Silicon Optical Diode Based on Cascaded Opto-Mechanical Microring Resonators

We propose and experimentally demonstrate a silicon optical diode with high nonreciprocal transmission ratio (NTR) based on three cascaded opto-mechanical microring resonators (MRRs). As half waveguides of the opto-mechanical MRRs are free-hanging, the nonlinear effects (including the thermo-optic effect and opto-mechanical effect) are both enhanced. With low input powers, the transmission characteristics of the opto-mechanical MRRs could be flexibly manipulated by the strong nonlinear effects. More importantly, due to the optimized design of the cascaded MRRs, the NTRs are improved. In the experiment, a high NTR is successfully obtained with a low input power. The proposed optical diode provides a complementary metal-oxide semiconductor (CMOS) compatible solution for on-chip nonreciprocal transmission with dominant advantages of high NTRs, low-power consumption and compact size, which has many significant applications in on-chip optical computing and logic gates.