EP0784366A2
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EP
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Optical semiconductor apparatus, fabrication method thereof, modulation method therefor, light source apparatus and optical communication system or method using the same
Assignee: Canon Inc
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Filing: 1997-01-09
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Granted: —
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Expires: 2017-01-09
Abstract
Abstract An optical semiconductor apparatus includes a substrate (1, 21, 41, 71, 101, 120, 141, 161), a first region (18, 77, 107, 127) formed on the substrate, a second region (19, 78, 108, 128) formed on the substrate, and a stimulating unit (8; 36, 37; 79, 80; 109, 110; 131, 133; 149, 150; 192, 193). The first region includes a first waveguide which extends in a light propagation direction and is constructed so as to permit light waves in two different polarization modes to be propagated in the propagation direction. The first waveguide contains a first active region which is constructed such that a gain for one of the different polarization modes is dominant. The second region includes a second waveguide which extends in the propagation direction, is coupled to the first waveguide and is constructed so as to permit light waves in the different polarization modes to be propagated in the propagation direction. The second waveguide contains a second active region which is constructed such that a gain for the other of the different polarization modes is dominant. At least one of the first and second active regions includes a first active layer (73, 103, 123, 144, 165), in which a gain for one of the different polarization modes is dominant, and a second active layer (74, 104, 124, 145, 169), in which a gain for the other of the different polarization modes is dominant. The stimulating unit stimulates the first and second active regions independently from each other.
Inventors
- 👤 Natsuhiko Mizutani
- 👤 Seiichi Miyazawa
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 15:05
CPC Classifications
B; B82; B82Y; B82Y20/00; H; H01; H01S; H01S5/00; H01S5/06; H01S5/062; H01S5/0625; H01S2301/00; H01S2301/14; H01S5/06233; H01S5/06236; H01S5/30; H01S5/34; H01S5/3403; H01S5/3404
Claims Analysis
Total Claims: 49
Claim 1
Independent Claim
267 words
An optical semiconductor apparatus comprising: a substrate (1, 21, 41, 71, 101, 120, 141, 161); a first region (18, 77, 107, 127) formed on said substrate, said first region including a first waveguide which extends in a light propagation direction, said first region being constructed so as to permit light waves in two different polarization modes to be propagated in the light propagation direction, said first waveguide containing a first active region which is constructed such that a gain for one of the two different polarization modes is dominant therein; a second region (19, 78, 108, 128) formed on said substrate, said second region including a second waveguide which extends in the light propagation direction, said second region being coupled to said first waveguide and being constructed so as to permit light waves in the two different polarization modes to be propagated in the light propagation direction, said second waveguide containing a second active region which is constructed such that a gain for the other of the two different polarization modes is dominant therein, at least one of said first active region and said second active region including a first active layer (73, 103, 123, 144, 165), in which a gain for one of the two different polarization modes is dominant, and a second active layer (74, 104, 124, 145, 169), in which a gain for the other of the two different polarization modes is dominant; and stimulating means (8; 36, 37; 79, 80; 109, 110; 131, 133; 149, 150; 192, 193) for stimulating said first active region and said second active region independently from each other.
Claim 2
Dependent Claim
35 words
An optical semiconductor apparatus according to claim 1, wherein said first region and said second region are serially arranged on said substrate (1, 21, 41, 71, 101, 120, 141, 161) along the light propagation direction.
Claim 3
Dependent Claim
33 words
An optical semiconductor apparatus according to claim 1 or 2, further comprising a wavelength selection means (2, g, 81, 111, 121, 151, 162) for selecting a radiation wavelength of said optical semiconductor apparatus.
Claim 4
Dependent Claim
33 words
An optical semiconductor apparatus according to claim 3, wherein said wavelength selection means comprises a diffraction grating (2, g, 81, 111, 121, 151, 162) formed along said first waveguide and said second waveguide.
Claim 5
Dependent Claim
20 words
An optical semiconductor apparatus according to claim 4, wherein said optical semiconductor apparatus is constructed as a distributed feedback laser.
