EP0386797A2 — Optical apparatus using wavelength selective phot…

Claim 1

Independent Claim 134 words

A photosensor comprising: a substrate; a first waveguide layer formed on said substrate; a second waveguide layer formed on said first waveguide layer to be stacked in a direction of thickness, said second waveguide layer having a guided mode different from that of said first waveguide layer; a diffraction grating formed on an overlapping region of the guided modes of said first and second waveguide layers, said diffraction grating coupling light components of a specific wavelength range of light propagating through said first waveguide layer to said second waveguide layer; a light absorption layer for absorbing at least some light components of the light components coupled to said second waveguide layer; and an electrode for converting the light components absorbed by said light absorption layer into an electrical signal and outputting the electrical signal.

Claim 2

Dependent Claim 134 words

A photosensor comprising: a substrate; a first waveguide layer formed on said substrate; a second waveguide layer formed on said first waveguide layer to be stacked in a direction of thickness, said second waveguide layer having a guided mode different from that of said first waveguide layer; a diffraction grating formed on an overlapping region of the guided modes of said first and second waveguide layers, said diffraction grating coupling light components of a specific wavelength range of light propagating through said first waveguide layer to said second waveguide layer; a light absorption layer for absorbing at least some light components of the light components coupled to said second waveguide layer; and an electrode for converting the light components absorbed by said light absorption layer into an electrical signal and outputting the electrical signal.

Claim 3

Dependent Claim 26 words

A photosensor according to claim 1, wherein said light absorption layer is formed in series with said second waveguide layer in a propagation direction of light.

Claim 4

Dependent Claim 39 words

A photosensor according to claim 1, wherein said light absorption layer comprises an i-type semiconductor, and p- and n-type semiconductor layers are formed on two sides of said light absorption layer, so that said photosensor constitutes a PIN photodiode.

Claim 5

Dependent Claim 18 words

A photosensor according to claim 1, wherein said diffraction grating comprises corrugations formed on said second waveguide layer.

Claim 6

Dependent Claim 63 words

A photosensor according to claim 1, wherein said photosensor satisfies the following equation: β₁(λ) - β₀(λ) = 2π/Λ where λ is a wavelength of guided light, β₀(λ) is a propagation constant of the guided mode of said first waveguide layer, β₁(λ) is a propagation constant of the guided mode of said second waveguide layer, and Λ is a pitch of said diffraction grating.

Claim 7

Dependent Claim 81 words

A photosensor according to claim 5, wherein said photosensor satisfies the following equation: ℓ = π/2g g = ∫ ε₁A₁(x)ε₀dx where ℓ is a region length of said diffraction grating, ε₀ is an electric field intensity distribution of the guided mode of said first waveguide layer, and ε₁ is an electric field intensity distribution of the guided mode of said second waveguide layer, and A₁(x) is a component corresponding to 1st-order diffracted light of the Fourier expansion of said diffraction grating.

Claim 8

Dependent Claim 40 words

A photosensor according to claim 1, further comprising first, second, and third cladding layers, said first cladding layer, said first waveguide layer, said second cladding layer, and said waveguide layer being sequentially stacked in an order named on said substrate.

Claim 9

Dependent Claim 24 words

A photosensor according to claim 7, wherein said substrate and said layers comprise a compound selected from the group consisting of GaAs and AlGaAs.

Claim 10

Dependent Claim 20 words

A photosensor according to claim 8, wherein each of said first and second waveguide layers comprises a multi-quantum well structure.

Claim 11

Dependent Claim 118 words

A photosensor comprising: a substrate; a first waveguide layer formed on said substrate; a second waveguide layer formed on said first waveguide layer to be stacked in a direction of thickness, said second waveguide layer having a guided mode different from that of said first waveguide layer, and absorbing light propagating therethrough; a diffraction grating formed on an overlapping region of the guided modes of said first and second waveguide layers, said diffraction grating coupling light components of a specific wavelength range of light propagating through said first waveguide layer to said second waveguide layer; and an electrode for converting the light components absorbed by said light absorption layer into an electrical signal and outputting the electrical signal.

