This PDF file contains the front matter associated with SPIE Proceedings Volume 12653, including the Title Page, Copyright information, Table of Contents, and Conference Committee information.

Two laser mirrors with a Bragg mirrors and diffraction grating were designed to achieve single-mode emission. At normal incidence, the reflected transverse electric (TE) and transverse magnetic (TM) polarized beams exhibit a phase difference near π and, in the case of the output coupler, a difference in the reflected amplitude. Laser mirrors with suitably adjusted di-attenuation and di-retardance can be used to achieve single-mode emission of a microchip laser without additional intracavity elements by canceling axial hole burning and suppressing the undesired competing polarization eigenstate. An integrated microchip laser design is also presented to support the potential of delivering a monolithic and compact solution for single-mode emission.

The purpose of this work is to obtain different kind of advanced nanostructures with four materials of interest: graphite, titanium, aluminum and silicon (C, Ti, Al and Si), deposited by Thermionic Vacuum Arc (TVA) technology on the Si substrate. In this respect we use three independent anode cathode plasma sources; the anode was represented by the coating material and the cathode by an electron thermos-emissive tungsten wire. The final thickness of the structures was 300 nm in the two cases: C/Ti/C/Al/C/Si multilayer film (34 nm C, 66 nm Ti, 35 nm C, 65 nm Al, 31 nm C, 69 nm Si) and C+Ti/C+Al/C+Si composite film (100 nm C+Ti, 100 nm C+Al, 100 nm C+Si). Also, for each type of samples there are some parameters varied: substrates temperature (Room Temperature, 200 °C, 300°C, 400°C) and bias voltage applied on substrates, i.e., - 400 V. In order to perform TEM measurement samples have been prepared as XTEM specimens using Ion Mill techniques. TEM bright field image was used to measure layers thickness. EDX and STEM mapping was carried out to evaluate sample composition. Also, HRTEM images were use for structural analyze. SEM and EDX (Elementalcomposition) characterization studies show a dependence of the atomic percentage of the elements Ti, Si and Al on the substrate deposition temperature. In both cases, C/Ti/C/Al/C/Si multilayer film and C+Ti/C+Al/C+Si composite film, the percentages for carbon were too low to be detected by this technique. XPS depth profiles reveal the atomic percentages of Si2p, C1s, Al2p, Ti2p, O1s peaks from 300 nm over Si substrate (zero etch time) to 0 nm (5000 s etch time), for Si/C/Al/C/Ti/C multilayer structures and C+Ti/C+Al/C+Si composite structures prepared at room temperature and at 300°C with -400 V bias voltage, respectively. For Si/C/Al/C/Ti/C multilayer structures the difference between the two cases is given by the oxygen concentration. For the composite sample deposited at room temperature, oxygen atomic percentage decreases in respect to the sample depth, however it has a peak around 4000 s etch time, probably due to the chemical affinity with the two elements Ti and Al respectively. The tribology measurements show that friction coefficient (values of minimum at 0.5 N load and values of maximum at 3 N load, at different deposition temperatures) reveal that the minimum values of the friction coefficient in the case of composite thin films are larger compared with the minimum values in the case of multilayer thin films. We suppose the measured values of friction coefficient are associated with the occurrence of atomic diffusion process to interfaces. Based on nanoindentation studies, Young modulus and Hardness in the cases of C/Ti/C/Al/C/Si multilayer thin films and C+Ti/C+Al/C+Si composite thin films are measured, using a force of 1000/2000 µN. It was noticed that the hardness is larger in the case of C+Ti/C+Al/C+Si composite samples (6.82 GPa) than in the case of C/Ti/C/Al/C/Si multilayer samples (2.15 GPa), i.e., for samples deposed at room temperature.

We present experimental results from the microfabrication and characterization of nanostructured thin films within prototype devices, which we refer to as Meissner-effect transition-edge-sensors, that may ultimately be utilized for sensing applications including microscale magnetometry and microcalorimetry. For the devices reported here, the change in magnetic flux from a microscale disk of electrodeposited tin may be detected by a planar pickup coil consisting of a niobium nanostructured thin film. The optimization of the nanostructured thin films requires sufficient control of sputtering deposition parameters including chamber pressure, gas flow, and power. Multiple mechanisms provide nanostructured pathways for infiltration of the niobium thin film during deposition. The nanostructured thin films were experimentally characterized in terms of thickness, stress, room-temperature resistivity, and resistance as a function of temperature. We find that the superconducting transition temperature for the niobium nanostructured thin film pickup coils spans a significant range from approximately 4 Kelvin to 11 Kelvin depending on the sputtering deposition parameters. We target operation in the regime where the microscale tin disk is in the transition between the normal and superconducting states but the nanostructured thin film pickup coil is fully superconducting and therefore compatible with Superconducting Quantum Interference Device (SQUID) readout.

