This PDF file contains the front matter associated with SPIE Proceedings Volume 11123, including the title page, copyright information, table of contents, and author and conference committee lists.

We report on the polymer nanocomposite coatings doped with the nanoparticles of rare-earth (RE)-doped fluoride phosphor NaYF4:Yb³⁺, Er³⁺ for luminescent solar concentrators (LSCs). Concurrent multi-beam multi-target pulsed laser deposition (CMBMT-PLD) of the phosphor and a polymer conducted in open air was investigated as a candidate process for such coatings. Polymer poly(methyl methacrylate) known as PMMA was considered to be deposited on a glass substrate from a solid target using fundamental harmonic (1064 nm) of a Q-switched Nd:YAG laser concurrently with the phosphor. The sun light was absorbed by the phosphor nanoparticles embedded in polymer film and converted into near-infrared (NIR) radiation via the mechanism of downconversion (quantum cutting). The NIR radiation propagated via the glass substrate as a light guide and was converted into electric power with photovoltaic cells attached to the edges of the glass plate. The polymer did not exhibit degradation during the open-air deposition process. The proposed method is capable to coat economically commercial window-size substrates. The polymer nanocomposite LSCs have broad absorption band covering a significant portion of the solar radiation spectrum, high spectral conversion efficiency, and low reabsorption due to minimal overlap between the absorption and emission spectra (large Stokes shift).

In this work, we demonstrate a refractive index (RI) sensor employing an annular-core photonic crystal fiber (AC-PCF), which exhibits a large dynamic range and high sensitivity. The AC-PCF represents a very recent type of fiber tailored for the transmission of vector/vortex beams. The mode of operation of the proposed sensor is based on the simple and convenient intensity modulation scheme. A numerical study of the effect of varying the refractive index of the air holes (composing the photonic crystal cladding) on the propagation loss of the fundamental guided mode at 488, 980 and 1550 nm wavelength was performed via a full-vector finite-element method simulation with PML boundary conditions. Our results indicate that the fiber loss increases exponentially as the RI of the holey cladding approaches the value of that of the fiber material (i.e. fused silica in this case) due to outer radiation and scattering. Our simulation assumes that the holey cladding can be filled with analytes of RI varying between 1 to 1.4; thus, showing a large dynamic sensing range. In particular, we observed a strong propagation loss (spanning 2 orders of magnitude in dB/m scale) for analytes with RI values ranging from 1.31 to 1.39 that cover many biochemical solutions of interest. The theoretical results show that the sensitivity is as high as 2.65 × 10⁴ (dB/m)/RIU at 1550 nm and 7.83 × 10³ (dB/m/)RIU at 980 nm experimentally. The numerical results were validated with experimental demonstrations using a custom-fabricated AC-PCF.

A titanium-diffused periodically poled lithium niobite (Ti:PPLN) waveguide device with ultra-short poling periods is developed for strongly nondegenerate quantum frequency conversion (QFC) from 369.5nm to 1550nm with a 485nm pump. A practical quantum information network requires a quantum state transfer link between disparate frequencies corresponding to atomic quantum memories and the telecommunication fiber network spectral window. QFC occurs in a nonlinear parametric amplifier. A Ti:PPLN diffused waveguide implementation allows for concentration of mode fields along the full interaction length of the nonlinear crystal. It also allows for engineering of an arbitrary desired nonlinear interaction based on poling parameters through quasi phase matching (QPM). Despite the relative maturity of PPLN technology, the target interaction is quasi phase matched at a period of 2.053μm which represents a significant technical challenge. The periodic poling process requires localization of strong electric fields on the order of 20kV/mm onto stripes which are on the order of 1μm. Thus, nickel- chromium (NiCr) electrodes are used to localize domain nucleation and enhance domain inversion quality by a factor of 200 compared to traditional periodic poling techniques. Devices are fabricated by diffusing Ti stripes into the crystal substrate, then sputtering and wet etching a NiCr layer to form the electrodes. High voltage is applied in an electrolyte bath using a Trek 20/20C high voltage amplifier with a custom high-speed controller utilizing an ARM processor core, FPGA, and A/D converter. Poled devices are then stripped of electrodes and their end faces are polished for optical measurement.

