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US 5,396,508 AGranted
Polarization switchable quantum well laser
AssigneeXerox Corporation
InventorsDavid P. Bour, Thomas L. Paoli, David W. Treat
Life of this patent
Estimating the term…
Abstract
A QW diode laser whose polarization can be switched. In one embodiment, the device incorporates a tensile strained quantum well active region, whose thickness is adjusted so that the heavy hole and light hole band edges are of the same energy. Since the heavy hole transition provides TE-mode gain, while the light hole band provides mostly TM-mode gain, the resulting laser polarization will be very sensitive to the threshold carrier density. With an intracavity loss modulator in such a structure, the polarization could be switched. Other switching techniques are also described.
Claims29
A polarization-switchable QW semiconductor laser, comprising:
- (a) a semiconductor body having one or more active portions of a material exhibiting heavy hole and light hole energy band edges and capable of lasing and providing TE-mode polarized gain from heavy hole band transitions and TM-mode polarized gain from light hole band transitions,
- (b) said active portions being constructed such that the heavy hole and light hole band edges substantially line up,
- (c) electrodes for introducing carriers into the active body portions,
- (d) optical reflectors associated with the active body portions,
- (e) means to cause the laser to selectively lase in either its TE-mode or its TM-mode in response to changing its threshold carrier density.
2 more elements
A polarization-switchable multi-emitting QW semiconductor laser, comprising:
- (a) a semiconductor body having at least one active portion of a material exhibiting heavy hole and light hole forbidden band defined by energy band edges and capable of lasing and providing TE-mode polarized gain from heavy hole band transitions and TM-mode polarized gain from light hole band transitions,
- (b) said active portion being tensile-strained and having a thickness and composition such that the heavy hole and light hole band edges substantially line up,
- (c) electrodes for introducing carriers into the active body portion,
- (d) optical reflectors associated with the active body portion,
- (e) means for selectively switching the semiconductor body active portion to lase in either its TE-mode or its TM-mode by changing its threshold gain or temperature.
2 more elements
A polarization-switchable multi-emitting QW semiconductor laser, comprising:
- (a) a semiconductor body having at least one active portion of a material exhibiting heavy hole and light hole forbidden band defined by energy band edges and capable of lasing and providing TE-mode polarized gain from heavy hole band transitions and TM-mode polarized gain from light hole band transitions,
- (b) said active portion being tensile-strained and having a thickness and composition such that the heavy hole and light hole band edges substantially line up,
- (c) electrodes for introducing carriers into the active body portion,
- (d) optical reflectors associated with the active body portion,
- (e) means for selectively switching the semiconductor body active portion to lase in either its TE-mode or its TM-mode, said means for selectively switching comprising means for changing the threshold gain and carrier density of the active portion.
2 more elements
A polarization-switchable QW semiconductor laser, comprising:
- (a) a semiconductor body having one or more active portions of a material exhibiting heavy hole and light hole band edges and capable of lasing and providing TE-mode polarized gain from heavy hole band transitions and TM-mode polarized gain from light hole band transitions,
- (b) said active portions being tensile-strain-induced near degeneracy of the heavy hole and light hole band edges,
- (c) electrodes for introducing carriers into the active body portions,
- (d) optical reflectors associated with the active body portions,
- (e) means for introducing a controlled loss into an active portion in order to cause the active body portion to lase in its TE or TM-polarization mode.
2 more elements
A polarization-switchable QW semiconductor laser, comprising:
- (a) a semiconductor body having one or more active portions of a material exhibiting heavy hole and light hole band edges and capable of lasing and providing TE-mode polarized gain from heavy hole band transitions and TM-mode polarized gain from light hole band transitions,
- (b) said active portions being tensile-strain-induced near degeneracy of the heavy hole and light hole band edges,
- (c) electrodes for introducing carriers into the active body portions,
- (d) optical reflectors associated with the active body portions,
- (e) means for introducing a controlled loss into an active portion in order to cause the active body portion to lase in its TE or TM-polarization mode, said means for introducing a controlled loss comprising an intra cavity loss modulator.
2 more elements
A polarization-switchable multi-emitting semiconductor laser, comprising:
- (a) a semiconductor body having an active portion of a material exhibiting heavy hole and light hole band edges and capable of lasing and providing TE-mode polarized gain from heavy hole band transitions and TM-mode polarized gain from light hole band transitions,
- (b) said active portion being constructed such that the heavy hole and light hole band edges substantially line up,
- (c) adjacent QW laser structures in said active portion,
- (d) electrodes for introducing carriers into the adjacent laser structures,
- (e) optical reflectors associated with each laser structure,
- (f) means connected to the adjacent laser structures for causing each selectively to lase in either its TE-mode or its TM-mode.
3 more elements
A polarization switchable emitting semiconductor QW laser, comprising:
- (a) a semiconductor body having first and second side-by-side active portions of the same material exhibiting heavy hole and light hole band edges and capable of lasing and providing TE-mode polarized gain from heavy hole band transitions and TM-mode polarized gain from light hole band transitions, said first and second active portions forming adjacent first and second QW laser structures emitting, respectively, in the TE-mode and TM-mode,
- (b) electrodes for introducing carriers into the active portions,
- (c) optical reflectors associated with each laser structure,
- (d) means connected to the adjacent laser structures for selectively activating same causing the first to lase in its TE-mode and the second to lase in its TM-mode.