The demand on the miniaturization of products has fostered the advancement of high-resolution fabrication technologies. Here, we demonstrate a simple and low-cost UV-LED-based lithography technique for structuring at micro- and nanoscale. The corresponding experimental setup was established with off-the-shelf components and allows for single structuring within seconds based on a standard microscope projection photolithography (MPP) process. Single lines with feature sizes down to 150 nm were successfully produced. In addition, high-resolution gratings, ring resonators as well as arrayed waveguide gratings at the micro- and nanoscale were successfully fabricated as well. This operation-friendly, highly efficient and low-cost approach exhibits great potential in micro- and nanomanufacturing for applications in fields such as nanophotonics, biophotonics and micro- and nanoelectromechanical systems.

Gallium Phosphide (GaP) is a semiconductor with advantageous optical properties for near- and middle infrared optical systems. However, optical applications of GaP are limited by its current low machinability. To cut brittle semiconductors such as GaP and generate optical quality surfaces, it is necessary to induce a High-Pressure Phase Transformation (HPPT) so that a phase is formed that behaves ductile when machined. Along the cutting process this can be achieved by applying a negative rake angle. Otherwise, cracks will appear on the machined surface, worsening its optical capabilities. A HPPT of GaP happens at an atomic scale when a zincblende structure changes into a β-tin one. The β-tin structure behaves ductile and is metastable. Hence, the metastable β-tin phase cannot be observed during the cutting process. Therefore, atomistic simulation, such as Classic Molecular Dynamics Simulation (CMDS), is required to study the machinability under HPPT. In this work, CMDS were used to analyze GaP cutting mechanisms. A diamond tool was modelled with a cutting edge radius r_β = 10 nm, rake angle γ = -20 º, and clearance angle α = 10 º. The cut was performed with a depth of cut a_p = 12 nm along the [100]-direction in a zincblende GaP workpiece. Stacking faults were found on the shear zone, {111}-planes, by two different post processes approaches. HPPT was found in the deformation zone only. A stagnation zone was found in front of the cutting edge proceeding a crack nucleation.

Spectroscopic measurements are used in increasingly diverse areas of manufacturing, disease detection, food quality inspection, indoor lighting control, etc. Commonly used spectral decomposition methods utilize several discrete dispersive optical elements to split the incoming light into its frequency components and direct them onto a linear photodetector array. In our previous work, we demonstrated that such mechanically fragile systems can be replaced by thin film dielectric Fourier spectral filters. However, the main disadvantage of this technique is the need for multiple filters with varying dielectric Fabry-Perot cavity lengths, which requires extensive fabrication processes to lithographically pattern and etch. In this work, we demonstrate a novel fabrication of a continuously variable filter, using glancing angle deposition, that can produce 10× more Fourier filters in a single deposition run without the need for lithographic patterning. We apply this method to a commercial off-the-shelf 38-channel linear photodetector array and demonstrate the ability to quickly decompose the incoming signal using only half of the available channels. This novel technique has the potential to enable highly compact and highly robust spectrometers that could be integrated into many handheld devices

Photodetectors are of great interest in several technological applications thanks to their capability to convert an optical signal into an electrical one through light-matter interactions. In particular, broadband photodetectors are used in multiple applications such as environmental monitoring, imaging, fire detection, and astronomical observations. We present a two-dimensional photodiode heterojunction based on reduced graphene oxide (rGO) deposited on an n-type Silicon substrate. We report on the electro-optical properties of the device that have been measured in dark and light conditions into a spectral range from UV to IR. The room temperature current–voltage (I–V) measurements of rGO/n-Si photodetector exhibits a reverse saturation current linearly dependent on the light power. The main figures of merit of the photodetector such as linearity and responsivity have been evaluated and compared with the recent progress obtained substituting the rGO with a graphene single layer (Gr) on the similar n-Si substrate. The photoconductive properties and analysis of the two devices are presented and discussed. Finally, the experimental results demonstrate the feasibility of the rGO/n-Si and Gr/n-Si device to detect light from UV to IR light, nominating graphene-based heterojunction as a novel candidate for the realization of new broadband photodetectors.

