Design and simulation of apodized SOI fiber to chip coupler by sub-wavelength structure

We report on a design and simulation of silicon on insulator apodized surface diffraction grating fiber to chip coupler by sub-wavelength structure, which is compatible with 193 nm laser DUV lithography. The structure of simulated fiber to chip coupler consists of relatively large tapered segment which adjusts cross-section of silicon on insulator wire single mode waveguide to standard single mode fiber diameter and surface diffraction grating with sub-wavelength structure for vertical coupling to the fiber. The simulation of the fiber to chip coupler is performed by FDTD tool. Four types of surface diffraction grating apodization by sub-wavelength structure are designed and simulated and simulation results of coupling effects for each apodization of surface diffraction grating are compared.