Miniaturization and image optimization of a full-color holographic display system using a vibrating light guide.

In this study, a miniaturized full-color holographic reconstruction system that uses a single spatial light modulator to achieve full-color image reconstruction was developed. The reconstruction system uses a single light guide for light combination and is therefore less voluminous than conventional reconstruction systems. The experimental results demonstrated that the system had a full-color display, corrected light combination, and eliminated zero-order light.

Polarization-insensitive GaN metalenses at visible wavelengths.

The growth of wide-bandgap materials on patterned substrates has revolutionized the means with which we can improve the light output power of gallium nitride (GaN) light-emitting diodes (LEDs). Conventional patterned structure inspection usually relies on an expensive vacuum-system-required scanning electron microscope (SEM) or optical microscope (OM) with bulky objectives. On the other hand, ultra-thin metasurfaces have been widely used in widespread applications, especially for converging lenses.

High-performance gallium nitride dielectric metalenses for imaging in the visible.

Metalens is one of the most promising applications for the development of metasurfaces. A wide variety of materials have been applied to metalenses working at certain spectral bands in order to meet the requirements of high efficiency and low-cost fabrication. Among these materials, wide-bandgap gallium nitride (GaN) is one of the most promising materials considering its advantages especially in semiconductor manufacturing.

A Vision toward Ultimate Optical Out-Coupling for Organic Light-Emitting Diode Displays: 3D Pixel Configuration.

Despite stringent power consumption requirements in many applications, over years organic light-emitting diode (OLED) displays still suffer unsatisfactory energy efficiency due to poor light extraction. Approaches have been reported for OLED light out-coupling, but they in general are not applicable for OLED displays due to difficulties in display image quality and fabrication complexity and compatibility. Thus to date, an effective and feasible light extraction technique that can boost efficiencies and yet keep image quality is still lacking and remains a great challenge.

Quantifying scattering coefficient for multiple scattering effect by combining optical coherence tomography with finite-difference time-domain simulation method.

In optical coherence tomography (OCT) systems, to precisely obtain the scattering properties of samples is an essential issue in diagnostic applications. Especially with a higher density turbid medium, the light interferes among the adjacent scatters. Combining an OCT experiment with the finite-difference time-domain simulation method, the multiple scattering effect is shown to affect the scattering properties of medium depending on the interparticle spacing.

Reflective EUVL tool design with generalized Gaussian constant mathematics.

This study aims to develop a systematic design procedure for extreme ultraviolet lithography tools. Through analysis using generalized Gaussian constants, relationships between optical properties and requirements can be obtained, and can be used to help ensure that optical system properties required for the tool are upheld during the design process. As verification of the design method, an eight-mirror 0.

AlGaInP Red LEDs with Hollow Hemispherical Polystyrene Arrays.

A hollow hemispherical polystyrene (HHPS) was fabricated to reduce total internal reflection in AlGaInP-based LEDs. At an injection current of 350 mA, the external quantum efficiencies of LED-I, LED-II, LED-III, and LED-IV are 20.92%, 24.

Analyses of optical out-coupling of organic light-emitting devices having micromesh indium tin oxide and conducting polymer as composite transparent electrode.

Unlabelled: We report the characterization and analyses of organic light-emitting devices (OLEDs) using microstructured composite transparent electrodes consisting of the high-index ITO (indium tin oxide) micromesh and the low-index conducting polymer

Pedot: PSS [poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)], that are fabricated by the facile and convenient microsphere lithography and are useful for enhancing light extraction. The rigorous electromagnetic simulation based on the three-dimensional finite-difference time-domain (FDTD) method was conducted to study optical properties and mechanisms in such devices. It provides a different but consistent viewpoint/insight of how this microstructured electrode enhances optical out-coupling of OLEDs, compared to that provided by ray optics simulation in previous works.

Efficient speckle-suppressed white light source by micro-vibrated and color-mixing techniques for lighting applications.

In this paper, we have demonstrated an efficient speckle-suppressed white light source generation when a blue laser diode illuminates on a micro-vibrated phosphor paper. Both micro-vibrated and color-mixing techniques are used in this system. With only micro-vibrated technique, the speckle contrast can be reduced from about 50% to 7.

Enhancing Optical Out-Coupling of Organic Light-Emitting Devices with Nanostructured Composite Electrodes Consisting of Indium Tin Oxide Nanomesh and Conducting Polymer.

A nanostructured composite electrode consisting of a high-index indium-tin-oxide nanomesh and low-index high-conductivity conducting polymer effectively enhances coupling of internal radiation of organic light-emitting devices into their substrates. When combining this internal extraction structure and the external extraction scheme, a very high external quantum efficiency of nearly 62% is achieved with a green phosphorescent device.

Front view and panoramic side view videoscope lens system design.

A novel structure of a rigid panoramic endoscope is designed and presented. The inspected target field is imaged on the sensor by an optical lens with a dynamic mechanical module. A microgear and motor are used to drive the dynamic lens components, and a compensation element is used in the system to correct the aberrations due to the protective cylindrical endoscope cover.

Full-frame projection displays using a liquid-crystal-on-silicon spatial light modulator for beam shaping and speckle suppression.

This paper presents a full-frame laser projection display system in which a spatial light modulator (SLM) is used for beam shaping and speckle suppression. Phase-only computer-generated holograms (CGHs) are used to transform a cross section of the incident laser beam into a square nearly the same size as that of the display device. Under different initial conditions, the diffraction patterns generated by the CGHs possess identical intensity distributions but differ with regard to random phase distribution.

