Distributed feedback lasers with an S-bent waveguide for high-power single-mode operation

DFB lasers with variations in the Bragg wavenumber along the cavity (corrugation-pitch modulation) can be designed to operate in a single mode up to high output powers. Practical implementation of various pitch-modulated DFB cavities is facilitated by bending the laser waveguide over a uniform grating, so that the Bragg wavenumber is varied along the cavity. In this paper, above-threshold behavior of such lasers is studied, and design rules for high power single-mode operation are developed. S-bent waveguide DFB lasers, fabricated according to our design criteria, exhibit single-mode operation with 40 dB side mode suppression ratio from threshold to 10/spl times/I/sub th/.>