Source: http://www.google.com/patents/US5539763?dq=7143430
Timestamp: 2013-12-10 22:31:47
Document Index: 101310642

Matched Legal Cases: ['art 1000', 'art 1000', 'art 1000', 'art 2000', 'art 2000', 'art 2000', 'art 3000', 'art 3000', 'art 4000', 'art 4000', 'art 4000', 'art 5000', 'art 5000', 'art 5000']

Patent US5539763 - Semiconductor lasers and methods for fabricating semiconductor lasers - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Advanced Patent Search | Sign inAdvanced Patent SearchPatentsAn integrated semiconductor laser and light modulator includes a semiconductor laser disposed at a first region on a semiconductor substrate, a light modulator of an electric field absorbing type disposed at a second region on the semiconductor substrate adjacent to the first region for outputting a...http://www.google.com/patents/US5539763?utm_source=gb-gplus-sharePatent US5539763 - Semiconductor lasers and methods for fabricating semiconductor lasersPublication numberUS5539763 APublication typeGrantApplication numberUS 08/302,488Publication dateJul 23, 1996Filing dateSep 12, 1994Priority dateSep 22, 1993Fee statusLapsedAlso published asDE4433873A1Publication number08302488, 302488, US 5539763 A, US 5539763A, US-A-5539763, US5539763 A, US5539763AInventorsHirotaka Kizuki, Masayoshi TakemiOriginal AssigneeMitsubishi Denki Kabushiki KaishaExport CitationBiBTeX, EndNote, RefManPatent Citations (5), Non-Patent Citations (14), Referenced by (24), Classifications (20), Legal Events (5) External Links: USPTO, USPTO Assignment, EspacenetSemiconductor lasers and methods for fabricating semiconductor lasersUS 5539763 AAbstract An integrated semiconductor laser and light modulator includes a semiconductor laser disposed at a first region on a semiconductor substrate, a light modulator of an electric field absorbing type disposed at a second region on the semiconductor substrate adjacent to the first region for outputting a modulated light by transmitting or absorbing the laser light generated in the semiconductor laser, a semiconductor laminated layer structure including a quantum well structure layer disposed in the first region and the second region on the semiconductor substrate, and a lattice mismatched layer having a lattice constant smaller than that of the semiconductor substrate, disposed on a part of the semiconductor laminated layer structure, in the second region. It is possible to enhance the transmission efficiency of the laser light to the light modulator and the quality of the active layer of the semiconductor laser and the light absorption layer of the light modulator. Thus, an integrated semiconductor laser and light modulator that has a high reliability and long lifetime is obtained.
What is claimed is: 1. An integrated semiconductor laser and light modulator comprising:a semiconductor substrate having a lattice constant; a semiconductor laser disposed at a first region of the semiconductor substrate; and a light modulator of an electric field absorbing type disposed at a second region of the semiconductor substrate adjacent to the first region for outputting modulated light by transmitting and absorbing light generated in the semiconductor laser, said semiconductor laser and said light modulator including semiconductor laminated layer structures including a quantum well structure layer in the first region and the second region and a lattice mismatched layer comprising a semiconductor material having a lattice constant smaller than the lattice constant of the semiconductor substrate in the second region. 2. The integrated semiconductor laser and light modulator of claim 1 wherein the quantum well structure layer includes a plurality of well layers and the minimum distance from a well layer of the quantum well structure layer to the lattice mismatched layer is more than 0.03 μm and the maximum distance from a well layer of the quantum well structure layer to the lattice mismatched layer is less than 0.08 μm.
3. The integrated semiconductor laser and light modulator of claim 1 wherein:the semiconductor substrate is InP; the semiconductor laminated layer structure includes at least some of InP, InGaAs, and InGaAsP layers; and said lattice mismatched layer is GaInP. 4. An integrated semiconductor laser and light modulator comprising:a semiconductor substrate having a lattice constant; a semiconductor laser disposed at a first region of the semiconductor substrate; and a light modulator of an electric field absorbing type disposed at a second region of the semiconductor substrate adjacent to the first region for outputting modulated light by transmitting and absorbing light generated in the semiconductor laser, said semiconductor laser and said light modulator including semiconductor laminated layer structures including a quantum well structure layer in the first region and the second region and a lattice mismatched layer comprising a semiconductor material having a lattice constant larger than the lattice constant of the semiconductor substrate in the first region. 5. The integrated semiconductor laser and light modulator of claim 4 wherein the quantum well structure layer includes a plurality of well layers and the minimum distance from a well layer of the quantum well structure layer to the lattice mismatched layer is more than 0.03 μm and the maximum distance from a well layer of the quantum well structure layer to the lattice mismatched layer is less than 0.08 μm.
6. The integrated semiconductor laser and light modulator of claim 4 wherein:the semiconductor substrate is INP; the semiconductor laminated layer structure includes at least some of InP, InGaAs, and InGaAsP layers; and said lattice mismatched layer is InAsP. 7. An integrated semiconductor laser and light modulator comprising:a semiconductor substrate having a lattice constant; a semiconductor laser disposed at a first region of the semiconductor substrate; and a light modulator of an electric field absorbing type disposed at a second region of the semiconductor substrate adjacent to the first region for outputting modulated light by transmitting and absorbing light generated in the semiconductor laser, said semiconductor laser and said light modulator including semiconductor laminated layer structures including a quantum well structure layer in the first region and the second region and a lattice mismatched layer comprising a semiconductor material having a lattice constant smaller than the lattice constant of the semiconductor substrate in the first and second regions wherein the thickness from a well layer of the quantum well structure layer of the lattice mismatched layer is t1 in the first region and t2 in the second region, where t1&gt;t2. 8. The integrated semiconductor laser and light modulator of claim 1 wherein one of t1 and t2 is more than 0.08 μm and one of t1 and t2 is less than 0.08 μm.
9. The integrated semiconductor laser and light modulator of claim 7 wherein;the semiconductor substrate is InP; the semiconductor laminated layer structure includes at least some of InP, InGaAs, and InGaAsP layers; and said lattice mismatched layer is GaInP. 10. An integrated semiconductor laser and light modulator comprising:a semiconductor substrate having a lattice constant; a semiconductor laser disposed at a first region of the semiconductor substrate; and a light modulator of an electric field absorbing type disposed at a second region of the semiconductor substrate adjacent to the first region for outputting modulated light by transmitting and absorbing light generated in the semiconductor laser, said semiconductor laser and said light modulator including semiconductor laminated layer structures including a quantum well structure layer in the first region and the second region and a lattice mismatched layer comprising a semiconductor material having a lattice constant smaller than the lattice constant of the semiconductor substrate in the first and second regions wherein the thickness from a well layer of the quantum well structure layer of the lattice mismatched layer is t1 in the first region and t2 in the second region, where t1&lt;t2. 11. The integrated semiconductor laser and light modulator of claim 10 wherein one of t1 and t2 is more than 0.08 μm and one of t1 and t2 is less than 0.08 μm.
