Compact, submilliwatt, 2 × 2 silicon thermo-optic switch based on photonic crystal nanobeam cavities

We propose and experimentally demonstrate a 2×2 thermo-optic (TO) crossbar switch implemented by dual photonic crystal nanobeam (PCN) cavities within a silicon-on-insulator (SOI) platform. By thermally tuning the refractive index of silicon, the resonance wavelength of the PCN cavities can be red-shifted. With the help of the ultrasmall mode volumes of the PCN cavities, only ∼0.16  mW power is needed to change the switching state. With a spectral passband of 0.09 nm at the 1583.75 nm operation wavelength, the insertion loss (IL) and crosstalk (CT) performances were measured as IL(bar)=−0.2  dB, CT(bar)=−15  dB, IL(cross)=−1.5  dB, and CT(cross)=−15  dB. Furthermore, the thermal tuning efficiency of the fabricated device is as high as 1.23 nm/mW.