Distributed feedback semiconductor laser diode, method for producing the same, and exposure method therefor

摘要

A distributed feedback semiconductor laser diode includes an active layer for generating stimulated emission light and also includes a diffraction grating. The diffraction grating serves as a structure for providing a refractive index distribution and a gain distribution where the refractive index and the gain for the stimulated emission light exhibit a periodical change at an identical single period in the guiding direction of the stimulated emission light. A distributed feedback based on refractive index coupling and a distributed feedback based on gain coupling coexist in the distributed feedback semiconductor laser diode. The diffraction grating includes a phase discontinuous section where a phase of the periodical change of the refractive index and the gain is discontinuous. The phase discontinuous section is configured so that the phase shifts are within a range greater than 0 [rad] but less than &pgr; [rad], or within a range greater than &pgr; [rad] but less than 2&pgr; [rad] .