Gain asymmetry in heterostructure junction lasers operating in a fundamental transverse mode

Claim 2

In a semiconductor junction laser, a semiconductor body comprising a pair of heterojunctions defining an optical waveguide, means disposed between said pair of heterojunctions for dividing said waveguide into two contiguous regions, one of said regions exhibiting loss (the lossy region) and the other exhibiting gain (the gain region) under lasing conditions, said gain region being thicker than said lossy region, CHARACTERIZED IN THAT: said dividing means comprises a third heterojunction, at least one of said heterojunctions is a p-n heterojunction, the majority carrier construction in said lossy region is equal to or greater than the electron concentration in said gain region under lasing conditions, and the thickness dg of said gain region satisfies the inequality delta ndg2 < 9 lambda 2/32ng where delta n is the refractive index discontinuity at said third heterojunction, lambda is the free space wavelength of the laser radiation and ng is the refractive index of said gain region.

Claim 3

The body of claim 1 wherein the thickness of said gain region is approximately twice that of said lossy region.

Claim 4

The body of claim 1 wherein said gain region comprises AlyGa1 yAs and said lossy region comprises AlxGa1 xAs, x > y > or = 0.

Claim 5

The body of claim 3 wherein y 0 and said gain region comprises GaAs.

Claim 6

The body of claim 4 wherein delta ndg2 < 6.2 X 10 2 Mu m2.

Claim 7

The body of claim 4 wherein said gain region is p-type and said lossy region is n-type.

Claim 8

The body of claim 6 wherein the donor concentration in said n-type lossy region is greater than or equal to approximately 2 X 1018 cm 3.

Claim 9

The body of claim 3 including a first layer of AlvGa1 vAs, v > x, contiguous with said lossy region, a second layer of AlzGa1 zAs, z > y, contiguous with said gain region, thereby forming one of said pair of heterojunctions at the interface between said first layer and said lossy region and forming the other one of said pair of heterojunctions at the interface between said second layer and said gain region.

Claim 10

The body of claim 8 wherein said first layer and said lossy region have one conductivity type and said second layer and said gain region have the opposite conductivity type.

Claim 11

The body of claim 8 wherein said gain and loss regions have the same conductivity type and said first and second layers have conductivity types opposite to one another.

Claim 12

The body of claim 8 including a pair of surfaces parallel to one another and perpendicular to the plane of said heterojunctions thereby forming an optical resonator and an antireflection coating formed on one of said surfaces, said coating comprising contiguous layers of ZnS and Al2O3.

Claim 13

The body of claim 8 including means defining a stripe geometry electrical contact on a major surface of said body.

Claim 14

The body of claim 1 including means for forward biasing said p-n junction and for applying current thereto in the form of pulses.

Claim 15

In a semiconductor junction laser a semiconductor body comprising an n-GaAs substrate and a plurality of epitaxial layers grown thereon in the following order: a layer of N-AlvGa1 vAs, a layer of n''-AlxGa1 xAs, v > x, a layer of p-AlyGa1 yAs, a layer of P-AlzGa1 zAs, z > y, a layer of p-GaAs, a metal contact formed on said p-GaAs layer, and a metal contact formed on said n-GaAs substrate, a pair of spaced parallel cleavage surfaces perpendicular to the plane of said layers and forming an optical resonator, an antireflection coating formed on one of said surfaces and comprising contiguous layers of ZnS and Al2O3, means defining a stripe geometry electrical contact to said p-GaAs layer comprising a pair of spaced proton-bombarded high resistivity zones extending between said cleavage surfaces and from the top of said p-GaAs layer through at least said p-AlyGa1 yAs layer, CHARACTERIZED IN THAT said p-AlyGa1 y As layer defines a gain region and said n''-AlxGa1 xAs layer defines a lossy region, the gain region being thicker than the lossy region, x is greater than y so that the bandgap in lossy region is greater than that in said gain region, the donor concentration in said lossy region is greater than or equal to the electron concentration in said gain region under lasing conditions, and the thickness dg of said gain region satisfies the inequality delta ndg2 < 9 lambda 2/32ng, where delta n is the refractive index at the interface between said gain and lossy regions, lambda is the free space wavelength of the laser radiation, and ng is the refractive index of said gain region.

Claim 16

In a semiconductor junction laser a semiconductor body comprising an n-GaAs substrate and a plurality of epitaxial layers grown thereon in the following order: a layer of N-AlvGa1 vAs, a layer of n''-AlxGa1 xAs, v > x, a layer of p-AlyGa1 yAs, a layer of P-AlzGa1 zAs, z > y, a layer of p-GaAs, a metal contact formed on said p-GaAs layer, and a metal contact formed on said n-GaAs substrate, a pair of spaced parallel cleavage surfaces perpendicular to the plane of said layers and forming an optical resonator, an antireflection coating formed on one of said surfaces and comprising contiguous layers of ZnS and Al2O3, means defining a stripe geometry electrical contact to said p-GaAs layer comprising a pair of spaced proton-bombarded high resistivity zones extending between said cleavage surfaces and from the top of said p-GaAs layer through at least said p-AlyGa1 yAs layer, CHARACTERIZED IN THAT said p-AlyGa1 y As layer defines a gain region and said n''-AlxGa1 xAs layer defines a lossy region, the gain region being thicker than the lossy region, x is greater than y so that the bandgap in lossy region is greater than that in said gain region, the donor concentration in said lossy region is greater than or equal to the electron concentration in said gain region under lasing conditions, and the thickness dg of said gain region satisfies the inequality delta ndg2 < 9 lambda 2/32ng, where delta n is the refractive index at the interface between said gain and lossy regions, lambda is the free space wavelength of the laser radiation, and ng is the refractive index of said gain region.

