EP0286350A2
Expired / Lapsed
EP
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Optical fiber communication system
Assignee: AT&T Inc
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Filing: 1988-04-05
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Granted: —
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Expires: 2008-04-05
Abstract
Abstract In an optical fiber communication system that operates at a wavelength λ o and comprises optical fiber (22) having a cut-off wavelength λ c > λ o . a grating (24) with parameters chosen such that the grating causes resonant coupling between a predetermined guided mode (e.g.. LP..) and a tunneling-leaky mode. can be advantageously used to remove unwanted guided modes. Such removal can substantially improve the bandwidth of such a system.
Inventors
- 👤 James Joseph Refi
- 👤 Ian Arthur White
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 12:01
CPC Classifications
H; H04; H04M; H04M9/00; G; G02; G02B; G02B6/00; G02B6/10; G02B6/14; G02B6/02; G02B6/02057; G02B6/02071; G02B6/24; G02B6/26; G02B6/34; H04B; H04B10/00; H04B10/25; H04B10/2581; H04B10/2589
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
257 words
An optical fiber communication system comprising a) at least a first and a second communication station (21.23: 30.30'). the first station comprising a source (31) of electromagnetic radiation of wavelength λ o , the second station comprising means (32) for detecting radiation of wavelength λ o ; b) an optical fiber transmission channel (22) linking the first and second station such that at least some of the radiation of wavelength λ o is transmitted from the first to the second station. the fiber transmission channel comprising optical fiber having a cut-off wavelength λ c >λ o . such that more than one guided mode of the radiation of wavelength λ o is propagating from the first towards the second station: and c) means (24.25) for removing at least a substantial part of at least one of the guided modes of the radiation from the fiber transmission channel prior to the detection of the radiation of wavelength λ o : CHARACTERISED IN THAT d) the means of c) comprise a fiber region (24) in which the transmission characteristics of the fiber are varying substantially periomcally or pseudo-penodicaify this region to be referred to as the "grating"). the parameters of the grating being selected such that at least one of the guided modes of the radiation in the optical fiber is substantially resonantly coupled to a tunneling-leaky mode of the optical fiber. the fiber parameters comprising the number of grating elements N. the repeat length A(z) (z being the longitudinal fiber coordinate). the envelope function g(z) and the amplitude.
Claim 2
Dependent Claim
257 words
An optical fiber communication system comprising a) at least a first and a second communication station (21.23: 30.30'). the first station comprising a source (31) of electromagnetic radiation of wavelength λ o , the second station comprising means (32) for detecting radiation of wavelength λ o ; b) an optical fiber transmission channel (22) linking the first and second station such that at least some of the radiation of wavelength λ o is transmitted from the first to the second station. the fiber transmission channel comprising optical fiber having a cut-off wavelength λ c >λ o . such that more than one guided mode of the radiation of wavelength λ o is propagating from the first towards the second station: and c) means (24.25) for removing at least a substantial part of at least one of the guided modes of the radiation from the fiber transmission channel prior to the detection of the radiation of wavelength λ o : CHARACTERISED IN THAT d) the means of c) comprise a fiber region (24) in which the transmission characteristics of the fiber are varying substantially periomcally or pseudo-penodicaify this region to be referred to as the "grating"). the parameters of the grating being selected such that at least one of the guided modes of the radiation in the optical fiber is substantially resonantly coupled to a tunneling-leaky mode of the optical fiber. the fiber parameters comprising the number of grating elements N. the repeat length A(z) (z being the longitudinal fiber coordinate). the envelope function g(z) and the amplitude.
Claim 3
Dependent Claim
33 words
The system of claim 1. comprising means (34.34') for impressing an undulation upon the fiber axis or means for locally changing the refractive index of the optical fiber. such that the grating results.
Claim 4
Dependent Claim
32 words
The system of claim 2. wherein the means for impressing an undulation upon the fiber axis comprise at least one corrugated oody. and means for urging the corrugated body against the fiber.
Claim 5
Dependent Claim
54 words
The system of claim 2. wherein the means for locally changing the refractive index of the fiber compnse a photo-refractively active chemical species present in the fiber. and means for exposing the fiber to actinic radiation adapted for changing the refractive index of the fiber in preselected regions by means of the photo-refractive effect.
Claim 6
Dependent Claim
52 words
The system of claim 2. wherein the means for locally changing the refractive index of the fiber comprise at least one corrugated body, and means for urging the corrugated body against the fiber. such that the refractive index in predetermined regions of the fiber is changed by means of the photo-elastic effect.
Claim 7
Dependent Claim
13 words
The system of claim 1. wnerein both A(z) and g(z) are nominally constant.
Claim 8
Dependent Claim
35 words
The system of claim 1, wherein the second station also comprises a source of radiation of wavelength λ o . and the first station aiso comprises means for detecting radiation of wavelength λ o .
Claim 9
Dependent Claim
114 words
The system of claim 7, wherein λ c is chosen such that the guided modes compnse two modes (to be designated LPc. and LP..) wherein the first station (30) comprises means (34) for resonantly coupling the LPc. mode to a tunneiing-leaky mode. wherein the second station (30') comonses means (34') for resonantly coupling the LP.. mode to a tunneling-leaky mode. wherein the first station detector means (32) are adapted for receiving LPc. mode radiation removed from the fiber after propagating from the second to the first station. and the second station detector means (32) are adaoted for receiving LP·· mode radiation removed from the fiber after propagating from the first to the second station
References Cited (Backward Citations)
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