Claim 12

Dependent Claim 118 words

A photosensor comprising: a substrate; a first waveguide layer formed on said substrate; a second waveguide layer formed on said first waveguide layer to be stacked in a direction of thickness, said second waveguide layer having a guided mode different from that of said first waveguide layer, and absorbing light propagating therethrough; a diffraction grating formed on an overlapping region of the guided modes of said first and second waveguide layers, said diffraction grating coupling light components of a specific wavelength range of light propagating through said first waveguide layer to said second waveguide layer; and an electrode for converting the light components absorbed by said light absorption layer into an electrical signal and outputting the electrical signal.

Claim 13

Dependent Claim 40 words

A photosensor according to claim 10, further comprising first, second, and third cladding layers, said first cladding layer, said first waveguide layer, said second cladding layer, and said waveguide layer being sequentially stacked in an order named on said substrate.

Claim 14

Dependent Claim 24 words

A photosensor according to claim 11, wherein said substrate and said layers comprise a compound selected from the group consisting of GaAs and AlGaAs.

Claim 15

Dependent Claim 20 words

A photosensor according to claim 12, wherein each of said first and second waveguide layers comprises a multi-quantum well structure.

Claim 16

Dependent Claim 55 words

A photosensor according to claim 11, wherein said first waveguide layer and said first and second cladding layers comprise a semiconductor of a first conductivity type, said third cladding layer comprises a semiconductor of a second conductivity type, and said second waveguide layer comprises an i-type semiconductor, so that said photosensor constitutes a PIN photodiode.

Claim 17

Dependent Claim 24 words

A photosensor according to claim 14, wherein the first conductivity type is an n type, and the second conductivity type is a p type.

Claim 18

Dependent Claim 90 words

A photosensor according to claim 11, wherein said substrate comprises a semi-insulating semiconductor, said first and second waveguide layers and said first, second, and third cladding layers comprise an i-type semiconductor, and a stripe-like region extending in a propagation direction of light is formed in a portion of a multilayered structure consisting of said substrate, said first and second waveguide layers, and said first, second, and third cladding layers, p- and n-type regions being formed on two sides of said stripe-like region, so that said photosensor constitutes a PIN photodiode.

Claim 19

Dependent Claim 127 words

A photosensor according to claim 11, wherein said substrate comprises a semi-insulating semiconductor, said first waveguide layer and said first, second, and third cladding layers comprise an i-type semiconductor, said second waveguide layer comprises an n-type semiconductor, and a stripe-like region extending in a propagation direction of light is formed in a portion of a multilayered structure consisting of said substrate, said first and second waveguide layers, and said first, second, and third cladding layers, p- and n-type regions being formed on two sides of said stripe-like region, source and drain electrodes being in contact with said p- and n-type regions, an insulating layer being formed on a portion said third cladding layer on said stripe-like region, and a gate electrode being formed on said insulating layer.

Claim 20

Dependent Claim 18 words

A photosensor according to claim 17, wherein said diffraction grating comprises corrugations formed on said second cladding layer.

Claim 21

Dependent Claim 18 words

A photosensor according to claim 10, wherein said diffraction grating comprises corrugations formed on said second waveguide layer.

Claim 22

Dependent Claim 63 words

A photosensor according to claim 10, wherein said photosensor satisfies the following equation: β₁(λ) - β₀(λ) = 2π/Λ where λ is a wavelength of guided light, β₀(λ) is a propagation constant of the guided mode of said first waveguide layer, β₁(λ) is a propagation constant of the guided mode of said second waveguide layer, and Λ is a pitch of said diffraction grating.

Claim 23

Dependent Claim 81 words

A photosensor according to claim 20, wherein said photosensor satisfies the following equation: ℓ = π/2g g = ∫ ε₁A₁(x)ε₀dx where ℓ is a region length of said diffraction grating, ε₀ is an electric field intensity distribution of the guided mode of said first waveguide layer, and ε₁ is an electric field intensity distribution of the guided mode of said second waveguide layer, and A₁(x) is a component corresponding to 1st-order diffracted light of the Fourier expansion of said diffraction grating.

