flowing wellbore temperature. Wellbore temperature anomaly is a function of the production profile which can be obtained using a wellbore enthalpy model in combination with single well geology, fluid PVT data, fluid thermal properties and well structure data etc. DFA interpretation is performed for Well XX indicating the main contributing layers are between 10279ft and 10350ft with production intensity lying between 5000m³/(d∙m) and 10⁴m³/(d∙m). Layer A₂ and layerA₆ are the main layers with low reserve utilization. Comparison between PLT analysis and DFA interpretation shows a high coherence with a higher interpretation accuracy provided by DFA interpretation.

Human sweat is mainly composed of water and small amounts of electrolytes (e.g. sodium, chloride, potassium, calcium), metabolites, amino acid and proteins. Variation of the pH value in sweat is closely associated with the health status of person that can indicate disease and metabolic activity. This study demonstrates a newly developed wearable sensor based on taper-in-taper structure for sweat pH detection with high sensitivity. To fabricate this biosensor, the pH sensitive PVA-PAA hydrogel layer (polyvinyl alcohol-polyacrylic acid) and pH sensitive indicator MO (Methyl Orange) are combined to be a coating layer of optical fiber with a three-dimensional network porous structure. The proposed optical biosensor in taper-in-taper structure for human sweat pH monitoring is demonstrated to have high sensitivity, wide dynamic range and short time response, which also present excellent long-term stability and durability that can be potentially applied in high-performance smart wearable device for health management.

Erbium-doped waveguide-integrated lasers (EDWLs) play an increasingly important role in optical interconnects, optical communication, and biochemical sensing, due to their advantages of tunable spectral bandwidths, narrow linewidths, and large output powers. However, compared with the near-infrared (near-IR) band, the study of mid-infrared (mid-IR) EDWLs is still in its infancy. In this paper, we theoretically studied an EDWL at a wavelength of 3.6 μm. The model is based on a mid-IR suspended membrane silicon waveguide microring resonator integrated with an Erbium-doped chalcogenide glass thin layer. The designed laser could be fabricated with the combination of a CMOS-compatible silicon chip and Erbium-doped chalcogenide glass deposition through a post-fabrication process, making it be possible for high-volume and low-cost fabrication. We numerically calculated output characteristics of the laser by solving rate equations and a beam propagation equation. Specifically, after optimizing coupling coefficients of the resonator, the output power of the laser can reach 0.25 μW. To further increase the laser slope efficiency, we designed a vertical Fabry- Perot cavity to increase the pump power intensity. Simulated results showed that the laser slope efficiency could be improved by a factor of six. Our study is expected to open an avenue to develop on-chip mid-IR lasers for exploring intriguing on-chip mid-IR applications in biochemical sensing, LiDAR, and nonlinear optics.

Anomaly detection finds data samples whose signatures are spectrally distinct from their surrounding data samples. One area of interest regarding hyperspectral images is anomaly detection. Anomaly detection becomes increasingly important in hyperspectral image analysis. Hyperspectral imagers can now uncover many material substances which were previously unresolved by multispectral sensors. Many anomaly detectors have been developed and most of them are based on the most widely used Reed-Yu’s algorithm, called RX detector (RXD). Principal component analysis (PCA) allows linear dimensionality reduction and feature extraction for hyperspectral remote sensing data. Kernel PCA (KPCA) is the nonlinear form of PCA, which better exploits the complicated spatial structure of high-dimensional features. In this paper, we first use PCA-global RX (PCA-GRX) algorithm for anomaly detection. Kernel Principal Component Analysis (KPCA)-GRX algorithm is investigated for anomaly detection from hyperspectral remote sensing data. Experimental results presented in this paper confirm the usefulness of the KPCA-GRX for the analysis anomaly detection of hyperspectral data. The detection accuracy increases with the proposed approach.

Here we demonstrated a single polarization waveguide and spot size converter for edge coupling working at O band based on Lithium niobate on insulator.The improvement extinction ratio of 35dB/cm is obtained for the single polarization waveguides. The insertion loss of bilayer spot size converters is 3.5dB/facet from our best results at the light length of 1310nm.

Lithium niobate (LN) devices have been used in optical communication and nonlinear optics widely due to its impressive optical properties. Thin-film lithium niobate on insulator (LNOI) improves performances of LN-based devices further. But a high-efficient fiber-chip optical coupler for the LNOI-based devices for practical applications is still absent. In this article, we demonstrate a wide-band, highly efficient and polarization independent edge coupler based on LNOI fabricated by planar semiconductor process. The measured ultra-high numerical aperture fiber (UHNAF)-to-chip optical coupling loss at 1550 nm is 0.54 dB/facet (0.59 dB/facet) for TE(TM). The coupler has the coupling loss lower than 1dB/facet for both TE and TM light at wavelengths longer than 1527nm.

With the continuous development of aerospace and aviation, the field of view of the interferometric spectrometer is getting larger and larger, and the field of view of the interferometer also increases. In order to realize the precise adjustment of the interferometer, it is necessary to input the interferometer through a large field of view target to form a large array of interference fringes. In order to improve the measurement accuracy of interference fringes, the large field of view target with small distortion and small chromatic aberration is required to produce interference fringes with a large field of view, so it is necessary to design wide-band collimator with a large field of view to provide an object that meets the above characteristics. In this paper, we designed a collimator whose focal length of the system is 307mm, the field of view is ±12°, the working wavelength is 450nm~900nm,the effective aperture is Φ50mm. The diameter of the diffusion spot in each field of view is smaller than the diameter of the Ellie disk, reaching the diffraction limit, and the distortion correction is better than 2%. The transfer function is almost close to the diffraction limit, meeting the design requirements of the wide-band collimator with large field of view and low distortion.

Hyperspectral image classification plays an important role in many remote sensing applications. However, the high-dimensional characteristics of hyperspectral images and the appropriate feature representations leave it with great challenges. In this article, these difficulties are addressed by developing a Spectrum Selection and Deep Feature Fusion based method. The proposed method has the following contributions: 1) reducing redundant information caused by high-dimension through spectrum selection which is just needed in training phase. 2) extracting the joint spectral-spatial features by deep feature fusion, which effectively improves the accuracy of scene classification. 3) increasing the network attention to scene classes of small number by the Class-Balanced loss function and overcome the influence of unbalanced distribution of experimental data. Experiments results in the Tiangong-1 natural scene images dataset (TG1-NSCD) demonstrate that the effectiveness of our algorithm and the OA is 17% higher than the baseline.

Schlieren technology can realize the visualization of flow field testing. The transmission schlieren device as a model, a laser light source with Gaussian distribution is used to pass through a cylindrical area with uniform refractive index distribution to obtain a simulated schlieren image and a flow field visualized diffraction fringe. Based on the theory of Fourier optics and applying Fresnel diffraction optics technology, the Fourier characteristics of the lens are derived, and the light field distribution at the focal plane of the lens is calculated. The Heaviside step function is combined to express the light field distribution on the back surface of the knife-edge device, and then the light field intensity expression of the imaging plane is obtained. The results show that the transmission schlieren method can obtain a high imaging quality light field intensity distribution map containing the parameters of the test object. When the cutting position of the knife edge is half of the light field spectrum surface, the imaging plane display effect is the best. In the comparative experiment, when the knife-edge device cuts the spectrum surface 2/5~1/2, the test object parameter information contained in the light field intensity map is the most complete. The intensity of the part that is shielded by the knife edge device is 0, and the intensity of the unshielded part is constant, which is consistent with the performance result of ray optics. This algorithm can provide theoretical basis and experimental reference for the visualization of typical flow field.

