Ultracompact 2×2 directional coupling optical switch with Si waveguides and phase-change material

We reported an ultracompact 2×2 directional coupling optical switch with Si waveguides and phase-change material. Switching operation was successfully demonstrated by 3-D FDTD method. The loss of 0.5 dB and the crosstalk of -20.5 dB were achieved for the cross-state. The loss of 3.0 dB and the crosstalk of -7.8 dB were achieved for the bar-state.