Metallo-dielectric structures are used as optical filters whose transmission and reflection characteristics can be changed by varying the thicknesses of the metal and dielectric, and the number of layers. A first estimate of their performance can be found by using effective medium theory and Berreman analysis. Incorporation of an electro-optic material within a metallo-dielectric sandwich can enable electronic tuning of the structure through application of an external voltage. We analyze the performance of metallo-dielectric electro-optic sandwiches using effective medium theory for the metallo-dielectric multilayers and the transfer matrix method for the three-layered sandwich.

This paper investigates the feasibility of using micro-optical resonators to develop a force sensor which can be embedded within a material to create members with inherent damage sensing capabilities. The optical resonator is comprised of a polymeric material and has a circular cross section with a diameter ranging from tens to hundreds of micrometers. When light is brought inside the resonator, it starts to travel along the internal surface through total internal reflection, exciting optical resonances, also known as Whispering Gallery Modes (WGMs). Any change in the morphology of the resonator determines a shift of the WGMs in the transmission spectrum. Being the optical resonances extremely narrow, a high optical quality factor is obtained, which in turn, produces a resonator that is very sensitive to external effects that determine small changes in the morphology of the resonator. By embedding the resonator in a polymeric slab, and applying external loading, the encased nature of the sensor results in the resonator deforming along with the slab. The resulting shifts can then be measured and used to calibrate instruments to determine various forces that act on a given structure. Finite element analysis simulations were conducted using a cantilever polymeric beam with Young's modulus of 1.06 MPa with a concentrated tip load varying from 0.001 N to 0.1 N. Results of these simulations showed a linear relationship between the applied load and the WGM shift resulting in a sensitivity ranging from 0.2044 N^-1 to 2.016 N^-1.

Single crystal fibers doped with Er or Tm and clad with a sapphire sol-gel were tested for both laser performance and super-continuum generation. Laser performance was explored for multiple sol-gel cladding deposition cycles (0 to 5) in addition to variable concentration (0.25% to 3%). A single sample showed exemplary performance (2% Tm with 3 deposition cycles) achieving 44.5% slope-efficiency. Super-continuum generation was compared in pure and doped fibers of both 150μm and 50μm diameters at five different pump wavelengths with an 80 fs source. Super-continuum was generated covering 1.5 octaves (790 nm pump) and <2.5 octaves (1645 nm pump) with a threshold pulse energy of 0.4 μJ (5 MW peak power).

Phase-only holograms could be displayed with a single phase-only SLM free from the zero-order diffraction and the twin image. Addition of random phase to the object light in computer-generated holograms (CGHs) can widely diffuse the object light and to avoid its concentration on the CGH. But it causes speckle noise in the reconstructed image. Speckle reducing methods could be classified as iterative and non-iterative methods. Non-iterative methods are fast and effective, such as random displaced phase distribution (RDPD) and error diffusion (ED). The drawbacks are degradation of the reconstruction at different spatial frequencies. Point spread function (PSF) works as the impulse response of optical reconstruction system. Its Fourier transform, optical transfer function (OTF), gives a set of coefficients for plane waves of various spatial frequencies and orientations. The evaluation of OTF could quickly determine which spatial frequency components are passed or attenuated for the CGH display. The non-iterative methods for speckle noise reduction on reconstructed images in spatial frequency domain is analyzed.

Phase-only liquid crystal spatial light modulator (SLM) has been widely used for accurate phase-manipulation in holographic display, optical tweezers, lithography, etc. Due to the nonlinear optical response of liquid crystal and manufacturing defects, the grayscale-phase response could be different for every single SLM device. The calibration for phase modulation is needed for improving the performance of the SLM involved system. The principles of phase-only SLM are reviewed. The main phase calibration methods for SLM are discussed and compared.

Energetic nitrogen-based compounds utilized in solid rocket propellants break down under typical environmental conditions. The breakdown of these energetic propellant compounds requires stabilizing additives to absorb excess acids that form. These chemical changes result in a reduction of stabilizers and an increase of inert compounds over time which decrease propellant performance. Vibrational spectroscopic techniques such as Raman can detect changes in chemical concentrations due to the strong spectrum that these compounds demonstrate. In this study two wavelengths, 532 nm and 783 nm, are used to analyze the Raman spectra of propellant samples to characterize the changes to compounds over time. Computational techniques are demonstrated to mitigate fluorescence and single out the ratio of chemical peaks specific to stabilizer compounds. In addition, fluorescence in the 532 nm spectrum is examined as a method for characterizing propellant compounds, as 2NDPA traditionally has more fluorescence than MNA, and the 532 nm Raman system traditionally detects more fluorescence than the 785 nm Raman system. Detection of the stabilizer MNA in concentrations of greater than .70% and lower than .40% are demonstrated. Raman spectroscopy is shown to provide a rapid method for analyzing high and low concentrations of stabilizer compounds to determine the remaining viability of propellant.