Laser speckle reduction by phase range limited computer generated hologram in laser projection display system.

The speckle phenomenon is an annoyance in laser projection display systems. We propose a novel speckle suppression method that utilizes the interference concept on a pixel point, which reduces the speckle contrast (SC) of the project image by limiting the phase distribution range in the optical field. The SC formula is derived in the uniform interval phase range for partially developed speckle conditions, showing that the SC can be lowered by lessening the phase range limitation.

Efficient speckle reduction for a laser illuminating on a micro-vibrated paper screen.

We have demonstrated an efficient speckle reduction method for laser illumination using a micro-vibrated paper screen along the projection direction. Using this method, a micro-vibrated amplitude of 0.532 μm, or a 2π phase change is sufficient to de-correlate the generated speckle pattern for a static SHG green laser beam image.

Plasmonic ITO-free polymer solar cell.

The aluminum and sliver multilayered nano-grating structure is fabricated by laser interference lithography and the intervals between nanoslits is filled with modified PEDOT:PSS. The grating structured transparent electrode functions as the anti-reflection layer which not only decreases the reflected light but also increases the absorption of the active layer. The performances of P3HT:PC₆₁BM solar cells are studied experimentally and theoretically in detail.

Design and fabrication of birefringent nano-grating structure for circularly polarized light emission.

Three different nano-grating structures are designed as phase retarders that can transform linearly polarized light to circularly polarized emission for the wavelengths of 488 nm, 532 nm and 632.8 nm, respectively. Gold based nano-grating structures with various periods are fabricated by utilizing laser interference lithography.

Investigation of designated eye position and viewing zone for a two-view autostereoscopic display.

Designated eye position (DEP) and viewing zone (VZ) are important optical parameters for designing a two-view autostereoscopic display. Although much research has been done to date, little empirical evidence has been found to establish a direct relationship between design and measurement. More rigorous studies and verifications to investigate DEP and to ascertain the VZ criterion will be valuable.

Effects of the spatial frequency composition of the target pattern and the number of quantization levels in diffractive beam shaper design.

A mathematical model is derived, and numerical simulation is analyzed for laser beam shaping by using multilevel phase-only diffractive optical elements (DOEs). We used the simulated annealing algorithm to design the beam shapers. The result has an essential effect on the diffractive pattern quality caused by the spatial frequency composition of target patterns for the same incident gaussian beam size and target pattern area.

Ultra-wide-view patterned polarizer type stereoscopic LCDs using patterned alignment.

The proposed patterned polarizer rather than the conventional ±λ/4 polarizer can further reduce the crosstalk through its corresponding glass for stereoscopic LCDs and can be fabricated by using the same patterned alignment technique. The patterned polarizer comprises a linear polarizer, a patterned retarder and a biaxial film. The maximum crosstalk ratio of the optimal design is reduced from 0.

Ultrasensitive guided-mode resonance biosensors superimposed with vertical-sidewall roughness.

In this paper, we present our investigations of the effects of vertical-sidewall roughness (VSR) on guided-mode resonance (GMR) filters made of subwavelength grating for applications to ultrasensitive biosensors operated under IR illumination. We designed the spectral FWHM of the grating filter to be as narrow as possible in order to emphasize the sensitivity and VSR effects. Three types of VSR morphologies on the grating-in terms of the correlation length ξ and the rms of the maximum roughness deviation σ-were considered and evaluated.

Design of polarization-insensitive multi-electrode GRIN lens with a blue-phase liquid crystal.

We report the design and simulation results of an adaptive GRIN lens based on multi-electrode addressed blue phase liquid crystal. A high dielectric constant layer helps to smoothen out the horizontal electric field and reduce the operating voltage. Such a GRIN lens is insensitive to polarization while keeping parabolic phase profile as the focal length changes.

Polarization-independent broad-band nearly perfect absorbers in the visible regime.

Polarization-independent broad-band absorbers in the visible regime are theoretically investigated. The absorbers are three-layered structures consisting of a lossy dielectric grating on top of a low-loss dielectric layer and a substrate of the same lossy dielectric placed at the bottom. Enhanced absorption in the underlying structure is attained over a broad range of frequency for both TE and TM polarizations.

Designs of broadband and wide-view patterned polarizers for stereoscopic 3D displays.

This work presents a new methodology to design patterned circular polarizers consisting of in-cell polarizers, in-cell retarders and biaxial films to achieve very wide viewing freedom for stereoscopic 3D color LCDs. The biaxial films with least materials and simple fabrication concepts are employed for off-axis compensation of the in-cell retarders. In the best result, the crosstalk ratio is less than 0.

Anomalous optical absorption in metallic gratings with subwavelength slits.

The absorption in metallic gratings with subwavelength slits is theoretically investigated. Anomalous optical absorption occurs over a wide range of incident angles for both polarizations. In particular, a nearly perfect absorbance up to 99.

Partitioning pixel of organic light-emitting devices with center-hollowed microlens-array films for efficiency enhancement.

A pixel partition scheme assisted with patterned or center-hollowed microlens-array films (MAFs) was proposed to improve the optical characteristics and electrical properties of organic light-emitting diodes (OLEDs). In our optical simulation results, a pixel of 1 × 1 mm(2) with a center-hollowed MAF has a 42% luminance enhancement; however, after dividing the large pixel into ten by ten smaller pixels of 100 × 100 μm(2), the partitioned units with a corresponding center-hollowed MAF can have a 104% luminance enhancement under the same total active area and the same optical power of organic emitters. Furthermore, a significant 127% luminance enhancement by the introduction of a high-refractive-index substrate can be obtained.