Si-wire grating couplers for integrated optical transceivers based on single-mode fiber connection

Recently, grating couplers (GCs) have been extensively reported as a promising device for optical coupling between Si-wire waveguides and standard single mode optical fibers. In this paper, we report the feasibility study of Si-wire type GCs fabricated by the 248-nm KrF lithography process on a 200-mm silicon-on-insulator (SOI) wafer with a 220-nm-thick Si layer. We report a 1D-GC for a transmitter that operates only with TE mode and a 2D-GC for a receiver that splits arbitrary polarization from a single mode fiber operating at a wavelength of 1550 nm. We investigated the fundamental feasibility with the simple design. Especially, the wafer uniformity in inter-dies of 1D and 2D-GC is mainly examined on a 200-mm SOI wafer. Additionally, we experimentally clarify the fundamental characteristics of the 1D-GC from the viewpoint of an insertion loss and a 1-dB fiber misalignment tolerance. As for the 2D-GC, in addition to the same aspects with the 1D-GC, an optical crosstalk and a polarization dependent loss will also be discussed around 1550 nm wavelength. Also, the center wavelength against a grating period of the 1D-GC and a circular hole diameter of the 2D-GC will be characterized.