Vertical silicon nanowire-based racetrack resonator optical sensor

We propose a highly sensitive optical sensor which is built from silicon nanowires. The silicon nanowires are arranged to form a ring resonator. The silicon nanowires cladding and voids are filled with the analyte. The sensor has a small footprint of 16 μm × 16.5 μm. The insertion loss of the sensor is only 0.4 dB, while it is characterized by its high sensitivity of 430 nm/RIU. As a biosensor, our device showed a 100 nm/RIU sensitivity when a thin biolayer of 10 nm thickness is attached to the silicon nanowire structures.Open Access funding provided by the Qatar National Library. This work was made possible by a NPRP award [NPRP7456-1-085] from the Qatar National Research Fund (member of the Qatar Foundation). The statements made herein are solely the responsibility of the authors. Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.Scopu

On Chip Optical Modulator using Epsilon-Near-Zero Hybrid Plasmonic Platform

In this work, we propose a micro-scale modulator architecture with compact size, low insertion loss, high extinction ratio, and low energy/bit while being compatible with the silicon-on-insulator (SOI) platform. This is achieved through the utilization of epsilon-near-zero (ENZ) effect of indium-tin-oxide (ITO) to maximize the attainable change in the effective index of the optical mode. It also exploits the ITO layer in a hybrid plasmonic ring resonator which further intensifies the effect of the changes in both the real and imaginary parts of the effective index. By electrically inducing carriers in the indium tin oxide (ITO), to reach the ENZ state, the resonance condition shifts, and the losses of the hybrid plasmonic ring resonator increases significantly. This mechanism is optimized to maximize the extinction ratio and minimize the insertion loss. The proposed structure is designed to maximize the coupling to and from standard SOI waveguide, used as access ports. In addition, the operational region is reconfigurable by changing the bias voltage. - 2019, The Author(s).This work was made possible by a NPRP award [NPRP7-456-1-085] from the Qatar National Research Fund (member of the Qatar Foundation). The statements made herein are solely the responsibility of the authors.Scopu

Sub-Femtojoule Hybrid Plasmonic Optical Modulator

A highly compact optical modulator is proposed and analyzed. The modulator is based on the hybrid plasmonic waveguide platform. The structure of the modulator is built from silicon, silver, and electro-optical polymer layers. Hybrid plasmonic modes of symmetric and asymmetric natures excited in the structure were investigated. The symmetric mode is characterized by its lower propagation loss, so it was selected for the excitation of the device. The modulator's operation mechanism is based on the racetrack resonator configuration. Full three-dimensional electromagnetic analysis was performed around the 1.55-?m telecommunication wavelength. Different parameters such as the power coupling to the bus waveguide, the bend loss, the propagation loss, and the Q-factor of the resonances were studied in order to optimize the racetrack resonator design. The modulator is characterized by its extremely low energy consumption of 0.5 fJ/bit, high modulation depth of 10.5 dB, while the insertion losses were limited to 0.5 dB. - 2009-2012 IEEE.Manuscript received June 2, 2019; revised June 27, 2019; accepted June 29, 2019. Date of publication July 2, 2019; date of current version July 18, 2019. This work was supported by a NPRP award [NPRP7456-1-085] from the Qatar National Research Fund (member of the Qatar Foundation). Corresponding author: Mohamed A. Swillam (e-mail: [email protected])

Amplitude modulation in infrared metamaterial absorbers based on electro-optically tunable conducting oxides

A class of electro-optically tunable metamaterial absorbers is designed and theoretically investigated in the infrared regime towards realizing free-space amplitude modulators. The spacer between a subwavelength metallic stripe grating and a back metal reflector is occupied by a bilayer of indium tin oxide (ITO) and hafnium oxide (HfO 2). The application of a bias voltage across the bilayer induces free-carrier accumulation at the HfO 2/ITO interface that locally modulates the ITO permittivity and drastically modifies the optical response of the absorber owing to the induced epsilon-near-zero (ENZ) effect. The carrier distribution and dynamics are solved via the drift-diffusion model, which is coupled with optical wave propagation studies in a common finite-element method platform. Optimized structures are derived that enable the amplitude modulation of the reflected wave with moderate insertion losses, theoretically infinite extinction ratio, sub-picosecond switching times and low operating voltages. 2018, Springer-Verlag GmbH Germany, part of Springer Nature.This report was made possible by a NPRP award [NPRP 7-456-1-085] from the Qatar National Research Fund (a member of The Qatar Foundation). The statements made herein are solely the responsibility of the authors.Scopu