Single-mode operation of a surface grating distributed feedback GaAs-AlGaAs laser with variable-width waveguide

Single-mode distributed feedback laser operation can be achieved by introducing an appropriate phase jump within the feedback grating, causing lasing to occur within the stop-band. One possible approach involves variation of the waveguide stripe width in an index-guided structure, in conjunction with a grating of uniform periodicity. If the phase change is allowed to accumulate over a sufficient length of the width perturbed stripe waveguide, a /spl lambda//4 shift can be realized. We report the first laser of this type using a surface grating structure with only postgrowth processing.< >