A brief review of integrated and passive photonic reservoir computing systems and an approach for achieving extra non-linearity in passive devices

Abstract

Photonic-based reservoir computing (RC) systems have attracted significant attention. Integrated and purely passive systems are compatible with complementary metal-oxide-semiconductor devices, but are limited by the lack of non-linear components. This study consists of two parts: firstly, a review on the published integrated and passive RC system is presented. The review focuses on the structural configuration (rather than the mathematical model) of the neural network; secondly, a new approach for achieving an integrated and passive photonic RC system is introduced and discussed. This approach employs a mode combiner in front of the reservoir to achieve an extra non-linearity in a purely passive device. Moreover, the approach is numerically investigated, and an XOR (exclusive or) task is used to test the device, and the result shows that the new approach satisfies the requirement of an RC system.