A flexible optical measuring device is laser rangefinder with flexible ranging direction which includes a TOF (time of flight) laser rangefinder, an optical fiber adapter and a dual branch flexible light guide. The TOF laser rangefinder includes a laser diode source, an optical receiver and a computing unit. The dual branch flexible light guide is disposed and connected the TOF laser rangefinder. Due to the flexibility of dual branch flexible light guide, the laser ranging direction can also achieve ranging in any direction. Its ranging curve line equation is highly linearity. The cofficient of determination (R²) is moer than 0.9. Therefore, this design has been presented to meet with requirement for measuring distance indeeds for many applications.

The development of precision farming technology (e.g., precise weeding, fertilization and pesticide) requires a higher level of technical support. The use of unmanned aerial vehicle (UAV) in agriculture is an innovation and has great potential for precision farming. It is shown that for the differentiated applications in agriculture, it is most expedient to use UAV. The directions of using UAV in agriculture are considered, as they most fully meet ecological and environmental requirements and ensure the safety of modern human-machine systems. This research aims at the development of a programmable, fully autonomous or remotely controlled unmanned aerial system (UAS) that contain complexes of automatic or remotely controlled UAV for precision farming technology. The basic requirements to the quality of the technological operation for the variable rate applications with the help of unmanned aerial vehicles will be developed. We will conduct selection and justification of the main parameters of the UAV for agricultural purposes. In addition to the flight-technical characteristics of UAV, it displays the technological parameters of differentiated application for a particular field being treated. The technological process of UAV application in the system of precise farming includes sequential interrelated operations: monitoring and sounding of crops (UAV equipped with multispectral camera), obtaining, processing and transmitting information to data center for precise farming management.

In the present study, a new Lieb lattice with five points(hereinafter referred to as Lieb-5 lattice) in the minimum periodic unit is used as a platform. The sites of Lieb-5 lattices are classified into two categories according to their spatial position, respectively, the center lattice and the edge lattices. We investigate the effect of two categories lattices with different intensity on the propagation of the out-of-phase octupole beam. According to simulation results, when the intensity of the center lattice is less than that of the edge lattices(the ratio of two lattice intensities is 2:3), eight-peak shape is always maintained during beam propagation, presenting “strong localization”. Otherwise, the energy between incident lattices is periodically coupled with the increase of propagation distance, presenting “weak localization.”

Femtosecond laser pulse systems allows to modify in a precise and permanent way the optical properties of a transparent materials. This process enables the direct writing of guiding structures in materials, commonly known as waveguides, which are the base for optical circuit fabrication. It is our interest to study the main characteristics of the waveguides manufactured by the laser micromachining technique. Here, an analysis of the resulting refractive index profile has been carried out. This characteristic is essential for the design and simulation of integrated optical circuits. In particular we have developed our research on the study of light coupling in a pair of type II waveguides made in Lithium Niobate (LiNbO₃). These experimental backgrounds provide us with elements to adjust and test the retrieved profile. Taking into account different distance between tracks and writing energies, it is well known that the coupling length changes and the coupling ratio too. Then this study allows us to reconstruct the refractive index profile according to its manufacturing conditions. Modeling of the refractive index distribution profile is a key parameter to perform beam propagation mode simulations (BPM) to achieve more realistic results. So, by means of this method it is possible to obtain a general procedure to describe the characteristics of these kinds of waveguides. As a model test, integrated waveguides were built to corroborate their light coupling. In a first stage it is designed through BPM simulations then it is manufactured in an X-cut LiNbO₃ crystal in order to check its operation according to the simulations carried out.

The cantilever optical fiber nutation structure is designed by using piezoelectric ceramic tube. The amplitude-frequency response of the structure is measured by micro-Doppler method, and the resonance characteristics are analyzed. When the optical fiber nutation structure works under resonance, the nutation amplitude is the largest. The expansion of field of view angle has the advantages of simple structure, stable and reliable performance, easy integration, and higher coupling efficiency from spatial light to optical fiber.

As there are high demand in the quantum treatment of fiber-optic communication technologies, investigation of inherent quaantum noise in pulse propagation along a waveguide is essential. In this paper, we simulate the pulse propagation through an optical fiber in presence of the third order dispersion coefficient and show the amplitude errors of the propagated soliton. Finally, we compare our simulation results with those obtained when the second order dispersion coefficient is just considered.