12. The integrated semiconductor laser and light modulator of claim 10 wherein:the semiconductor substrate is InP; the semiconductor laminated layer structure includes at least some of InP, InGaAs, and InGaAsP layers; and said lattice mismatched layer is InAsP. 13. A method for producing an integrated semiconductor laser and light modulator in which a semiconductor laser is disposed on a first region of a semiconductor substrate and a light modulator of an electric field absorbing type is disposed at a second region on the semiconductor substrate adjacent to the first region for outputting modulated light by transmitting and absorbing light generated in the semiconductor laser comprising:forming a semiconductor laminated layer structure including a quantum well structure layer on the first region and the second region of the semiconductor substrate; forming a lattice mismatched layer comprising a semiconductor material having a lattice constant smaller than the lattice constant of the semiconductor substrate on the semiconductor laminated layer structure; and etching and removing the portion of the lattice mismatched layer in the first region. 14. A method for producing an integrated semiconductor laser and light modulator in which a semiconductor laser is disposed on a first region of a semiconductor substrate and a light modulator of an electric field absorbing type is disposed at a second region on the semiconductor substrate adjacent to the first region for outputting modulated light by transmitting and absorbing light generated in the semiconductor laser comprising:forming a semiconductor laminated layer structure including a quantum well structure layer on the first region and the second region of the semiconductor substrate; forming an insulating film on the semiconductor laminated layer structure and patterning the insulating film into a configuration having an aperture on the semiconductor laminated layer structure in the second region; and forming a lattice mismatched layer comprising a semiconductor material having a lattice constant smaller than the lattice constant of the semiconductor substrate selectively on the semiconductor laminated layer structure in the second region employing the patterned insulating film as a selective growth mask. 15. A method for producing an integrated semiconductor laser and light modulator in which a semiconductor laser is disposed on a first region of a semiconductor substrate and a light modulator of an electric field absorbing type is disposed at a second region on the semiconductor substrate adjacent to the first region for outputting modulated light by transmitting and absorbing light generated in the semiconductor laser comprising:forming a semiconductor laminated layer structure including a quantum well structure layer on the first region and the second region of the semiconductor substrate; forming a lattice mismatched layer comprising a semiconductor material having a lattice constant larger than the lattice constant of the semiconductor substrate selectively on the semiconductor laminated layer structure; and etching and removing the portion of the lattice mismatched layer in the second region. 16. A method for producing an integrated semiconductor laser and light modulator in which a semiconductor laser is disposed on a first region of a semiconductor substrate and a light modulator of an electric field absorbing type is disposed at a second region on the semiconductor substrate adjacent to the first region for outputting modulated light by transmitting and absorbing light generated in the semiconductor laser comprising:forming a semiconductor laminated layer structure including a quantum well structure layer on the first region and the second region of the semiconductor substrate; forming an insulating film on the semiconductor laminated layer structure and patterning the insulating film into a configuration having an aperture on the semiconductor laminated layer structure in the first region; and forming a lattice mismatched layer comprising a semiconductor material having a lattice constant larger than the lattice constant of the semiconductor substrate selectively on the semiconductor laminated layer structure employing the patterned insulating film as a selective growth mask. 17. A method for producing an integrated semiconductor laser and light modulator in which a semiconductor laser is disposed on a first region of a semiconductor substrate and a light modulator of an electric field absorbing type is disposed at a second region on the semiconductor substrate adjacent to the first region for outputting modulated light by transmitting and absorbing light generated in the semiconductor laser comprising:forming a semiconductor laminated layer structure including a continuous semiconductor layer having a larger thickness in the first region than in the second region disposed opposite a quantum well structure layer in the first region and the second region; and forming a lattice mismatched layer comprising a semiconductor material having a lattice constant smaller than the lattice constant of the semiconductor substrate on the semiconductor laminated layer structure continuously in the first and second regions. 18. A method for producing an integrated semiconductor laser and light modulator in which a semiconductor laser is disposed on a first region of a semiconductor substrate and a light modulator of an electric field absorbing type is disposed at a second region on the semiconductor substrate adjacent to the first region for outputting modulated light by transmitting and absorbing light generated in the semiconductor laser comprising:forming a semiconductor laminated layer structure including a continuous semiconductor layer having a larger thickness in the first region than in the second region disposed opposite a quantum well structure layer in the first region and the second region; and forming a lattice mismatched layer comprising a semiconductor material having a lattice constant larger than the lattice constant of the semiconductor substrate on the semiconductor laminated layer structure continuously in the first and second regions. 19. A semiconductor laser comprising:a semiconductor substrate having a lattice constant; a semiconductor laminated layer structure including an active layer having a quantum well structure disposed on the semiconductor substrate; a lattice mismatched layer comprising a semiconductor material having a smaller lattice constant than the lattice constant of the semiconductor substrate disposed at a region of the semiconductor laminated layer structure; and a light emitting facet including a portion of the active layer directly opposite the region where the lattice mismatched layer is located. 20. The semiconductor laser of claim 19 wherein the quantum well structure layer includes a plurality of well layers and the minimum distance from a well layer of the quantum well structure layer to the lattice mismatched layer is more than 0.03 μm and the maximum distance from a well layer of the quantum well structure layer to the lattice mismatched layer is less than 0.08 μm.
21. The semiconductor laser of claim 19 wherein:the semiconductor substrate is GaAs; the semiconductor laminated layer structure includes at least some of GaAs, AlGaAs, GaInP, and AlGaInP layers; and the lattice mismatched layer is a GaInP layer which has a smaller lattice constant than GaAs. 22. A semiconductor laser comprising:a semiconductor substrate having a lattice constant; a semiconductor laminated layer structure including an active layer having a quantum well structure disposed on the semiconductor substrate; a lattice mismatched layer comprising a semiconductor material having a larger lattice constant than the lattice constant of the semiconductor substrate disposed above a region of the semiconductor laminated layer structure; and a light emitting facet including a portion of the active layer directly opposite the region where the lattice mismatched layer is absent. 23. The semiconductor laser of claim 22 wherein the quantum well structure layer includes a plurality of well layers and the minimum distance from a well layer of the quantum well structure layer to the lattice mismatched layer is more than 0.03 μm and the maximum distance from a well layer of the quantum well structure layer to the lattice mismatched layer is less than 0.08 μm.
