TM-mode coupling coefficients in guided-wave distributed feedback lasers

An equation is derived for TM-mode coupling coefficients in guided-wave distributed feedback (DFB) lasers. Results for GaAs:GaAlAs double-heterostructure lasers with rectangular, triangular, and sawtooth-shaped teeth, various Bragg diffraction orders, and transverse mode numbers are presented for TM modes and compared with those for TE modes. Generally, but not always, coupling coefficients for TE modes exceed those for TM modes.