This PDF file contains the front matter associated with SPIE Proceedings Volume 12682, including the Title Page, Copyright information, Table of Contents, and Conference Committee information.

We report on polymer nanocomposite films with Ultraviolet (UV) spectrum down-shifting that can be transferred using the open-air Multi-Beam Multi-Target Pulsed Laser Deposition (MBMT-PLD) on opto-electronic devices, such as Photo-Voltaic (PV) cells, for the enhancement of their performance. The nanocomposites were made of the space-grade polymer CORIN impregnated with Nanoparticles (NPs) of Rare-Earth (RE) doped compound NaYF4: Eu³⁺. NPs had a peak of down-shifted photoluminescence (PL) at 623 nm and a PL quantum yield (PLQE) of approximately 50%. The enhancement of the coated PV cells was two-fold: (a) protection from harmful solar UV radiation and (b) the increase of the PV conversion efficiency. We describe the results of characterization of the NPs using dynamic light scattering, x-ray diffraction, and optical spectroscopy. The nanocomposite films were deposited on Silicon Heterojunction (SHJ), Copper-Indium-Gallium-Selenide (CIGS) and Inverted Metamorphic Multijunction (IMM) solar cells. The cells were exposed to 365-nm UV radiation from a light emitting diode (LED). The I-V characteristics of the cells were measured with a solar simulator using AM0 filter. The proposed films improved UV stability of all three cell types: the power degradation significantly slowed down, CIGSs (by half). The proposed films have great commercial potential, especially for the applications to space power.

Magnetoelectric nanocomposites of cobalt ferrite cores with barium titanate shells are studied for applications in wireless sensor networks. Inkjet printing is an additive manufacturing method for depositing functional nanomaterials in micrometer scale patterns. This work investigates the fabrication of cobalt ferrite, barium titanate nanocomposites with 0:3 connectivity into micrometer dot arrays assisted by inline ultraviolet (UV) and Near Infrared (NIR) photonic processing to remove the ink solvent. Sol-gel synthesis of the cubic spinel cobalt ferrite and tetragonal perovskite barium titanate is confirmed by XRD with nanoparticle diameters less than 200 nm observed by SEM. UV-vis and FTIR absorption spectra of ink solvents and nanocomposite are used to explain the impact of UV and NIR photonic processing. Experiments printing cobalt ferrite, barium titanate nanocomposite ink yield arrays of features 20 to 30 μm in diameter.

Zinc oxide (ZnO) possesses many desirable photonic, electronic, and electrochemical properties. By tuning the nanoscale morphology of ZnO, outsized effects within zinc oxide nanocrystals can arise, including increased photo-optic response, heightened catalytic effects, and high piezoelectricity, among others. The reactive inkjet printing method is explored in this work to demonstrate the feasibility of defining ZnO morphology on a drop-on-demand basis. This work has been carried out to identify reaction conditions and morphological products for the conversion of Zinc Acetylacetonate [Zn(AcAc)2] to ZnO by applying thermal, chemical, and photonic inputs. The use of in-line UV irradiation for reactive inkjet printing was especially investigated to control ZnO morphology fabricated, and to evaluate patternability and scalability of the approach. Reactive inkjet deposited ZnO are characterized upon a range of UV irradiation, by x-ray diffraction, scanning electron microscopy, and UV-Vis spectroscopy.

We proposed a Maxwellian-view display based on Volume Holographic Optical Element (VHOE) and light-guide for see-through Head-Mounted Display (HMD) system. The diffractive light-guide is advantageous because of compact construction that leads to smaller and lighter devices. Furthermore, the advantage of VHOEs lies in their potential to achieve reducing energy loss and increasing battery endurance, owing to the higher diffraction efficiency. The Maxwellian-view display is unique because the image quality is almost not affected by the observer's focus distance or the diopter of their pupils. The proposed system utilizes a VHOE with linear grating as the in-coupling device and a VHOE with convex lens function as the out-coupling. In order to achieve a high Field of View (FOV), a prefabricated holographic lens with a high Numerical Aperture (NA) was utilized to record the out-coupling. The proposed device achieved the diagonal FOV as 50°. In this study, the detailed fabrication method of the holographic light-guide based on VOHEs was presented. Furthermore, the design method in order to improve image quality was also proposed. The optical simulation for determining image quality and optimizing was achieved based on the ray tracing method. In this case, astigmatism aberration caused by the diffractive light-guide degraded the image quality. Therefore, a cylindrical lens is necessary if the compensation of astigmatism is desired.

