Optically Tunable Delay Line in Silicon Microring Resonator Based on Thermal Nonlinear Effect

We experimentally demonstrate optically tunable delay line in a silicon microring resonator with a 20- m radius. The delay-tuning mechanism is based on the red shift of the resonance induced by thermal nonlinear effect. We investigate the delay performance of three modulation formats-non-return-to-zero (NRZ), return-to-zero (RZ), and differential phase-shift keying (DPSK) signals at different data rates. Tunable delay is achieved by controlling the power of the continuous-wave (CW) pump with very low tuning threshold, which could be used in microring-resonator-based slow-light structure.