24. The semiconductor laser of claim 22 wherein:the semiconductor substrate is GaAs; the semiconductor laminated layer structure includes at least some of GaAs, AlGaAs, GaInP, and AlGaInP layers; and the lattice mismatched layer is a GaInP layer which has a larger lattice constant than GaAs. 25. A semiconductor laser comprising:a semiconductor substrate having a lattice constant; a semiconductor laminated layer structure including an active layer having a quantum well structure and a semiconductor layer having a smaller thickness in a prescribed region than at another portion disposed on the semiconductor substrate; a lattice mismatched layer comprising a semiconductor material having a smaller lattice constant than the lattice constant of the semiconductor substrate disposed at a region of the semiconductor laminated layer structure; and a light emitting facet including the region of the semiconductor laminated layer structure having the semiconductor layer of the smaller thickness. 26. The semiconductor laser of claim 25 wherein the quantum well structure layer includes a plurality of well layers and the minimum distance from a well layer of the quantum well structure layer to the lattice mismatched layer at the portion of the semiconductor laminated layer structure having the semiconductor layer of larger thickness is more than 0.08 μm and the maximum distance from the well layer of the quantum well structure layer to the lattice mismatched layer at the portion of the semiconductor laminated layer structure having the semiconductor layer of the smaller thickness is less than 0.08 μm.
27. The semiconductor laser of claim 25 wherein:the semiconductor substrate is GaAs; the semiconductor laminated layer structure includes at least some of GaAs, AlGaAs, GaInP, and AlGaInP layers; and the lattice mismatched layer is a GaInP layer which has a smaller lattice constant than GaAs. 28. A semiconductor laser comprising:a semiconductor substrate having a lattice constant; a semiconductor laminated layer structure including an active layer having a quantum well structure and a semiconductor layer having a larger thickness in a region than at another portion disposed on the semiconductor substrate; a lattice mismatched layer comprising a semiconductor material having a larger lattice constant than the lattice constant of the semiconductor substrate disposed at a region of the semiconductor laminated layer structure; and a light emitting facet including the region of the semiconductor laminated layer structure having the semiconductor layer of the larger thickness. 29. The semiconductor laser of claim 28 wherein the quantum well structure layer includes a plurality of well layers and the minimum distance from a well layer of the quantum well structure layer to the lattice mismatched layer at the portion of the semiconductor laminated layer structure having the semiconductor layer of larger thickness is more than 0.08 μm and the maximum distance from the well layer of the quantum well structure layer to the lattice mismatched layer at the portion of the semiconductor laminated layer structure having the semiconductor layer of the smaller thickness is less than 0.08 μm.
30. The semiconductor laser of claim 28 wherein:the semiconductor substrate is GaAs; the semiconductor laminated layer structure includes at least some of GaAs, AlGaAs, GaInP, and AlGaInP layers; and the lattice mismatched layer is a GaInP layer which has a larger lattice constant than GaAs. 31. A method for producing a semiconductor laser comprising:forming a semiconductor laminated layer structure including an active layer having a quantum well structure on a semiconductor substrate; forming a lattice mismatched layer comprising a semiconductor material having a lattice constant smaller than that of the semiconductor substrate on the semiconductor laminated layer structure; and etching and removing the lattice mismatched layer except for portions adjacent light emitting facets. 32. A method for producing a semiconductor laser comprising:forming a semiconductor laminated layer structure including an active layer having a quantum well structure on a semiconductor substrate; forming an insulating film on the semiconductor laminated layer structure and patterning the insulating film into a configuration having an aperture on the semiconductor laminated layer structure at a portion including a region for a light emitting facet; and forming a lattice mismatched layer comprising a semiconductor material having a lattice constant smaller than the lattice constant of the semiconductor substrate selectively on the semiconductor laminated layer structure including the region for a light emitting facet employing the patterned insulating film as a selective growth mask. 33. A method for producing a semiconductor laser comprising:forming a semiconductor laminated layer structure including an active layer having a quantum well structure on a semiconductor substrate; forming a lattice mismatched layer comprising a semiconductor material having a lattice constant larger than that of the semiconductor substrate on the semiconductor laminated layer structure; and etching and removing the lattice mismatched layer only at portions adjacent light emitting facets. 34. A method for producing a semiconductor laser comprising:forming a semiconductor laminated layer structure including an active layer having a quantum well structure on a semiconductor substrate; forming an insulating film on the semiconductor laminated layer structure and patterning the insulating film into a configuration having an aperture on the semiconductor laminated layer structure at a portion except for a region including a light emitting facet and the vicinity thereof; and forming a lattice mismatched layer comprising a semiconductor material having a lattice constant larger than the lattice constant of the semiconductor substrate selectively on the semiconductor laminated layer structure except for the region including the light emitting facet and the vicinity thereof employing the patterned insulating film as a selective growth mask. 35. A method for producing a semiconductor laser comprising:forming on a semiconductor substrate a semiconductor laminated layer structure including a semiconductor layer disposed on and opposite an active layer of a quantum well structure, the layer being thinner in a region including a light emitting facet and the vicinity thereof than elsewhere; and forming a lattice mismatched layer comprising a semiconductor material having a lattice constant smaller than the lattice constant of the semiconductor substrate on the the semiconductor laminated layer structure. 36. A method for producing a semiconductor laser comprising:forming on a semiconductor substrate a semiconductor laminated layer structure including a semiconductor layer disposed on an active layer of a quantum well structure, the layer being thicker in a region including a light emitting facet and the vicinity thereof than elsewhere; and forming a lattice mismatched layer comprising a semiconductor material having a lattice constant larger than the lattice constant of the semiconductor substrate on the the semiconductor laminated layer structure. Description
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Embodiment 1 FIG. 1 is a partially sectioned perspective view illustrating a structure of an integrated semiconductor laser and light modulator according to a first embodiment of the present invention and FIG. 2 is a cross-section along the resonator length direction of a main portion of a semiconductor laser shown in FIG. 1. In the figures, reference numeral 101 designates an n type InP substrate. In the mesa stripe part 1000, an n type InP lower cladding layer 102 is disposed on the n type InP substrate 101, and undoped InGaAs/InGaAsP multi-quantum well layers 103a, 103b are disposed on the n type InP cladding layer 102. A p type InP first upper cladding layer 104 is disposed on the undoped multi-quantum well layers 103a and 103b, and a p type GaInP lattice mismatched layer 105 is disposed on the p type InP upper cladding layer 104 on a predetermined region in a stripe shape for a prescribed length. A p type InP second upper cladding layer 106a is disposed on the p type InP first upper cladding layer 104, a p type InP second upper cladding layer 106b is disposed on the p type GaInP lattice mismatched layer 105. A p type InGaAsP light guiding layer 107 formed as a diffraction grating is disposed on the p type second upper cladding layer 106a, a p type InP cap layer 108a is disposed on the p type second upper cladding layer 106a so as to bury the p type InGaAsP light guide layer 107, and a p type InP cap layer 108b is disposed on the p type InP upper cladding layer 106b. Fe doped InP blocking layers 109 are disposed at both sides of the mesa stripe part 1000. Stripe shaped p type InGaAs contact layers 110a and 110b are disposed on a part of the upper surface of the Fe doped InP blocking layers 109, and the upper surface of mesa stripe part 1000. A silicon nitride film 111 is disposed covering the boundary portion, i.e., connecting portion between the p type InGaAs contact layers 110a and 110b, and the upper surface of the Fe doped InP blocking layers 109. A p side electrode for the semiconductor laser 112a is disposed on the silicon nitride film 111 so that a portion thereof is in contact with the upper surface of the p type InGaAs contact layer 110a, and a p side electrode for the light modulator 112b is disposed on the silicon nitride film 111 so that a portion thereof is in contact with the upper surface of the p type InGaAs contact layer 110b. A common n side electrode 112c is disposed on the rear surface of the n type InP substrate 101.
