Photonic integrated circuit with multiple waveguide layers for broadband high-efficient 3D OPA.

The traditional photonic integrated circuit (PIC) inherits the mature CMOS fabrication process from the electronic integrated circuit (IC) industry. However, this process also limits the PIC structure to a single-waveguide-layer configuration. In this work, we explore the possibility of the multi-waveguide-layer PIC by proposing and demonstrating a 3D optical phased array (OPA) device, with the light exiting from the edge of the device, based on multi-layer SiN/SiO stacks.

Phase-combining unit for aliasing suppression in an optical phased array.

Integrated optical phased array (OPA) devices have been widely studied as a solution for solid-state light detection and ranging technology in the autonomous driving application. In this work, a phase-combining unit (PCU) is proposed and studied. With a given number (N) of phase shifters, instead of the general N (phase shifters) to N (emitters) control, the PCU can enable an N to 2N-1 control, which efficiently suppresses the aliasing effect.

Optimization of aperiodic 3D optical phased arrays based on multilayer SiN/SiO platforms.

Silicon-based optical phased arrays (OPAs) have been widely explored, while the design of the structure with high sidelobe level reduction, remains a big challenge. This work investigated the optimization of the optical path-modulated 3D OPAs with as the core layer and as the cladding layer. We used the particle swarm optimization algorithm to optimize high-performance random distributed OPAs.

Optimization of the silicon-based aperiodic optical phased array antenna.

Beam engineering is one of the most important functionalities in light detection and ranging (LiDAR). In this work, a silicon optical phased array (OPA) is employed to control the beam profile. Machine-learning-based genetic algorithm optimization is utilized to suppress the sidelobes of the far field pattern assuming the random distribution of aperiodic arrays.

Light Trapping in Single Elliptical Silicon Nanowires.

Light trapping in single nanowires (NWs) is of vital importance for photovoltaic applications. However, circular NWs (CNWs) can limit their light-trapping ability due to high geometrical symmetry. In this work, we present a detailed study of light trapping in single silicon NWs with an elliptical cross-section (ENWs).

Off-Resonant Absorption Enhancement in Single Nanowires via Graded Dual-Shell Design.

Single nanowires (NWs) are of great importance for optoelectronic applications, especially solar cells serving as powering nanoscale devices. However, weak off-resonant absorption can limit its light-harvesting capability. Here, we propose a single NW coated with the graded-index dual shells (DSNW).

High-efficiency end-fire 3D optical phased array based on a multi-layer SiN/SiO platform.

Beam-steering devices such as optical phased arrays (OPAs) are key components in the applications of solid-state Lidar and wireless communication. The traditional single-layer OPA results in a significant energy loss due to substrate leakage caused by the downward coupling from the grating coupler structure. In this work, we have investigated a structure based on a multi-layer ${\rm Si}_{3}{\rm N}_{4}/{\rm SiO}_{2}$SiN/SiO platform that can form a 3D OPA to emit light from the edge of the device with high efficiency; a 2D converged out-coupling beam will be end-fired to the air.

Compound period grating coupler for double beam generation and steering.

Grating couplers are one of the most basic integrated photonic structures. They have raised tremendous research interest due to their outstanding performance in compact nonmechanical beam steering. Here we propose a new compound period grating coupler formed by combining two grating structures with different periodicities.

Controllable Biosynthesis and Properties of Gold Nanoplates Using Yeast Extract.

Abstract: Biosynthesis of gold nanostructures has drawn increasing concerns because of its green and sustainable synthetic process. However, biosynthesis of gold nanoplates is still a challenge because of the expensive source and difficulties of controllable formation of morphology and size. Herein, one-pot biosynthesis of gold nanoplates is proposed, in which cheap yeast was extracted as a green precursor.

Orthogonal and parallel lattice plasmon resonance in core-shell SiO(2)/Au nanocylinder arrays.

Height induced coupling behavior between the plasmonic modes and diffraction orders were studied in the core-shell SiO(2)/Au nanocylinder arrays (NCAs) using finite difference time domain (FDTD) simulations. New lattice plasmon modes (LPMs) are observed in the structures with high aspect ratio. Specifically, parallel coupling between the plasmonic modes and diffraction orders is obtained here, which shows different coupling behavior from orthogonal LPMs.

Lattice plasmon resonance in core-shell SiO₂/Au nanocylinder arrays.

Core-shell SiO2/Au nanocylinder arrays (NCAs) are studied using finite-difference time-domain simulations. The increase of height induces new surface plasmon resonances along the nanocylinders, i.e.

Giant light extraction enhancement of medical imaging scintillation materials using biologically inspired integrated nanostructures.

We have utilized biologically inspired (bio-inspired), moth-eye nanostructures and further improved this biomimetic structure to enhance the scintillator materials external quantum efficiency significantly. As a proof of concept, we have demonstrated very high light output efficiency enhancement for Lu(2)SiO(5):Ce(3+) (LSO:Ce) film in large area, the X-ray mammographic instrument was employed to demonstrate the light output enhancement of the Lu(2)SiO(5):Ce thin film with biologically inspired (bio-inspired) moth-eye-like nanophotonic structures. Our work could be extended to other thin film scintillator materials and is promising to achieve lower patient dose, higher resolution images of human organs and even smaller scale medical imaging.

Position-independent normal-mode splitting in cavities filled with zero-index metamaterials.

We study the normal-mode splitting when an oscillator is placed in a two-dimensional photonic crystal microcavity embedded with an impedance-matched or an impedance-mismatched zero-index medium (ZIM). Because of the (nearly) uniform localized fields in the ZIM, the normal-mode splitting remains (almost) invariant no matter where the oscillator is. When a split ring resonator is coupled to a transmission-line- based effective ZIM at various locations, nearly position-independent mode splitting is observed.

Defect-induced whispering-gallery-mode resonances in optical microdisk resonators.

In this Letter we present results of theoretical and experimental studies of whispering-gallery modes in optical microdisk resonators interacting with subwavelength dielectric particles. We predict theoretically and confirm by direct observations that, contrary to the generally accepted models, both peaks of the particle-induced doublet of resonances are redshifted with respect to the position of the initial resonance.

Metallic nanoparticle on micro ring resonator for bio optical detection and sensing.

We have numerically investigated the unique effects of metallic nanoparticle on the ring resonator, especially multiple Au nanoparticles on the micro ring resonator with the 4-port configuration on chip. For the Au nanoparticle, because it has smaller real refractive index than air and large absorption refractive index, we found that there is a blue shift for the ring resonance wavelength, instead of red shift normally observed for dielectric nanoparticles. The drop port intensity is strongly dependent on both number and size of nanoparticles, while relatively independent on position of nanoparticles.

On-chip Si-based Bragg cladding waveguide with high index contrast bilayers.

A new silicon based waveguide with full CMOS compatibility is developed to fabricate an on-chip Bragg cladding waveguide that has an oxide core surrounded by a high index contrast cladding layers. The cladding consists of several dielectric bilayers, where each bilayer consists of a high index-contrast pair of layers of Si and Si3N4. This new waveguide guides light based on omnidirectional reflection, reflecting light at any angle or polarization back into the core.