Open AccessTwo-dimensional grating coupler on silicon with a high coupling efficiency and a low polarization-dependent loss
Author(s) -
B Chen,
X Zhang,
Jianping Hu,
Yuntao Zhu,
Xinlun Cai,
P Chen,
L Liu
Publication year - 2020
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.380338
Subject(s) - grating , optics , coupling loss , materials science , polarization (electrochemistry) , wavelength , insertion loss , coupled mode theory , optoelectronics , coupling (piping) , photonic integrated circuit , photonics , optical fiber , refractive index , physics , chemistry , metallurgy
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.