Distributed-feedback semiconductor laser

Details Distributed-feedback semiconductor laser Distributed-feedback semiconductor laser

1998-03-16

2000-08-29

Font, Frank G.

Coherent light generators

Particular resonant cavity

Distributed feedback

372 44, 372102, H01S 308

Patent

active

061119067

ABSTRACT:
A stable single-mode oscillation semiconductor laser is obtained by flattening the distribution of electric field intensity in the direction of the resonator axis, and to provide a distributed-feedback semiconductor laser generator having a more satisfactory difference in threshold gain between the principal and subsidiary modes. The laser includes an active layer which radiates light as a result of the injection of electrons, a light guide layer which is next to this active layer guides light emitted from the active layer, a plurality of semiconductor layers between which the active layer and light guide layer are interposed, electrodes which permit electrons to be injected from these semiconductor layers into the active layer, a non-reflective coating provided on both ends of the active layer in the direction of oscillation, and a diffraction grating which is provided on the light guide layer for selecting the oscillatory wavelength of the light. The diffraction grating has a plurality of uniform pitch areas formed with a uniform and equal pitch, and a varying pitch area interposed between the uniform pitch areas and having a plurality of pitches longer and shorter than those of these uniform pitch areas, the latter serving to select the oscillatory wavelength of the light, where the absolute value of the sum-total of the amount of phase change in the varying pitch area (cumulative amount of phase change) in relation to the phase in the uniform pitch areas is between 3/2 and 11/2 times the pitch of the diffraction grating of the uniform pitch areas.

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