Surface emitting, low threshold (SELTH) laser diode
First Claim
1. A surface emitting semiconductor laser diode structure formed on a substrate, the structure comprising:
- a first section operable for wavelength tuning and an adjacent second section for effecting surface-emission of laser light, the first and second sections including;
an optical waveguide having an active layer for the generation of laser light and a separate confinement heterostructure (SCH) having plural heterojunctions operatively connected to the optical waveguide;
means for providing periodic variation in the refractive index of at least one of the surrounding heterojunctions to provide optical coupling of the laser light to the second section;
an index-guiding buried heterostructure operatively connected to the optical waveguide for partial confinement of the laser light; and
means operably connected to the second section for effecting current flow therethrough for inducing emission of laser light.
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Accused Products
Abstract
Two novel structures of a high-quantum efficiency, wavelength-tunable, surface-emitting, low threshold laser diode which optimally utilizes certain advantages of a distributed feedback (DFB) structure. The preferred embodiments combine a separate confinement heterostructure (SCH), surface-emitting distributed feedback laser diode structure with a multiple quantum well (MQW) active layer and an index-guiding buried heterostructure. A wave-length tuning section is included in the device structure for wavelength adjustment, and an arrangement of transparent electrodes useable for ohmic contacts to the device provide anti-reflection coatings for the emitting portion of the device. A first preferred embodiment is termed the SELTH laser diode (surface emitting, low threshold). A second, related preferred embodiment combines the SELTH laser diode structure with additional optical elements to provide a collimated output beam and is termed the COSELTH laser diode (collimated, surface emitting, low threshold).
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Citations
13 Claims
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1. A surface emitting semiconductor laser diode structure formed on a substrate, the structure comprising:
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a first section operable for wavelength tuning and an adjacent second section for effecting surface-emission of laser light, the first and second sections including; an optical waveguide having an active layer for the generation of laser light and a separate confinement heterostructure (SCH) having plural heterojunctions operatively connected to the optical waveguide; means for providing periodic variation in the refractive index of at least one of the surrounding heterojunctions to provide optical coupling of the laser light to the second section; an index-guiding buried heterostructure operatively connected to the optical waveguide for partial confinement of the laser light; and means operably connected to the second section for effecting current flow therethrough for inducing emission of laser light. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A surface emitting semiconductor laser diode structure, comprising:
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a substrate; a plurality of semiconductive material layers formed on said substrate, said plurality of layers forming an output wavelength tuning section and a distributed feedback (DFB) section, said plurality of layers including; a multiple quantum well active layer formed of plural quantum well layers, each quantum well layer having shared adjacent barrier layers; a separate confinement heterostructure, operably connected to the active layer, that includes an integrally-formed diffractive grating; and an epitaxial burying heterostructure, formed around said plurality of semiconductive material layers, for partial confinement of the laser light.
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11. A surface emitting semiconductor laser diode structure formed on a substrate, the structure comprising in succession:
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a first layer of N-Alx Ga1-x As; a second layer of N-Aly Ga1-y As; a third layer forming a multiple quantum well active layer, the third layer having plural layers of Ga1-z Alz As quantum wells each having adjacent barrier layers of Alb Ga1-b As; a fourth layer of P-Aly Ga1-y As incorporating a diffractive grating formed therein; a fifth layer of P-Alx Ga1-x As; a sixth layer of P-GaAs; and the structure further comprising; an epitaxial burying heterostructure formed laterally adjacent the first through sixth layers; a transparent electrode superimposed on the sixth layer; and a metal alloy ohmic contact superimposed on the transparent electrode. - View Dependent Claims (12)
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13. A collimated surface emitting semiconductor laser diode structure, comprising:
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a first section operable for wavelength tuning and an adjacent second section for effecting surface-emission of laser light, the first and second sections including; an optical waveguide having an active layer for the generation of laser light and a separate confinement heterostructure (SCH) having plural heterojunctions operatively connected to the optical waveguide; means for providing periodic variation in the refractive index of at least one of the surrounding heterojunctions to provide optical coupling of the laser light to the second section; an index-guiding buried heterostructure operatively connected to the optical waveguide for partial confinement of the laser light; means operably connected to the second section for effecting current flow therethrough for inducing emission of laser light; and a diffractive lens, formed in the second section, the diffractive lens being operable to collimate the laser light optically coupled to the second section.
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Specification