High-performance optical 3 bit Gray-code counter using T-flip-flop circuits with GaAlAs directional couplers

This work presents the design and performance analysis of a high-performance optical 3 bit Gray-code counter that employs electro-optic modulation using GaAlAs directional couplers. The developed system comprises a mix of T-flip flops and directional couplers for optical logic operations and state transitions. The miniaturized layout design leverages the electro-optical concept to modulate signals with sufficient efficiency, resulting in an all-photonic synchronous counter. The functioning of the structure is fully explained using K-map-based Boolean logic synthesis to generate the required conditions for the flip flops used in the system. The suggested device configuration consists of GaAlAs material designed with a 3µm×3µm modulator. The coupling length (L_C) of the device is set at L_C=1cm. The EODC achieves optimal switching at a light wavelength of 900nm by inducing a refractive index shift (Δn) of approximately Δn≅1×10^-4. The required electric field magnitude of approximately 3×10⁴V/cm to perform optical switching is transformed into a voltage of 10 V placed across the electrodes of the EODC along the 3 µm channel. The counter operation is established using simulation results, including 3D MATLAB simulations and temporal simulations of counter state changes. This work presents a comprehensive analysis of the extinction ratio, contrast ratio, and amplitude modulation characteristics of the proposed optical 3 bit Gray-code converter circuit. These findings have gained wide appeal due to their low circuit complexity and faster circuit design compared to electrical circuits.