We propose a new stratified waveguide grating coupler (SWGC) to couple light from a fiber at normal incidence into a planar waveguide. SWGCs are designed to operate in the strong coupling regime without intermediate optics between the fiber and the waveguide. Two-dimensional finite-difference time-domain simulation in conjunction with microgenetic algorithm optimization shows that ∼72% coupling efficiency is possible for fiber (core size of 8.3 µm and Delta=0.36%) to slab waveguide (1.2-µm core and Delta=3.1%) coupling. We show that the phase-matching and Bragg conditions are simultaneously satisfied through the fundamental leaky mode.
© 2005 Optical Society of America
(230.3120) Optical devices : Integrated optics devices
(230.3990) Optical devices : Micro-optical devices
(230.7370) Optical devices : Waveguides
(250.5300) Optoelectronics : Photonic integrated circuits
Bin Wang, Jianhua Jiang, Diana M. Chambers, Jingbo Cai, and Gregory P. Nordin, "Stratified waveguide grating coupler for normal fiber incidence," Opt. Lett. 30, 845-847 (2005)