Claim 6
Dependent Claim
34 words
An optical semiconductor apparatus according to claim 3, 4 or 5, further comprising end facets and an antireflection coating (11) provided on at least one of said end facets of said optical semiconductor apparatus.
Claim 7
Dependent Claim
36 words
An optical semiconductor apparatus according to any one of claims 1 to 6, wherein both of said first active region and said second active region respectively include said first active layer and said second active layer.
Claim 8
Dependent Claim
61 words
An optical semiconductor apparatus according to any one of claims 1 to 7, wherein both of said first active region and said second active region respectively include common active layers (74, 104, 123, 146, 169) whose constructions are identical with each other and which are respectively comprised of at least one of said first active layer and said second active layer.
Claim 9
Dependent Claim
59 words
An optical semiconductor apparatus according to claim 8, wherein one of said first active region and said second active region only includes said common active layer (74, 104, 123, 146, 169) and the other of said first active region and said second active region includes said common active layer and an additional active layer (73, 103, 124, 144, 165).
Claim 10
Dependent Claim
25 words
An optical semiconductor apparatus according to claim 9, wherein said additional active layer comprises one of said first active layer and said second active layer.
Claim 11
Dependent Claim
32 words
An optical semiconductor apparatus according to claim 9 or 10, wherein said additional active layer (73, 103, 124) is placed closer to a p-side than said common active layer (74, 104, 123).
Claim 12
Dependent Claim
47 words
An optical semiconductor apparatus according to any one of claims 1 to 11, wherein said first active layer comprises a non-strained or compressively-strained quantum well layer (13, 24, 46, 84, 115) and said second active layer comprises a tensile-strained quantum well layer (15, 30, 44, 87, 112).
Claim 13
Dependent Claim
45 words
An optical semiconductor apparatus according to claim 12, wherein at least one of said non-strained or compressively-strained quantum well layer (13, 24, 46, 84, 115) and said tensile-strained quantum well layer (15, 30, 44, 87, 112) comprises a plurality of kinds of quantum well layers.
Claim 14
Dependent Claim
77 words
An optical semiconductor apparatus according to claim 12 or 13, wherein said first active layer (73, 103, 123, 144, 165) and said second active layer (74, 104, 124, 145, 169) respectively have substantially the same transition energy between a ground level of electrons in a conduction band of said quantum well layer (13, 15, 24, 30, 44, 46, 84, 87, 112, 115) and a ground level of holes in a valence band of said quantum well layer.
Claim 15
Dependent Claim
71 words
An optical semiconductor apparatus according to any one of claims 1 to 6, wherein one of said first active region and said second active region includes said first active layer (73, 103, 144, 165) and said second active layer (74, 104, 146, 169) formed on said first active layer and the other of said first active region and said second active region includes said second active layer (74, 104, 146, 169).
Claim 16
Dependent Claim
36 words
An optical semiconductor apparatus according to claim 15, wherein said second active layers (74, 104, 146, 169) respectively contained in said first active region and said second active region are identical with each other in construction.
Claim 17
Dependent Claim
30 words
An optical semiconductor apparatus according to claim 15 or 16, wherein said first active layer (73, 103) is placed closer to a p-side than said second active layer (74, 104).
Claim 18
Dependent Claim
64 words
An optical semiconductor apparatus according to any one of claims 1 to 6, wherein one of said first active region (127) and said second active region (128) includes said first active layer (123) and said second active layer (124) formed on said first active layer and the other of said first active region and said second active region includes said first active layer (123).
Claim 19
Dependent Claim
33 words
An optical semiconductor apparatus according to claim 18, wherein said first active layers (123) respectively contained in said first active region and said second active region are identical with each other in construction.
Claim 20
Dependent Claim
28 words
An optical semiconductor apparatus according to claim 18 or 19, wherein said second active layer (124) is placed closer to a p-side than said first active layer (123).
Claim 21
Dependent Claim
35 words
An optical semiconductor apparatus according to any one of claims 1 to 20, further comprising an etching stopper layer (28, 143, 164) for stopping an etching process performed during fabrication of said optical semiconductor apparatus.