In this work, a disordered medium, comprised of Rhodamine dye-doped phenol and Au nanoparticles in an optical waveguide, is used to realize transverse Anderson localization of light waves. The optical waveguide facilitates to suppress unwanted optical modes and produce just a single dominant Anderson mode. Through coupling into a particular Anderson localized cavity, the dye molecules' transition rate is determined to be increased to a factor of 7.6. This paves the way for future research to understand and utilize the transverse Anderson localized modes in a 3D random plasmonic medium to manipulate light−matter interaction.

The semiconductor industry is an unbelievable fast-growing field with an exponential growth in the space optimization. But also, other large industrial field are getting smaller in the structure size, for example the field of optics. On the other hand, the customer demands get more and more complex and individual. This leads to an enormous growth potential for micro- and nanofabrication with direct laser writing. Under this circumstance the idea for a micro- and nanostructuring possibility with high precision on large areas was born. A setup was developed to combine a nanopositioning and nanomeasuring machine (NMM-1) with an extremely high precision and a two-photon based illumination system to realize a high-precision direct laser writing system. Besides its high positioning resolution of 0.1 nm and its metrological traceability based on an interferometrical measurement setup, the NMM-1 offers a positioning range of 25 mm x 25 mm x 5 mm. The aim is to design a direct laser writing setup, which enables a trans-scale fabrication without any stitching or combination of different positioning systems necessary. In order to benefit from this high positional accuracy, studies have been made to investigated the two photon absoption process and reduce line widths. The presented research shows investigations, which were made with the developed laser writing setup, to invested illumination dose and the voxel position of the writing laser, in order to improve microstructuring and to reduce structure widths.

An optical phased array (OPA) is a high-speed beam steering device which has no mechanical moving part. An antenna pitch of the OPA is important factor to determine the steering angle. We focused on high-speed phase modulator using an organic electro-optic (EO) polymer and plasmonic waveguide structure which has nano-scale light confinement effect to suppress crosstalk. We proposed OPA structure combined with organic EO polymer and inorganic materials such as Nb2O5 and metals. Mode converters from EO polymer optical phase modulator to Nb2O5 waveguide and plasmonic waveguide were designed by numerical simulation.

Over the last decade various researchers have demonstrated optical transmission enhancement for fused silica substrate surfaces using random antireflective structures (rARS). The nano-structured surfaces effectively redirect incident light in the axial transmission direction, thus nearly eliminating Fresnel reflectivity. To quantify relations between the random surface nano-structures and optical performance, statistical analysis of surface heights (roughness) is often used, which can predict scatter but not axial transmission enhancement. The alternate analysis method, using an effective-medium approximation for the surface layer, can predict transmission enhancement using an average refractive index but it fails to determine angular scatter. We characterized rARS surfaces by employing Shannon's entropy, to quantify their randomness through complexity. The objective is to construct a figure-of-merit by studying the distribution, organization, and population density of the nanostructures that result in various scales of reflectivity suppression across the 300 nm to 800 nm spectrum. We fabricated various rARS silica surface modifications, which resulted in different measured spectral transmissions, to examine possible relations between the entropy (order) of the transverse profile feature cross-sections and distributions, with the resulting antireflective functionality. We demonstrate that size-based grouping of spatial data correlates specific transverse-feature population orders to specific transmission enhancements based on a diffractive analysis model.

Multilayer Laue lenses (MLLs) are diffractive optics to achieve nanometer-scale hard x-ray focusing. Flat and wedged MLLs are fabricated by sectioning multilayer films made of thousands of planar or laterally graded and depth-graded layers. The total thickness of the films could extend to over 100 micrometers. The outmost zone width of an MLL is one to a few nanometers. After the deposition of multilayers, the films are sectioned to an appropriate thickness targeting the optimal focusing efficiency over the operating x-ray energy range. Wedged MLLs are candidates to achieve higher efficiency and sub-10 nm hard x-ray focusing, which are more complex optics to produce. In particular, wedged MLL fabrication brings additional critical requirements on section(s) extraction. At the National Synchrotron Light Source II (NSLSII) of Brookhaven National Laboratory (BNL), we made evolutions in MLL fabrication by mechanical polishing methods over the last decade. We started with conventional polishing and then developed the polish-on-diamond and the combined polishing with focused ion beam (FIB) methods. The introduction of new techniques has proven effective in improving our MLL fabrication efficiency. In this paper, the current progress of each method is discussed in detail.

