Low-loss and high stability standard single mode fiber edge couplers for silicon photonics

Efficient optical coupling between standard single mode fibers and nanophotonic waveguides has been recognized as a major practical challenge since the early years of photonics. In this work, a low-loss and wide band edge coupler based on subwavelength gratings (SWG) for standard single mode fibers is proposed and demonstrated on 220 nm SOI platform. The edge coupler has a minimum feature size of 130 nm and a 630-m length, which was fabricated in CUMEC’s 200 mm CMOS production facilities. The best coupling losses are 1.60 and 1.95 dB for TE and TMin1500-1600 nm wavelength range, respectively, achieving a minimum PDL of 0.2 dB at 1500 nm. Moreover, by taking advantage of SiN-on-Si integrated process and wafer bonding process, the edge coupler exhibits high process and package reliability, making it attractive for the commercial application.