Next-generation high-performance complex optical sequential circuits: an electro-optic modulation in GaAlAs directional couplers

The concept of optical switching utilizing directional couplers and the electro-optic effect has been leveraged to design various sequential circuits. By applying an appropriate voltage to the core of the couplers, switching of optical pulse signals is achieved through optical tunneling phenomena. This paper presents a comprehensive mathematical analysis of electro-optic effect-based switching, demonstrating its efficacy through 3-D MATLAB simulations of the optical switch layout. A clocked D flip-flop, incorporating an optical delay unit, is examined using 3-D numerical simulations, illustrating the spatial propagation of optical pulses and providing time domain plots for verification. Employing the proposed clocked D flip-flop as a basic module, optically clocked ripple up/down-counters are implemented. Additionally, the design and analysis of an optical 4-bit shift register are discussed, showcasing its ability to effectively shift pulses via 3-D simulations of optical field propagation and time domain plots. This study presents a comprehensive analysis of the extinction ratio, contrast ratio, and amplitude modulation characteristics of the proposed optical code converter circuit. These findings offer an effective methodology for implementing both basic sequential models and complex optical circuits.