Patent ID: 6526087
Filing Date: 2003-02-25
Classification: H01S

Abstract:
A distributed feedback semiconductor laser having a substantially flat top surface, a buried layer disposed below the top surface, at least an active layer disposed under the buried layer, a light guide layer disposed below the active layer and a diffraction grating disposed on a semiconductor substrate disposed under the light guide layer, and so constructed that a current is injected uniformly over an axial direction of a resonator wherein a bandgap wavelength of the active layer in the neighborhood of a light outputting end or a backward end opposite to said light outputting end, is shorter than that in the other region of said active layer along the axial direction of the resonator, the resonator extending from a low reflectance layer disposed upon a first vertical cleaved surface on the light outputting end to a high reflectance layer disposed upon a second vertical cleaved surface on the backward end.