Shouyuan Shi

Three-dimensional analysis of subwavelength diffractive optical elements with the finite-difference time-domain method

We present a three-dimensional (3D) analysis of subwavelength diffractive optical elements (DOEs), using the finite-difference time-domain (FDTD) method. To this end we develop and apply efficient 3D FDTD methods that exploit DOE properties, such as symmetry. An axisymmetric method is validated experimentally and is used to validate the more general 3D method. Analyses of subwavelength gratings and lenses, both with and without rotational symmetry, are presented in addition to a 2 x 2 subwavelength focusing array generator.

Engineering dispersion properties of photonic crystals for spatial beam routing and non-channel waveguiding

In this research we present various implementations of novel photonic devices using photonic crystals, by engineering the dispersive properties of these periodic structures . Applications such as spatial beam routing, and non-channel waveguiding can be attained through careful optimization of various Equi-Frequency Contours (EFC).

High fill factor RF aperture arrays for improved passive, real-time millimeter wave imaging

Sensors operating in the millimeter wave region of the electromagnetic spectrum provide valuable situational awareness in degraded visual environments, helpful in navigation of rotorcraft and fixed wing aircraft. Due to their relatively long wavelength, millimeter waves can pass through many types of visual obscurants, including smoke, fog, dust, blowing sand, etc. with low attenuation. Developed to take advantage of these capabilities, ourmillimeter wave imager employs a unique, enabling receiver architecture based on distributed aperture arrays and optical upconversion. We have reported previously on operation and performance of our passive millimeter wave imager, including field test results in DVE and other representative environments, as well as extensive flight testing on an H-1 rotorcraft. Herein we discuss efforts to improve RF and optical component hardware integration, with the goal to increase manufacturability and reduce c-SWaP of the system. These outcomes will allow us to increase aperture sizes and channel counts, thereby providing increased receiver sensitivity and overall improved image quality. These developments in turn will open up new application areas for the passive millimeter wave technology, as well as better serving existing ones.

Fabrication of Large Area “Woodpile” Photonic Crystal Structures for Near IR

We have fabricated large area 3D polymer photonic crystals by modifying planar lithography to achieve exposure confinement and multiple resist application. This fabrication process allows arbitrary defect introduction and is suitable for batch fabrication.

Fabrication of Large Area Polymer-Based 3D Photonic Crystals

Polymer based photonic crystals are ideal candidates for applications relying on engineering the dispersive properties of those periodic structures. We present a process for fabricating arbitrary large area 3D photonic crystal structures in polymers.

Engineering Dispersive Properties of Polymer-Based Photonic Crystals

We present practical lattice configurations and devices built from low-index polymers and detail our work in fabricating these devices. These techniques allow for the creation of a variety of novel PhCs for new applications areas.

Design, Fabrication and Application of Three Dimensional Dispersion Engineered Photonic Crystal Devices

Three-dimensional self-collimation and subwavelength-imaging by full 3D negative refraction were experimentally demonstrated by 3D dispersion engineering. The experiment realized microwave electromagnetic trapping and manipulation of neutral particles using the full 3D negative-refraction flat lens.

Characterization of photonic crystal coupled waveguides

In this research, we present an analysis of coupled photonic crystal (PhC) waveguides. Fabricated planar PhC coupled waveguides are characterized and experimental results are presented. Applications for PhC directional couplers include frequency selective filters, dispersion compensators, and optical switches.