Novel design concept of waveguide mode adapter for low-loss mode conversion

We proposed a novel design concept of a mode adapter using a new parameter. The overlap integration of two adjacent mode profiles is defined as a sing le step loss (SSL) parameter for the characterization of optical mode confi nement as well as the quantification of mode mismatch. The variation of SSL is described with two parameters. These parameters are V, a normalized fre quency, and s, a differential width variation ratio. The contour for consta nt SSL in the V, s plane provides the optimized s curve as a function of V, The design concept with this constant SSL is shown to provide optimized ad apters of minimized conversion loss.