Compared with the optical modulator based on 1310 nm and 1550 nm wavelength band, the silicon-based modulator at 2 μm band has a higher absorption loss, since the free carrier effect is more significant in the 2 μm band. In this paper, we demonstrate an optical modulator at 2 μm wavelength band, using a doping compensation method. We reduce absorption loss and keep the modulation extinction ratio at a high level through optimizing waveguide width, PN junction offset and compensated area. With doping compensation, the modulator has an absorption loss by PN junction of 2.8 dB/cm at 0 V and an extinction ratio of 14.2 dB at bitrates of 40 Gb/s.

A high efficient cantilever-type mode size converter applied at 800 nm wavelength is proposed and analyzed in this letter. The converter can compress and couple the light spot from a single mode fiber into the Silicon nitride waveguide effectively and smoothly. The core of the entire structure is supported by the SiO₂ cantilever beam to make the device suspended, which can effectively prevent the light leaking from the substrate to cause great coupling loss. A Gaussian light source with a diameter of 4.5 μm and wavelength of 800nm is used for the coupling test. The coupling loss of the device with both TE and TM mode are greater than 0.54 dB. The alignment tolerances for 1-dB excess loss are both ± 0.8 μm in horizontal and vertical directions.

A nanosecond pulsed dielectric barrier discharge (ns-DBD) setup is built to preliminarily analyze effect of different discharge repetition (600Hz ~ 1800Hz) and voltage (6.0kV ~ 10.4kV) on CH4-air diffusion flame. Emission spectral is used to understand temperature and relative change of components’ concentrations in diffusion flame, such as O radical (777nm band), OH radical (308nm band). Plasma induced consumption process of repetitive pulsed nanosecond discharges on O radical has been directly observed at 900Hz discharge repetition. Based on time resolved emission spectral, significant changes of OH radical distribution at early discharge stage can be observed, which can be due to air-discharge plasma, and rapidly recover in microsecond scale due to rapidly consumption of generated OH radical. Besides, great differences in reaction time scale of OH radical (half-value period of OH radical consumption ~81.8μs) and O atom (half-value period of O atom consumption ~3.6min) is observed, corresponding to different chemical reaction mechanism of O atom and OH radical. A model based on rate equation is built to describe generation and consumption process of O atom and OH radical, which can also well predict voltage behavior of 777nm band at steady state (6.0kV ~ 10.4kV).

A stable, single- and dual-wavelength, single-longitudinal-mode operation ring erbium-doped fiber laser with ultranarrow linewidth and high optical signal to noise ratio is proposed and demonstrated experimentally. Different from using traditional fiber Bragg gratings as narrow band filters, a guided-mode resonance reflector with high quality value, fabricated on a silicon-on-insulator wafer, acts as an external reflector to realize optical feedback and wavelength selectivity in the fiber laser. Using unpumped erbium-doped fiber as a saturable absorber, different areas of the guided-mode resonance reflector as mode restricting elements, we obtain a single-wavelength laser with optical signal to noise ratio over 67 dB and ultra-narrow linewidth of 525 Hz, and a dual-wavelength laser with optical signal to noise ratios higher than 61 dB and linewidths less than 800 Hz for both lasing wavelengths. Meanwhile, all the central wavelength variations and power fluctuations of the laser are less than 0.024 nm and 0.106 dB, respectively, showing favorable stability.

Confocal 3D Micro-XRF is a well established and none-destructive analytical method which has a wide range of fields for applications such as environmental science, archaeology, material science and so on. This kind of technique showed dramatic results in 3D image reconstruction, surface morphology and elemental depth sensitive profiles. Therefore, 3D Micro-XRF analysis method based on a confocal X-ray set-up is very suitable for evaluation and illustration with depth sensitive investigation of oil paintings. It is meaningful to characterize the surface elemental distribution in different layer depth by surface scanning. In this work, a 3D Micro-XRF experimental set-up is established based on a Mo target X-ray source. The operated voltage is 20kV and the currents is 0.5mA. The core optical components, two polycapillary X-ray lenses were designed and manufactured by the Key Laboratory of Beam Technology of the Ministry of Education, Beijing Normal University. The FWHMs of the confocal volume is 33.0 μm , 32.4 Μm and 35 μm in three dimensions, respectively. With a proposed progressive approximation method, a modern oil painting segament was anlysed using 3D Micro-XRF spectroscopy. The surface elemental distributions were mapped through surface scanning in different motor steps. This investigation can be referred for furture works that attempt to answer for questions on painting techniques, pigmant palette, production process, counterfeit identification and so on.

The X-ray diffraction analysis is a nondestructive phase analytical method has been widely used in archaeology, physical chemistry, geoscience and materialogy, etc.. In this study, we developed a type of X-ray diffractometer equipped with slightly-focusing ploycapillary optics and reported some new results of this instrument. By comparing the diffraction peaks of irregular surface of the RMB 5 Jiao coin in our instrument with that of X-Pert Pro MPD (PANalytical, Holland) diffractometer. The results show that our instrument can get the accurate phases but the peaks’ positions of the phases of X-Pert Pro MPD drift largely. Moreover, our instrument measured the color glaze of a piece of ancient porcelain fired in Jizhou kiln. It shows that the 3Al₂O₃·2SiO₂ (PDF 15-0776) and Fe₂O₃ (PDF 25-1402) are the main crystal structures in white glaze, the black glaze is mainly composed of the Fe₃O₄ (PDF 28-0491) and 3Al₂O₃·2SiO₂ and the main phase of body is 3Al₂O₃·2SiO₂ (PDF 15-0776) and quartz (PDF 46-1045). From those results, we can understand that the white glazes are fired in a high temperature about 1250°C while the black glaze is fired in low temperature. That is helpful to understand the firing and coloring process with color glaze of ancient porcelain fired Jizhou kiln. Therefore, it can be concluded that slightly-focusing ploycapillary optics diffractometer has broader application prospects in the analysis of samples with irregular or curving surface.

Hyperspectral imaging technique and artificial neural network were used to investigate the feasibility of the nondestructive prediction for firmness and soluble solids content (SSC) of “Red” and “Green” plums. And the standard normal variation (SNV) was adopted to preprocess original spectral reflectance of region of interests. Then 5 and 28 characteristic wavelengths were selected from 256 full wavelengths by the methods of successive projection algorithm (SPA) and competitive adaptive reweighted sampling (CARS), respectively. An error back propagation (BP) network model was proposed based on selected characteristic variables to predict firmness and SSC of plums. The SSC prediction accuracy of CARS-BP model in calibration set (r_c = 0.989, RMESC = 0.451 °Brix) was slightly higher than SPA-BP model (r_c = 0.978, RMESC = 0.589 °Brix), while the SSC prediction accuracy of SPA-BP model in prediction set (r_p = 0.964, RMESP = 0.778 °Brix) was slightly higher than CARS-BP model (rp = 0.955, RMESP = 0.851 °Brix).

A novel fundus imaging system is proposed. Gullstrand-Le Grand eye model is used to simulate normal human eye in imaging system, and parallel optical path is used to facilitate the combination of different functional components. The observation and aiming system of the traditional fundus camera is given away, and the automatic alignment system is added. The ring light source is used to eliminate corneal reflex. Through optimization design and simula- tion analysis of the imaging system,a fundus optcial system with great fabrication feasibility is designed. Results show that the modulation transfer function (MTF) values of all fields are higher than 0.3 at 130 lp/mm, the field curve is less than 0.2 mm and the distortion is less than 5%. The scheme can be applied to ophthalmic examination to promote the development of intelligent fundus examination and functional integration of fundus camera.