Then, a p type Ga.sub.0.37 In.sub.0.63 P lattice mismatched layer 105 of 6 nm thick is epitaxially grown on the p type InP first upper cladding layer 104, and the GaInP lattice mismatched layer 105 is patterned into a stripe shape by employing conventional photolithography and etching as shown in FIG. 3(b). The stripe width of the lattice mismatched layer 105 is about 1.2 μm.
In FIG. 5(a), reference numeral 50 designates a GaAs substrate. On the substrate 50, an Al.sub.0.3 Ga.sub.0.7 As lower cladding layer 51 18 nm thick, a GaAs single quantum well layer 52 6 nm thick, an Al.sub.0.3 Ga.sub.0.7 As upper cladding layer 53 18 nm thick, a GaAs layer 54 3 nm thick, an In.sub.0.35 Ga.sub.0.65 As lattice mismatched layer 55 6 nm thick, and a GaAs layer 56 20 nm thick are successively epitaxially grown. The GaAs layer 54, the InGaAs lattice mismatched layer 55, and the GaAs layer 56 are formed in a wire configuration having a width W of 120 nm by vapor phase etching. FIG. 5(b) shows an energy band structure of the GaAs single quantum well layer 52 in the layer structure shown in FIG. 5(a).
In this prior art, an InGaAs lattice mismatched layer having a different lattice constant from GaAs is disposed on a GaAs single quantum well layer via the AlGaAs layer, and a stress is applied to the single quantum well layer, whereby the energy band structure of the single quantum well layer is partially modulated. In other words, the lattice constant of In.sub.0.35 Ga.sub.0.65 As is larger than that of GaAs by about 2.6%, and a tensile stress is applied to the GaAs single quantum well layer 52 directly above which the lattice mismatched layer 55 is disposed. As a result, in the layer structure shown in FIG. 5(a), the GaAs single quantum well layer 52 forms an energy band edge at a region directly above the quite thin InGaAs lattice mismatched layer 55 that is modulated so that the energy band is decreased. On the contrary, when a semiconductor layer having a smaller lattice constant than that of the well layer is employed, the well layer is subjected to a compressive stress, and the energy band edge of the well layer is modulated so that the energy band gap is increased.
In this embodiment, the lattice constant of the Ga.sub.0.37 In.sub.0.63 P lattice mismatched layer 105 is smaller than that of the InP substrate 101 by about 2.6%, and the multi-quantum well layer 103 directly below the GaInP lattice mismatched layer 105 is subjected to a compressive stress by the GaInP lattice mismatched layer 105. As a result, the energy band structure of the multi-quantum well layer 103 of the region which receives this stress is modulated, and the energy band gap thereof becomes larger than that of the multi-quantum well layer 103 of the region which does not receive the stress.
The layer thickness d.sub.1 of the layer disposed between the first quantum well layer (QW1) 65 and the lattice mismatched layer 68 is about 20 nm, the changed energy of the conduction band which the first quantum well layer (QW1) 65 receives is large, i.e., 13 meV, and the edge effect is large. On the other hand, the layer thickness d.sub.2 of the layer disposed between the second quantum well layer (QW2) 63 and the lattice mismatched layer 68 is about 52 nm, the changed energy of the conduction band which the second quantum well layer (QW2) 63 receives is 7 meV, and there is almost no edge effect. In addition, the layer thickness d.sub.3 of the layer disposed between the third quantum well layer (QW3) 61 and the lattice mismatched layer 68 is about 99 nm, and the changed energy of the conduction band which the third quantum well layer (QW3) 61 receives is 1 meV.
Embodiment 2 FIG. 7 is a partially sectioned perspective view illustrating an integrated semiconductor laser and light modulator according to a second embodiment of the present invention and FIG. 8 is a cross-section along the resonator length direction of a main portion of the semiconductor laser shown in FIG. 7. In the figures, reference numeral 121 designates an n type InP substrate. In the mesa stripe part 2000, an n type InP lower cladding layer 122 2 μm thick is disposed on the n type InP substrate 121, and undoped InGaAs/InGaAsP multi-quantum well active layers 123a, 123b are disposed on the n type InP cladding layer 122. The structure of the multi-quantum well is the same as that of the first embodiment. That is, it has a plurality of barrier layers each 7 nm thick comprising InGaAsP having an energy band gap corresponding to the wavelength of 1.32 μm and a plurality of InGaAs well layers each 3 nm thick, where the number of wells is five. A p type InP first upper cladding layer 124 0.03 μm thick is disposed on the undoped multi-quantum well active layers 123a and 123b, a p type InAs.sub.0.8 P.sub.0.2 lattice mismatched layer 125 6 nm thick is disposed on the p type InP upper cladding layer 124 on a predetermined region in a stripe shape for a prescribed length. P type InP second upper cladding layers 126a, 126b 0.2 μm thick are respectively disposed on the p type InAsP lattice mismatched layer 125 and on the p type InP first upper cladding layer 124. A p type InGaAsP light guide layer 127 45 nm thick is disposed on the p type InP second upper cladding layer 126a, which is formed in a diffraction grating, and a p type InP cap layer 128a is disposed on the p type InP second upper cladding layer 126a so as to bury the p type InGaAsP light guide layer 127, and a p type InP cap layer 128b is disposed on the p type InP second upper cladding layer 126b. Fe doped InP blocking layers 129 are disposed at the both sides of the mesa stripe part 2000. Stripe shaped p type InGaAs contact layers 130a and 130b 0.5 μm thick are disposed on a portion of the upper surface of the Fe doped InP blocking layer 129 and the upper surface of the mesa stripe part 2000. A silicon nitride film 131 is disposed so as to cover the boundary part (connecting part) between the p type InGaAs contact layers 130a and 130b, and the upper surface of the Fe doped InP blocking layers 129. A p side electrode for semiconductor laser 132a is disposed on the silicon nitride film 131 so that a portion thereof is in contact with the upper surface of the p type InGaAs contact layer 130a, and a p side electrode for light modulator 132b is disposed on the silicon nitride film 131 so that a portion thereof is in contact with the upper surface of the p type InGaAs contact layer 130b. The common n side electrode 132c is disposed at the rear surface of the n type InP substrate 121.
