Inverse design of silicon-based photonic digital circuit components using topology optimization

The field of electronics and digital technology is constantly changing, and logic gates continue to play a crucial role in it. In this dynamic environment, photonic gates offer a variety of advantages such as signal transmission over long distances with minimal loss, compactness, and high-speed data processing. As such, photonic logic gates are paving the way for the development of photonic computing; however, their integration into high-performance systems remains a challenge. To address this problem, we proposed Silicon-photonics based analog signal optical logic operations utilizing complex interference phenomena. The study deals with the wave analysis using the finite-difference time-domain method and inverse design technique to develop topologically-optimized scalable photonic logic gates and their complex combinations. In our study, we designed the fundamental OR, AND, NOT gates and achieved a good contrast ratio greater than 17 dB in terms of the devices' transmission for the wavelength range of 1520-1600 nm. We could also demonstrate their successful integration to construct a half-adder and XOR gate. This represents a significant advancement in the search for effective photonic computing and also highlights the potential for these structures to be used as the foundation for more complex and sophisticated on-chip photonic computing architectures in the future.