Low-power all-optical microwave filter with tunable central frequency and bandwidth based on cascaded opto-mechanical microring resonators.

Abstract

We propose and experimentally demonstrate an all-optical microwave filter with tunable central frequency and bandwidth based on two cascaded silicon opto-mechanical microring resonators (MRRs). Due to the Vernier effect, transmission spectrum of the cascaded MRRs is a series of notch bimodal distribution. In the case of intensity modulation with optical double-sideband (ODSB) signals, the optical carrier is fixed between the two resonant peaks of one notch bimodal distribution. By injecting two pump powers to control the above two resonance red-shifts based on the nonlinear effects in opto-mechanical MRRs, the frequency intervals between the optical carrier and the two resonances could be flexibly manipulated for tunable microwave processing. In the experiment, with the highest required pump powers of 1.65 mW and 0.96 mW, the central frequency and bandwidth of the notch microwave photonic filter (MPF) could be tuned from 5 GHz to 36 GHz and 6.7 GHz to 10.3 GHz, respectively. The proposed opto-mechanical device is competent to process microwave signals with dominant advantages of all-optical control, compact footprint, wide tuning range and low-power consumption, which has significant applications in on-chip microwave systems.