This paper studied semiconductor parameters for the thermal effect of laser to the others quadrants when the millisecond-pulsed laser interacted with one quadrant of the Si-based p-i-n QPD. The thermal model and intrinsic carrier model were built on the basis of the semiconductor physics and thermal conduction theory, and a 3-D simulation model was built by the method of finite element, using COMSOL Multi-physics simulation software. It was taken into consideration that when the carrier was mainly derived from impurity ionization, the intrinsic carrier concentration is lower than impurity concentration at least an order of magnitude, it means that the concentration of intrinsic carrier is no more than 5×10¹⁴cm^-3, and Si-Based semiconductor detector limit working temperature is 520K. The concentration distribution of intrinsic carrier and temperature distribution of all quadrants of QPD were simulated, and got rules which they changed over time. The conclusion was gotten, the thermal-induced failure time of the other quadrants of QPD decreased with the increase of laser energy density under the same laser spot. The thermal-induced failure time of the others quadrants of QPD extended with the increase of the lengths from every quadrant to the point of peak energy when the laser energy density was same. This paper provided important data basis for further research on the study of the interaction between laser and silicon-based semiconductor detectors.

A single-laser-shot N2 Q-branch Coherent Anti-Stokes Raman Scattering (CARS) is used to measure the instantaneous temperature of supersonic combustion in kerosene/air flame with Mach 2.6. The Unstable-resonator spatially enhanced detection (USED) phase matching is used to reduce turbulence effects and to improve the CARS signal intensity. An USED CARS measurement system, which has a high spatial solution of ~100μm in diameter, and a CARS spectrum calculating and fitting program CARSCF are developed. The CARS signal in supersonic combustion is measured and then used to calculate temperature, the results show that, during kerosene/Air ignited in Mach 2.6, the CARS signal first rise rapidly then fall sharply and finally rise slowly, while the temperature increase sharply and then decrease slowly and the average temperature is 1970 ± 144K with 6.5% of repeatability.

To detect dim small target in infrared images, considering the target velocity and intensity characteristics we proposed a new spatial and temporal method. The new spatial and temporal method consists of a 2D spatial model and a 3D spatial and temporal model. The 2D spatial model is utilized to pre-process of the original infrared images. The 3D spatial and temporal model is used to enhance the probable targets by estimating the direction of the target and accumulating the grayscale to the central pixel. Experiments show that our method gains better detection performance in infrared videos with the complex background.

The traditional fusion method for polarization image and color image is difficult to be satisfied in practice, so the method based on SCM in the fusion of polarization image and color image is designed and combined with HSV color field adaptive enhancement, so as to achieve the effect of distinguishing objects under shadow or reflection. Using the multi-scale decomposition of guided filter and Gaussian filter, different fusion schemes are proposed for different scale information: the average energy fusion method is used for the low-frequency coefficients, and the SCM with the edge energy (EOE) as the stimulation is used to replace the traditional high-frequency fusion rules, so as to enhance the spatial information expression. Finally, the parameters are corrected by the consistency test. Experiments show that this method not only has a good color expression ability, but also effectively adds the polarization information of the target object, and achieves good performance in objective and supervisor evaluation.

Germanium photodetectors have been considered to be mature components in the silicon photonics systems, especially for applications in the near infrared communication band. In order to avoid the restriction between quantum efficiency and carrier transit time, attentions should be payed to integrated waveguide photodetectors, which control the light transmission and the transmission of carriers in two perpendicular directions. Integrated waveguide coupling mainly include end-coupling and evanescent coupling. Compared with end-coupling, evanescent coupling is more easily realized though its coupling efficiency is lower than that of end-coupling. This paper reports an integrated waveguide photodetector exploiting evanescent coupling with some design that the center of silicon rib waveguide would be halfsurrounded by the germanium region. And light could be coupled from the top and both sides of the silicon rib waveguide into the germanium region. Simulations were carried out to compare our design with the conventional evanescent coupling configuration by finite difference time domain (FDTD) algorithm on the same condition such as the incident light power and the size of the light absorbing region. Compared with the conventional evanescent coupling configuration, the half-surrounded configuration could contribute a more substantial light absorption efficiency and responsivity.

This paper reports a compact yet highly sensitive all-optical acoustic pressure sensor which is designed to operate under a pre-designed resonant mode, targeting to achieve ultra-high sensitivity for underwater applications. It consists of a micro-opto-mechanical silicon cantilever beam which is fabricated by a CMOS-compatible process flow based on a silicon-on-insulator (SOI) substrate, and integrated with a rib waveguide located on the top of the cantilever beam. Two grooves are created on the same substrate and aligned in line with the rib waveguide. Two optical fibers are then fixed into the pre-aligned two grooves on both sides of the rib waveguide, separately, for optical signal coupling in and out. The deflection of the cantilever beam caused by the acoustic waves is transferred to a variation of the output optical intensity from the optical fiber due to the fiber-to-waveguide end coupling strategy. For proof of concept, a silicon cantilever beam with a length of 9.5 mm, a width of 2.5 mm and a thickness of 10 μm is fabricated to provide an ultra highly sensitive acoustic sensor operating at the frequency of 150 Hz. The results show that an acoustic pressure detection sensitivity of 8.34 V/Pa with the minimum detectable acoustic pressures of 35 nPa/Hz^1/2 at the designed frequency is successfully demonstrated. The proposed acoustic pressure sensor may be useful in particular applications such as defense and security equipment, as it is different from most existing acoustic pressure sensors which pursue a compromise between high sensitivity and wide working bandwidth.

Carbon fiber is an excellent functional and structural material with combining a variety of properties. In order to combat photoelectronic reconnaissance and guidance weapons, carbon fiber is widely used in the military field as interference millimeter wave smoke agent, and has become a hot issue in smoke screen passive interference technology. In order to explore the millimeter wave attenuation performance of carbon fiber and compare the interference effect of carbon fiber powder and short-cut carbon fiber on millimeter wave, experiments have measured the attenuation performance of carbon fiber powder with particle sizes of 25, 35, 70, 140, 200, 400, 800 and chopped carbon fiber to 3 millimeter waves and 8 millimeter waves. The research results show that chopped carbon fiber has a strong interference effect on millimeter waves. Short-cut carbon fibers with lengths of 1.5mm and 4mm are most effective at attenuation of 3mm waves and 8mm waves. In order to improve the millimeter wave attenuation performance of chopped carbon fiber, the carbon fiber is modified by electroless cobalt plating. It is found that the modified chopped carbon fiber has better millimeter wave attenuation performance than simple chopped carbon fiber, and it is closely related to the thickness of the coating. Compared with the attenuation ability of carbon fiber before modification, under the condition of optimal loading (optimum weight gain rate), after electroless cobalt plating, the attenuation rate of 3mm wave increased by 11.5%, and the attenuation rate of 8mm wave increased by 10.37%.

In this paper, the temperature and damage morphology of silicon induced by ms-ns combined-pulse laser with different pulse delay are investigated. The small holes and trapped bubbles were formed on the center of damage morphology when the pulse delay is 0.8ms -1ms. The temperature of target exceeds the melting point and the molten pool begins to be formed before the irradiation of ns laser. It was found that the process of droplet ejection and phase explosion might occurred after the irradiation of ns laser. The relationship between temperature and damage morphology induced by ms–ns combined-pulse laser with different pulse delays was discussed. The results in this paper can provide foundation for ms-ns combined-pulse laser processing of semiconductor materials in the future.

As a common alloy material, aluminum alloy has a good application prospect in the fields of construction, automobile, electric power and aerospace.There is a layer of high melting point oxide film on the surface of aluminum alloy, which will hinder the laser energy transfer, lead to poor welding stability, and easily lead to welding defects such as porosity and inclusion in the weld; the surface of aluminum alloy has high reflectivity of laser, which makes the utilization rate of laser energy low, which is easy to cause welding defects such as incomplete penetration and incomplete fusion. Therefore, the surface of aluminum alloy should be pretreated before laser welding. Laser cleaning is an advanced and environmentally friendly cleaning technology. A Nd: YAG laser with 1064 ns pulse width was used to study the morphology of aluminum alloy under the action of nanosecond laser pulse cleaning.The laser-treated surfaces were characterised using metallurgical microscope. Successful oxide removabove certain thresholds that defined the lower end of the process operating window for pulse operation . The ablationechanisms involved in the removaloxide firom 1064nm and found to combineboth thermal and mechanical effects , the surface melting first occurring at fluences lower than those at which cleaning is initialised.In the process of laser cleaning, new oxide layer is formed.