Claim 22
Dependent Claim
28 words
An optical semiconductor apparatus according to claim 21, wherein said etching stopper layer (28) is formed in one of said first active region and said second active region.
Claim 23
Dependent Claim
28 words
An optical semiconductor apparatus according to claim 21, wherein said etching stopper layer (143, 164) is formed immediately under said first active region and said second active region.
Claim 24
Dependent Claim
50 words
An optical semiconductor apparatus according to claim 21, 22 or 23, wherein said substrate (21, 141, 161), said first region and said second region are formed with materials of In x Ga 1-x As y P 1-y series, and said etching stopper layer (28, 143, 164) is made of InP.
Claim 25
Dependent Claim
38 words
An optical semiconductor apparatus according to any one of claims 1 to 24, further comprising a boundary surface improving layer (166) for improving a boundary condition between said first active layer (165) and said second active layer (169).
Claim 26
Dependent Claim
44 words
An optical semiconductor apparatus according to claim 25, wherein said substrate (161), said first region and said second region are formed with materials of In x Ga 1-x As y P 1-y series, and said boundary surface improving layer (166) is made of InP.
Claim 27
Dependent Claim
45 words
An optical semiconductor apparatus according to any one of claims 1 to 26, wherein at least one of said first active layer (73, 103, 123, 144, 165) and said second active layer (74, 104, 124, 145, 169) is at least partially doped with an impurity.
Claim 28
Dependent Claim
45 words
An optical semiconductor apparatus according to any one of claims 1 to 27, further comprising a barrier layer (88, 116) formed between said first active layer and said second active layer for separating said first active layer and said second active layer from each other.
Claim 29
Dependent Claim
26 words
An optical semiconductor apparatus according to any one of claims 1 to 28, wherein said optical semiconductor apparatus is constructed as an oscillation polarization-mode switchable laser.
Claim 30
Dependent Claim
27 words
An optical semiconductor apparatus according to any one of claims 1 to 28, wherein said optical semiconductor apparatus is constructed as a polarization-mode insensitive semiconductor optical amplifier.
Claim 31
Independent Claim
166 words
A method for driving an optical semiconductor apparatus recited in any one of claims 1 to 30, said driving method comprising the steps of: establishing a bias state, in which a round-trip gain for one of the two different polarization modes competes with a round-trip gain for the other of the two different polarization modes, by controlling amounts of currents respectively injected into the first active region and the second active region by the stimulating means (8; 36, 37; 79, 80; 109, 110; 131, 133; 149, 150; 192, 193); establishing a modulation bias point, in which light in one of the two different polarization modes is oscillated, by slightly increasing the amount of the current injected into one of the first active region and the second active region; and switching the polarization mode of the oscillated light between the two different polarization modes by injecting a signal of a minute modulation current into at least one of the first active region and the second active region.
Claim 32
Independent Claim
101 words
A method for fabricating an optical semiconductor apparatus recited in any one of claims 1 to 30, said fabrication method comprising the steps of: forming the first active layer (123) and the second active layer (124) consecutively over the first region and the second region on the substrate (1, 21, 41, 120); etching at least the second active layer at least partially in one of the first region and the second region on the substrate; and forming remaining layers (5, 6, 7; 33, 34, 35; 49, 50, 51; 129, 130) over the first region and the second region on the substrate.
Claim 33
Dependent Claim
27 words
A method for fabricating an optical semiconductor apparatus according to claim 32, further comprising a step of forming an etching stopper layer (28) in the active layer.
Claim 34
Dependent Claim
33 words
A method for fabricating an optical semiconductor apparatus according to claim 32, further comprising a step of forming an etching stopper layer (28) between the first active layer and the second active layer.
Claim 35
Independent Claim
37 words
A method for fabricating an optical semiconductor apparatus according to any one of claims 32 to 34, further comprising a step of forming a protective layer (32, 48) immediately after the formation of the second active layer.
Claim 36
Independent Claim
41 words
A method for fabricating an optical semiconductor apparatus according to any one of claims 32 to 35, further comprising a step of doping at least part of the first active layer (123) and the second active layer (124) with an impurity.
