This PDF file contains the front matter associated with SPIE Proceedings Volume 10542, including the Title Page, Copyright information, Table of Contents, Introduction (if any), and Conference Committee listing.

The extraordinary reflectivity and resonance features of high-contrast gratings are consequences of the interference of two grating modes. From this observation, an extension of the Fabry-P´erot interferometer to the bimodal case is proposed, in view of describing rigorously the physical mechanisms occurring in the grating. The closedform expressions of the interferometer reflection and transmission, obtained starting from a novel parametrization of the unitary symmetric 3 × 3 scattering matrix characterizing the bar-air interface, allow a complete exploration of the device parameter space, explaining and predicting phenomena such as ultra-broadband quasi-100% reflectivity.

We discuss the design of two complimentary media for analog detection of sources placed at subwavelength separation using time reversal of observed signals. We have used two metasurfaces composed of bianisotropic structures to code and decode the evanescent fields of the sources to propagating waves. In order to reduce losses and create a perfect focus, resonances are avoided to achieve negative index. We have studied various shapes such as, split ring resonators to determine the least lossy structure for time reversal. We have used simulations to study the behavior of permittivity and permeability values of these structures at various frequencies. Shape parameters such as size of the gap and thickness is being optimized to achieve refractive index of ± 1 at the same frequency and minimize losses in the metasurfaces.

We review recent progress on developing passive subwavelength grating (SWG) waveguide devices in silicon photonics (SiP), including optical filters based on Bragg structures, ring resonators, and contra-directional couplers. We also discuss how to use SWG structures to implement an index variable optical true time delay line based on spatial diversity with an equal length waveguide array. These components expand significantly the SiP SWG waveguide ‘toolbox’ thereby enabling the design and implementation of more complex devices for advanced signal processing and filtering.

Photonic crystal (PhC) laser, with specific merits of low astigmatism, single mode operation and integration into silicon photonic system, has been studied for many years. Compared with the edge emitting lasers (EELs), surface emitting light emitters have many advantages such as small and symmetric divergence angle and platform of array-based capability. The resonance along in-plane direction preserves the high modal gain to overcome optical loss and leads to lasing action. These photonic crystal designs which has superior essential performance to that of next-generation light sources which can propose to tunable lasing multi-wavelengths with polarization control and single-mode high beam-quality. In this report, we demonstrate the fabricated realization of a novel electrically driven high-power PhC laser incorporating indium-tin-oxide (ITO) layer as a newly designed cladding layer, which could improve the laser characteristics and achieve the much lower cost of the integrated optoelectronic application. The series of investigated actual nanofabrication lasing devices with distinct designs were observed to verify the structural parameters including grating periods and area regions by tailoring the photonic crystal structure. Based upon experimental results, lasing characteristics through high current injection at room temperature inclusive of I-V curves, L-I curves, near/far field patterns, and lasing spectra were characterized and discussed. We believe this practical watt-level light output achievement should have an impact on numerous photonic devices of the coherent operations and helpful attribution to the two-dimension integrated platform in the future.

We report a GaN-based VCSEL with a high-contrast grating (HCG) as the top mirror. The HCG consisted of TiO₂ and rested directly on the n-GaN without an airgap or the use of any DBR layers to boost the reflectivity. The full VCSEL structure was optically pumped at room temperature and showed a lasing threshold of approximately 0.69MW/cm² and a lasing wavelength at 369.1 nm. This first demonstration of lasing in a HCG GaN-based VCSEL opens up the possibility to explore all the potential benefits of HCGs in the blue and ultraviolet spectral regime.

Plasmonic metasurface lenses based on polarization conversion are inherently limited in efficiency, and as a result, they have been given sparse attention in favor of higher-performing dielectric variants. However, recent proposals for expanding the design beyond a single interface offer hope for efficient plasmonic structures. Before developing these multi-layer structures, we wish to better understand dependencies of 2D plasmonic designs. Here we demonstrate the spectral, polarization and geometrical sensitivities of nine large-scale variants of the original V-antenna lens design at λ₀ = 8μm. We show that the spectral response oscillates rapidly within a span as small as λ₀/320, and that strong focusing can occur at both the designed polarization state, and its orthogonal state–and with differing focal distances. Additionally, we determine that the lens performance is only weakly tied to the size of the discretization, offering only marginal improvement as the discretization approaches a continuum.

