Design and analysis of digital logic modules using electro-optic GaAlAs directional couplers for photonic integrated circuit implementation

This study investigates the operating principles and design of an electro-optic directional coupler (EODC) based on the electro-optic effect for optical logic applications. A comprehensive theoretical framework is presented, incorporating the fundamental mathematical relationships and coupled-mode analysis requires to characterize the switching activity of proposed optical logic devices. Utilizing this methodology, several optical digital logic circuits have been designed and analyzed, including Inverter (NOT), XOR/XNOR, OR/NOR, and NAND/AND gates. Extending this work, the integrated operation of these fundamental gates has also been investigated to realize an optical AND-OR-Inverter (AOI) cell. The proposed EODC is based on a GaAlAs material platform and employs a \:3μ\:m\:×\:3μ\:m modulator structure with a coupling length of $$\:1\:cm$$ . At an operating wavelength of $$\:900\:nm$$ , efficient switching is achieved under an applied electric field of approximately \:3×\:10⁴ V/cm, resulting in a refractive-index change of approximately \:\:n\:1×\:10⁻⁴ . In addition to logic implementation, the performance of the proposed structure has been evaluated in terms of extinction ratio, contrast ratio, and amplitude modulation characteristics. The obtained results confirm that electro-optically controlled directional couplers can effectively perform optical signal processing and serve as promising building blocks for future optical computing and high-speed digital photonic systems.