In this embodiment, the lattice constant of the InAs.sub.0.8 P.sub.0.2 lattice mismatched layer 125 is larger than that of the InP substrate 121 by about 2.6%, and the multi-quantum well layer 123 direct below the InAsP lattice mismatched layer 125 receives a tensile stress from the InAsP lattice mismatched layer 125. As a result, the energy band structure of the multi-quantum well layer 123 of the region which receives the stress is modulated and the energy band gap thereof becomes smaller than that of the multi-quantum well layer 123 of the region which does not receive the stress. In other words, the energy band gap of the light absorption layer 123b is larger than that of the active layer 123a. Accordingly, when no voltage is applied to the light modulator part (in a case of no bias), the laser light passes through the light modulator region without being absorbed by the light absorption layer 123b, and it is emitted from the cleaved facet of the light absorption layer 123b. On the other hand, when a reverse bias is applied to the light modulator while applying a plus voltage to the n side electrode 132c, and a minus voltage to the p side electrode 132b, an electric field is applied to the light absorption layer 123b, and due to the Quantum-Confined Stark Effect, the absorption edge due to the excitons is shifted to the longer wavelength side, whereby the effective energy band gap of the light absorption layer 123b decreases to a value lower than the value at the laser region, and the laser light is absorbed and disappears in the light modulator.
Embodiment 3 FIG. 9 is a partially sectioned perspective view illustrating a structure of an integrated semiconductor laser and light modulator according to a third embodiment of the present invention. In the figure, reference numeral 151 designates an n type InP substrate. A diffraction grating 157 is formed on a part of the substrate 151. In the mesa stripe part 3000, an n type InP lower cladding layer 152 is disposed on the n type InP substrate 151, and undoped InGaAs/InGaAsP multi-quantum well layers 153a, 153b are disposed on the n type InP cladding layer 152. A p type InP first upper cladding layer 154 is disposed on the undoped multi-quantum well layers 153a and 153b, and a p type GaInP lattice mismatched layer 155 is disposed on a predetermined region of the p type InP upper cladding layer 154 in a stripe shape for a prescribed length. In addition, a p type InP second upper cladding layer 156a is disposed on the p type InP first upper cladding layer 154, and a p type InP second upper cladding layer 156b is disposed on the p type GaInP lattice mismatched layer 155. A p type InP cap layer 158a is disposed on the p type second upper cladding layer 156a, and a p type InP cap layer 158b is disposed on the p type InP upper cladding layer 156b. Fe doped InP blocking layers 159 are disposed at the both sides of the mesa stripe part 3000.
Embodiment 4 FIG. 10 is a partially sectioned perspective view illustrating a structure of an integrated semiconductor laser and light modulator according to a fourth embodiment of the present invention. In the figure, reference numeral 171 designates an n type InP substrate. A diffraction grating 177 is formed at a portion of the substrate 171. In the mesa stripe part 4000, an n type InP lower cladding layer 172 is disposed on the n type InP substrate 171, and undoped InGaAs/InGaAsP multi-quantum well active layers 173a and 173b are disposed on the n type InP cladding layer 172. A p type InP first upper cladding layer 174 is disposed on the undoped multi-quantum well active layer 173a and 173b, a p type InAsP lattice mismatched layer 175 is disposed at a prescribed region on the p type InP upper cladding layer 174 in a stripe shape for a prescribed length, a p type InP second upper cladding layer 176a is disposed on the p type InAsP lattice mismatched layer 175, and a p type InP second upper cladding layer 176b is disposed on the p type InP first upper cladding layer 174. A p type InP cap layer 178a is disposed on the p type second upper cladding layer 176a, and a p type InP cap layer 178b is disposed on the p type InP upper cladding layer 176b. Fe doped InP blocking layers 179 are disposed at both sides of the mesa stripe part 4000. Stripe shaped p type InGaAs contact layers 180a and 180b are disposed on a part of the upper surface of Fe doped InP blocking layers 179 and the upper surface of the mesa stripe part 4000. A SiN film 181 is disposed so as to cover the boundary portion (connecting portion) of the p type InGaAs contact layers 180a and 180b and the upper surface of the Fe doped InP blocking layers 179. A p side electrode for semiconductor laser 182a is disposed on the SiN film 181 so that a portion thereof is in contact with the upper surface of the p type InGaAs contact layer 180a and a p side electrode for light modulator 182b is disposed on the SiN film 181 so that a portion thereof is in contact with the upper surface of the p type InGaAs contact layer 180b. A common n side electrode is disposed at the rear surface of the n type InP substrate 171.
Embodiment 5 FIG. 11 is a partially sectioned perspective view illustrating a structure of an integrated semiconductor laser and light modulator according to a fifth embodiment of the present invention, and FIG. 12 is a cross-sectional view illustrating along the resonator length direction of a main portion of the semiconductor laser shown in the figure 11. In the figures, reference numeral 201 designates an n type InP substrate. In the mesa stripe part 5000, an n type InP lower cladding layer 202 is disposed on the n type InP substrate 201, and undoped InGaAs/InGaAsP multi-quantum well structure layers 203a and 203b are disposed on the n type InP lower cladding layer 202. A p type first upper cladding layer 204 is disposed on the undoped InGaAs/InGaAsP multi-quantum well structure layers 203a and 203b. A p type InP second upper cladding layer 205 is disposed on the p type InP first upper cladding layer 204, being thin at a prescribed region 205b and thick at other region 205a. A p type GaInP lattice mismatched layer 206 is disposed on the p type InP second upper cladding layer 205, and a p type InP third upper cladding layer 207 is disposed on the p type GaInP lattice mismatched layer 206. A p type InGaAsP light guide layer 208 formed as a diffraction grating is disposed on the p type InP third upper cladding layer 207a, and a p type InP cap layer 209a is disposed on the p type third upper cladding layer 207a so as to bury the p type InGaAsP light guide layer 208 formed in a diffraction grating, and a p type InP cap layer 209b is disposed on the p type InP third upper cladding layer 207b. Fe doped InP blocking layers 210 are disposed at both sides of the mesa stripe part 5000. Stripe shaped p type InGaAs contact layers 211a and 211b are disposed on a part of the upper surface of the Fe doped InP blocking layers 210 and the upper surface of the mesa stripe part 5000. A SiN film 212 is disposed on the boundary portion (connecting portion) of the p type InGaAs contact layers 211a and 211b and the upper surface of the Fe doped InP blocking layers 210. A p side electrode for semiconductor laser 213a is disposed on the SiN film 212 so that a portion thereof is in contact with the upper surface of the p type InGaAs contact layer 211a and a p side electrode for light modulator 213b is disposed on the SiN film 212 so that a portion thereof is in contact with an upper surface of the p type InGaAs contact layer 211b. The common n side electrode 213c is disposed at the rear surface of n type InP substrate 201.