Claim 24

Dependent Claim 154 words

A photosensor comprising: a substrate; a first waveguide layer formed on said substrate; a second waveguide layer formed on said first waveguide layer to be stacked in a direction of thickness, said second waveguide layer having guided modes different from those of said first waveguide layer; a diffraction grating formed on an overlapping region of the guided modes of said first and second waveguide layers, said diffraction grating coupling light components of a specific wavelength range of light propagating through said first waveguide layer to said second waveguide layer; a light absorption layer formed on said second waveguide layer to be stacked in a direction of thickness, guided modes of said light absorption layer less overlapping those of said first waveguide layer, and much overlapping those of said second waveguide layer; and an electrode for converting the light components absorbed by said light absorption layer into an electrical signal and outputting the electrical signal.

Claim 25

Dependent Claim 154 words

A photosensor comprising: a substrate; a first waveguide layer formed on said substrate; a second waveguide layer formed on said first waveguide layer to be stacked in a direction of thickness, said second waveguide layer having guided modes different from those of said first waveguide layer; a diffraction grating formed on an overlapping region of the guided modes of said first and second waveguide layers, said diffraction grating coupling light components of a specific wavelength range of light propagating through said first waveguide layer to said second waveguide layer; a light absorption layer formed on said second waveguide layer to be stacked in a direction of thickness, guided modes of said light absorption layer less overlapping those of said first waveguide layer, and much overlapping those of said second waveguide layer; and an electrode for converting the light components absorbed by said light absorption layer into an electrical signal and outputting the electrical signal.

Claim 26

Dependent Claim 43 words

A photosensor according to claim 22, wherein said photosensor is divided into a waveguide region, a wavelength section region, and a light detection region in a propagation direction of light, and said light absorption layer is formed in only said light detection region.

Claim 27

Dependent Claim 18 words

A photosensor according to claim 23, wherein said diffraction grating is formed in only the wavelength selection region.

Claim 28

Dependent Claim 40 words

A photosensor according to claim 22, further comprising first, second, and third cladding layers, said first cladding layer, said first waveguide layer, said second cladding layer, and said waveguide layer being sequentially stacked in an order named on said substrate.

Claim 29

Dependent Claim 26 words

A photosensor according to claim 25, wherein said second cladding layer and said second waveguide layer constitute stripe-like ridges extending in the propagation direction of light.

Claim 30

Dependent Claim 61 words

A photosensor according to claim 25, further comprising a fourth cladding layer formed on said light absorption layer, and wherein said first waveguide layer and said first, second and third cladding layers comprise a semiconductor of a first conductivity type, and said fourth cladding layer comprises a semiconductor of a second conductivity type, so that said photosensor constitutes a PIN photodiode.

Claim 31

Dependent Claim 24 words

A photosensor according to claim 27, wherein the first conductivity type is an n type, and the second conductivity type is a p type.

Claim 32

Dependent Claim 24 words

A photosensor according to claim 25, wherein said substrate and said layers comprise a compound selected from the group consisting of GaAs and AlGaAs.

Claim 33

Dependent Claim 20 words

A photosensor according to claim 26, wherein each of said first and second waveguide layers comprises a multi-quantum well structure.

Claim 34

Dependent Claim 27 words

A photosensor according to claim 22, wherein said electrode comprises source, drain, and gate electrodes which constitute a field effect transistor together with said light absorption layer.

Claim 35

Dependent Claim 22 words

A photosensor according to claim 22, wherein said diffraction grating comprises diffraction grating formation layers cyclically formed on said second waveguide layer.

Claim 36

Dependent Claim 63 words

A photosensor according to claim 22, wherein said photosensor satisfies the following equation: β₁(λ) - β₀(λ) = 2π/Λ where λ is a wavelength of guided light, β₀(λ) is a propagation constant of the guided mode of said first waveguide layer, β₁(λ) is a propagation constant of the guided mode of said second waveguide layer, and Λ is a pitch of said diffraction grating.

Claim 37

Dependent Claim 81 words

A photosensor according to claim 33, wherein said photosensor satisfies the fc,llowing equation: ℓ = π/2g g = ∫ ε₁A₁(x)ε₀dx where ℓ is a region length of said diffraction grating, ε₀ is an electric field intensity distribution of the guided mode of said first waveguide layer, and ε₁ is an electric field intensity distribution of the guided mode of said second waveguide layer, and A₁(x) is a component corresponding to 1st-order diffracted light of the Fourier expansion of said diffraction grating.