In the industrial field, in order to protect the metal, the metal surface is painted. However, when metals need to be welded, coating becomes a problem. Since the solid polymer coating sublimates during the high temperature welding process, pores are generated in the weld bead[1] .So removal coating is very importance in industry and there have numerous ways to removal coating. Paint removal by laser ablation is favoured among cleaning techniques due to its high efficiency. How to predict the optimal laser parameters without producing damage to substrate still remains challenging for accurate paint removal [2] .In this paper, based on the laser ablation morphology, combined with experiments and numerical simulations, the mechanism and optimal conditions of laser ablation for paint removal are deeply studied. Our studies suggest that laser removal have many physics and chemistry phenomenon including the redox reaction, carbonization, melting and gasification. The threshold value of laser paint removal is 30W obtained from the laser cleaning experiment. The model of laser temperature rise is established, and it is found by numerical simulation that the theory is in good agreement with the experiment

Graphene(GR) have developed rapidly since 2004, when the graphene monolayer was successfully stripped by British physicists Novoselor and Geim. Porous graphene and graphene oixde have attracted more and more attention and researches because of the porous graphene ,its special three-dimensional defect structure, high specific surface area, and high electronic conductivity. Compared with the inert graphene surface, the structure of porous graphene material can promote material transport efficiency, and hole structure can also open the energy band. These characteristics enable it to be applied to electronic devices such as super capacitor, chemical sensor, FET and other aspects. With the continuous discovery of preparation methods and characteristics of porous graphene and graphene oxide, the application of porous graphene in optical fiber sensor auniquerea has obtained great achievements. In this paper, the principle and device performance of the optical fiber sensor made by porous graphene and graphene oxide were comprehensively described and summarized.

Considering the demand of performance test of infrared spectral imaging equipment, as the key indicator, the 3-D noise model of noise equivalent temperature difference is analyzed. The seven components and their meanings are presented. A test algorithm based on standard deviation of NETD is put forward. The paper shows the composing and principle of the detection system, and introduces the computational procedure and detection process of NETD. The test algorithm is verified by experiments. According to the comparison with the imported equipment, the test results have good duplication and high precision. The test system has been applied to the performance test for several kinds of infrared spectral imaging equipment, which meets the demand of engineering support.

Based on the principle of infrared target system, the emissivity and reflectivity of the coating material of the target plate of the infrared target system are studied in depth. The relationship between the emissivity, reflectivity and light wavelength of the target is discussed in this paper. First, 50 target plates are selected and the diffuse reflectance of 1.06 μm laser is measured. The experimental results show that the minimum reflectivity is 0.202 and the maximum reflectivity is 0.217, which is in the range [0.2,0.3]. The average value of reflectivity is 0.20886, and the measurement error is in the range [-0.00686, 0.00814]. Then, the non-uniformity value of each measured value is calculated, the maximum value is 3.89%, less than 7.5%. Finally, the emissivity of the coating material is measured in the wavelength range of 2.5 μm ~ 13.5 μm, and the minimum value is 0.869, better than 0.7. At the same time, four kinds of coating materials are compared and the results show that the coating materials in this paper had higher emissivity. The infrared target system can model all kinds of infrared targets, which provides a method for target attack experiment.

In this paper, a method is proposed to increase the field uniformity of holographic near-eye display system based on liquid crystal spatial light modulator (LC-SLM). The holographic near-eye display system consists of a projector, a display component and a receiver. The projector is used as an image source that based on LCOS, LCD, Micro-LED, DLP or other projection technique. The display component transmits images from the projector to the receiver, which contains at least one layer optical waveguide, in-coupling holographic grating and holographic out-coupling grating. The grating is a periodic structure formed by interference exposure on a photopolymer material. The exposure dosage determines its diffraction efficiency controlling the energy ratio of 0th-order transmitted light and 1st-order diffracted light. The average refractive index of the holographic grating is determined by the photopolymer material, and the refractive index modulation is determined by the interference exposure dosage. The higher refractive index modulation contributes to higher diffraction efficiency. The projection light diffracts into the optical waveguide through in-coupling holographic grating, and propagates to out-coupling holographic grating by total internal reflection. The out-coupling grating diffracts the light out of optical waveguide to the receiver that can be an eye or a CCD detector. The display component plays a key role in holographic near-eye display system, which directly determines the display performance (FOV, field uniformity, brightness, etc.).

The thin film lithium niobate (LNOI) platform has attracted great interest towards integrated photonics devices, featuring high-speed electrooptical responsion and low-loss light propagation. To enhance the function of passive devices in LNOI, the fundamental mode hybridization (TE₀, TM₀) in an LNOI ridge waveguide is therotically analysed and experimentally demonstrated. A microring resonator with Q-factor of 1.78 million is fabricated, revealing the appearance of the mode hybridization by observing sudden jumps in the FSRs of both fundamentally resonating modes. The central wavelength of the fundamental mode hybridization is designed at 1562nm and observed at 1537nm. Potential applications include fundamental mode conversion, polarization rotation, polarization splitter, and polarization insensitive waveguides in optical receiver module.

In this paper, we proposed an infrared absorber based on multilayer film. Through the thickness resonance of ZnS dielectric layers and the loss properties of ultra-thin titanium film, a good absorption is achieved in the infrared band. The outermost ZnS is employed to reduce impedance mismatch and protects ultra-thin Ti film. This sample does not need inplane microstructure design, which reduces the processing difficulty and can be prepared on large scales.

Aiming at the problem that improper selection of detector spectrum has a serious impact on detection efficiency in point target detection. This paper analyzes the main factors affecting point target detection and proposes a point target detection spectrum selection method based on constant false alarms. This method takes detection probability as an evaluation index, comprehensively considers the target and background radiation characteristics, atmospheric radiation transmission, background clutter and sensor noise level. It can calculate the optimal detection spectrum for different target and background information. Taking the typical target detection as an example, the spectrum range where the detection probability meets the requirements under several conditions is calculated, and its feasibility is verified. Through the method in this paper, the point target detection spectrum that meets the requirements of false alarm rate and detection probability can be obtained

Glyoxal is one of the most important volatile organic compounds in the atmosphere and the tracer of the photochemical oxidation process of VOCs, which can effectively reflect the emission level and reactivity of atmospheric VOCs. Due to the very low concentration of glyoxal, general measurement technology is difficult to accurately and fast detect glyoxal. Here, we reported a self-designed broadband cavity-enhanced absorption spectrometer (BBCEAS) on mobile platforms for measurements of atmospheric glyoxal, and for 30 seconds averaged data the average detection limits (2σ) for glyoxal was about 0.024 ppb. To measure the spatial distribution of glyoxal, the BBCEAS instrument was deployed in a car and gas was draw into the BBCEAS instrument through an inlet fixed on the roof of the car. The spatial distribution of glyoxal in Hefei was measured on Sep 8th , 2020, the measured glyoxal concentrations ranged from 0.010 ppb to 0.258 ppb. The results demonstrated that the BBCEAS instrument has overcome the effect of vibrations for the measurements on mobile platforms and can get the spatial distribution of glyoxal.

