On-chip optical nonreciprocal devices have always been the fundamental problems in an integrated optical communication system. Just like the diode in an electric system, it allows light to pass in a direction while blocking it in the opposite direction. Nowadays, the most integrated methods we utilize is by growing a magnetic-optic material layer on the silicon-on-insulator (SOI) wafer. While these methods are incompatible with the traditional CMOS fabrication, and the device could only operate in an external magnetic field environment. The obvious drawbacks make it be unsuitable for the trend of low consumption, low cost, compact integration optical communication system. In 2012, Qi et al demonstrated a passive optical diode on silicon-on-insulator (SOI) platform, the physical mechanism of which is the thermo-optic effect in a silicon asymmetric microring resonator (MRR). And some other works related have been reported later. In 2015, we demonstrated a pure silicon optical circulator on the basis of the thermo-optic effect in two asymmetric MRR which is compatible with CMOS fabrication well. But because of the low thermal-optic coefficient in silicon material, the input power is large and so to the power consumption. Thus, a well CMOS compatibility, simple fabrication process, low cost, compact integration and low consumption on-chip nonreciprocal device scheme is urgent to be proposed.
After a long-term research on the optomechanical effect, several researchers in Wuhan National Lab for Optoelectronics, including Prof. Xinliang Zhang, Prof. Jianji Dong, and Huaqing Qiu, etc. have put forward an optical diode based on the optomechanical effect in an asymmetric MRR. The scheme retains the advantages such as well CMOS compatibility, simple fabrication process, low cost and compact integration of our previous work. Moreover, Owning to the large red-shift of the optomechanical effect, the energy consumption is reduced obviously. Comparing to the thermo-optic effect, we increased the energy-efficiency by around 10 times.
This work has been on-line published in Optics Express on 7th April, 2017 . Relative work was supported by the National Natural Science Foundation of China (Grant No. 61622502 and 61475052). Full text can be viewed by
1 Qiu, Huaqing, et al. "Energy-efficient on-chip optical diode based on the optomechanical effect." Optics Express 25.8 (2017): 8975-8985.
Fig. 1. Theoretically analysis of optical diode based on optomechanical effect. (a) Layout of the proposed optical diode; (b) Cross-sectional view of the proposed diode; (c) Top view of the proposed diode; (d) Theoretical forward and backward propagation spectrum.