Bidirectional electrostatic MEMS-tunable VCSELs.

Microelectromechanical system (MEMS) vertical cavity surface-emitting lasers (VCSELs) are the fastest coherently tunable lasers (nm/ns) due to their unique Doppler-assisted tuning mechanism. However, in standard electrostatic actuation, the response is highly nonlinear and large (>100 V) dynamic voltages are needed for MHz sweep rates. We present a bidirectional MEMS VCSEL as a solution to these challenges where static voltages can be used to enable substantially linear and amplified wavelength tuning with respect to the fast tuning (MEMS) voltage.

Design of a robust photonic crystal mirror for MEMS VCSELs.

Wavelength tunable lasers with narrow dynamic linewidths are essential in many applications, such as optical coherence tomography and LiDAR. In this letter, we present a 2D mirror design that provides large optical bandwidth and high reflection while being stiffer than 1D mirrors. Specifically, we investigate the effect of rounded corners of rectangles as they are transferred from the CAD to the wafer by lithography and etching.

Active Fano resonance switch using dual-layer graphene in an embedded dielectric metasurface.

We propose an active optical Fano switch (OFS) based on an embedded dielectric metasurface (EDM) including dual-layer graphene (DLG). An EDM is a dielectric grating overlapped by two cladding layers, and it excites a Fano resonance. DLG is positioned inside the upper cladding layer to maximize light-graphene interaction.

Critically coupled Fabry-Perot cavity with high signal contrast for refractive index sensing.

Perfect absorption at a resonance wavelength and extremely low absorption at the wavelength range of off-resonance in a one-port optical cavity is required for refractive index (RI) sensing with high signal contrast. Here, we propose and analyze an absorption-enhanced Fabry-Perot (MAFP) cavity based on a critical coupling condition in a near-infrared wavelength range. For a one-port cavity, a thick bottom Au is used as a mirror and an absorber.

Tunable dual-wavelength absorption switch with graphene based on an asymmetric guided-mode resonance structure.

We propose a tunable dual-wavelength absorption (TDWA) switch based on an asymmetric guided mode resonance (AGMR) structure. A TDWA switch consists of a graphene layer and an AGMR structure sandwiched by cap and slab layers on a buffer/silicon substrate. The AGMR structure adds a smaller grating unit cell next to a larger one, exciting a second resonance close to but distinct from the first resonance.

Dual-guiding-layer resonance structure with an embedded metasurface for quasi-critical coupling without a perfect mirror.

We propose an all-dielectric quasi-one-port resonance structure that achieves near perfect absorption without the use of a back mirror. The structure mainly consists of a high-refractive-index silicon metasurface and surrounding high-refractive-index guiding layers. The dual-guiding-layer (DGL) structure has high background reflectance and is designed to have a ratio of two decay rates into the upper and lower regions within a wider range.

Ultrahigh-speed Si-integrated on-chip laser with tailored dynamic characteristics.

For on-chip interconnects, an ideal light source should have an ultralow energy consumption per bandwidth (operating en-ergy) as well as sufficient output power for error-free detection. Nanocavity lasers have been considered the most ideal for smaller operating energy. However, they have a challenge in obtaining a sufficient output power.

Hybrid III-V/SOI resonant cavity enhanced photodetector.

A hybrid III-V/SOI resonant-cavity-enhanced photodetector (RCE-PD) structure comprising a high-contrast grating (HCG) reflector, a hybrid grating (HG) reflector, and an air cavity between them, has been proposed and investigated. In the proposed structure, a light absorbing material is integrated as part of the HG reflector, enabling a very compact vertical cavity. Numerical investigations show that a quantum efficiency close to 100 % and a detection linewidth of about 1 nm can be achieved, which are desirable for wavelength division multiplexing applications.

Hybrid grating reflector with high reflectivity and broad bandwidth.

We suggest a new type of grating reflector denoted hybrid grating (HG) which shows large reflectivity in a broad wavelength range and has a structure suitable for realizing a vertical cavity laser with ultra-small modal volume. The properties of the grating reflector are investigated numerically and explained. The HG consists of an un-patterned III-V layer and a Si grating.

Antireflective grassy surface on glass substrates with self-masked dry etching.

Although recently developed bio-inspired nanostructures exhibit superior optic performance, their practical applications are limited due to cost issues. We present highly transparent glasses with grassy surface fabricated with self-masked dry etch process. Simultaneously generated nanoclusters during reactive ion etch process with simple gas mixture (i.

Size-dependent optical behavior of disordered nanostructures on glass substrates.

We demonstrate the distinctive optical properties of disordered nanostructures on glass substrates in accordance with changes in the average size of the nanostructures. Dissimilar sizes of nanostructures were fabricated by using different thicknesses of thermally dewetted Ag nanoparticles as etch masks. Unlike a flat glass substrate, the nanostructured glasses (NSGs) show a changed optical characteristic.

Broadband antireflective glasses with subwavelength structures using randomly distributed Ag nanoparticles.

We demonstrate broadband antireflective glasses with subwavelength structures (SWSs) using randomly distributed Ag nanoparticles. Ag nanoparticles formed by a thermal dewetting process were used as an etch mask for dry etching to fabricate antireflective SWSs on the glass surface. The size and shape of Ag nanoparticles are changed by the different thickness of the Ag thin film.

Disordered antireflective subwavelength structures using Ag nanoparticles for GaN-based optical device applications.

This study reports disordered antireflective subwavelength structures (SWS) on GaN and indium tin oxide (ITO) surfaces fabricated using thermally dewetted Ag nanoparticles. It is shown that the average diameter of Ag nanoparticles, which determines the optical characteristics, can be simply controlled by changing the thickness of the Ag thin film and the annealing temperature. The fabricated GaN and ITO SWS with tapered profile exhibited very low reflectance compared to that of a flat surface over a wide wavelength range.

Multifunctional light escaping architecture inspired by compound eye surface structures: From understanding to experimental demonstration.

We present bioinspired artificial compound eye surface structures that consist of antireflective subwavelength structures (SWSs) on hexagonally patterned microstructures (MSs), for the purpose of efficient light escaping inside light-emitting materials/devices. Theoretical understanding and geometrical optimization of SWSs on MSs are described together with rigorous coupled-wave analysis. As a proof of this concept, AlGaInP red light-emitting diodes (LEDs) with SWS/MSs were fabricated, and a light output power enhancement of 72.