High-efficiency reflector-less dual-level silicon photonic grating coupler
Valerio Vitali, Thalía Domínguez Bucio, Cosimo Lacava, R. Marchetti, Lorenzo Mastronardi, Teerapat Rutirawut, Glenn Churchill, Joaquín Faneca, James C. Gates, Frédéric Y. Gardes, Periklis Petropoulos
Abstract
We present the design and experimentally demonstrate a dual-level grating coupler with subdecibel efficiency for a 220 nm thick silicon photonics waveguide which was fabricated starting from a 340 nm silicon-on-insulator wafer. The proposed device consists of two grating levels designed with two different linear apodizations, with opposite chirping signs, and whose period is varied for each scattering unit. A coupling efficiency of −0.8 dB at 1550 nm is experimentally demonstrated, which represents the highest efficiency ever reported in the telecommunications C-band in a single-layer silicon grating structure without the use of any backreflector or index-matching material between the fiber and the grating.