Injection molding process is one of the most productive techniques having potential to fabricate nanostructures rapidly and efficiently in large numbers. We have developed a high aspect ratio nanostructure replication process for metalens with multi height nanopillars by injection molding. The process that we have developed consists of three main steps: master mold replication, Ni stamper fabrication and injection molding. The master mold was surface-treated with a lowmolecular-weight fluorine material to produce replica of high aspect ratio nanopillars by imprinting. The composite process of conformal deposition to form base electrode layer and nickel electroplating realized the fabrication of a stout, void-free Ni stamper from the master mold replica. In injection molding for nanopillars with a high aspect ratio, the Ni stamper surface was treated by the surfactant to improve releasability and the thermoplastics temperature at the injection was controlled to adjust its flow rate. The influences of the Ni stamper surface treatment and the thermoplastics temperature on the final replication quality were investigated. It was found that the Ni stamper surface treatment improved the releasability and suppressed the elongation and inclination of the formed nanopillars. Also, the wellcontrolled thermoplastics temperature realized the high aspect ratio nanopillar replication. Finally, we have obtained a plastic metalens by injection molding, which replicates the mold properly. It shows that injection molding process has great potential for metasurface mass-production.

Nanoimprint Lithography (NIL) is a lithography technique suitable for mass production because it can replicate complex patterns down to the nanometer scale with reduced time and cost. The master is one of the key elements of NIL. It determines the resolution of the replicated patterns and plays a role in defectivity. Therefore, it must be characterized to control the replication as properly as possible. Here, we target to create a resist master to achieve 3D structures. This master is made by grayscale electron beam lithography to obtain submicron resolution. In this study, full characterization of structures are presented to validate resist master quality.

We propose a plasmonic-niobium pentoxide coupling structure to achieve a high-speed and wide-steering optical phased array with reduced crosstalk and low power consumption.

Dielectric metalenses realized by economic photolithography technology are vital to their mass deployment in optoelectronic applications. However, pattern fidelity has become a serious issue that degrades the device performance due to optical proximity effects. Here, we demonstrate an intelligent reticle modification system which modifies the sizes and shapes of designed patterns based on a neural-network U-net lithographic model to produce nanostructures with desired dimensions. We demonstrate 2 mm-diameter visible metalenses with diffraction-limited focusing using DUV KrF 248 nm photolithography. This work bridges between the semiconductor process and lens-making industries to realize high-volume manufacturing of versatile metalens and metasurface products.

In this research, Yb³⁺ -Tm³⁺ co-doped ZrO₂ nanoparticles (ZrO₂:2Yb³⁺ -xTm³⁺; x=0.0125, 0.025, 0.05, 0.1, and 0.2 mol%) were synthesized using ethylenediamine and Pluronic F-127® as precipitating and surfactant agents, respectively, through a sonochemical method assisted by hydrothermal treatment and subsequent annealing as an innovative, simple, and fast route. Structural, morphological, and chemical characterization was determined by XRD, SEM, and FT-IR. The photoluminescent characterization was performed using a spectrometer with an excitation wavelength of 975 nm. The SEM technique confirms the formation of spherical and semispherical nanoparticles dispersed of sizes less than 110 nm. Furthermore, XRD results proved that the solids have monoclinic and tetragonal crystalline structure for undoped ZrO₂ and the tetragonal phase was stabilized with Yb³⁺ -Tm³⁺ co-doped ZrO₂. At the same time, FT-IR spectroscopy showed the functional groups corresponding to –OH residual, C-H, and C=C bonds due to surfactant agent remand and metallic oxide bonding of Zr-O, corresponding to the tetragonal crystal structure, principally. On the other hand, photoluminescent characterization exhibited upconversion (UC) emissions at 488, 656, and 800 nm due to 1G4→3H6, 1G4→3F4, and 3H4→3H6 transitions of Tm³⁺, respectively. These emissions increase in intensity due to the increment of Tm³⁺ concentration until 0.1mol%; lower and higher to this concentration, the photoluminescent intensity decrease. ZrO₂:2Yb³⁺ -0.1Tm³⁺ nanoparticles showed the highest enhancement (144%) at 800 nm concerning the ZrO₂:2Yb³⁺ -0.0125Tm³⁺ sample.

