Semiconductor laser device with plural active layers and changing optical properties
AssigneeHitachi, Ltd.
InventorsAkihiko Oka, Shinji Sakano, Naoki Chinone, Tsukuru Ohtoshi, Kazuhisa Uomi, Tomonobu Tsuchiya, Makoto Okai
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Abstract
A wavelength-tunable semiconductor laser device presenting a large wavelength-tunable range or a very-high-speed modulating semiconductor laser device having a distributed feedback structure including a diffraction grating as in the case of a DBR laser or a DFB laser incorporates therein a plurality of active layers differing from one another in constituent elements or composition ratio or thickness for reducing spectral line widths, while improving single-mode spectral oscillation characteristics.
Claims36
A semiconductor laser device, comprising:
- a plurality of semiconductor regions having active layers optically coupled to one another and susceptible to undergo changes in gain upon injection of carriers;
- said plurality of semiconductor regions including an amplification region having an optical amplification active layer for emitting light in response to the injection of the carriers, and a DBR regions having a gain active layer for guiding the light emitted by said optical amplification active layer and a distributed feedback structure for feeding back the light being guided;
- means for injecting the carriers into said plurality of semiconductor regions;
- and
- a resonator structure for amplifying the light of a specific wavelength of those emitted by said optical amplification active region by selective feedback through said feedback structure;
- wherein differential gain coefficient to the injected carrier density of said gain active layer is made different from the differential gain coefficient to the injected carrier density in said optical amplification active layer.
A semiconductor laser device, comprising:
- a plurality of semiconductor regions including a plurality of active layers coupled optically and having gains susceptible to change upon injection of carriers;
- means for injecting the carriers into said plurality of the active regions;
- and
- a resonator structure for amplifying and oscillating light of a specific wavelength differing from said gain peak wavelengths by selectively feeding back the light of said specific wavelength;
- wherein said plurality of the active layers compensate mutually for variations in the refractive index induced by variations in the carrier density.
A semiconductor laser device, comprising:
- a plurality of active regions;
- means for injecting the carriers into said active regions;
- and
- a diffraction grating for feeding back light having a specific wavelength of those emitted from said active regions;
- wherein said diffraction grating is disposed in the vicinity of at least one of said plural active regions, and wherein said plural regions inclusive of said one region differ from one another in respect to change in the gain brought about by the injection of carriers.
A semiconductor laser device, comprising:
- a plurality of active regions;
- means for injecting the carriers into said active regions;
- and
- a diffraction grating for feeding back light having a specific wavelength of those emitted from said active regions;
- wherein said diffraction grating is disposed in the vicinity of at least one of said plural active regions, and wherein said plural regions inclusive of said one region differ from one another in respect to change in the refractive index brought about by the injection of carriers.
A semiconductor laser device, comprising:
- a plurality of active regions;
- means for injecting the carriers into said active regions;
- and
- a diffraction grating for feeding back light having a specific wavelength of those emitted from said active regions;
- wherein said diffraction grating is disposed in the vicinity of at least one of said plural active regions;
- and
- wherein said plural active layers are made different from one another in respect to magnitude of change in the gain for an amount of carriers injected to thereby suppress self-oscillation only in a specific one of said plural active layers.
A semiconductor laser device, comprising:
- a plurality of active layers;
- means for injecting the carriers into said plural active layers;
- and
- a diffraction grating provided locally for oscillating light cf a specific wavelength of those emitted by said active layers;
- wherein at least one of said plural active layers is disposed in the vicinity of said diffraction grating, whereby said plural active layers are rendered to differ from one another in respect to magnitude of change in the refractive index for an amount of carriers
A semiconductor laser device, comprising:
- a plurality of active layers;
- means for injecting the carriers into said plural active layers;
- and
- a diffraction grating provided locally for oscillating light of a specific wavelength of those emitted by said active layers;
- wherein change of refractive index/change in gain brought about by carrier injection in the first active layer disposed in the vicinity of said diffractive index and/or in at least one of the second one or more active layers are greater than those in the other one(s) of said second active layers.
A semiconductor laser device, comprising:
- a plurality of active layers;
- means for injecting the carriers into said plural active layers;
- and
- a diffraction grating provided locally for oscillating light of a specific wavelength of those emitted by said active layers;
- wherein in the first active layer disposed in the vicinity of said diffractive grating and in the second one or more other active layer, either one or both of said first active layer and said second active layer are formed in a multi-layer structure, and wherein at least one of the active layers has a quantum well layer whose thickness is smaller than that of said second active layer.
A semiconductor laser device, comprising:
- a plurality of active layers;
- means for injecting carriers into said plural active layers;
- and
- a diffraction grating provided locally on a region through which light travels for oscillating light of a specific wavelength of those emitted by said active layers;
- wherein variations in refractive index brought about by variations in the amount of injected carriers in said plurality of the active regions are mutually compensated for.
A semiconductor laser device, comprising:
- a plurality of active layers;
- means for injecting carriers into said plural active layers;
- and
- a diffraction grating provided on an optical axis along which light travels for oscillating light of a specific wavelength of those emitted by said active layers;
- wherein changes in gain brought about by injection of carriers in said plurality of the active regions are different from one to another active regions.
A semiconductor laser device, wherein the optical path length of light traveling through a passive semiconductor optical waveguide is changed by changing refractive index of said optical waveguide by injecting carriers thereto, and wherein an optical active layer is disposed in said optical waveguide in parallel with the direction in which light travels through said optical waveguide to thereby reduce absorption loss produced in said optical waveguide by the injection of the carriers.
Dependencies are inferred from the claim text.