In the field of uncooled Long Wave Infra Red (LWIR) imaging, CMOS compatible bolometers technology is being more and more popular, exhibiting precise temperature measurement at moderate cost. The price of this technology is proportional to the number of components produced per wafer, leading to a shrinkage of the pixel. Enhancing the resolution level of the focal plane array (FPA) requires an improvement of the point spread function (PSF) of the optical system, leading to more and more complex aspheric lenses, and an increased cost of imaging systems. We propose to add a sub-wavelength blade to the existing parts of the imaging system to ease the overall improvement of the image quality in applications with a constraint budget. The main function of such a subwavelength blade should be to control the phase of the light into an optical system to compensate optical aberrations. A cost effective solution consists to make such devices using microelectronics based collective fabrication process. The main difficulty is to predict the subwavelength blade behavior within an optical system that is to say combining millimeter sized optical components that are modeled using ray-tracing or electromagnetic simulations. In this paper we present the results obtained from an effort to simulate, fabricate and characterize all-dielectric subwavelength blade. In an imaging system, our devices will have to deal with non-flat wavefronts. Our method is based on Fourier Modal Method and Angular Spectrum Method to simulate subwavelength optics into such an optical system. Finally, we have compared our simulations results to experiments on basic examples, like spherical aberration correction of a commercial lens.

Water quality monitoring has become important in today’s scenario due to severe chemical and bacterial contamination in urban and rural water bodies. However, current monitoring methods do not provide fast and reliable results. By using intrinsic fluorescence, microbial contamination and industrial pollutants in water can be monitored in real-time, continuously and at very low concentrations. Intrinsic fluorescence can be enhanced by using High Contrast Gratings (HCGs) spectrally tuned to the fluorescence signatures of pollutants. Compared to metallic gratings which suffer from higher losses especially at lower wavelengths and are easily prone to oxidation, an all dielectric approach can overcome these limitations. HCGs using silicon nitride as grating material on a glass substrate are optimized to detect the presence of tryptophan (a bio-chemical marker for bacterial contamination) and phenanthrene (chemical contaminant). Tryptophan and phenanthrene have a fluorescence emission wavelength of 410 nm and 420 nm respectively. HCGs are optimized to enhance fluorescence emission at both of these wavelengths, therefore the optimized grating parameters for tryptophan (period: 255 nm, duty cycle: 0.8 and thickness: 260 nm) and phenanthrene (period: 282 nm, duty cycle: 0.8 and thickness: 289 nm) resulted in Q factor of 683 and 709 respectively. The optimized HCGs show an electric field enhancement of eight times concentrated in the air region between the gratings which would result in enhanced fluorescence.

The quest for the development of portable thermophotovoltaic (TPV) systems has been a growing interest due to the ability to achieve high power and energy densities using hydrocarbon based fuels. Recent studies based on intermediate filters and photonic crystals have shown significant improvement in system efficiencies for combustion driven and solar-based TPV systems. The key goal is to engineer directionally and spectrally selective thermal emitters ideally matched to the solar cell. Here, a high contrast grating based thermal emitter using silicon as a grating material on a quartz substrate is proposed which is suitable for integrating to GaSb solar cell based thermophotovoltaic systems powered by microcombustor. The intrinsic properties of quartz substrate filter the below bandgap (greater than 4.5 μm) radiation in the infrared region. The silicon gratings are optimized (period = 2.4 μm, duty cycle = 40 % and thickness = 0.55 μm), to provide transmission only for photons with wavelengths lower than 1.8 μm thus inhibiting below bandgap radiation of GaSb cell. The spectrally tuned emitter structure shows transmission of more than 70% of convertible photons (above the bandgap) and reflection of 80% of unconvertible photons (below bandgap) back to the combustor thus reducing the heat losses in the photovoltaic conversion and increasing the combustion system temperature there by contributing to overall increase in TPV system efficiency.

Metamaterials (MMs) are composite structures that exhibit non-conventional optical properties. Conventional threedimensional MMs are rather bulky, usually require complicated fabrication techniques and are not CMOS technology compatible. On the other hand, there has been a great ongoing interest in two-dimensional Metamaterials (Metasurfaces). Metasurfaces are two dimensional periodic structures that allow controllable change in the amplitude and phase of the incoming wave upon interaction that allows for designing ultrathin optical components with various functionalities. This can be achieved through optical resonances through the metasurface. These resonances can be achieved either through plasmonic antennae or dielectric resonators. Due to their lossy nature in the optical domain, plasmonic and metallic based metasurfaces can lead to inefficient operation and limit the applicability of such structures. In this work we discuss an all silicon metasurface design using cross-shaped unit cells. This cross design in addition to being polarization insensitive is capable of achieving phase difference from 0 to 2π by optimizing two degrees of freedom and thus offers a promising platform for various metasurface applications. We show through numerical simulations the properties of this polarization independent design and how it can be used for mid-infrared beam steering and lensing applications.

Sub-wavelength patterned structures like cavity resonator integrated grating filters are relevant in various optical applications. Due to their highly resonant nature and due to their relatively large size it can be demanding to perform accurate optical simulations for such devices. In this contribution we investigate performance of hp finite-element based methods for this simulation problem. We demonstrate numerical convergence of the obtained solutions up to very high accuracy levels. We compare performance of our methods to results from the literature and investigate the influence of physical parameters on device performance, enhancing the Q-factor and reducing the horizontal size of the device.