All-optical 2-bit decoder based on a silicon waveguide device for BPSK-modulated signals

Abstract

Optical computing technology has gained attention as a solution to address the computational latency caused by the resistance-capacitance (RC) delay in processors based on complementary metal-oxide-semiconductor (CMOS). However, many optical computing technologies tend to rely on nonlinear effects, resulting in an increase in the device length and input light intensity to enhance nonlinear efficiency. This study proposed what we believe is a new optical decoder device based on linear effects. The device was composed of two cascaded delay-line interferometers (DLIs) made of a silicon waveguide. Targeting 2-bit binary phase-shift keying (BPSK) signals, it outputs ON state for a specific bit pattern by setting different phase conditions. The experimental results confirmed the functionality of the device, including measurements of the impulse response, evaluation of the phase-shift conditions, and successful decoding operations for a signal at 10 Gbps. The proposed decoder, which does not rely on nonlinear effects, offers advantages in terms of low latency and power consumption.