A fringe projection technique embedded into a stereo microscope to perform 3D deformation measurements is presented. Fringes projected on the inspected object are blurred by motion, providing additional information to describe the surface deformation. In conjunction to a stereo microscope, to inspect the deformation of micro-objects is available. Only oneshot measurement is required. The full-field property makes it possible to inspect several objects at the same time.

A contrast-encoded method based on the phase-shifting technique for 3D shape measurements is presented. Phase extraction is performed by the phase-shifting technique, while unwrapping is discerned by the quaternary contrastencoded patterns. There is no need to take additional projections for phase unwrapping. The fringe patterns used for phase extraction can be analyzed for unwrapping directly. This makes it more efficient to perform high speed, real time, and low cost 3-D shape measurements.

A one-shot technique for profile measurements is presented. A sinusoidal fringe pattern embedded with one-dimensional pulses is used to illuminate the inspected object. The pattern projected on the inspected object is observed by a CCD camera at another view angle. The pulse-encoded fringe pattern provides additional information to identify the fringe order. Even though the surface color or reflectivity varies periodically with positions, it distinguishes the fringe order very well.

A mask optimization algorithm is presented for the scanning projected fringe profilometry. It uses a sinusoidal pattern to illuminate the inspected object. Fringes on the inspected objects are recorded by the image sensor array. The mask optimization algorithm helps to identify the amplitude of the projected fringes. With the mask optimization, to analyze surfaces with low reflectance is possible.

Mechanical weeding is a necessary means to produce organic soybean in vast area and is the most effective for seedling of weed. However, the growth of weed is inconsistent; we must rely on the quantity of closely weeding to achieve the expected results. Organic cultivation adopts strip planting to reduce the cost of weeding, and uses the cultivator to remove weeds. This operation is slow and with high cost, and the artificial weeding is necessary in the later stage. In contrast, the field weeding robot can provide mechanical or physical prevention of weeds via monitor and image analysis. Therefore, this study aims to effectively increase production and solve the problems of labor shortage and high cost on labors by combining an unmanned ground vehicle with a developing smart laser weeding system for autonomous precise weeding. An intelligent image recognition is adopted to identify the position of the weed, and then through the laser tissue fibrosis to achieve the goal of precise weeding.

Dynamic Scraped Surface Heat Exchangers (DSSHE) are widely used in chemical, pharmaceutical and food industries to homogenize solutions containing multiple substances in a pressurized and temperature monitored environment. This research is focused on the utilization of spectroscopy measurements in the visible spectrum to study the material phase transition characteristics in turbulent flows produced in a DSSHE to obtain information about the rate of crystallization, the freezing process, and the material phase transition, which are characteristics of rotating turbulent flows. Optical absorbance of chemical solutions containing high fructose corn syrup (HFCS) and CO2 are measured in the visible range to characterize the material phase transition process at controlled pressure and temperature conditions. The results show substantial sensitivities to the physical and chemical difference of the components as well as their solubility as function of temperature and pressure. The ability to measure physical and optical properties of mixtures using spectroscopy is valuable because of the complex nature of heat exchanging in a scraped surface heat exchange and the ability to capture material phase transition details in turbulent flows. The objective of this work is to further explore optical techniques for quality control and regulation of chemical processes.

The making of new nanomaterials for deep tissue imaging is important for clinic applications. In this work, Erbium based metal organic complex nanoparticles is synthesized. They show near-infrared fluorescence (800-1100 nm) when excited by 785 nm light. Deep tissues imaging is demonstrated using a nanoparticle-loaded 2 mL centrifuge tube covered with pig bacon meat tissue. The maximum imaging depth larger than 1.4 cm is achieved. Our work provides a validated procedure to make nanoparticles for near infrared deep tissue imaging.

A rectangular photonic crystal fiber in GeSe₂-As₂Se₃-PbSe chalcogenide system has been numerically modeled for coherent mid-infrared supercontinuum generation.. The proposed design offers zero dispersion wavelength at 4100 nm for the optimized geometrical parameters. The nonlinear coefficient is found as high (206 W^-1.km^-1) corresponding to the effective mode area of 8.5 μm² against pump wavelength at 4.1 μm. The proposed fiber is expected to be a good candidate for the generation of coherent supercontinuum mid-infrared lasers sources.