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US3821549A
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US
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Semiconductor drift photodetector for equalization of optical fiber material dispersion
Assignee: AT&T Inc
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Filing: 1973-09-18
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Granted: 1974-06-28
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Expires: 1993-09-18
Abstract
Abstract An optical signal having a non-negligible bandwidth suffers a distortion while propagating in an optical fiber caused by the fact that signal components of different optical wavelengths propagate at different velocities through the fiber material, that is, by the dependence of refractive index upon wavelength (material dispersion). In order to compensate for this distortion, an optical prism (or diffraction grating) is located in the path of the output wave exiting from the fiber, which angularly separates the various output wavelengths. The angularly separated output waves are then incident upon a semiconductor P-N junction detector of the charge carrier drift type, such that the time delays of different wavelengths in the fiber are compensated by the different drift time delays of the different charge carriers generated by the different wavelengths absorbed in the drift region of the semiconductor.
Inventors
- 👤 D Gloge
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 15:45
CPC Classifications
G; G02; G02B; G02B6/00; G02B6/24; G02B6/26; G02B6/28; G02B6/293; G02B6/29379; G02B6/29392; G02B6/29394; G02B6/42; G02B6/4201; G02B6/4204; G02B6/4215
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
117 words
Apparatus for equalization of optical fiber material dispersion which comprises: a a semiconductor body portion terminated in a P-N junction, said portion having a drift region in which charge carriers can drift to said P-N junction; b optical deflection means for deflecting optical radiation exiting from the fiber in accordance with the wavelength of components of said radiation onto said drift region, such that those wavelength components which are more delayed in propagating through the fiber are incident upon the drift region at locations less remote from the P-N junction, whereby the charge carriers generated by absorption of said more delayed wavelength components in the said drift region are less delayed while drifting to the P-N junction.
Claim 2
Dependent Claim
117 words
Apparatus for equalization of optical fiber material dispersion which comprises: a a semiconductor body portion terminated in a P-N junction, said portion having a drift region in which charge carriers can drift to said P-N junction; b optical deflection means for deflecting optical radiation exiting from the fiber in accordance with the wavelength of components of said radiation onto said drift region, such that those wavelength components which are more delayed in propagating through the fiber are incident upon the drift region at locations less remote from the P-N junction, whereby the charge carriers generated by absorption of said more delayed wavelength components in the said drift region are less delayed while drifting to the P-N junction.
Claim 3
Dependent Claim
59 words
Apparatus according to claim 1 in which said optical deflection means deflects the radiation through an angle which varies at least approximately linearly with the wavelength of said components, so that these wavelength components are directed for absorption in the semiconductor body portion at locations whose distances from the P-N junction vary at least approximately linearly with said wavelength.
Claim 4
Dependent Claim
32 words
Apparatus according to claim 2 which further includes said fiber characterized in that the time delays of said wavelength components propagating through the fiber vary at least approximately linearly with said wavelength.
Claim 5
Dependent Claim
18 words
Apparatus according to claim 2 which further includes means for electrically reverse-biasing said P-N junction during detector operation.
Claim 6
Dependent Claim
18 words
Apparatus according to claim 1 which further includes means for electrically reverse-biasing said P-N junction during detector operation.
Claim 7
Dependent Claim
30 words
Apparatus according to claim 1 which further includes optical means for focusing said wavelength components upon the said semiconductor portion at said locations, in cooperation with said optical deflection means.
Claim 8
Dependent Claim
15 words
Apparatus according to claim 6 in which said optical deflection means comprises an optical prism.
Claim 9
Dependent Claim
14 words
Apparatus according to claim 6 in which said deflection means comprise an optical grating.
Claim 10
Dependent Claim
15 words
Apparatus according to claim 1 in which said optical deflection means comprise an optical prism.
Claim 11
Dependent Claim
14 words
Apparatus according to claim 1 in which said deflection means comprise an optical grating.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-06-27 | 1977-12-27 | 1978-06-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-06-27 | 1981-12-27 | 1982-06-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-06-27 | 1985-12-27 | 1986-06-28 | $7700.00 | Window Closed / Lapsed |