Special Issue Article
Li Liu
Abstract
Nano-structure passive optical diodes are highly desirable for on-chip optical signal processing, such as optical computing and logic gates. Recently, the high-power consumption (~10 dBm) and low nonreciprocal transmission ratios (NTRs) (<30 dB) of the most demonstrated optical diodes limit their practical applications for optical signal processing. Therefore, to pursue high reliability and low system cost, it is still highly desirable to realize optical diodes with low-power consumption and high NTRs. In our experiment, we demonstrate a passive nano-mechanical optical diode based on cascaded opto-mechanical microring resonators (MRRs). Due to the enhanced inelastic interaction between the photons and the nano-mechanical MRR, the opto-mechanical devices could be effectively driven by the optical force. Therefore, the forward and backward transmissions of the integrated optical diode could be flexibly manipulated based on the nonlinear opto-mechanical effect, which could be effectively excited by ultra-low input powers. With injecting an ultra-low optical power of -3.1 dBm, a high NTR of 45.3 dB and a relatively broad operation bandwidth are achieved. 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, a relatively broad 30-dB bandwidth and compact footprint, which has significant applications for on-chip optical computing and logic gates.