Patent US5325226A successfully refreshed from Google Patents.
US5325226A
Expired / Lapsed
US
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Optical coherent receiver
Assignee: US Philips Corp
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Filing: 1992-01-31
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Granted: 1994-06-28
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Expires: 2012-01-31
Abstract
Abstract An optical coherent receiver including apparatus for preventing radiation from the local oscillator (40) from being reflected in the transmission fibre (10). As a result this radiation, after reflection on imperfect couplings (11, 12, 13) in the transmission fibre, is prevented from reaching the receiver again and from detrimentally influencing the received signal. Reflection of local oscillator radiation is prevented by obliquely polishing entrance and exit faces of fibres (51, 52, 61, 62), by providing anti-reflection coatings (50', 60', 53', 54', 63', 64') on the appropriate faces and by arranging an optical isolator behind the input (20) of the coherent receiver.
Inventors
- 👤 Giok D. Khoe
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 06:07
CPC Classifications
H; H04; H04B; H04B10/00; H04B10/60; H04B10/61; H04B10/614; H04B10/64; H04B10/65
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
111 words
An optical coherent receiver having an input for coupling an optical input transmission fiber thereto for supplying an optical signal beam, a local oscillator for generating a local oscillator beam, at least one beam-combining reflective optical element for combining radiation from the signal beam transmitted through an optical fiber with radiation from the local oscillator transmitted by a second optical fiber and at least one radiation-sensitive detector for converting combined radiation into an electric signal, characterized in that at least one of said optical fibers, said beam combining optical element and said radiation-sensitive detector are provided with means for substantially preventing radiation from the local oscillator from reaching the said input.
Claim 2
Dependent Claim
111 words
An optical coherent receiver having an input for coupling an optical input transmission fiber thereto for supplying an optical signal beam, a local oscillator for generating a local oscillator beam, at least one beam-combining reflective optical element for combining radiation from the signal beam transmitted through an optical fiber with radiation from the local oscillator transmitted by a second optical fiber and at least one radiation-sensitive detector for converting combined radiation into an electric signal, characterized in that at least one of said optical fibers, said beam combining optical element and said radiation-sensitive detector are provided with means for substantially preventing radiation from the local oscillator from reaching the said input.
Claim 3
Dependent Claim
38 words
An optical receiver as claimed in claim 1, characterized in that said radiation preventing means comprise anti-reflection means which are provided on at least one of radiation entrance and exit faces of the optical fibers in the receiver.
Claim 4
Dependent Claim
32 words
An optical receiver as claimed in claim 2, characterized in that the anti-reflection means comprise that at least one of said entrance and exit faces of the optical fibers are obliquely polished.
Claim 5
Dependent Claim
33 words
An optical receiver as claimed in claim 2, characterized in that the anti-reflection means comprise an anti-reflection coating provided on at least one of the entrance and exit faces of the optical fibers.
Claim 6
Dependent Claim
39 words
An optical receiver as claimed in claim 1, characterized in that an optical isolator is arranged in the light path between the said input and the beam-combining element for blocking radiation coming from the direction of the beam-combining element.
Claim 7
Dependent Claim
140 words
An optical coherent receiver having an input for coupling an input optical transmission fiber thereto for supplying an optical signal beam and optical elements, comprising a local oscillator for generating a local oscillator beam, at least one beam-combining element for combining radiation from the signal beam with radiation from the local oscillator beam to at least one combined radiation beam, a further optical fiber for transmitting radiation of the signal beam to said beam-combining element, at least one radiation-sensitive detector for converting radiation of said combined radiation beam into an electrical signal, characterized in that at least one of said optical fibers, said beam combining element and said radiation sensitive detector are provided with means arranged in the optical path of at least one of said beams for substantially preventing radiation from the local oscillator from reaching said receiver input.
Claim 8
Dependent Claim
140 words
An optical coherent receiver having an input for coupling an input optical transmission fiber thereto for supplying an optical signal beam and optical elements, comprising a local oscillator for generating a local oscillator beam, at least one beam-combining element for combining radiation from the signal beam with radiation from the local oscillator beam to at least one combined radiation beam, a further optical fiber for transmitting radiation of the signal beam to said beam-combining element, at least one radiation-sensitive detector for converting radiation of said combined radiation beam into an electrical signal, characterized in that at least one of said optical fibers, said beam combining element and said radiation sensitive detector are provided with means arranged in the optical path of at least one of said beams for substantially preventing radiation from the local oscillator from reaching said receiver input.
Claim 9
Dependent Claim
40 words
An optical receiver as claimed in claim 6, characterized in that the radiation preventing means comprise anti-reflection means which are provided on at least one of the radiation entrance and exit faces of at least one of said optical elements.
Claim 10
Dependent Claim
32 words
An optical receiver as claimed in claim 7, characterized in that the anti-reflection means comprise that at least one of the entrance and exit faces of said optical fibers are obliquely polished.
Claim 11
Dependent Claim
30 words
An optical receiver as claimed in claim 7, characterized in that the anti-reflection means comprise an anti-reflection coating provided on said at least one of the entrance and exit faces.
Claim 12
Dependent Claim
39 words
An optical receiver as claimed in claim 6, characterized in that an optical isolator is arranged in the light path between said receiver input and said beam-combining element for blocking radiation coming from the direction of the beam-combining element.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1997-06-27 | 1997-12-27 | 1998-06-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-06-27 | 2001-12-27 | 2002-06-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-06-27 | 2005-12-27 | 2006-06-28 | $7700.00 | Window Closed / Lapsed |