The development of Head-Mounted Displays (HMDs) for Augmented Reality (AR) has gained increasing attention due to their portability. However, traditional combiner-based HMDs are bulky, and thus limited their further application. To miniaturize the devices, diffractive waveguide devices are the best solutions. A relief grating is presented in this study. Through the Finite Element Method (FEM) rather than the traditional Rigorous Coupled-Wave Analysis (RCWA), the diffractive efficiency of relief gratings with different slant angles and different slit depths have been investigated with the wavelength around 532 nm and several incident angles. The relief grating had slits with a slant angle α, depth d, and periods a. In the FEM simulation environment, the grating was fabricated on the glass substrate surrounded by air, and the refractive indices are n_glass = 1.5 and n_air = 1. The diffractive efficiencies were analyzed in several slant angles with depths varying from 50 nm to 500 nm. The results showed that a deeper grating depth produced higher efficiency, and a larger incident angle resulted in stronger contributions to the corresponding diffraction order. The relief grating with different slant angles showed greater efficiency in the +1 order, while the efficiency of the −1 order decreased. The relief grating with a larger slant angle showed higher efficiency than the grating with a smaller slant angle. Overall, a larger slant angle effectively induced higher efficiency in the +1 order, and the depth can also give contributions to the diffractive efficiency enhancement.

A phase unwrapping method using the error-controlled fringe projection scheme for phase-shifting projected fringe profilometry is presented. Most unwrapping methods cannot cope with the problems caused by low signal-to-noise ratios. The presenting method can detect such kind of errors and recover the mistake.

A 2D fringe pattern is presented for projected fringe profilometry in the tele-centric system. Compared with the methods which embeds multiple frequencies in one pattern, the proposed one-shot method is more tolerant to low signal-to-noise ratios and more reliable for surface with large color or reflectance variation.

A phase unwrapping method using the phase-encoded algorithm for phase-shifting projected fringe profilometry is presented. There is no need to take additional projections for phase unwrapping. The patterns used to perform the phase-extraction can be employed for unwrapping directly.

A 2D fringe pattern is designed and employed to perform 3D profile measurements by means of coaxial fringe projections and image acquisitions. To enhance the reliability and systematic accuracy, a signal processing algorithm is proposed as well. Accuracy of the retrieved 3D profile can be achieved in the order of sub-millimeters.

The proposed work presents the design of a photonic crystal structure based on silicon with a square lattice arrangement. It probes the effect of pressure variation on the photonic bandgap and midgap wavelength of the structure. The photonic crystal structure shows a bandgap for the TM mode. The variation in the refractive index of silicon with pressure is utilized to study the bandgap characteristics of the structure with a change in applied pressure. It is observed that the midgap wavelength varies linearly with variations in pressure. This linear variation indicates the application of the proposed structure as a pressure sensor.

In this paper, we propose to fabricate the Geometric Phase (GP) optical device in a Nematic Liquid Crystal cell (NLC cell) by using photo-alignment technique with poly [1- [4-(3-carboxy-4-hydroxyphenylazo)benzenesulfonamido]-1,2- ethanediyl, sodium salt] azo-polymer (PAZO) as alignment layer. During fabrication, the necessary surface alignment pattern of GP modulations for the device is firstly created and written on the PAZO films of an empty cell by using polarization holographic method. With filling E7 LC molecule, GP grating and lens are formed. The design principle, fabrication and characterization of both GP diffractive grating and lens are presented. The results show that the device can appear as a polarization-selective transmission hologram with single diffractive order, although the thickness of cell is 5 μm. In addition, the polarization state and wavefront of diffracted wave can be converted simultaneously. Thus, the device can be named as the diffractive waveplate, which provides many unique photonic applications, becoming effective way for minimizing and integrating optical devices for a photonic modular.

The performance of optical readout of Digital Volume Reflection Holograms (DVRHs) introduced into a Spatial Light Modulator (SLM) is investigated. Liquid crystal SLMs have been used to control a two-dimensional light beam to achieve beam deflection, beam shaping, and holographic imaging. We use the spatial light modulator as a holographic element for DVRH. This is achieved by computing the DVRH numerically from multiple digital transmission holograms recorded at different wavelengths, and optically reading out the information from the DVRH that is introduced into the SLM. The effectiveness of the SLM to read out information from the DVRH with high wavelength selectivity is investigated.

We show applications of our analytical approach to predict the performance of multilayer metallo-dielectric bandpass filters, which also enables estimation of their effective permittivity without relying on homogenization techniques. The approach is based on the one-dimensional dispersion relation for an infinite metallo-dielectric structure that accounts for the complex nature of the permittivities for the metal and dielectric constituents. The dispersion relation clearly reveals the band structure (often comprising multiple passbands), directly provides transmittance characteristics such as center wavelengths and bandwidths and enables the calculation of effective propagation constant and effective attenuation. In this work, we evaluate the dispersion relations for metallo-dielectric structures with complex refractive index data for the metal, viz., Ag, acquired from different sources to show the differences in the center wavelength and the cutoff wavelengths. We verify the accuracy of our method numerically by comparing the transmittance spectrum of finite metallo-dielectric structures using the transfer matrix method. We also plot the dispersion relation using Al as the metal and show the differences in the dispersion relations of the infinite structure and the transmittances of the finite structures relative to Ag. Extension to determination of dispersion relations for other polarizations, viz., transverse magnetic, is discussed, along with corresponding transmittance spectra for oblique incidence.

