Efficient Chip-to-Chip Silicon Grating Coupler With High Alignment Tolerance at O-Band

We theoretically investigate an O-band efficient and tolerant chip-to-chip silicon grating coupler with the bottom reflector. The coupling efficiency is increased greatly with the added bottom reflector, reaching a coupling efficiency of 91.2% (−0.4dB) at 1316 nm wavelength. The 3-dB alignment tolerance in the x direction of 23 $\mu$m and 3.5-dB tolerance exceeding 35 $\mu$m are achieved thanks to the waveguiding effect constructed by two reflectors.