Claim 38

Dependent Claim 116 words

A semiconductor laser comprising: a substrate; a first waveguide layer formed on said substrate and including a laser active layer, said laser active layer emitting a laser beam upon injection of a current; an electrode for supplying a current to said laser active layer; a second waveguide layer formed on said first waveguide layer to be stacked in a direction of thickness, said second waveguide layer having a guided mode different from that of said first waveguide layer; and a diffraction grating formed on an overlapping region of the guided modes of said first and second waveguide layers, said diffraction grating coupling the laser beam emitted from said laser active layer to said second waveguide layer.

Claim 39

Dependent Claim 116 words

A semiconductor laser comprising: a substrate; a first waveguide layer formed on said substrate and including a laser active layer, said laser active layer emitting a laser beam upon injection of a current; an electrode for supplying a current to said laser active layer; a second waveguide layer formed on said first waveguide layer to be stacked in a direction of thickness, said second waveguide layer having a guided mode different from that of said first waveguide layer; and a diffraction grating formed on an overlapping region of the guided modes of said first and second waveguide layers, said diffraction grating coupling the laser beam emitted from said laser active layer to said second waveguide layer.

Claim 40

Dependent Claim 35 words

A semiconductor laser according to claim 35, wherein said second waveguide layer comprises a light isolator for rotating a polarization direction of light propagating through said second waveguide layer through 45° by a Faraday effect.

Claim 41

Dependent Claim 16 words

A semiconductor laser according to claim 36, wherein said second waveguide layer essentially consists of CdMnTe.

Claim 42

Dependent Claim 38 words

A semiconductor laser according to claim 36, wherein said semiconductor laser is divided into a laser unit and an isolator unit in the propagation direction of light, and said diffraction grating is formed on only said isolator unit.

Claim 43

Dependent Claim 19 words

A semiconductor laser according to claim 38, wherein said second waveguide layer is formed on only said isolator unit.

Claim 44

Dependent Claim 16 words

A semiconductor laser according to claim 38, wherein said laser unit comprises a distributed feedback reflector.

Claim 45

Dependent Claim 49 words

A semiconductor laser according to claim 38, wherein two said diffraction gratings are formed to be separated by a predetermined distance in a propagation direction of light, light coupled from said first waveguide layer and propagating through said second waveguide layer being coupled to said first waveguide layer again.

Claim 46

Dependent Claim 41 words

A semiconductor laser according to claim 36, further comprising first, second, and third cladding layers, said first cladding layer, said first waveguide layer, said second cladding layer, and said waveguide layer being sequentially stacked in an order named on said substrate.

Claim 47

Dependent Claim 58 words

A semiconductor laser according to claim 42, wherein said substrate, said first cladding layer, and said first wave guide layer comprise a compound selected from the group consisting of GaAs and AlGaAs, and said second cladding layer, said second waveguide layer, and said third cladding layer comprise a compound selected from the group consisting of CdTe and CdMnTe.

Claim 48

Dependent Claim 21 words

A semiconductor laser according to claim 35, wherein each of said first and second waveguide layers comprises a multi-quantum well structure.

Claim 49

Dependent Claim 19 words

A semiconductor laser according to claim 35, wherein said diffraction grating comprises corrugations formed on said second waveguide layer.

Claim 50

Dependent Claim 19 words

A semiconductor laser according to claim 35, wherein said diffraction grating comprises corrugations formed on said first waveguide layer.

Claim 51

Dependent Claim 65 words

A semiconductor laser according to claim 35, wherein said semiconductor laser satisfies the following equation: β₁(λ) - β₀(λ) = 2π/Λ where λ is a wavelength of guided light, β₀(λ) is a propagation constant of the guided mode of said first waveguide layer, β₁(λ) is a propagation constant of the guided mode of said second waveguide layer, and Λ is a pitch of said diffraction grating.

Claim 52

Dependent Claim 83 words

A semiconductor laser according to claim 47, wherein said semiconductor laser satisfies the following equation: ℓ = π/2g g = ∫ ε₁A₁(x)ε₀dx where ℓ is a region length of said diffraction grating, ε₀ is an electric field intensity distribution of the guided mode of said first waveguide layer, and ε₁ is an electric field intensity distribution of the guided mode of said second waveguide layer, and A₁(x) is a component corresponding to 1st-order diffracted light of the Fourier expansion of said diffraction grating.

