Vertical-cavity surface-emitting diode laser

Claim 2

A vertical-cavity surface-emitting diode laser providing high output power at a high quantum efficiency, the laser comprising: a semiconductor supporting structure, including a substrate; a combination of generally planar semiconductor layers formed on one side of the substrate and including an active layer in which lasing takes place, and a pair of cladding layers positioned one on each side of the active layer; a first stack reflector formed on the combination of active and cladding layers and providing a highly reflective first mirror for a vertical cavity within the laser; a second stack reflector formed in a well recessed into the other side of the substrate, and having a reflectivity less than that of the first stack reflector, to provide a second mirror for the vertical cavity of the laser, through which light is emitted; and a pair of electrical contact layers, one on the first stack reflector and the other on the other side of the substrate, to inject current into the laser cavity; wherein the diode laser is mountable on a heat sink with the active layer positioned between the semiconductor supporting structure and the heat sink.

Claim 3

A vertical-cavity surface-emitting diode laser as defined in claim 1, wherein: the first stack reflector has a relatively small area, defining a relatively narrow cross-sectional area of the vertical cavity; and the laser further comprises a current confinement layer laterally surrounding the first stack reflector and extending into one of the cladding layers.

Claim 4

A vertical-cavity surface-emitting diode laser as defined in claim 2, wherein: the first stack reflector is a semiconductor stack reflector; and the second stack reflector is a dielectric stack reflector.

Claim 5

A vertical-cavity surface-emitting diode laser as defined in claim 1, wherein: the active layer is of gallium arsenide; the cladding layers are of aluminum gallium arsenide; and the substrate is of gallium arsenide.

Claim 6

A vertical-cavity surface-emitting diode laser as defined in claim 1, wherein: the first stack reflector is a semiconductor stack reflector having alternating layers of doped aluminum gallium arsenide (Al x Ga 1-x As) of different thicknesses and different proportions of aluminum defined by the factor x.

Claim 7

A vertical-cavity surface-emitting diode laser as defined in claim 5, wherein: their are twenty-five pairs of layers in the semiconductor stack reflector; and the first layer of each pair has an x value of 0.1 and a thickness of approximately 620Å; and the second layer of each pair has an x value of 0.7 and a thickness of approximately 700Å.

Claim 8

A vertical-cavity surface-emitting diode laser as defined in claim 1, wherein: the combination of semiconductor layers further includes a buffer layer adjacent to the substrate, and an etch stop layer formed between the buffer layer and the active and cladding layers, wherein the etch stop layer facilitates formation of the second stack reflector.

Claim 9

A vertical-cavity surface-emitting diode laser providing high output power at a high quantum efficiency, the laser comprising: a semiconductor supporting structure, including a substrate of n type gallium arsenide; a combination of generally planar semiconductor layers formed on the semiconductor supporting structure and including an active layer of gallium arsenide, in which lasing takes place, and a pair of cladding layers of n type and p type aluminum gallium arsenide, surrounding the active layer; a semiconductor stack reflector formed on the combination of active and cladding layers and providing a highly reflective first mirror for a vertical cavity within the laser, the semiconductor stack reflector being formed from alternating layers of p type aluminum gallium arsenide of different thicknesses and aluminum proportions, the alternating layers being etched away except in a mesa region that limits the cross-sectional area of the vertical cavity; a semiconductor current confinement layer formed to laterally surround the mesa, and to form a back-biased junction with the adjacent p type cladding layer, thereby confining current to the semiconductor stack reflector; a dielectric stack reflector formed in a well recessed into the substrate, and having a reflectivity less than that of the first stack reflector, to provide a second mirror for the vertical cavity of the laser, through which light is emitted, the dielectric stack reflector having alternating layers of silicon dioxide and zirconium dioxide, each of thickness approximately equal to one quarter of the wavelength of the laser; and a pair of electrical contact layers, one on the semiconductor stack reflector and the other on the substrate, to inject current into the laser cavity; wherein the diode laser is mountable on a heat sink, with the active layer positioned between the semiconductor supporting structure and the heat sink.

Claim 10

A vertical-cavity surface-emitting diode laser providing high output power at a high quantum efficiency, the laser comprising: a semiconductor supporting structure, including a substrate of n type gallium arsenide; a combination of generally planar semiconductor layers formed on the semiconductor supporting structure and including an active layer of gallium arsenide, in which lasing takes place, and a pair of cladding layers of n type and p type aluminum gallium arsenide, surrounding the active layer; a semiconductor stack reflector formed on the combination of active and cladding layers and providing a highly reflective first mirror for a vertical cavity within the laser, the semiconductor stack reflector being formed from alternating layers of p type aluminum gallium arsenide of different thicknesses and aluminum proportions, the alternating layers being etched away except in a mesa region that limits the cross-sectional area of the vertical cavity; a semiconductor current confinement layer formed to laterally surround the mesa, and to form a back-biased junction with the adjacent p type cladding layer, thereby confining current to the semiconductor stack reflector; a dielectric stack reflector formed in a well recessed into the substrate, and having a reflectivity less than that of the first stack reflector, to provide a second mirror for the vertical cavity of the laser, through which light is emitted, the dielectric stack reflector having alternating layers of silicon dioxide and zirconium dioxide, each of thickness approximately equal to one quarter of the wavelength of the laser; and a pair of electrical contact layers, one on the semiconductor stack reflector and the other on the substrate, to inject current into the laser cavity; wherein the diode laser is mountable on a heat sink, with the active layer positioned between the semiconductor supporting structure and the heat sink.

Claim 13

Method as defined in claim 9, and further including, after the step of forming the first stack reflector, the additional steps of: removing the first stack reflector layer except in a mesa region defining the reflector; and growing a current confinement layer in a region laterally surrounding the mesa region, to form a back-biased junction with one of the cladding layers, thereby confining current substantially to the mesa region.

Claim 14

A method as defined in claim 10, and further comprising the steps of: forming a buffer layer on the substrate prior to the formation of the cladding and active layers; forming an etch stop layer on the buffer layer; and, before formation of the second stack reflector, or, etching a well in the substrate, whereby the etch stop layer facilitates formation of a flat-bottom well without damage to the cladding or active layers.