FDTD investigation on compact and wideband optical integration between Si3N4 and Ge-based waveguide devices via amorphous Si and GeSi lateral tapers
Worawat Traiwattanapong, Kazumi Wada, Papichaya Chaisakul
Abstract
We report on the theoretical investigation and optimization of optical coupling performance between Si3N4 waveguide and Ge-based waveguide via an amorphous GexSi lateral linear taper. Different compositions of the amorphous tapers including amorphous Si (0% Ge), amorphous Ge0.60Si0.40 (60% Ge), and amorphous Ge0.83Si0.17 (83% Ge) are investigated over various telecommunication wavelength values of 1310 nm (O-band), 1410 nm (E-band), 1495 nm (S-band), 1550 nm (C-band), and 1595 nm (L-band). Si3N4 waveguide dimensions with different values of width and thickness are also studied. From the analysis, competitive optical coupling performance from the amorphous lateral tapers were found to be obtainable over the entire wavelength ranges by changing only the taper end width and length. This work demonstrates that the coupling structure can be potentially employed for low-loss wideband optical integration between two Si-based waveguide components with relatively high refractive index contrast over the entire telecommunication regions.