Two-dimensional grating coupler on silicon with a high coupling efficiency and a low polarization-dependent loss

Authors:
  • BCbin Chen
    bin Chen
  • XZXian Zhang
    Xian Zhang
  • JHJinyao Hu
    Jinyao Hu
  • YZYuntao Zhu
    Yuntao Zhu
  • XCXinlun Cai
    Xinlun Cai
  • PCPengxin Chen
    Pengxin Chen
  • LLLiu Liu
    Liu Liu
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Abstract
Two-dimensional grating couplers are important components for silicon photonic circuits to achieve light coupling from/to a fiber for both polarizations. A two-dimensional grating coupler structure with a high coupling efficiency and a low polarization dependent loss is demonstrated. Using two crossing ellipses as the grating scatter and a diamond-like grating lattice, the polarization dependent loss of the grating coupler can be reduced. The coupling loss is further decreased with a metal mirror, which reaches −1.73 dB theoretically at 1310 nm wavelength. Experimentally, −2.37 dB coupling loss is achieved with an 1 dB coupling bandwidth of 29 nm. The corresponding PDL was measured lower than 0.2 dB in a wavelength range of 78 nm. The proposed configuration for the metal mirror also facilitates a robust wafer-scale post-processing as well as an easy fiber alignment.
Funding Information
  • National Major Research and Development Program (2018YFB2200200)
  • Guangzhou Science and Technology Program (201707010444)
  • Special Funds for the Cultivation of Guangdong College Students’ Scientific and Technological Innovation
  • National Natural Science Foundation of China (61675069)

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