First of all, as shown in FIG. 13(a), the n type InP lower cladding layer 202, the undoped InGaAs/InGaAsP multi-quantum well structure layer 203, and the p type InP first upper cladding layer 204 are successively epitaxially grown on the n type InP substrate 201 by MOCVD or the like. Further, SiO.sub.2 film 215 is deposited on the p type InP first upper cladding layer 204, and this SiO.sub.2 film 215 is patterned into two stripes having narrower widths at the region for the light modulator than at the region for the semiconductor laser and extending in a stripe shape confronting both sides of the resonator along the resonator length direction of the semiconductor laser and having a predetermined interval by employing conventional photolithography and etching (FIG. 13(b)). As shown in FIG. 13(c), the p type InP second upper cladding layer 205 is epitaxially grown on the first upper cladding layer 204. FIG. 14(a) is a cross section taken along line 14a--14a in FIG. 13(c). As shown in FIG. 14(a), in the region having a wide width of the SiO.sub.2 film pattern 215, the p type InP second upper cladding layer 205 has a thicker grown film thickness than that of the region having a narrow width of the SiO.sub.2 film pattern 215. In the following description, the p type InP second upper cladding layer having a thicker film thickness is represented as the p type InP second upper cladding layer 205a, and the p type InP second upper cladding layer having a thinner film thickness is represented as the p type InP second upper cladding layer 205b.
Further, after removing the SiO.sub.2 film pattern 215 by etching, the p type GaInP lattice mismatched layer 206 is epitaxially grown, and further the GaInP lattice mismatched layer 206 is patterned to a stripe configuration by employing photolithography and etching (FIG. 13(d)). FIG. 14(b) is a cross section taken along line 14b--14b in FIG. 13(d).
The lattice constant of the GaInP lattice mismatched layer 206 is smaller than that of the InP substrate 201, and the InGaAs/InGaAsP multi-quantum well structure layer 203 directly below the GaInP lattice mismatched layer 206 receives a compressive stress from the GaInP lattice mismatched layer 206, and the energy band gap structure thereof is modulated. In this embodiment, the film thickness of p type InP second upper cladding layer 205 should be set so that the energy band gap of the InGaAs/InGaAsP multi-quantum well structure layer 203 is extended relative to before growing the GaInP lattice mismatched layer 206 in the region for the p type InP second upper cladding layer 205b having a thinner layer, while the energy band gap of the InGaAs/InGaAsP multi-quantum well structure layer 203 does not change relative to before growing the GaInP lattice mismatched layer 206 in the region for the p type InP upper second cladding layer 205a having a thicker layer. In other words, the grown layer thickness of the p type InP upper second cladding layer 205 is controlled so that in the region for the p type InP upper second cladding layer 205b having a thin layer, the distance from the upper end of the well layer disposed at the lowermost of the well layers forming the quantum well structure layer 203 to the lattice mismatched layer 206 is below 0.08 μm while in the region for the p type InP upper second cladding layer 205a having a thick layer, the distance from the upper end of the uppermost of the well layers forming the quantum well structure layer 203 is above 0.08 μm. This control can be performed by setting an appropriate width of the SiO.sub.2 film pattern 215 in the light modulator region and in the semiconductor laser region.
Embodiment 6 FIG. 15(a) is a perspective view illustrating a facet window structure semiconductor laser according to a sixth embodiment of the present invention and FIG. 15(b) is a cross section along line 15b--15b in FIG. 15(a).
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partially sectioned perspective view illustrating a structure of an integrated semiconductor laser and light modulator according to a first embodiment of the present invention.
FIELD OF THE INVENTION The present invention relates to semiconductor lasers and, more particularly, to an integrated semiconductor laser and light modulator that is used as a light source enabling high speed modulation and is monolithically integrated on the same semiconductor substrate. The present invention also relates to a semiconductor laser including a facet window layer having a larger energy band gap than that of the active layer at the light emitting facet. This invention also relates to methods for fabricating these semiconductor lasers.
BACKGROUND OF THE INVENTION An integrated light source integrating a long wavelength band semiconductor light emitting element (hereinafter referred to as a semiconductor laser) and an electric field absorption type light modulator (hereinafter referred to as a light modulator) on a same semiconductor substrate such as an InP substrate is employed as a signal light source for high speed modulation optical communication.
A description is given of the process for fabricating the integrated semiconductor laser and light modulator. First of all, as shown in FIG. 18(a), a diffraction grating 357 is formed on the InP substrate 351 at a surface of the region for the semiconductor laser and a stripe shaped silicon dioxide film 370 is formed along the light waveguiding direction of the semiconductor laser on both sides of the diffraction grating 357 (in the figure, a region for producing a light modulator portion is closer). The dimension of the silicon oxide film 370 is, for example, about 200 μm oxide films 370 (the width of the region where the diffraction grating 357 is formed) is about 200 μm.
A description is given of the operation. The InGaAs/InGaAsP multi-quantum well layer 353 serves as an active layer at the region of the semiconductor laser and as a light absorption layer at the region of the light modulator. When a forward direction bias is applied across the p side electrode and the n side electrode of the semiconductor laser, carriers are injected into the InGaAs/InGaAsP multi-quantum well layer 353 and a laser oscillation occurs at a wavelength in accordance with the effective energy band gap of the MQW layer and the period of the diffraction grating 357. The energy band gap of the MQW layer depends on the thickness of the well layer of the MQW layer, and as the well layer thickness becomes thinner, the energy band gap becomes larger. As already described, during the selective growth by MOCVD, the well layer thickness is larger in the semiconductor laser region than in the light modulator region, and the band gap energy Eg1 of the MQW layer in the DFB laser region is larger than the band gap energy Eg2 of that in the light modulator region. When the light modulator is set in the no bias state and the DFB laser is set in a forward bias state to continuously oscillate, the laser light of wavelength (λ1=1.24/Eg1) is not absorbed at the light modulator region because Eg1&lt;Eg2 and is emitted from the facet. On the other hand, when a reverse bias is applied to the light modulator, due to the Quantum-Confined Stark Effect of an MQW layer, the absorbing edge due to excitons is shifted toward the long wavelength side as shown in FIG. 20 and the effective energy band gap Eg'2 is shorter than the value at the DFB laser region (Eg'2&lt;Eg1), whereby the laser light is absorbed by the light modulator and the light output is turned off. Accordingly, the laser light can be turned on or off by modulating a voltage applied to the light modulator.