In order to solve the problems of many defects in common digital PCR chips, an integrated droplet digital PCR chip was designed based on microfluidic, biology, optoelectronics, machinery and computer technology, which integrates droplet generation part, PCR amplification part and droplet fluorescence detection part. The droplet generation part used the flow focus micro structure to achieve droplet generation with two phase liquid, where the oil was used as continuous phase, the sample liquid as discrete phase. After the droplet generation process, the droplets were injected into collection chamber by the pressure of the pump. The amplification part uses the flat-plate PCR to achieve nucleic acid amplification in the integrated droplet digital PCR chip. After amplification, the integrated droplet digital PCR chip moves to detection location, under the irradiation of the excitation light the specificity target in the droplets will emit fluorescence, thus the fluorescence image is scanned by COMS camera and the result was analyzed by the software. The chips were made through injection molding process and the autofluorescence intensity of chip material was weak. Experimental results show that the coefficient of variation (CV) value of the droplet diameter was less than 2% and the temperature uniformity of the chip was less 0.5°C. That proves the chip designed has good droplet formation and thermal conductivity for nucleic acid amplification. The chip designed can reduce the manual operation error, operation difficulty and avoid the problems of droplet fusion, breakage and sample pollution in the process of pipetting.

According to the geometric relationship of the thermal stable cavity of the intracavity pumped dual wavelength narrow line-width laser structure and fundamental mode, the temperature distribution inside two gain mediums were analyzed, the temperature on the end surface of Nd:GdVO₄ laser gain medium is 295.51K, it means that the heat source temperature of the thermal temperature distribution of Nd:YVO₄ laser gain medium in the cavity. The thermal temperature distribution of Nd:YVO4 laser gain medium in the cavity is obtained, the result shows that exist a relatively serious thermal effect in the quasi-three-level laser gain medium Nd:GdVO₄, which restrict the improvement of intracavity pumped dual wavelength narrow line-width laser performance.

In a large-yield blast experiment, detonation velocity is an important index to estimate whether the large-scale explosives reach full detonation. An optical fiber test system for detonation velocity measurement is developed, which consists of optical fiber probes and a matched optical fiber detonation velocity meter. The system is used in a blast experiment of 81.5kg of TNT. All four fiber probes arranged achieve accurate signals. The experimental results indicate that the fiber system features anti-electromagnetic interference, high measuring precision, easy and safe operation, and low cost.

In this paper, a polarization filter based on photonic crystal fiber (PCF) with nanoscale gold film is proposed and analyzed theoretically. The cross-section of the structure is composed of four-layer air holes with a hexagonal lattice and two symmetrical air holes in the sub-internal layer are coated with gold film. We research that the PCF structure parameters affect the performances of the polarization filter through employing the finite element method. It is indicated by the numerical results that the resonance strength in y-polarization direction can reach a most value of 272.8 dB/cm at the communication wavelength of 1.55 μm. The extinction ratio can be better than 20 dB within a wavelength range from 1.45 μm to 1.75 μm when the length of the PCF is longer than 500μm. Therefore, such a length can make the communication filtering effect be realized using a shorter fiber. The calculated results can provide some references to the design of polarization micro-filter devices.

Plasma properties are diagnosed in parallel-plane electrodes under 1-15 kPa within input power of 0-25 W by coupling Optical Emission Spectroscopy (OES) and Planar Laser-induced fluorescence (PLIF). Electron excitation temperature (T_e), electron density (N_e) are obtained based on the intensities and broadenings of atomic and ionic spectral lines of argon. The spatial resolution of T_e and N_e are measured by a high-precision setup based on fiber. At the gas pressure of 1 kPa, T_e reaches maximum of 8.745×10³ K while the peak of N_e appears in 15 kPa, is 3.237×10¹⁶ cm^-3 . Besides, spatial distribution of 1s₅ metastable atoms (Ar^M) with transition scheme 4s( ²P⁰ _3/2)₂ -4p ( P (²P⁰ _1/2)₁-4s(²P⁰ _3/2)₁ are revealed by PLIF, as a complementary of plasma properties. The number density of Ar^M also shows a larger number density in 15 kPa. Combined with OES, T_e, N_e and number of Ar^M are higher around the surface of anode within discharge area. The current experimental results are demonstration of optimal plasma state under different external parameters and validation of relevant discharge models

We have demonstrated a silicon traveling wave Mach-Zehnder modulator adopting the single-drive push-pull scheme. The traveling wave electrode is made of coplanar stripline structure. Several key parameters have been optimized to get a high-speed modulator. It is shown that using the coplanar stripline electrode, group velocity matching and impedance matching are achieved by careful design. After optimization, the VπL of the modulator is calculated to be 2.23 V·cm with the phase shifter length of 4.2 mm. The insertion loss of the modulator excluding the grating couplers loss is 3.4 dB. The 3 dB electro-optic bandwidth of the modulator is simulated to be 32 GHz at 0 V reverse bias. A modulation speed of 70 Gbps under the driving voltage of 1 Vpp is realized with an extinction ratio of 4.9 dB. A higher data transmission capability can be get when high modulation formats such as PAM-4, together with digital signal processing is implemented. Such high-speed silicon modulator can be utilized for next generation communication networks.

Passive interference from smoke screen is an important part of optoelectronic countermeasure. With the rapid development of photoelectric weapons, the status of the smoke screen aerosol is increasing day by day, and multi- spectrum composite jammers have become the top priority of smokescreen passive interference technology. In order to promote the research and application transformation of smoke screen materials, understand the research status of composite interference materials and improve the jamming performance of smoke screens on infrared/millimeter wave band, this paper finishes the analysis of the system from the interference of material composition, extinction mechanism, problems and development trend under the condition of selecting composite interference of infrared/millimeter wave smoke materials as the main research object. The research results show that: the combined interference material and the integrated interference material have their own advantages and disadvantages. New types of composite interference materials with better composite interference effects and a complete range are constantly emerging. The status quo of the current research is mainly manifested in the different limitations of different smoke screen materials and the poor systemicity of the compound extinction mechanism. Smoke screen materials are generally developing in the direction of excellent dynamic characteristics, low cost, easy survival and environmental protection.

With the advantages of high resolution, high sensitivity, wide spectral coverage and rapid measurement, the dual-comb spectroscopy technology has developed rapidly in the field of molecular and atomic spectroscopy. This article firstly uses various methods such as balanced optical cross-correlation method and beat frequency with ultra-stable laser to measure the phase noise of the dual optical comb system for different optical comb locking schemes. Then the absorption spectra of C₂H₂ were measured for the dual comb system under different locking schemes. The phase noise obtained under different locking schemes is compared, and the C₂H₂ absorption spectrum under each scheme is calculated at the same time, so as to obtain the influence of phase noise on the spectral resolution in the dual-comb spectrum measurement.

Under the condition of information war, combat equipment is faced with the serious threat of "discovery is destruction". In the all-weather and all-day reconnaissance environment, the infrared spectrum characteristics of the target and its effective control become the key to change detectability and improve survivability.In view of the important value of infrared spectrum characteristics in battle, this paper carries out data collection and comprehensive processing of MWIR spectrum in equipment testing. Firstly, combining with typical task process, a data collection method is established, which forms a theoretical analysis, atmospheric transmission, data collection, radiometric calibration model. Then, the radiation data processing research is carried out. Taking the digital image as the original data, the radiation emittance is obtained by radiation calibration. Based on the transmittance and radiation model, the calculation method of apparent temperature is established. To verify the method proposed in this paper, combined with helicopter infrared image data, the distribution of MWIR radiation field and temperature field of the equipment during takeoff, landing and dynamic flight is obtained, reaching 5% calibration measurement accuracy.The feasibility and validity of the method are verified.In this paper, the collection and processing of infrared spectrum characteristics is a useful exploration to improve the quality and efficiency of equipment inspection capability. It has practical value for improving equipment data and fully characterizing equipment capability in the actual environment.

The Brillouin Optical Time Domain Analyzer (BOTDA) is based on the Brillouin scattering effect which is sensitive to the temperature and strain of the fiber at the same time. It is widely used in the field of large-scale structural monitoring. With the continuous development of market demand, the dynamics of the original BOTDA equipment The response speed, sensing distance, spatial resolution, and measurement error can no longer meet the application of various scenarios. This puts forward higher requirements for the signal-to-noise ratio of the BOTDA system. The image denoising algorithm based on non-local mean filtering can be Make full use of the similarity between two-dimensional image signals. In this article, we proposed an adaptive image denoising algorithm to be applied to the BOTDA system, and got good results.

