An Efficient Silicon Grating Coupler for a 2 mu m Waveband Based on a Polysilicon Overlay

The short-wavelength mid-infrared spectral range of the 2 mu mwaveband has the advantages of low transmission loss and broad gain bandwidth, making it a promising candidate for the next optical fiber communication window. It is thus highly desired to develop high-performance silicon photonic components in this waveband. Here, an efficient dual-layer grating coupler was designed on a 220 nm thick silicon-on-insulator based on raised polysilicon to address the low directionality issue. For the fiber tilted at an angle of 10 degrees, the grating coupler's simulated coupling efficiency reaches 80.3% ( 0.95 dB) at a wavelength of 2002 nm. The 1 dB bandwidth is 66 nm. The structure is completely compatible with the standard silicon photonic fabrication process, making it suitable for large volume fabrication.