Adiabatic guided wave optics – a toolbox of generalized design and optimization methods

Abstract

Starting from the fully vectorial coupled local-mode theory, a general design rule for adiabatic waveguide design is derived. The design rule guarantees adiabaticity and puts an upper limit on the transmission loss of any guided wave transformation. The rule is applicable to any waveguide geometry, admits multi-dimensional optimization, and accounts for radiative loss to guided and radiation modes. Moreover, the design technique is enhanced with further optimization procedures that eliminate coupling between particular pairs of modes. The utility of this toolbox of design rules and methods is illustrated through the design of a 2×2 coupler and a bilayer waveguide transition. These design procedures can be used to optimize single-mode and multimode photonic devices by varying one or more waveguide parameters.