Based on the Planck formula, this paper uses a color CMOS high-speed camera to image multiple β-SiC filaments which were placed in the laminar flame of a Bunsen burner fueled with premixed CH₄/Air. This paper calculated the filament temperature by establishing the relationship between the image pixel value and the integral intensity of filament radiation and then converted the filament temperature into the flame temperature. The wavelength-integrated filament pyrometer method was developed during this process, and the temperature profiles in the two-dimensional Bunsen burner methane flame were measured and reconstructed.

To ensure sufficient absorption of tandem-pumping energy, a large-scale aluminophosphosilicate fiber with 55 μm core and 400 μm inner-clad in diameter, i.e., a 55/400 Yb-APS fiber, was experimentally fabricated by using modified chemical vapor deposition system combining with chelate precursor doping technique. Based on an all-fiberized master oscillator power-amplifier laser setup tandem-pumped by 1018 nm fibber laser, a 150 W 1080 nm seed was amplified to 11.18 kW successfully, along with an optical-to-optical efficiency of 79.7%.

The single-mode fiber coupling efficiency with graded-index rod lenses can achieve higher coupling efficiency, compared with the direct alignment coupling of the single-mode fiber. The assembly error of direct alignment has a far greater impact on the coupling efficiency of the fiber than the GRIN lenses coupling to fiber. The analysis of the influence of the coupling error on the optical fiber coupling efficiency provides important theoretical support and guidance for processing and assembly. Axial error, radial error and angular tilt will all have different effects on fiber coupling efficiency. However, the fiber coupling system is not only limited to the coupling of the fiber and GRIN lenses, but also can be coupled with one or more lenses to analyze the advantages and disadvantages of multiple coupling methods.

Fiber optic shape sensing has a great potential for diverse medical and industrial applications to measure curvatures and even shapes. Featuring small footprint, strong immunity to radiation and high flexibility integration, fiber optic shape sensing opens up a new era in the fields of position tracking, human wearable devices, catheter navigation, bending detection and deformation monitoring. This paper focuses on a branch of fiber optic shape sensing techniques, with an emphasis on shape sensing based on fiber Bragg gratings (FBGs). Key technologies of shape sensing based on FBG are introduced in detail together with a critical view of its evolutionary trend. In addition, the major problems that exist in FBG shape sensing have been discussed in the end.

After Kelvin unit implementation on May 2019, doppler broadening thermometry (DBT) method as a primary thermometry has become based on a fixed value of the Boltzmann constant rather than by measuring temperature with respect to reference points. This paper is focused on the measurement of the Doppler broadening of the vibration-rotation line of the acetylene v₁+v₃ band near 1.54 μm. The preliminary result showed that the relative error of thermodynamic temperature measurement could achieved 0.37% at room temperature. Our analysis indicates that it has the potential to realize miniaturization and calibration free thermodynamic temperature measurement by further studying on DBT.

In this paper, fiber Bragg grating (FBG) sensors for strain monitoring at cryogenic temperatures were proposed and demonstrated. The strain sensitivity, strain repeatability and temperature compensation effect of FBG sensors were studied, within the temperature range of -196°C to 20°C. The strain sensitivity of FBG sensors at cryogenic temperatures was tested by quartz specimens with low thermal expansion coefficient. Experimental results show that the strain sensitivity of the relative change of the central wavelength for the FBG is 0.784, which almost does not change with the temperature. The repeatability of the adhesive used for FBG strain sensors at cryogenic temperatures was tested. Experimental results show that FBG sensors have good adaptability to cryogenic temperatures, and the strain repeatability is within 1.0% FS. The zero drift of the FBG strain sensor was compensated by using the FBG temperature sensor, and the strain error is less than 5% of the measured values with the compensation at cryogenic temperatures. Compared with the traditional electrical strain gauge used at cryogenic temperatures, FBG strain sensors have advantages in non-sensitivity drift and good zero drift compensation effect, and they can play an important role in the structural health monitoring at cryogenic temperatures such as spacecraft tanks, fuel pipelines, and so on.

This paper presents an silicon-based integrated hybrid detector that can perform the tasks of ultraviolet (UV) light detecting, visible (VIS) light detecting and near-infrared (NIR) light detecting. The detector is based on hybrid photodiodes that uses a vertical p+/N-well/Deep p-well/n-sub junction photodiodes which are available in CMOS processes, and can be configured to work as UV light detector, VIS light detector or NIR light detector in variable light environment by the using of transimpedance amplifier(TIA), subtractor(SUB), comparator and some simple switch logic gates. Device theory, structures, doping profiles and simulations are presented to verify the concept and feasibility. The simulation results show that the three photodiodes present different spectral responses, and dark current is as low as 10^-14A, and the optical signal of different wavelength can be effective detected with a high sensitivity and selectivity.

A multiline-multiband absorption spectroscopy strategy is proposed and numerically studied in the present work to address the limited detection range of the conventional two-line thermometry. The new method utilizes the information and spectral characteristics of multiple transitions at multiple bands to derive temperature and species concentration. Various combinations of absorption lines are evaluated when measuring the combustion fields of a standard McKenna flame and a jet-in-hot-coflow flame. Results show that the proposed multiline-multiband absorption spectroscopy with the tomographic algorithm is effective in resolving the high-gradient region of the flames. Wide detection range and high accuracy are achieved simultaneously in the tomographic reconstructions of the thermochemical profiles. Using a 3-line scheme, the temperature and species profiles at the temperature range from 300 K to 2000 K are successfully reconstructed. The present study demonstrates the great potential of multiline-multiband absorption spectroscopy for flames with a high gradient region or a steep boundary layer.

High-sensitivity sensing of force is realized through an all-fiber cavity ring-down structure. Based on a fiber coupler with a coupling ratio of 99:1, instead of a traditional ring-down cavity mirror, an all-fiber ring-shaped decay cavity was designed and manufactured. This experiment uses a continuously tunable narrow linewidth laser for wavelength scanning, and uses an FBG with a center wavelength of 1550 nm for wavelength filtering in the scanning process. A zigzag micro-bend modulation module with a period of 2mm is designed, the fiber in the cavity passes through the module twice, and the length of the sensing area is 8 cm. The detection sensitivity corresponding to the pressure of 8~16N measured at room temperature is 0.07722μs ^-1·N^-1 . The results show that the fiber cavity ring-down structure based on the whole fiber has high sensitivity and a good application prospect in the field of real-time pressure monitoring.

Aiming at the key parameter measurement bottlenecks and urgent needs of high-resolution optical loads such as satellite panchromatic multi-spectral cameras, full-spectrum multi-modal imaging spectrometers, and high-resolution imaging spectrometers, a set of wide-spectrum super-large area array optical loads is designed The device was calibrated for key parameters of absolute spectral responsivity, and the measurement uncertainty of the device was evaluated. This device is mainly composed of a broad spectrum light source, monochromator, optical system, standard radiometer, two-dimensional control translation stage, scanning control system, data acquisition and integrated control system. The measurement range is a wide spectral band, 0.4μm～1.6μm, the measurement resolution can reach 10k×10k, and the measurement uncertainty of absolute spectral radiance responsivity is 3% (k=2) [radiance range: 0.1W/(sr∙m²)～10W/(sr∙ m²)]. Establish a set of absolute spectral responsivity calibration device for wide-spectrum super-large area array optical load to solve the technical problem that the key parameters of wide-spectrum high-resolution optical cameras cannot be calibrated in the process of development, debugging, scientific research and production, and provide high-resolution earth observation for my country Provide services for quantitative needs in engineering, military reconnaissance, marine monitoring, and meteorological monitoring.

