Abstract

We have theoretically studied the threshold-longitudinal-mode structure and the grating coupled radiation of thin-film or semiconductor-type distributed feedback (DFB) lasers. Grating form, including tooth shape and chirp, influences mode confinement and coupling. Using coupled-mode theory and Green’s function methods, we have estimated far-field radiation patterns, mode spectrum, and longitudinal field distributions of DFB lasers with several grating forms. Results indicate that the choice of grating form can strongly influence radiation coupling and mode discrimination. We discuss the far-field radiation patterns of these structures and the effects of this coupling on laser mode spectrum.

© 1987 Optical Society of America