Claim 53

Dependent Claim 127 words

An optical amplifier comprising: a substrate; a first waveguide layer formed on said substrate; a second waveguide layer formed on said first waveguide layer to be stacked in a direction of thickness, said second waveguide layer having a guided mode different from that of said first waveguide layer; a diffraction grating formed on an overlapping region of the guided modes of said first and second waveguide layers, said diffraction grating optically coupling said first and second waveguide layers in a specific wavelength range; a laser active region formed on at least a portion of said second waveguide layer, said laser active region amplifying light propagating through said second waveguide layer upon supply of a current; and an electrode for supplying a current to said laser active region.

Claim 54

Dependent Claim 127 words

An optical amplifier comprising: a substrate; a first waveguide layer formed on said substrate; a second waveguide layer formed on said first waveguide layer to be stacked in a direction of thickness, said second waveguide layer having a guided mode different from that of said first waveguide layer; a diffraction grating formed on an overlapping region of the guided modes of said first and second waveguide layers, said diffraction grating optically coupling said first and second waveguide layers in a specific wavelength range; a laser active region formed on at least a portion of said second waveguide layer, said laser active region amplifying light propagating through said second waveguide layer upon supply of a current; and an electrode for supplying a current to said laser active region.

Claim 55

Dependent Claim 67 words

An optical amplifier according to claim 49, wherein two said diffraction gratings are formed to be separated by a predetermined distance in a propagation direction of light, light propagating through said first waveguide layer being coupled to said second waveguide layer by one diffraction grating, and the light coupled by said second waveguide layer being coupled to said first waveguide layer again by the other diffraction grating.

Claim 56

Dependent Claim 32 words

An optical amplifier according to claim 50, wherein an impurity is diffused in a portion of said second waveguide layer located on a region excluding a portion between said two diffraction gratings.

Claim 57

Dependent Claim 41 words

An optical amplifier according to claim 49, further comprising first, second, and third cladding layers, said first cladding layer, said first waveguide layer, said second cladding layer, and said waveguide layer being sequentially stacked in an order named on said substrate.

Claim 58

Dependent Claim 25 words

An optical amplifier according to claim 52, wherein said substrate and said layers comprise a compound selected from the group consisting of GaAs and AlGaAs.

Claim 59

Dependent Claim 20 words

An optical amplifier according to claim 53, each of said first and second waveguide layers comprises a multi-quantum well structure.

Claim 60

Dependent Claim 53 words

An optical amplifier according to claim 52, wherein said first cladding layer, said first waveguide layer, said second cladding layer, said second waveguide layer, and said third cladding layer are mesa-etched excluding a stripe-like region extending in a propagation direction of light, buried layers being formed on two sides of the mesa region.

Claim 61

Dependent Claim 35 words

An optical amplifier according to claim 52, wherein stripe-like ridges extending in a propagation direction of light are formed in said second cladding layer, said second waveguide layer, and said third cladding layer by etching.

Claim 62

Dependent Claim 19 words

An optical amplifier according to claim 49, wherein said diffraction grating comprises corrugations formed on said first waveguide layer.

Claim 63

Dependent Claim 65 words

An optical amplifier according to claim 49, wherein said optical amplifier satisfies the following equation: β₁(λ) - β₀(λ) = 2π/Λ where λ is a wavelength of guided light, β₀(λ) is a propagation constant of the guided mode of said first waveguide layer, β₁(λ) is a propagation constant of the guided mode of said second waveguide layer, and Λ is a pitch of said diffraction grating.

Claim 64

Dependent Claim 83 words

An optical amplifier according to claim 58, wherein said optical amplifier satisfies the following equation: ℓ = π/2g g = ∫ ε₁A₁(x)ε₀dx where ℓ is a region length of said diffraction grating, ε₀ is an electric field intensity distribution of the guided mode of said first waveguide layer, and ε₁ is an electric field intensity distribution of the guided mode of said second waveguide layer, and A₁(x) is a component corresponding to 1st-order diffracted light of the Fourier expansion of said diffraction grating.

Optical apparatus using wavelength selective photocoupler

Abstract

Inventors

Bibliographic Details

Claims Analysis

References Cited (Backward Citations)

USPTO Annuity & Maintenance Windows

Assigned Categories & Tags

Assign Category Tag