Most industrial gases such as methane(CH₄), ethylene (C₂H₄) and sulfur hexafluoride (SF6) have obvious absorption characteristics in the infrared band. The infrared absorption spectrum of leaking gas can be obtained through multispectral or hyper-spectral detection technologies to realize gas identification. However, these methods need a lot of work calibrating the detector response curve to target gas. In this work, a sparse infrared absorption spectrum based support vector machine (SVM) recognition method is proposed to obtain the gas absorption peak information without response curve calibration. An uncooled infrared imaging component is utilized to compose a multi-broadband long-pass differential filter infrared imaging setup that filters in the range of 7.5μm ~13.5 μm. Data extracted from multi-band infrared images of C2H4 and SF6 collected by the setup, combined with the simulated data generated by the simulated sparse spectrum algorithm, constitute training set to SVM. C₂H₄ and SF₆ can be accurately identified under laboratory conditions with the path-concentration of 500 ppm·m ~1000 ppm·m. The easy to implement and cost-effective method is expected to realize real-time identification of leaking gas.

Taper is a basic device widely used in photonics technology which transmits light between the waveguides with different widths. Tapers are usually designed to be trapezoidal in shape, which is simple but has many limits. If the taper is designed to be too short, the broken lines at the junction positions between the strip waveguides (SWGs) and the taper will excite high-order modes and cause high fundamental mode loss. As a result, the traditional tapers are always with a long length which limits the miniaturization of photonic systems. To solve this problem, we proposed a method based on forth-order Bezier curve that made the taper has both small size and good performances on the transmission loss of fundamental mode and the mode excitation ratios (MERs) of high-order modes. According to the obtained results, the proposed Bezier curve method decreased the length of a taper from 100μm to 30μm on the premise of maintaining the performances.

Grating interferometers are widely used in many miniaturized sensors requiring displacement measurement, such as microphone and accelerometers, because of its small volume and high measurement accuracy. However, the traditional grating can generate a zeroth-order reflected beam, which results in reduced sensor performance, packaging limitations, and laser instability. In this paper, design and manufacture method of a multi-step phase modulation grating is demonstrated. The application of this multi - step grating interferometer is to modulate the intensity of light of level 0 to level ±1 so as to avoid the return to the laser light so as to improve the system stability. On the other hand, due to the increased testing classes of diffraction efficiency, the SNR of the system is improved.

CO is an important process product of hydrocarbon fuel combustion, and its concentration can represent the combustion reaction process of hydrocarbon fuel in scramjet combustion chamber, which always generate the flow field with high pressure and temperature. In this paper, CO concentration measurement under high pressure was studied. The absorption line near 2.3um was selected and the detection limit of CO concentration was improved by cavity enhanced absorption spectroscopy. A resonator for high pressure measurement was designed and developed, based on which, the CO concentration measurement experiments under different pressures were carried out, and the linear relationship between the absorption line width and the pressure was verified. The lower detection limit of CO concentration of the measurement system was 34ppm at 100kPa, and 225ppm at 500kPa.

A method used for precision displacement measurement of plane based on fiber sensor array spatial light intensity modulation is proposed. The effect of fiber radius, numerical aperture (NA) of fiber, space of fiber array, the linear displacement and angle displacement of the plane on the received spatial light intensity of fiber array was analysis. The simulation results shown that the spatial light intensity distribution of fiber array have very good sensitivity with the linear or angle displacement changes.

Sites prone to vibration waves such as mining, earthquake-prone areas or also border regions under vibration monitoring increasingly require vibration sensors with a wide frequency range and good sensitivity. In this article, we propose a fiber Bragg grating (FBG) vibration sensor based on a boundary (BM) or warning marker. By dimensioning the warning marker by adding a low reflectivity FBG vibration detector with a sensitive mass attached to the central part of the fiber, a vibration detection zone is thus set up. By producing several vibratory excitations of different frequencies in the main-axis of measurement of the sensor and in the cross-axis, the results show that the sensor resonance frequency is about 10 Hz, it has a good sensitivity, a wide working frequency range of 40-500 Hz in the main-axis of measurement and a good crossinterference test result of 2.4%. The sensor dynamic range is at least 39 dB and can achieve up to 67 dB for the precision of 0.4 pm, when the interrogator has readings taken at this wavelength precision.

Tunable diode laser absorption spectroscopy can achieve simultaneous measurements of gas temperature, concentrations, and pressure of the combustion field. The wavelength modulated spectroscopy method can improve the signal-to-noise ratio of measurements in the harsh engine flow environment, but the signal demodulation time is long. After the experiment, a database of the integrated absorption area and 2f/1f maximum of the two spectral lines per unit length is established via the same absorption spectral, scan frequency and modulation frequency are used to traverse the temperature T, concentration χ and pressure P. For the subsequent the fast measurement of the combustion field parameters is achieved by comparing the experimental measurements with the database values at the same experiment. The results show that the database method requires 2.2h to process 1.5GB of experimental data with three channels and 4.6s measurement time, which is up to 7 times shorter than the traditional demodulation method.

A broadband photonic microwave signal processor based on integrated dual-polarization dual-parallel Mach-Zehnder modulator (DP-DPMZM) is proposed. The processor has a tunable local oscillator (LO) signal, which is generated by the optoelectronic oscillator (OEO) loop in one of the sub-DPMZM with high spectral purity and low phase noise, and its center frequency can be tuned by electronic band-pass filter (EBPF). Using the bias voltage of DP-DPMZM and fiber Bragg grating, the carrier-suppressed single-sideband (CS-SSB) modulation of LO and RF signals can be realized, and the up or down conversion of frequency converter can be realized by adjusting the single bias voltage of DP-DPMZM. Moreover, the power fading caused by dispersion is well compensated with the SSB modulation. The experimental results show that the tunable LO signal of 6-20 GHz is successfully generated, the side mode rejection ratio is as high as 48.4 dB, and the 10 kHz phase noise is 107.6 dBc/Hz at 8 GHz. The spurious rejection ratio of up-down conversion signal is 31.4 dB and 33.6 dB, respectively.

A minitype optical fiber acceleration sensor based on the cantilever is investigated. The sensor mainly makes up of the cantilever and the distributed feedback (DFB) fiber laser. The beam is deformed when the vibration due to the acoustic field applied on the beam. The DFB fiber laser is stuck on the surface of the cantilever beam. It leads to the frequency shift of the output of the fiber laser. By measuring the frequency shift, the acceleration of the vibration can be realized. The center element of the sensor is the cantilever beam and fiber laser, so the mass and volume of the sensor are greatly reduced. The largest dimension of the cantilever beam in this work is just 30mm. And then the cantilevers are taken into simulations and experiments. The experimental results are coincident with the simulations. The experiments of the sensors shows that the acceleration sensitivity is flat and can reach 10⁸Hz/g below 80Hz. And the highest sensitivity is 2.02×10⁹Hz/g. Compared with existing acceleration sensors, this cantilever acceleration sensor can obtain high sensitivity in small scale and light weight.

Greenhouse gases (GHG) have negative impacts on the climate changes. Carbon dioxide (CO₂), one of the dominant GHG, comes mainly from the anthropogenic emissions in urban areas. In this work, we develop a CO₂ sensor based on TDLAS-WMS (tunable diode laser absorption spectroscopy – wavelength modulation spectroscopy) to detect the daily CO₂ concentration in the atmosphere. Firstly, the residual amplitude modulation (RAM) in the first harmonic is eliminated using the phasor decomposition method. Then, the multi-harmonic detection is employed to improve the precision of the sensor. It reveals that the precision can reach 0.02 ppm for CO₂ measurement. The atmospheric CO₂ measurement is conducted in urban area for a whole year. The results indicate that the anthropogenic activities can be observed in the diurnal CO₂ cycles, especially in the wintertime. The developed sensor has a great potential for the air quality monitoring in urban areas.