Claim 17

The body of claim 14 wherein the donor concentration in said lossy region is greater than or equal to approximately 2 X 1018 cm 3.

Claim 18

The body of claim 14 wherein the thickness of said gain region is approximately twice that of said lossy region.

Claim 19

The body of claim 14 including means for forward biasing said body and for applying current thereto in the form of pulses.

Claim 20

In a semiconductor junction laser a semiconductor body comprising an n-GaAs substrate and a plurality of epitaxial layers grown thereon in the following order: a layer of N-AlvGa1 vAs, a layer of n-AlxGa1 xAs, v > x, a layer of p''-AlyGa1 yAs, a layer of P-AlzGa1 zAs, z > y, a layer of p-GaAs, a metal contact formed on said p-GaAs layer, and a metal contact formed on said n-GaAs substrate, a pair of spaced parallel cleavage surfaces perpendicular to the plane of said layers and forming an optical resonator, an antireflection coating formed on one of said surfaces and comprising contiguous layers of ZnS and Al2O3, means defining a stripe geometry electrical contact to said p-GaAs layer comprising a pair of spaced proton-bombarded high resistivity zones extending between said cleavage surfaces and from the top of said p-GaAs layer through at least said p''-AlyGa1 yAs layer, CHARACTERIZED IN THAT said n-AlxGa1 xAs layer defines a gain region and said p''-AlyGa1 yAs layer defines a lossy region, the gain region being thicker than the lossy region, y is greater than x so that the bandgap in lossy region is greater than that in said gain region, the acceptor concentration in said lossy region is greater than or equal to the electron concentration in said gain region under lasing conditions, and the thickness dg of said gain region satisfies the inequality delta ndg2 < 9 lambda 2/32ng, where delta n is the refractive index at the interface between said gain and lossy regions, lambda is the free space wavelength of the laser radiation, and ng is the refractive index of said gain region.

Claim 21

In a semiconductor junction laser a semiconductor body comprising an n-GaAs substrate and a plurality of epitaxial layers grown thereon in the following order: a layer of N-AlvGa1 vAs, a layer of n-AlxGa1 xAs, v > x, a layer of p''-AlyGa1 yAs, a layer of P-AlzGa1 zAs, z > y, a layer of p-GaAs, a metal contact formed on said p-GaAs layer, and a metal contact formed on said n-GaAs substrate, a pair of spaced parallel cleavage surfaces perpendicular to the plane of said layers and forming an optical resonator, an antireflection coating formed on one of said surfaces and comprising contiguous layers of ZnS and Al2O3, means defining a stripe geometry electrical contact to said p-GaAs layer comprising a pair of spaced proton-bombarded high resistivity zones extending between said cleavage surfaces and from the top of said p-GaAs layer through at least said p''-AlyGa1 yAs layer, CHARACTERIZED IN THAT said n-AlxGa1 xAs layer defines a gain region and said p''-AlyGa1 yAs layer defines a lossy region, the gain region being thicker than the lossy region, y is greater than x so that the bandgap in lossy region is greater than that in said gain region, the acceptor concentration in said lossy region is greater than or equal to the electron concentration in said gain region under lasing conditions, and the thickness dg of said gain region satisfies the inequality delta ndg2 < 9 lambda 2/32ng, where delta n is the refractive index at the interface between said gain and lossy regions, lambda is the free space wavelength of the laser radiation, and ng is the refractive index of said gain region.

Claim 22

In a semiconductor junction laser a semiconductor body comprising an n-GaAs substrate and a plurality of epitaxial layers grown thereon in the following order: a layer of n''-AlvGa1 vAs, a layer of n''-AlxGa1 xAs, v > x, a layer of n-AlyGa1 yAs, a layer of P-AlzGa1 zAs, z > y, a layer of p-GaAs, a metal contact formed on said p-GaAs layer, and a metal contact formed on said n-GaAs substrate, a pair of spaced parallel cleavage surfaces perpendicular to the plane of said layers and forming an optical resonator, an antireflection coating formed on one of said surfaces and comprising contiguous layers of ZnS and Al2O3, means defining a stripe geometry electrical contact to said p-GaAs layer comprising a pair of spaced proton-bombarded high resistivity zones extending between said cleavage surfaces and from the top of said p-GaAs layer through at least said P-AlzGa1 zAs layer, CHARACTERIZED IN THAT said n-AlyGa1 yAs layer defines a gain region and said n''-AlxGa1 xAs layer defines a lossy region, the gain region being thicker than the lossy region, x is greater than y so that the bandgap in lossy region is greater than that in said gain region, the donor concentration in said lossy region is greater than or equal to the electron concentration in said gain region under lasing conditions, and the thickness dg of said gain region satisfies the inequality delta ndg2 < 9 lambda 2/32ng, where delta n is the refractive index at the interface between said gain and lossy regions, lambda is the free space wavelength of the laser radiation, and ng is the refractive index of said gain region.

