Electromagnetic analysis of waveguide Bragg reflectors

Bragg gratings are used extensively in fiber and integrated optics as, e.g., input/output couplers and semiconductor-laser mirrors. Typically these devices are analyzed using coupled-mode methods,which are reasonably accurate at least for weakly modulated structures. However, such methods can not model out-of-plane scattering or the effect of grating irregularities. In this paper we model distributed-feedback Bragg reflectors using a rigorous electromagnetic formalism adapted from the theory of conventional gratings much as described in Ref. 3. The method facilitates precise analysis of practically any waveguide grating structure, even in the presence of irregularities introduced, e.g., by fabrication errors.