A long period fiber grating (LPG) based sensor coated with Chitosan/polyacrylic acid polymer film for heavy metal ion Ni⁺ detecting was proposed in this study. Multiple Chitosan/polyacrylic acid (PAA) layers which could chelate with Ni⁺ were coated on the LPG sensor via Layer by layer (LbL) self-assembly technique to achieve Ni⁺ concentration sensing in liquids. Results showed that when the concentration of Ni+ in the range of 0.02mMol/L to 0.08mMol/L, there is a sensitivity of 5.564nm/mMol, when the concentration between 0.3mMol/L to 0.7mMol/L, the sensitivity reduced to 1.345nm/mMol, and in high concentration of 1mMol/L to 10mMol/L, the degree of linear correlation is extremely low.

A kind of fiber PH sensor coated with PANI (polyaniline) on the surface of LPFG (long-period fiber grating) has been developed in the work. PANI film was nurtured in the solution by in-situ chemical oxidative polymerization and the growth process of the PH sensitive film was traced by an optical spectrum analyzer to optimize the response of the sensor. The RI and optical properties of PANI change regularly in the PH range of 2-12, which is the basic principle of LPFG coated with PANI sensing material for PH measurement. Though the experiment, the sensor can achieve a high sensitivity of 152pm/ph. Besides, other performances of the sensor, such as response time, temperature stability, reversibility and long-term stability were studied in the experiment. As a result, The PANI-LPFG sensor has such advantages as fast response speed, excellent temperature stability, low cost, easy to be used, and continuous measurement of the environment.

A weak fiber grating demodulator based on the distributed feedback laser array (DFB-LA) was proposed used for the large-capacity ultra-weak fiber grating sensor network. This article describes the overall design, DFB-LA-based tunable narrow linewidth pulse light source module, and control demodulation process in detail. After design, the narrow linewidth tunable light source module composed of DFB-LA can realize nanosecond laser pulse output with a wide tuning range of 30nm. A prototype of a weak fiber grating（W-FBG） demodulator was developed, and a sensor demodulation test was carried out with an ultra-weak fiber grating with a reflectivity of -30dBm. The test results show that the system is stable. The prototype achieves a wavelength measurement range of 27nm and a resolution of 1.4pm. The measured W-FBG wavelength-temperature coefficient is 11.88pm/℃ and the temperature resolution is 0.1°C.

We propose and experimentally demonstrate an in-line interferometer, which is based on a capillary spliced between two single mode fibers (SMFs) with a certain of transverse offset. As two main modes, LP01 and LP11, are excited and propagate in the capillary wall, they will interfere with each other when they meet again in the output-SMF. Due to the characteristic of polarization dependent in the LP11 mode, the proposed capillary-based interferometer can be designed for twist sensing. Experimental results show that our proposed capillary-based interferometer can provide sensitivities higher than 90 pm/° in both anticlockwise and clockwise twist in the range of 10° – 90°.

The application of distributed optical fiber sensing technology in nuclear island safety monitoring is mainly studied in this paper. The anti-radiation ability of the system is an important index. The distributed optical fiber system in this paper is designed with a special anti-radiation optical fiber. The temperature of power supply cables and other facilities in the nuclear island containment can be distributed monitored in full period in real time. Radiation tests are carried out to validate the anti-radiation performance of the system. 60Co is used as a gamma ray radiation source to generate continuous pulses with an average energy of 1.25 MeV. The rate of radiation dose is 1800 Gy/h and the total radiation dose is 1950 Gy. The anti-radiation ability of anti-radiation optical fiber and common optical fiber is compared. It is proved by tests that common optical fiber sensor has great fiber loss in radiation environment, about 0.5dBm, and the loss is decreasing continuously. Anti-radiation optical fiber has little fiber loss in radiation environment, about 0.12 dBm, and the loss tends to be saturated. During the radiation test, the temperature measurement performance of the distributed optical fiber sensing system using anti-radiation optical fiber and the one using common optical fiber is tested in real time. The results show that the anti-radiation distributed optical fiber sensing system performs well in the whole process, which meets the requirements of temperature monitoring for 1339.2 Gy total radiation dose in the refueling cycle of nuclear island.

CO₂ and H₂O are important combustion products of hydrocarbon fuels. This paper uses wavelength modulation spectroscopy (WMS) to simultaneously measure the pressure, temperature and CO₂ component concentration information. Two absorption lines near 2.7um were selected, and the measurement experiment was carried out on the high-temperature furnace. The results showed that the measurement error of the three parameters was within 6% under the conditions of less than 1atm, 300-1200K temperature range and 10% concentration range, which verified the feasibility and accuracy of the method.

A novel ultralow loss bent waveguide for single-mode operation was designed based on the Euler spiral. The proposed 180° bend (U-bend) was composed of two identical 90° Euler bends with gradient width from 1.6μm to 0.45μm and a 0.45μm wide, 2μm long strip waveguide. The proposed U-bend had ultralow losses (<−0.0005dB) and very low mode excitation ratios (MERs) of high-order modes (<−35dB) over a broad wavelength-band by lumerical simulation software. The effective radius R_eff of the designed U-bend was as small as 42.547μm and the transmission ratio of fundamental-mode was 0.99988 that almost equal to 1. After simulation and computation, only the fundamental-mode could be retained and propagated in the designed U-bend waveguide with ultralow loss.

Guangxi is located in the subtropical monsoon climate zone, which is suitable for the growth of various subtropical fruits. There are many subtropical fruits. The nondestructive detection method is helpful to the development of fruit industrialization. In this paper, the methods of non-destructive inspection of fruits by spectral technology are summarized, which will contribute to the development of fruit industry in China.

We propose a new non-intrusive flowmeter using the distributed feedback (DFB) fiber laser as a flowmeter to monitor the flow rate in the pipe. The DFB flowmeter is set on the outer wall of the pipe. And the relationship between the wavelength and the phase changes of the DFB flowmeter and the liquid flow rate in the pipeline is derived via turbulent vibration. Under the guidance of this theory, the design and test of the DFB flowmeter is completed. The result shows that this DFB flowmeter can measure the pipe flow from 0.71 m³/h to 2.35 m³/h accurately via frequency analysis in different frequency regions, which demonstrates the feasibility of the new non-intrusive flow measurement method based on DFB-FL and has achieved accurate measurement of small flow rates.

In digital circuit design, the design defect of signal integrity is also the root of EMC problem. This paper introduces the mechanism of electromagnetic compatibility problem due to circuit signal integrity problem, based on the case analysis of a project circuit jamming satellite receiver frequency band, we used the method of combining actual measurement with signal integrity and electromagnetic compatibility simulation based on Hyperlynx software, to find the causes of the problem, and the solution and design improvement suggestions are given. The experimental results show that the problem of electromagnetic radiation interference has been effectively solved.

To deal with the problems of electromagnetic informat ion leakage, electromagnetic environment pollution and electromagnetic interference, carbon fiber reinforced cement-based composite materials are adopted as new electromagnetic protection materials. In the experiment, graphite was used as a shielding medium, and ultrafine Fe powder was used as a wave absorbent, and the carbon fiber cement-based composite materials were respectively mixed to prepare new electromagnetic shielding materials. Using the coaxial method and the shielded chamber method to study the shielding effectiveness of the cement-based material compounded with graphite and carbon fiber; using the bow-shaped method to study the absorbing performance of the cement -based material compounded with ultrafine iron powder and carbon fiber; Energy spectroscopy and X-ray diffraction were used to study the surface morphology and microstructure of the carbon fiber cement-based composites. The results showed that the shielding effectiveness of the samples compounded with graphite and carbon fiber reached a maximum of 38.4dB, and the average shielding effectiveness of the sample reached 25.6dB; the reflectivity of the samples compounded with ultrafine Fe powder and carbon fiber reached -17.1dB, the average reflectivity reaches -9.85dB at 0.95GHz-10GHz.