Mohamed Abdel-Rahman

Design, Optimization and Fabrication of a 28.3 THz Nano-Rectenna for Infrared Detection and Rectification

The increasing energy demands of the worlds population and the quickly diminishing fossil fuel reserves together suggest the urgent need to secure long-lasting alternative and renewable energy resources. Here, we present a THz antenna integrated with a rectifier (rectenna) for harvesting infrared energy. We demonstrate a resonant bowtie antenna that has been optimized to produce highly enhanced localized fields at the bow tip. To benefit from this enhancement, the rectifier is realized between the overlapped antennas arms using a 0.7 nm copper oxide. The thin film diode offers low zero bias resistance of 500 Ω, thus improving the impedance matching with the antenna. In addition, the rectenna prototype demonstrates high zero bias responsivity (4 A/W), which is critical in producing DC current directly from THz signals without the application of an external electric source, particularly for energy harvesting applications.

Design, fabrication, and characterization of antenna-coupled metal-oxide-metal diodes for dual-band detection

Two designs for antenna-coupled Ni-NiO-Ni diodes are fabricated and tested for dual-band detection in the millimeter-wave (MMW), 94-GHz, and infrared (IR), 28.3-THz, frequencies. The detector noise, antenna receiving properties, and noise equivalent power (NEP) are measured. The simultaneous dual-band response is verified.

Antenna-coupled MOM diodes for dual-band detection in MMW and LWIR

An antenna-coupled metal-oxide-metal (MOM) diode for dual-band Infrared (IR)-millimeter wave (MMW) detection is presented. Electron-beam lithography and conventional sputtering techniques were used to fabricate a Ni-NiO-Ni diode coupled to an Infrared slot antenna at 28 THz and a coplanar waveguide (CPW)-fed MMW twin slot antenna at 94 GHz; simultaneous dual-band detection was tested and verified.

Choice of flap affects fistula rate after salvage laryngopharyngectomy.

Due to the significant morbidity and mortality associated with pharyngocutaneous fistula in pharyngoesophageal reconstruction following cancer resection, the purpose of this retrospective study is to examine the selection of tubed skin flaps that impact anastomotic integrity. The flaps evaluated included radial forearm flap versus anterolateral thigh flap, and fasciocutaneous anterolateral thigh flap versus chimeric anterolateral thigh flap. The outcome of interest is the incidence of pharyngocutaneous fistula. The radial forearm group had a significantly higher rate of fistula than the anterolateral thigh group (56.6% vs. 30.2%, p = 0.03). No significant difference in the incidence of fistula was demonstrated between fasciocutaneous and chimeric anterolateral thigh flap (36.8% vs. 25%, p = 0.51). The anastomotic integrity in pharyngoesopharyngeal reconstruction is affected by choice of skin flaps. Anterolateral thigh flap appears to be a viable option for pharyngoesophageal reconstruction. The more technical demand of the anterolateral thigh flap must be weighed against an easily harvested radial forearm flap.

Performance Investigations of Quasi-Yagi Loop and Dipole Antennas on Silicon Substrate for 94 GHz Applications

This paper introduces the design and implementation of two high gain Quasi-Yagi printed antennas developed on silicon substrate for 94 GHz imaging applications. The proposed antennas are based on either driven loop or dipole antennas fed by a coplanar waveguide (CPW) feeding structure. For better matching with the driven antennas, a matching section has been added between the CPW feedline and the driven antenna element. To improve the gain of either loop or dipole antennas, a ground reflector and parasitic director elements have been added. Two Quasi-Yagi antenna prototypes based on loop and dipole antenna elements have been fabricated and experimentally tested using W-band probing station (75–110 GHz). The measured results show good agreement with simulated results and confirm that the proposed antennas are working. In addition, a feed and matching configuration is proposed to enable coupling a microbolometer element to the proposed Quasi-Yagi antenna designs for performing radiation pattern measurements.

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.

Wavelength tuning of an antenna-coupled infrared microbolometer

Wavelength tuning is demonstrated in an antenna-coupled infrared microbolometer. With a 300-mV control voltage, we observed a tuning range of 0.15 μm near 10 μm. A metal-oxide-semiconductor capacitor underneath the antenna arms causes the shift of resonance wavelength with applied voltage. We develop a device model that agrees with measured results.

Thermal annealing induced multiple phase in V/V2O5 alternating multilayer structure

In this paper, we report on microstructural, optical and electrical properties of alternating multilayer of vanadium pentoxide (V2O5), 25 nm, and vanadium (V), 5 nm, thin films deposited at room temperature by radio frequency (RF) and DC magnetron sputtering, respectively. Raman and photoluminescence (PL) spectroscopy have been employed to investigate the effects of thermal annealing for 20, 30 and 40 min at 400∘C in Nitrogen (N2) atmosphere on the multiple phase formation and its impact on the film resistance and temperature coefficient of resistance (TCR). We demonstrate that the oxygen free annealing environment allows the formation of multiple phases including V2O5, V6O13 and VO2 through oxygen diffusion and consequent deficiency in V2O5 layer.

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-

Characterization of a wavelength-tunable antenna-coupled infrared microbolometer

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