Semiconductor laser device having a diffraction grating on a light emission side

摘要

A semiconductor device and method for providing a light source suitable for use as a pumping light source in a Raman amplification system are provided. The device upon which the method is based includes an active layer configured to radiate light; a light reflecting facet positioned on a first side of the active layer; a light emitting facet positioned on a second side of the active layer thereby forming a resonant cavity between the light reflecting facet and the light emitting facet; and a partial diffraction grating having a predetermined length and positioned on a light emission side of the resonator. The predetermined length of the partial diffraction grating is selected such that the semiconductor device emits a light beam having a plurality of longitudinal modes within a predetermined spectral width of an oscillation wavelength spectrum of the semiconductor device. The predetermined length of the partial diffraction grating may be set in relation to a length of the resonant cavity, or in relation to a coupling coefficient kappai of the partial diffraction grating.