FIG. 21 is a perspective view illustrating a structure of the vicinity of the laser facet of a high output semiconductor laser having a window structure at the laser oscillation facet, recited in Japanese Journal of Applied Physics, Vol. 30, (1991), 1904-1906. In the figure, reference numeral 401 designates a p type GaAs substrate. Reference numeral 402 designates an n type GaAs current blocking layer, numeral 403 designates a p type Al.sub.0.33 Ga.sub.0.67 As cladding layer, numeral 404 designates a p type Al.sub.0.08 Ga.sub.0.92 As active layer, numeral 405 designates an n type Al.sub.0.33 Ga.sub.0.67 As cladding layer, and numeral 406 designates an n type GaAs contact layer. Reference numeral 407 designates a (101) facet formed by cleavage, and numeral 408 designates an undoped AlGaAs window layer formed on the cleavage facet 407.
A material having an energy band gap larger than that of the laser light is grown on the laser resonator facet 407 produced by cleavage by MOCVD. In this prior art device, the laser oscillation wavelength is 830 nm which corresponds to an energy of about 1.49 eV, and an undoped Al.sub.0.4 Ga.sub.0.6 As layer 408 having an energy band gap of about 1.93 eV is employed as a window layer. After electrodes are formed, coating of the window layer facet and chip separation are performed, thereby completing a laser chip.
SUMMARY OF THE INVENTION It is an object of the present invention to provide an integrated semiconductor laser and light modulator in which an active layer of a semiconductor laser and a light absorption layer of a light modulator can be produced simultaneously by a conventional epitaxial growth, and which is superior in the element reliability and has a lengthy lifetime.
According to a third aspect of the present invention, a semiconductor laser device includes a semiconductor laser disposed on a first region of a semiconductor substrate, and a light modulator of an electric field absorbing type which is disposed at a second region on the semiconductor substrate adjacent the first region and outputs a modulated light by transmitting or absorbing the light generated in the semiconductor laser. Further it includes a semiconductor laminating layer structure including a quantum well structure layer disposed over the first region and the second region on the semiconductor substrate, and a lattice mismatched layer produced over the semiconductor laminating layer structure disposed on the first and the second region and comprising a semiconductor having a lattice constant smaller than that of the semiconductor substrate, and the thickness from the upper surface of the well layer producing the quantum well structure to the lower surface of the lattice mismatched layer is t1 at the first region and t2 at the second region, where t1&gt;t2.
According to a fourth aspect of the present invention, a semiconductor laser device includes a semiconductor laser disposed on a first region of a semiconductor substrate, and a light modulator of an electric field absorbing type which is disposed at a second region on the semiconductor substrate adjacent the first region and outputs a modulated light by transmitting or absorbing the light generated in the semiconductor laser. Further, it includes a semiconductor laminating layer structure including a quantum well structure layer disposed over the first region and the second region on the semiconductor substrate, and a lattice mismatched layer produced over the semiconductor laminating layer structure disposed on the first and the second region and comprising a semiconductor having a lattice constant larger than that of the semiconductor substrate, and the thickness from the upper surface of the well layer producing the quantum well structure to the lower surface of the lattice mismatched layer is t1 at the first region and t2 at the second region, where t1&lt;t2.
Patent CitationsCited PatentFiling datePublication dateApplicantTitleUS3993963 *Jun 20, 1974Nov 23, 1976Bell Telephone Laboratories, IncorporatedHeterostructure devices, a light guiding layer having contiguous zones of different thickness and bandgap and method of making sameUS4523316 *Oct 29, 1982Jun 11, 1985Rca CorporationSemiconductor laser with non-absorbing mirror facetUS5048036 *Jan 4, 1991Sep 10, 1991Spectra Diode Laboratories, Inc.Heterostructure laser with lattice mismatchUS5119393 *Jun 13, 1990Jun 2, 1992Hitachi, Ltd.Semiconductor laser device capable of controlling wavelength shiftGB2273813A * Title not available* Cited by examinerNon-Patent CitationsReference1Aoki et al, "High-Speed (10Gbit/s) And Low-Drive-Voltage (1V Peak To Peak) InGaAs/InGaAsP MOW Electroabsorption-Modulator Integrated DFB Laser With Semi-Insulating Buried Heterostructure", Electronics Letters, vol. 28, No. 12, Jun. 1992, pp. 1157-1158.2Aoki et al, "Novel Structure MOW Electroabsorption Modulator/DFB Laser Integrated Device Fabricated By Selective Area MOCVD Growth", Electronics Letters, vol. 27, No. 23, Nov. 1991, pp. 2138-2140.3 *Aoki et al, High Speed (10Gbit/s) And Low Drive Voltage (1V Peak To Peak) InGaAs/InGaAsP MOW Electroabsorption Modulator Integrated DFB Laser With Semi Insulating Buried Heterostructure , Electronics Letters, vol. 28, No. 12, Jun. 1992, pp. 1157 1158.4 *Aoki et al, Novel Structure MOW Electroabsorption Modulator/DFB Laser Integrated Device Fabricated By Selective Area MOCVD Growth , Electronics Letters, vol. 27, No. 23, Nov. 1991, pp. 2138 2140.5Maciejko et al, "Selective TE-TM Mode Pumping Efficiencies For Ridge-Waveguide Lasers In Presence Of Stress", IEEE Journal of Quantum Electronics, vol. 29, No. 1, 1993, pp. 51-61 (Jan.).6 *Maciejko et al, Selective TE TM Mode Pumping Efficiencies For Ridge Waveguide Lasers In Presence Of Stress , IEEE Journal of Quantum Electronics, vol. 29, No. 1, 1993, pp. 51 61 (Jan.).7Suzuki et al, "λ/4-Shifted DFB Laser/Electroabsorption Modulator Integrated Light Source For Multigigabit Transmission", IEEE Transactions on Lightwave Technology, vol. 10, No. 1, (Jan.) 1992, pp. 90-95.8 *Suzuki et al, /4 Shifted DFB Laser/Electroabsorption Modulator Integrated Light Source For Multigigabit Transmission , IEEE Transactions on Lightwave Technology, vol. 10, No. 1, (Jan.) 1992, pp. 90 95.9Tan et al, "Systematic Observation Of Strain-Induced Lateral Quantum Confinement In GaAs Quantum Well Wires Prepared By Chemical Dry Etching", Applied Physics Letters, vol. 59, No. 15, Oct. 1991, pp. 1875-1877.10 *Tan et al, Systematic Observation Of Strain Induced Lateral Quantum Confinement In GaAs Quantum Well Wires Prepared By Chemical Dry Etching , Applied Physics Letters, vol. 59, No. 15, Oct. 1991, pp. 1875 1877.11Xu et al, "Lateral Band Gap Modulation By Buried Stressor Structures In III-V Compounds Semiconductor Quantum-Well Structures", Applied Physics Letters, vol. 60, No. 5, 1992, pp. 586-588.12 *Xu et al, Lateral Band Gap Modulation By Buried Stressor Structures In III V Compounds Semiconductor Quantum Well Structures , Applied Physics Letters, vol. 60, No. 5, 1992, pp. 586 588.13Yamada et al, "Strained InGaAs/GaAs Single Quantum Well Lasers With Saturable Absorbers Fabricated By Quantum Well Intermixing", Applied Physics Letters, vol. 60, No. 20, May 1992, pp. 2463-2465.14 *Yamada et al, Strained InGaAs/GaAs Single Quantum Well Lasers With Saturable Absorbers Fabricated By Quantum Well Intermixing , Applied Physics Letters, vol. 60, No. 20, May 1992, pp. 2463 2465.* Cited by examinerReferenced byCiting PatentFiling datePublication dateApplicantTitleUS5646064 *Jan 20, 1995Jul 8, 1997Alcatel N.V.Method of fabricating a segmented monocrystalline chipUS5717710 *Nov 15, 1995Feb 10, 1998Mitsubishi Denki Kabushiki KaishaOptical semiconductor deviceUS6031859 *Aug 19, 1997Feb 29, 2000Nec CorporationMode-locked semiconductor laserUS6222867 *May 18, 1998Apr 24, 2001Nec CorporationOptical semiconductor device having waveguide layers buried in an InP current blocking layerUS6391671Jan 9, 2001May 21, 2002Nec CorporationMethod of producing an optical semiconductor device having a waveguide layer buried in an InP current blocking layerUS6455338 *Sep 21, 1999Sep 24, 2002Mitsubishi Denki Kabushiki KaishaMethod of manufacturing an integrated semiconductor laser-modulator deviceUS6580740 *Jul 18, 2001Jun 17, 2003The Furukawa Electric Co., Ltd.Semiconductor laser device having selective absorption qualitiesUS6594295Nov 16, 2001Jul 15, 2003Fox-Tek, Inc.Semiconductor laser with disordered and non-disordered quantum well regionsUS6611007May 9, 2002Aug 26, 2003Fiber Optic Systems Technology, Inc.Method for locally modifying the effective bandgap energy in indium gallium arsenide phosphide (InGaAsP) quantum well structuresUS6628686Nov 16, 2001Sep 30, 2003Fox-Tek, IncIntegrated multi-wavelength and wideband lasersUS6731850Nov 16, 2001May 4, 2004Fox-TekSingle-waveguide integrated wavelength demux photodetector and method of making itUS6795466 *Jan 13, 2000Sep 21, 2004Pioneer CorporationDistributed feedback type semiconductor laser deviceUS6797533Oct 4, 2002Sep 28, 2004Mcmaster UniversityQuantum well intermixing in InGaAsP structures induced by low temperature grown InPUS6807214 *Aug 1, 2002Oct 19, 2004Agilent Technologies, Inc.Integrated laser and electro-absorption modulator with improved extinctionUS6878562Jul 26, 2001Apr 12, 2005Phosistor Technologies, IncorporatedMethod for shifting the bandgap energy of a quantum well layerUS6888666Nov 16, 2001May 3, 2005Dakota Investment Group, Inc.Dynamically reconfigurable optical amplification elementUS7103079Jun 28, 2004Sep 5, 2006Applied Materials, Inc.Pulsed quantum dot laser system with low jitterUS7555027Apr 20, 2007Jun 30, 2009Innolume GmbhLaser source with broadband spectrum emissionUS7561607Dec 7, 2005Jul 14, 2009Innolume GmbhLaser source with broadband spectrum emissionUS7835408Nov 12, 2007Nov 16, 2010Innolume GmbhOptical transmission systemUS8411711Dec 3, 2009Apr 2, 2013Innolume GmbhSemiconductor laser with low relative intensity noise of individual longitudinal modes and optical transmission system incorporating the laserUS8441018 *Feb 16, 2010May 14, 2013The Trustees Of Columbia University In The City Of New YorkDirect bandgap substrates and methods of making and usingUS20100213467 *Feb 16, 2010Aug 26, 2010The Trustees Of Columbia University In The City Of New YorkDirect bandgap substrates and methods of making and usingEP0824274A2 *Aug 4, 1997Feb 18, 1998Oki Electric Industry Co., Ltd.Light emitting diode and manufacturing method therefor* Cited by examinerClassifications U.S. Classification372/50.1, 257/E27.12, 372/26, 372/45.13International ClassificationH01L33/00, H01S5/06, H01L27/15, G02B6/124, H01S5/026, G02B6/12, H01S5/00Cooperative ClassificationH01L33/0062, H01S5/0265, G02B6/124, H01L27/15, G02B2006/12128European ClassificationH01L33/00G3, H01L27/15, G02B6/124, H01S5/026FLegal EventsDateCodeEventDescriptionSep 19, 2000FPExpired due to failure to pay maintenance feeEffective date: 20000723Jul 23, 2000LAPSLapse for failure to pay maintenance feesFeb 15, 2000REMIMaintenance fee reminder mailedSep 12, 1994ASAssignmentOwner name: MITSUBISHI DENKI KABUSHIKI KAISHA, JAPANFree format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:TAKEMI, MASAYOSHI;KIZUKI, HIROTAKA;REEL/FRAME:007138/0034Effective date: 19940824Sep 12, 1994AS02Assignment of assignor's interestOwner name: KIZUKI, HIROTAKAEffective date: 19940824Owner name: MITSUBISHI DENKI KABUSHIKI KAISHA 2-3, MARUNOUCHIOwner name: TAKEMI, MASAYOSHIRotateOriginal ImageGoogle Home - Sitemap - USPTO Bulk Downloads - Privacy Policy - Terms of Service - About Google Patents - Send FeedbackData provided by IFI CLAIMS Patent Services©2012 Google