Claim 37
Independent Claim
36 words
A method for fabricating an optical semiconductor apparatus according to any one of claims 32 to 36, further comprising a step of forming a barrier layer between the first active layer and the second active layer.
Claim 38
Dependent Claim
33 words
A method for fabricating an optical semiconductor apparatus according to claim 32, wherein said etching step is stopped halfway between a barrier layer (47-2) in a quantum well layer of the active layer.
Claim 39
Independent Claim
32 words
A method for fabricating an optical semiconductor apparatus according to any one of claims 32 to 38, further comprising a step of forming a diffraction grating (2, g, 121) on the substrate.
Claim 40
Independent Claim
112 words
A method for fabricating an optical semiconductor apparatus recited in any one of claims 1 to 30, said fabrication method comprising the steps of: forming the first active layer (73, 103, 144, 165) over the first region and the second region on the substrate (71, 101, 141, 161); etching the first active layer at least partially in one of the first region and the second region on the substrate; forming the second active layer (74, 104, 145, 169) over the first region and the second region on the substrate; and forming remaining layers (75, 76; 105, 106; 147, 148; 190, 191) over the first region and the second region on the substrate.
Claim 41
Dependent Claim
33 words
A method for fabricating an optical semiconductor apparatus according to claim 40, further comprising a step of forming an etching stopper layer (143, 164) immediately before the formation of the first active layer.
Claim 42
Dependent Claim
27 words
A method for fabricating an optical semiconductor apparatus according to claim 40, further comprising a step of forming an etching stopper layer in the first active layer.
Claim 43
Independent Claim
47 words
A method for fabricating an optical semiconductor apparatus according to any one of claims 40 to 42, further comprising a step of doping at least part of the first active layer (73, 103, 144, 165) and the second active layer (74, 104, 145, 169) with an impurity.
Claim 44
Independent Claim
38 words
A method for fabricating an optical semiconductor apparatus according to any one of claims 40 to 43, further comprising a step of forming a barrier layer (88, 116) between the first active layer and the second active layer.
Claim 45
Independent Claim
38 words
A method for fabricating an optical semiconductor apparatus according to any one of claims 40 to 44, further comprising a step of forming a boundary surface improving layer (166) immediately after the formation of the first active layer
Claim 46
Independent Claim
33 words
A method for fabricating an optical semiconductor apparatus according to any one of claims 40 to 45, further comprising a step of forming a diffraction grating (81, 111, 151, 162) on the substrate.
Claim 47
Dependent Claim
98 words
An optical communication method for transmitting a signal from a transmitter (504) to a receiver (503) through an optical transmission line (500, 800, 900), said method comprising the steps of: modulating the polarization mode of light output from an optical semiconductor apparatus between two different polarization modes by controlling current injected into the optical semiconductor apparatus, the optical semiconductor apparatus being recited in any one of claims 1 to 30; selecting only the light output in one of the two different polarization modes to create an amplitude-modulated signal; and transmitting the amplitude-modulated signal through the optical transmission line.
Claim 48
Dependent Claim
119 words
An optical communication system for transmitting a signal from a transmitter (504) to a receiver (503) through an optical transmission line (500, 800, 900), said system comprising: an optical semiconductor apparatus provided in the transmitter, a polarization mode of light output from said optical semiconductor apparatus being modulated between two different polarization modes by controlling current injected into said optical semiconductor apparatus, and said optical semiconductor apparatus being recited in any one of claims 1 to 30; and means (507) for selecting only the light output in one of the two different polarization modes so as to create an amplitude-modulated signal, the amplitude-modulated signal being the signal transmitted from the transmitter to the receiver through the optical transmission line.
Claim 49
Dependent Claim
68 words
A light source apparatus comprising: an optical semiconductor apparatus, a polarization mode of light output from said optical semiconductor apparatus being modulated between two different polarization modes by controlling current injected into said optical semiconductor apparatus, and said optical semiconductor apparatus being recited in any one of claims 1 to 30; and means (507) for selecting only the light output in one of the two different polarization modes.
References Cited (Backward Citations)
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