Reducing bend-induced loss and crosstalk in a two-mode ridge waveguide by steplike thickness structuring.

This study demonstrated that two-step structuring of the waveguide thickness in a bent section significantly reduces bend-related inter-mode crosstalk, excess loss, and pure bending loss. A simple analytical formula was derived linking the thickness change required to compensate for bend-induced effects with geometrical parameters of the waveguide and bending radius. The effectiveness of the proposed approach was verified through rigorous numerical simulations of the loss and inter-mode crosstalk based on transformation optics formalism. The numerical results obtained for a : medium index contrast waveguide exhibited significant improvement of all relevant parameters for and modes.