US5345464A
Expired / Lapsed
US
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Semiconductor laser
Assignee: Mitsubishi Electric Corp
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Filing: 1993-09-21
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Granted: 1994-09-06
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Expires: 2013-09-21
Abstract
Abstract A semiconductor laser includes a semiconductor substrate of a first conductivity type; a double heterojunction structure comprising a lower cladding layer of the first conductivity type disposed on the semiconductor substrate and having a first energy band gap, a band gap discontinuity reduction layer of the first conductivity type having a thickness from five to forty nanometers disposed on the lower cladding layer and having a second energy band gap, an undoped active layer disposed on the band gap discontinuity reduction layer and having a third energy band gap smaller than the first energy band gap, the second energy band gap being intermediate the first and third energy band gaps, and an upper cladding layer of a second conductivity type, opposite the first conductivity type, disposed on the active layer and having a fourth energy band gap larger than the third energy band gap, the double heterojunction structure having a ridge shape; a current confinement structure disposed on opposite sides of the double heterojunction structure for confining current flow to the double heterojunction structure; and first and second electrodes electrically contacting the semiconductor substrate and the upper cladding layer, respectively.
Inventors
- 👤 Akira Takemoto
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 21:30
CPC Classifications
H; H01; H01S; H01S5/00; H01S5/30; H01S5/32; H01S5/20; H01S5/2004; H01S5/22; H01S5/227; H01S5/2275; H01S5/321; H01S5/3211; H01S5/323; H01S5/3235; H01S5/32391
Claims Analysis
Total Claims: 25
Claim 1
Independent Claim
190 words
A semiconductor laser comprising: a semiconductor substrate of a first conductivity type; a double heterojunction structure comprising a lower cladding layer of the first conductivity type disposed on the semiconductor substrate and having a first energy band gap, a band gap discontinuity reduction layer of the first conductivity type having a thickness from five to forty nanometers disposed on the lower cladding layer and having a second energy band gap, an undoped active layer disposed on the band gap discontinuity reduction layer and having a third energy band gap smaller than the first energy band gap, the second energy band gap being intermediate the first and third energy band gaps, and an upper cladding layer of a second conductivity type, opposite the first conductivity type, disposed on the active layer and having a fourth energy band gap larger than the third energy band gap, the double heterojunction structure having a ridge shape; a current confinement structure disposed on opposite sides of the double heterojunction structure for confining current flow to the double heterojunction structure; and first and second electrodes electrically contacting the semiconductor substrate and the upper cladding layer, respectively.
Claim 2
Dependent Claim
190 words
A semiconductor laser comprising: a semiconductor substrate of a first conductivity type; a double heterojunction structure comprising a lower cladding layer of the first conductivity type disposed on the semiconductor substrate and having a first energy band gap, a band gap discontinuity reduction layer of the first conductivity type having a thickness from five to forty nanometers disposed on the lower cladding layer and having a second energy band gap, an undoped active layer disposed on the band gap discontinuity reduction layer and having a third energy band gap smaller than the first energy band gap, the second energy band gap being intermediate the first and third energy band gaps, and an upper cladding layer of a second conductivity type, opposite the first conductivity type, disposed on the active layer and having a fourth energy band gap larger than the third energy band gap, the double heterojunction structure having a ridge shape; a current confinement structure disposed on opposite sides of the double heterojunction structure for confining current flow to the double heterojunction structure; and first and second electrodes electrically contacting the semiconductor substrate and the upper cladding layer, respectively.
Claim 3
Dependent Claim
14 words
The semiconductor laser of claim 1 wherein the first conductivity type is p type.
Claim 4
Dependent Claim
14 words
The semiconductor laser of claim 1 wherein the first conductivity type is n type.
Claim 5
Dependent Claim
46 words
The semiconductor laser of claim 1 including a second band gap discontinuity reduction layer disposed between the active layer and the upper cladding layer and having an energy band gap intermediate the third and fourth energy band gaps and a thickness of five to forty nanometers.
Claim 6
Dependent Claim
44 words
The semiconductor laser of claim 1 wherein the band gap discontinuity reduction layer comprises a plurality of laminated semiconductor films, each film having an energy band gap no larger than the first energy band gap and no smaller than the third energy band gap.
Claim 7
Dependent Claim
43 words
The semiconductor laser of claim 1 wherein the energy band gap of the band gap discontinuity reduction layer varies continuously with position from the first energy band gap to the third energy band gap between the lower cladding layer and the active layer.
Claim 8
Dependent Claim
16 words
The semiconductor laser of claim 1 wherein the current confinement structure comprises a pnpn thyristor structure.
Claim 9
Dependent Claim
16 words
The semiconductor laser of claim 1 wherein the current confinement structure comprises a semi-insulating semiconductor material.
Claim 10
Dependent Claim
26 words
The semiconductor laser of claim 1 wherein the upper and lower cladding layers are InP and the active and band gap discontinuity reduction layers are InGaAsP.