Mercury telluride (HgTe) nanocrystal quantum dot-based infrared photodetectors provide a low-cost alternative to mercury cadmium telluride (MCT) bulk alloy devices made through epitaxial growth methods. The size-tunable optical properties of HgTe colloidal quantum dots (CQDs) make it possible to synthetically target a range of absorption edge wavelengths encompassing the infrared region. In this work, we report the synthesis of HgTe CQDs with high aspect ratios using solution-based colloidal techniques. The radial diameter of the arms of tripodal HgTe CQDs can be adjusted between 3 and 7 nm, with corresponding decreases in aspect ratios (arm length/radial diameter) from six to two, respectively. Tripodal HgTe CQDs exhibit room temperature photoconductivity with optical response ranging from the short wavelength infrared (SWIR) to mid-wavelength infrared (MWIR) spectral region, with optical cutoffs increasing from 1.7 to 3.5 µm with increasing CQD arm diameter. These tripodal HgTe CQDs with high aspect ratios exhibit relatively strong photoconductivity response and are promising for CQD-based infrared photodetectors.

Ga₂O³ has established to be a promising material for deep UV and UV optoelectronics and sensing applications. However, a major drawback of Ga₂O³ thin film based optoelectronic devices is the existence of native point defects which can result in the creation of sub-bandgap absorption, carrier scattering centres, and leakage channels and becomes an obstruction to their efficient device applications. To overcome this high temperature annealing processes are required which not only leads to a rise in the thermal budget but also put many fabrication and technological bounds in device fabrication. Therefore, in this work we report room temperature ultraviolet-ozone (UVO) annealing as a facile and cost-effective method which can control defect states and improve the optical efficiency of Ga₂O³ thin film. The Ga₂O³ thin films were deposited by radio frequency (RF) sputtering technique on p-Si at room temperature. The grown films were subsequently subjected to UV-Ozone (UVO) annealing for 30, 50, 70, and 90 min at room temperature. The atomic force microscopy result shows the impacts of UV-Ozone (UVO) annealing time on the film roughness which further associated with reduced oxygen vacancies (Vo) concentration. Optimum time of UVO annealing for Ga₂O³ thin films was estimated to be 50 min. Finally, the variation in current-voltage (I-V) characteristics of Ga₂O³/p-Si heterojunctions are estimated to understand the effect UVO annealing on its electrical properties of RF sputtered Ga₂O³ thin film.

We demonstrate a novel approach to designing a distributed Bragg reflector consisting of a complex-index material (i.e., gold and VO₂). The design with a gold center layer has been fabricated and characterized. The field enhancement is used to reduce the optical limiting threshold and increase nonlinearity.

Guo et al, 2023, report that NbOCl₂ is a novel thin-material SPDC source, but further optical measurements on thicker samples of the material suggest that NbOCl₂ does not behave like conventional SPDC producing materials. In this paper, we report the following: (1) NbOCl₂ is not completely transparent at the reported pump wavelength of 404 nm, (2) NbOCl₂ behaves as a polarizer at 405 nm, (3) coincidences above noise level around 810 nm were obtained when pumping NbOCl₂ at 405 nm and varied with pump polarization, and (4) pumping at the more transparent wavelength of 780 nm fails to yield any detectable SPDC photon pairs.

Localized surface plasmon resonance (LSPR) from metal nanoparticles (NPs) has been widely applied to enhance the performance of photodetectors and has been studied by many groups. Due to the limitation of the bandgap, silicon-based (Si-based) devices encounter challenges in sensing infrared region. To overcome this issue, this study discusses how the silver (Ag) NPs to modify Si-based Schottky photodetectors and enhance mid-infrared (MIR) responsivity via rapid thermal annealing (RTA) process by inducing LSPR when illuminating. Under an incident light source at 3460 nm wavelength, the responsivity of the device annealing at 175°C is increased from 0.4481 mA/W to 0.6872 mA/W, which is enhanced 1.533 times compared to device without annealing. In addition, using COMSOL software for electric field intensity simulation confirms that Ag NPs can indeed enhance the electric field intensity to increase the induced LSPR. Therefore, it is demonstrated that the response signal of MIR can be enhanced and amplified by Ag NPs in Schottky devices under the same measurement conditions, achieving the ability to detect MIR region in Si-based Schottky devices.