Low-Loss MEMS Phase Shifter for Large Scale Reconfigurable Silicon Photonics

We experimentally demonstrate a silicon MEMS phase shifter achieving more than $\pi$ phase shift with sub-dB insertion loss (IL). The phase is tuned by reducing the gap between a static suspended waveguide and a free silicon beam, via comb-drive actuation. Our device reaches $1.2\pi$ phase shift at only 20 V, with only 0.3 dB insertion loss – an order of magnitude improvement over previously reported MEMS devices. The device has a small footprint of $50\times 70\ \mu \mathrm{m}^{2}$ and its power consumption is 5 orders of magnitude lower than that of traditional thermal phase shifters. Our new phase shifter is a fundamental building block of the next-generation large scale reconfigurable photonic circuits which will find applications in datacenter interconnects, artificial intelligence (AI), and quantum computing.