We design and fabricate an ultrahigh coupling efficiency (CE) fully etched apodized grating coupler on the silicon- on-insulator (SOI) platform using subwavelength photonic crystals and bonded aluminum mirror. Fabrication error sensitivity andcoupling angle dependence are experimentally investigated. A recordultrahighCE of − 0 . 58 dB with a 3 dB bandwidth of 71 nm and low back reflection are demonstrated.
Optics Letters, 2014, Vol 39, Issue 18, p. 5348-50