1 more element
A polarization-switchable semiconductor laser, comprising:
- (a) a semiconductor body having a strained active portion of GaInP exhibiting heavy hole and light hole band edges and capable of lasing and providing TE-mode polarized gain from heavy hole band transitions and TM-mode polarized gain from light hole band transitions, said active portion being flanked by claddings of AlGaInP,
- (b) a QW laser structure in said active portion,
- (c) electrodes for introducing carriers into the laser structure,
- (d) optical reflectors associated with the laser structure,
- (e) means connected to the laser structure for causing it selectively to lase in either its TE-mode or its TM-mode by changing its threshold gain or temperature.
2 more elements
A polarization switchable emitting semiconductor QW laser, comprising:
- (a) a semiconductor body having first and second side-by-side active portions of a material exhibiting heavy hole and light hole band edges and capable of lasing and providing TE-mode polarized gain from heavy hole band transitions and TM-mode polarized gain from light hole band transitions, said first and second active portions forming adjacent first and second QW laser structures emitting, respectively, in the TE-mode and TM-mode, each laser structure comprising the same QW having the same thickness and composition,
- (b) electrodes for introducing carriers into the active portions,
- (c) optical reflectors associated with each laser structure,
- (d) means connected to the adjacent laser structures for selectively activating same causing the first to lase in its TE-mode and the second to lase in its TM-mode.
1 more element
A polarization-switchable semiconductor laser, comprising
- (a) a semiconductor body having an active portion of a material exhibiting heavy hole and light hole band edges and capable of lasing and providing TE-mode polarized gain from heavy hole band transitions and TM-mode polarized gain from light hole band transitions,
- (b) a QW laser structure having a single QW for which the heavy hole and light hole band edges substantially line up in said active portion,
- (c) electrodes for introducing carriers into the laser structure,
- (d) optical reflectors associated with the laser structure,
- (e) means connected to the laser structure for causing it selectively to lase in either its TE-mode or its TM-mode, said means for selectively causing it to lase comprises means for changing the threshold gain and current density.
2 more elements
A polarization-switchable semiconductor laser, comprising:
- (a) a semiconductor body having an active portion of a material exhibiting heavy hole and light hole band edges and capable of lasing and providing TE-mode polarized gain from heavy hole band transitions and TM-mode polarized gain from light hole band transitions,
- (b) a QW laser structure having separate QWs providing respectively TE-mode gain and TM-mode gain in said active portion,
- (c) electrodes for introducing carriers into the laser structure,
- (d) optical reflectors associated with the laser structure,
- (e) means connected to the laser structure for causing it selectively to lase in either its TE-mode or its TM-mode.
2 more elements
A polarization-switchable semiconductor laser, comprising:
- (a) a semiconductor body having an active portion of a material exhibiting heavy hole and light hole band edges and capable of lasing and providing TE-mode polarized gain from heavy hole band transitions and TM-mode polarized gain from light hole band transitions,
- (b) a QW laser structure comprising separate Qws in said active portion,
- (c) electrodes for introducing carriers into the laser structure,
- (d) optical reflectors associated with the laser structure,
- (e) means connected to the laser structure for causing it selectively to lase in either its TE-mode or its TM-mode, the means for selectively causing it to lase comprising means for selectively activating one or the other of the separate QWs.
2 more elements
A polarization-switchable QW semiconductor laser, comprising:
- (a) a semiconductor body having one or more active portions of a material exhibiting heavy hole and light hole band edges and capable of lasing and providing TE-mode polarized gain from heavy hole band transitions and TM-mode polarized gain from light hole band transitions,
- (b) said active portion being tensile-strain-induced near degeneracy of the heavy hole and light hole band edges, said active portion comprising a quantum well having a thickness related to its composition to give substantial alignment between the heavy hole and light hole valence band edges,
- (c) electrodes for introducing carriers into the active body portions,
- (d) optical reflectors associated with the active body portions,
- (e) means for introducing a controlled loss into an active portion in order to cause the active body portion to lase in its TE or TM-polarization mode.
2 more elements
A polarization-switchable QW semiconductor laser, comprising:
- (a) a semiconductor body having one or more active portions of a material exhibiting heavy hole and light hole band edges and capable of lasing and providing TE-mode polarized gain from heavy hole band transitions and TM-mode polarized gain from light hole band transitions,
- (b) said active portions being tensile-strain-induced near degeneracy of the heavy hole and light hole band edges, said active portion comprising a quantum well having a thickness in the range of about 20-300 .ANG..
- (c) electrodes for introducing carriers into the active body portions,
- (d) optical reflectors associated with the active body portions,
- (e) means for introducing a controlled loss into an active portion in order to cause the active body portion to lase in its TE or TM-polarization mode.
2 more elements
Dependencies are inferred from the claim text.