EP0469793A2
Expired / Lapsed
EP
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Monolithic integrated optical amplifier and photodetector
Assignee: AT&T Inc
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Filing: 1991-07-25
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Granted: —
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Expires: 2011-07-25
Abstract
Abstract An optical amplifier and photodetector are monolithically integrated, with the photodetector being optically coupled to the optical amplifier through a low radiative loss and low back reflectivity branching waveguide. Because of the low reflectivity, the branching waveguide, although having a truncated wedge tip, is able to redirect a small portion of optical radiation from the amplifier to the photodetector without deleteriously effecting the performance of the optical amplifier. The branching waveguide is realized by employing between the branches of the waveguide, a junction region having a gradual decrease in effective refractive index such as to decrease the difference between the refractive indices at the optical interface of the truncated wedge tip as seen by optical radiation incident thereto from the optical amplifier.
Inventors
- 👤 Uziel Koren
- 👤 Kang-Yih Liou
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 16:36
CPC Classifications
H; H01; H01S; H01S5/00; H01S5/50; G; G02; G02B; G02B6/00; G02B6/10; G02B6/12; G02B6/12004; H01S5/02; H01S5/026; H01S5/0262; H01S5/0264
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
98 words
A device having in combination a monolithically integrated photodetector, optical amplifier and branching waveguide, said photodetector being optically coupled to said optical amplifier by said branching waveguide, and said branching waveguide comprising: a first waveguide; a second waveguide intersecting and coupling optically to said first waveguide to form a Y-junction having a truncated wedge tip, said Y-junction having a junction region located between said first and second waveguides, and said branching waveguide CHARACTERIZED IN THAT said junction region comprises means for reducing the back reflection of optical radiation from said optical amplifier incident on said truncated wedge tip.
Claim 2
Dependent Claim
57 words
The device as defined in claim 1 wherein said means for reducing the back-reflection further comprises in said junction region a gradient in the effective refractive index along the axis of optical propagation of said first waveguide so as to reduce the difference between the effective refractive indices at the optical interface of said truncated wedge tip.
Claim 3
Dependent Claim
29 words
The device as defined in claim 2 wherein said gradient in effective refractive index varies from the core refractive index to the cladding refractive index of said first waveguide.
Claim 4
Dependent Claim
56 words
The device as defined as claim 3 wherein said gradient in the effective refractive index further comprises a first semiconductor material having a gradual decrease in thickness and a second semiconductor material disposed over said first semiconductor material, said first semiconductor material having a higher refractive index than the refractive index of said second semiconductor material.
Claim 5
Dependent Claim
21 words
The device as defined in claim 4 wherein said optical amplifier, branching waveguide and photodetector are integrated on a InP substrate.
Claim 6
Dependent Claim
27 words
The device as defined in claim 5 wherein said first and second waveguides comprise passive InGaAsP having a bandgap energy corresponding to a wavelength of 1.1 µm.
Claim 7
Dependent Claim
26 words
The device as defined in claim 6 wherein said optical amplifier further comprises active InGaAsP having a bandgap energy corresponding to a wavelength of 1.3 µm.
Claim 8
Dependent Claim
19 words
The device as defined in claim 7 wherein said first and second semiconductor materials comprise InGaAsP and InP, respectively.
Claim 9
Dependent Claim
13 words
The device as defined in claim 8 wherein said InP material is semi-insulating.
Claim 10
Dependent Claim
23 words
The device as defined in claim 9 wherein said first waveguide intersects said second waveguide at an angle of less than 5 °.
Claim 11
Dependent Claim
17 words
The device as defined in claim 10 wherein said first and second waveguides are single mode waveguides.
Claim 12
Dependent Claim
29 words
The device as defined in claim 11 wherein said first and second waveguides are tapered for adiabatic mode propagation in a region located away from said truncated wedge tip.
Claim 13
Dependent Claim
31 words
The device as defined in claim 1 further comprising a feedback means jointly coupled to said photodetector and said optical amplifier to control the optical output power of said optical amplifier.
Claim 14
Independent Claim
95 words
A device having in combination a monolithically integrated photodetector, laser and branching waveguide, said photodetector being optically coupled to said laser by said branching waveguide, and said branching waveguide comprising: a first waveguide; a second waveguide intersecting and coupling optically to said first waveguide to form a Y-junction having a truncated wedge tip, said Y-junction having a junction region located between said first and second waveguides, and said branching waveguide CHARACTERIZED IN THAT said junction region comprises means for reducing the back reflection of optical radiation from said laser incident on said truncated wedge tip.
Claim 15
Dependent Claim
29 words
The device as defined in claim 14 further comprising a feedback means jointly coupled to said photodetector and said laser to control the optical output power of said laser.
Claim 16
Dependent Claim
49 words
The device as defined in claim 14 further comprising a feedback means jointly coupled to said photodetector and said laser to control the thickness of a reflective coating deposited on a back facet of said laser such that the optical resonances within the cavity of said laser is maximized.
Claim 17
Dependent Claim
46 words
The device as defined in claim 1 further comprising a polarization controller for adjusting the polarizarion of optical radiation incident on said optical amplifier, and feedback means jointly coupled to said photodetector and said optical amplifier to control the optical output power of said optical amplifier.
Claim 18
Dependent Claim
41 words
The device as defined in claim 1 further comprising a polarization controller for adjusting the polarization of optical radiation incident on said optical amplifier, and feedback means jointly coupled to said photodetector and said optical amplifier to maintain maximum amplifier gain.
Claim 19
Dependent Claim
49 words
The device as defined in claim 1 further comprising a feedback means jointly coupled to said photodetector and said optical amplifier to control the thickness of an anti-reflective coating deposited on an end facet of said optical amplifier such that Fabry-Perot resonances associated with said end facet are minimized.
References Cited (Backward Citations)
No citation records indexed.
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