Claim 11
Dependent Claim
43 words
The semiconductor laser of claim 9 wherein the band gap discontinuity reduction layer is In 0 .82 Ga 0 .18 As 0 .4 P 0 .6 and the active layer is In 0 .58 Ga 0 .42 As 0 .9 P 0 .1.
Claim 12
Dependent Claim
21 words
The semiconductor laser of claim 1 including a contacting layer of the second conductivity type electrically contacting the upper cladding layer.
Claim 13
Dependent Claim
29 words
The semiconductor laser of claim 11 including a second upper cladding layer of the second conductivity type interposed between and contacting the upper cladding layer and the contacting layer.
Claim 14
Dependent Claim
195 words
A semiconductor laser comprising: a semiconductor substrate of a first conductivity type; a double heterojunction structure comprising a lower cladding layer of the first conductivity type disposed on the semiconductor substrate and having a first energy band gap, an undoped active layer disposed on the lower cladding layer and having a second energy band gap smaller than the first energy band gap, a band gap discontinuity reduction layer of a second conductivity type, opposite the first conductivity type, having a thickness from five to forty nanometers disposed on the active layer and having a third energy band gap, and an upper cladding layer of the second conductivity type, disposed on the band gap discontinuity reduction layer and having a fourth energy band gap, the third energy band being intermediate the second and fourth energy band gaps and the first energy band gap being larger than the second band gap, the double heterojunction structure having a ridge shape; a current confinement structure disposed on opposite sides of the double heterojunction structure for confining current flow to the double heterojunction structure; and first and second electrodes electrically contacting the semiconductor substrate and the upper cladding layer, respectively.
Claim 15
Dependent Claim
195 words
A semiconductor laser comprising: a semiconductor substrate of a first conductivity type; a double heterojunction structure comprising a lower cladding layer of the first conductivity type disposed on the semiconductor substrate and having a first energy band gap, an undoped active layer disposed on the lower cladding layer and having a second energy band gap smaller than the first energy band gap, a band gap discontinuity reduction layer of a second conductivity type, opposite the first conductivity type, having a thickness from five to forty nanometers disposed on the active layer and having a third energy band gap, and an upper cladding layer of the second conductivity type, disposed on the band gap discontinuity reduction layer and having a fourth energy band gap, the third energy band being intermediate the second and fourth energy band gaps and the first energy band gap being larger than the second band gap, the double heterojunction structure having a ridge shape; a current confinement structure disposed on opposite sides of the double heterojunction structure for confining current flow to the double heterojunction structure; and first and second electrodes electrically contacting the semiconductor substrate and the upper cladding layer, respectively.
Claim 16
Dependent Claim
14 words
The semiconductor laser of claim 13 wherein the first conductivity type is p type.
Claim 17
Dependent Claim
14 words
The semiconductor laser of claim 13 wherein the first conductivity type is n type.
Claim 18
Dependent Claim
46 words
The semiconductor laser of claim 13 including a second band gap discontinuity reduction layer disposed between the active layer and the lower cladding layer and having an energy band gap intermediate the first and second energy band gaps and a thickness of five to forty nanometers.
Claim 19
Dependent Claim
44 words
The semiconductor laser of claim 13 wherein the band gap discontinuity reduction layer comprises a plurality of laminated semiconductor films, each film having an energy band gap no larger than the first energy band gap and no smaller than the third energy band gap.
Claim 20
Dependent Claim
44 words
The semiconductor laser of claim 13 wherein the energy band gap of the band gap discontinuity reduction layer varies continuously with position from the second energy band gap to the fourth energy band gap between the lower active layer and the upper cladding layer.
Claim 21
Dependent Claim
16 words
The semiconductor laser of claim 13 wherein the current confinement structure comprises a pnpn thyristor structure.
Claim 22
Dependent Claim
26 words
The semiconductor laser of claim 13 wherein the upper and lower cladding layers are InP and the active and band gap discontinuity reduction layers are InGaAsP.
Claim 23
Dependent Claim
43 words
The semiconductor laser of claim 20 wherein the band gap discontinuity reduction layer is In 0 .82 Ga 0 .18 As 0 .4 P 0 .6 and the active layer is In 0 .58 Ga 0 .42 As 0 .9 P 0 .1.
Claim 24
Dependent Claim
21 words
The semiconductor laser of claim 13 including a contacting layer of the second conductivity type electrically contacting the upper cladding layer.
Claim 25
Dependent Claim
29 words
The semiconductor laser of claim 22 including a second upper cladding layer of the second conductivity type interposed between and contacting the upper cladding layer and the contacting layer.
References Cited (Backward Citations)
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| 3.5 Years (Year 4) | 1997-09-05 | 1998-03-07 | 1998-09-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-09-05 | 2002-03-07 | 2002-09-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-09-05 | 2006-03-07 | 2006-09-06 | $7700.00 | Window Closed / Lapsed |