In this study, a near-eye display system is presented based on a dual-layer holographic light-guide structure. Each holographic light-guide is generated with wavelength multiplexing for color display and is designed to offer half FOV for the whole system. The full FOV of the system can reach 50°. The holographic light-guide utilized Volume Holographic Optical Elements (VHOEs) with linear grating function as the in-coupler and out-coupler. For a light-guide display, the full-color information light must propagate in the light-guide within Total Internal Reflection (TIR) condition. Therefore, it is imperative that the device must employ the gratings with distinct periods for directing red, green, and blue information light. Then the information light with different colors must propagate in different light-guides, in order to prevent crosstalk and ghost noise induced by Raman-Nath gratings, such as surface relief grating, with different periods. In comparison, the VHOEs can record the gratings with distinct periods on a single material with low crosstalk because of their strong wavelength selectivity. In the wavelength multiplexing process, each photopolymer material recorded three gratings for red, green, and blue images. Each grating primarily affects the information light of its corresponding color and guides the information light with different colors into the same light-guide within the TIR condition. In our case, a single waveguide provided the color images with about 25 degrees horizontal FOV. The diffraction efficiency of the primary information light is much larger than crosstalk noise.

We report on a chromatic dispersion slope compensator fabricated with a silica waveguide. The compensator was composed of two arrayed-waveguide grating wavelength filters and an array of delay lines. Output ports of the first filter were jointed to input ports of the second filter through the delay lines. Each wavelength component demultiplexed at the first filter was assigned with delay, which was needed for realizing the dispersion slope compensation characteristics. The obtained dispersion slope and bandwidth were -3.03 ps/nm² and 19.8 nm, respectively, at 1.55 μm. The compensator has the ability to equalize the dispersion slope of about a 43 km-long dispersion-shifted fiber.

A novel Negative Curvature hollow-core Fiber (NCF) design is proposed capable of spectral and polarization filtering in the near-infrared region. The designed six-tube silica-based NCF contains nest elements in the form of suspended tubes radially anchored with a pole to the outer cladding in the vertical direction. In contrast, standard nested cladding elements without any suspension are used through the horizontal axis. This fiber configuration introduces an asymmetry in the core, which helps maintain the orthogonal X and Y polarization states in the fiber core. Pole anchors in vertically positioned tubes only give rise to the spectral filtering confinement loss profile for a vertically polarized state. Based on the geometrical optimization of the fiber, we achieved an improved birefringence on the order of 10^-5 with filtered wavelength losses below 0.01 dB/km in the wavelength range of 1.4 μm to 1.7 μm. The operational bandwidth, polarization extinction ratio, filtered wavelengths, birefringence, and modulation depth loss can be tuned by optimizing the fiber parameters, including outer tube thickness, nest tube diameter, and pole dimensions. This proposed fiber design with selective transmission spectrums has untapped potential sensing capabilities in hollow-core negative curvature fibers.

In this paper, we present theoretic modelling of color breaking in a holographic-optical-element based Augmented Reality (AR) display. We first build up a theoretic optical model of the AR display system using scalar diffraction method. The discussions about the design parameters of holographic optical elements (HOE) for Augmented Reality (AR) glasses, focusing on color uniformity as a function of the waveguide thickness are conducted. It can be used to evaluate the color breaking of a displayed white image from user’s point of view. The simulation results show that color breaking occurs due to the limitations of pupil size and image shifting caused by the extended eye-box. Moreover, the thickness of the waveguide also causes uneven color distribution. Our model can also provide a way to analyze the relationship between waveguide thickness and color uniformity. In addition, based on those results, we propose a color correction algorithm by applying a pre-compensation scheme to the R/G/B values of each display pixel. Results show light display colors can be better corrected in the wider region of user’s field of view. It demonstrates the feasibility of compensation of color breaking in a holographic-optical-element based AR display.

We propose a unique design of negative curvature optical fibers utilizing rotational elliptical cladding structures. The silica-based fibers were numerically characterized using a finite element method-based electromagnetic solver. Different topologies consisting of rotational cladding elements with different tube thicknesses and core diameters were studied. The investigation focused on confinement losses, birefringence, and higher-order mode extinction based on varying tube sizes and rotational angles. Results showed up to 20% improvement in confinement losses for rotated structures, with minimum losses of 4.47*10^-4 dB/m at 1.5 μm wavelength. The designed fibers possess polarization-dependent characteristics, and higher-order mode extinction analysis showed dominant single-mode transmission.