Tunable Microwave Phase Shifter Based on Silicon-on-Insulator Microring Resonator

We demonstrate microwave phase shifters based on electrically tunable silicon-on-insulator microring resonators (MRRs). MRRs with different quality factors are fabricated and tested. A continuously tunable phase shift of up to 336° at a microwave frequency of 40 GHz is obtained using a high-quality-factor ( ~28 000) MRR with only 1.6-mW power consumption. A quasi-linear phase shift in the range of 0° -204° at 40 GHz with a radio-frequency power variation less than 1.3 dB is also achieved by using a lower-quality-factor MRR.