Ehab Awad

Checkerboard Nanoplasmonic Gold Structure for Long-Wave Infrared Absorption Enhancement

A localized nanoplasmonic induced absorption enhancement in silicon nitride (Si3N4) dielectric material using a nanoscale novel checkerboard gold (Au) structure is demonstrated. The checkerboard structure is fabricated on a Si3N4 layer using electron-beam lithography and sputter deposition techniques. The plasmonic electric field and optical absorption enhancement are measured using scanning near-field optical microscopy. Finite-difference time-domain simulations are utilized to characterize the absorption spectral response enhancement together with its dependence on incidence angle and polarization. The checkerboard shows a broadband average spectral absorption enhancement of 63.2% over the wavelength range 8-12 μm with a maximum enhancement of 107% at 8 μm and a minimum enhancement of 24.8% at 12 μm. The degradation of enhanced absorption with incidence angle variation (00-60ο) is less than 1.6% at 10.6-μm wavelength. The checkerboard device shows polarization-independent absorption enhancement with incidence angles.

Comparison of V 2 O 5 Microbolometer Optical Performance Using NiCr and Ti Thin-Films

The optical performance characteristics of vanadium-oxide microbolometer with on-top nichrome (NiCr) thin-film metal absorber layer are evaluated using numerical simulations. A thin-film NiCr metal is sputter deposited and its optical parameters are experimentally characterized over the long-wave infrared (LWIR) range 8-

Multicore optical fiber Y-splitter.

12~\mu

Fabrication and design of vanadium oxide microbolometer

m. The optical performance of microbolometer with NiCr has been compared with titanium (Ti) and without any metal thin-film. The comparison indicates that the optical absorption response of NiCr device is nearly flat and has a broadband enhancement over the LWIR range. In addition, it shows large insensitivity to variations in air-gap and metal thin-film thickness, which permits for a large fabrication tolerance. In addition, the optimized air-gap devices show that the NiCr-based device has the smallest air-gap thickness, which can lead to short leg-length and mechanically robust device.

Space-Division Y-Splitter for Multicore Optical Fibers

In future high capacity multicore optical fiber (MCF) networks, signal-processing devices should be able to manipulate data without sacrificing network capacity or MCFs advantages. Thus, it is crucial to have high performance novel devices that can be connected directly to MCFs without conversion to conventional single-core fibers. In this work, a novel Y-splitter for multicore optical fibers is proposed and numerically demonstrated for the first time. The splitter can directly split the power of input MCF cores by 50/50 splitting-ratio into two output MCFs cores. The splitter principle of operation mainly depends on novel double-hump graded-index (DHGI) profile that can space-division split (SDS) optical power by half. Both finite-difference-time-domain and eigenmode-expansion simulations are performed to design, verify, and characterize performance of Y-splitter. It shows wideband operation over the S, C, L, U-bands with polarization insensitivity. It also demonstrates high performance with reasonable insertion-loss, in addition to very low excess-loss and return-loss. Moreover, the splitter shows good performance tolerance to both MCF and design parameters variations.

Design and optimization of microbolometer multilayer optical cavity

Vanadium oxide (VxOy) multilayer sandwich structures previously studied by our group were found to yield a sensitive thermometer thin film material suitable for microbolometer applications. In this work, we aim to estimate the performance of a proposed air-bridge microbolometer configuration based on VxOy multilayer sandwich structure thermometer thin films. For this purpose, a microbolometer was fabricated on silicon (Si) substrate covered with a silicon nitride (Si3N4) insulating layer using VxOy thermometer thin film material. The fabricated microbolometer was patterned using electron-beam lithography and liftoff techniques and it was characterized in terms of its voltage repsonsivity (Rv), signal to noise ratio (SNR), noise equivalent power (NEP) and detectivity D*. A model was then developed by the aid of numerical optical/thermal simulations and experimentally measured parameters to estimate the performance of the microbolometer when fabricated in an air-bridge configuration. The estimated D* was fo...

Electrical and Infrared Optical Properties of Vanadium Oxide Semiconducting Thin-Film Thermometers

A Novel multicore-fiber Y-splitter is numerically demonstrated. It can space-division split input multicore-fiber power by 50:50 into two output multicore-fibers. The splitter shows high performance and wideband operation over S, C, L, U-bands with polarization-insensitivity.

Data interchange across cores of multi-core optical fibers

Microbolometers are the most widely used detectors in long-wave infrared uncooled thermal imagers. An optical cavity is required within a microbolometer structure to increase its optical absorption. In this work we present a detailed study on the design and optimization of a microbolometer optical cavity using Essential-Macleod package. In the simulations, the cavity is considered as thin film multi-layers that form cascaded Fabry-Perot optical cavities. In the design phase, the layers structures are selected including materials and initial thickness. The absorbing layers are chosen to be vanadium-pentoxide (V2O5) and titanium (Ti). In the optimization phase, the designed layer thicknesses are varied to maximize optical absorption within the absorbing layers. The simulations show that Ti layer absorption dominates over V2O5 layer. Also, the optimization proves that the air-gap cavity thickness is not simply quarter-wavelength because of the complex cascaded Fabry-Perot structure. The optimized air-gap thi...