Claim 23

In a semiconductor junction laser a semiconductor body comprising an n-GaAs substrate and a plurality of epitaxial layers grown thereon in the following order: a layer of n''-AlvGa1 vAs, a layer of n''-AlxGa1 xAs, v > x, a layer of n-AlyGa1 yAs, a layer of P-AlzGa1 zAs, z > y, a layer of p-GaAs, a metal contact formed on said p-GaAs layer, and a metal contact formed on said n-GaAs substrate, a pair of spaced parallel cleavage surfaces perpendicular to the plane of said layers and forming an optical resonator, an antireflection coating formed on one of said surfaces and comprising contiguous layers of ZnS and Al2O3, means defining a stripe geometry electrical contact to said p-GaAs layer comprising a pair of spaced proton-bombarded high resistivity zones extending between said cleavage surfaces and from the top of said p-GaAs layer through at least said P-AlzGa1 zAs layer, CHARACTERIZED IN THAT said n-AlyGa1 yAs layer defines a gain region and said n''-AlxGa1 xAs layer defines a lossy region, the gain region being thicker than the lossy region, x is greater than y so that the bandgap in lossy region is greater than that in said gain region, the donor concentration in said lossy region is greater than or equal to the electron concentration in said gain region under lasing conditions, and the thickness dg of said gain region satisfies the inequality delta ndg2 < 9 lambda 2/32ng, where delta n is the refractive index at the interface between said gain and lossy regions, lambda is the free space wavelength of the laser radiation, and ng is the refractive index of said gain region.

Claim 24

In a semiconductor junction laser a semiconductor body comprising an n-GaAs substrate and a plurality of epitaxial layers grown thereon in the following order: a layer of N-AlvGa1 vAs, a layer of p-AlxGa1 xAs, v > x, a layer of p''-AlyGa1 y As, a layer of P-AlzGa1 zAs, z > y, a layer of p-GaAs, a metal contact formed on said p-GaAs layer, and a metal contact formed on said n-GaAs substrate, a pair of spaced parallel cleavage surfaces perpendicular to the plane of said layers and forming an optical resonator, an antireflection coating formed on one of said surfaces and comprising contiguous layers of ZnS and Al2O3, means defining a stripe geometry electrical contact to said p-GaAS layer comprising a pair of spaced proton-bombarded high resistivity zones extending between said cleavage surfaces and from the top of said p-GaAs layer through at least said p-AlxGa1 xAs layer, CHARACTERIZED IN THAT said p-AlxGa1 xAs layer defines a gain region and said p''-AlGa1 yAs layer defines a lossy region, the gain region being thicker than the lossy region, y is greater than x so that the bandgap in lossy region is greater than that in said gain region, the acceptor concentration in said lossy region is greater than or equal to the electron concentration in said gain region under lasing conditions, and the thickness dg of said gain region satisfies the inequality delta ndg2 < 9 lambda 2/32ng, where delta n is the refractive index at the interface between said gain and lossy regions, lambda is the free space wavelength of the laser radiation, and ng is the refractive index of said gain region.

Claim 25

In a semiconductor junction laser a semiconductor body comprising an n-GaAs substrate and a plurality of epitaxial layers grown thereon in the following order: a layer of N-AlvGa1 vAs, a layer of p-AlxGa1 xAs, v > x, a layer of p''-AlyGa1 y As, a layer of P-AlzGa1 zAs, z > y, a layer of p-GaAs, a metal contact formed on said p-GaAs layer, and a metal contact formed on said n-GaAs substrate, a pair of spaced parallel cleavage surfaces perpendicular to the plane of said layers and forming an optical resonator, an antireflection coating formed on one of said surfaces and comprising contiguous layers of ZnS and Al2O3, means defining a stripe geometry electrical contact to said p-GaAS layer comprising a pair of spaced proton-bombarded high resistivity zones extending between said cleavage surfaces and from the top of said p-GaAs layer through at least said p-AlxGa1 xAs layer, CHARACTERIZED IN THAT said p-AlxGa1 xAs layer defines a gain region and said p''-AlGa1 yAs layer defines a lossy region, the gain region being thicker than the lossy region, y is greater than x so that the bandgap in lossy region is greater than that in said gain region, the acceptor concentration in said lossy region is greater than or equal to the electron concentration in said gain region under lasing conditions, and the thickness dg of said gain region satisfies the inequality delta ndg2 < 9 lambda 2/32ng, where delta n is the refractive index at the interface between said gain and lossy regions, lambda is the free space wavelength of the laser radiation, and ng is the refractive index of said gain region.