GB2191596A - Optical fibre cables - Google Patents

Optical fibre cables Download PDF

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Publication number
GB2191596A
GB2191596A GB08614344A GB8614344A GB2191596A GB 2191596 A GB2191596 A GB 2191596A GB 08614344 A GB08614344 A GB 08614344A GB 8614344 A GB8614344 A GB 8614344A GB 2191596 A GB2191596 A GB 2191596A
Authority
GB
United Kingdom
Prior art keywords
optical fibre
cable
fibre
along
conductive material
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
GB08614344A
Other versions
GB8614344D0 (en
Inventor
John Philip Dakin
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Plessey Co Ltd
Original Assignee
Plessey Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Plessey Co Ltd filed Critical Plessey Co Ltd
Priority to GB08614344A priority Critical patent/GB2191596A/en
Publication of GB8614344D0 publication Critical patent/GB8614344D0/en
Publication of GB2191596A publication Critical patent/GB2191596A/en
Withdrawn legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/24—Coupling light guides
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/0128—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on electro-mechanical, magneto-mechanical, elasto-optic effects
    • G02F1/0131—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on electro-mechanical, magneto-mechanical, elasto-optic effects based on photo-elastic effects, e.g. mechanically induced birefringence
    • G02F1/0134—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on electro-mechanical, magneto-mechanical, elasto-optic effects based on photo-elastic effects, e.g. mechanically induced birefringence in optical waveguides

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Nonlinear Science (AREA)
  • Communication Cables (AREA)
  • Mechanical Light Control Or Optical Switches (AREA)

Abstract

An optical fibre cable comprises an optical fibre 1 effectively mechanically coupled in radial directions along its length to piezoelectric material 2 which makes electrical contact with axially-extending electrically- conductive material 4, 5 embodied in the outer protective sheathing of the cable for the optical fibre whereby electrical signals applied to the electrically-conductive material at points 6, 7 along the length of the optical fibre cause mechanical strain to be produced in the piezoelectric material which in turn induces phase modulation in light propagating along the mechanically coupled optical fibre. <IMAGE>

Description

SPECIFICATION Improvements relating to optical fibre cables This invention relates to optical fibre cables and relates more specifically to such cablesforuse in socalled non-invasive optical fibre communication systems in which data signals to be transmitted along an optical fibre highway of the cable may be applied non-invasivelyto the optical fibre highwayatdis- tributed points therealong.One such non-invasive communication system which forms the subject of our co-pending Patent Application No.216511 SA utilises piezoelectric transducers for imparting mechanical strains to the optical fibre highway at points therealong in response to electrical data signals applied thereto in order to produce phase modulation ofthe light propagating along the fibre which is arranged to be detected by a phase demo dulator at the far end of the fibre highway.
The present invention is directed to an optical fibre cable construction eminently suitable for use in noninvasive optical fibre communication systems.
According to the present invention an optical fibre cable comprises an optical fibre effectively mech anically coupled in radial directions along its length to piezoelectric material which is electrically in contact with axially extending electrically-conductive material embodied in the outer protective sheathing ofthecableforthe optical fibre whereby electrical signals applied to the electrically-conductive material at points along the length of the optical fibre cause mechanical strain to be produced in the piezoelectric material which in turn induces phase modulation in light propagating along the mechanically coupled optical fibre.
The optical fibre cable construction according to the invention provides for non-invasive coupling of data signals into the optical fibre highwaywhilst providing good protection for the optical fibre against mechanical damage.
In carrying outthe invention the piezoelectric material may be extruded overthe optical fibre or it may be provided in the form of a longitudinal strip orfilament of such material located in close proximity to the optical fibre so as to be closely mechanically coupled to itwherebythe expansion and contraction of the strip or filament in the radial direction ofthe optical fibre causes the latterto be mechanically strained for producing phase modulation of light propagating along the optical fibre highway.
The electrically conductive material may take the form of diametrically-opposed conductive regions (e.g. sectors or strips) embodied in the cable protective sheathing.
These opposed regions may be spaced at intervals along the length of the cable or if the electrically conductive regions are of relatively poor conductivity (e.g. electrically-conductive plastics material) they may extend over the entire length of the optical fibre cable without interruption so that the naturally lossy nature ofthe material is related upon to provide isolation between suitably spaced transmitter stations at which data is to be non-invasivelyinjected into the data highway.
The mechanical strain induced in the optical fibre highway due to the electrical excitation of the piezoelectric material by data signals injected at trans mitterstations along the cable length may be merely radially symmetrical compressions or expansions providing identical phase shifts in the different modes of any polarisation. However, the excited piezoelectric material may be arranged to apply a radially anisotropic strain to a polarisation-maintaining optical fibre so that one polarisation mode in the optical fibre is phase-modulated with respect to an orthogonal polarisation mode thereby causing in effect a modulation of the polarisationtransmitted bythe fibre which may be detected by a polarisation analyser located at the far end ofthe optical fibre highway.
Byway of example the present invention will now be described with reference to the accompanying drawing in which: Figures land 2 show radial and axial crosssectional views of an optical fibre cable constructed according to the present invention.
Referring to the drawings the optical fibre cable construction illustrated comprises an optical fibre 1 having extruded over its length a layer of piezoelectric material 2. An outer protective sheathing 3 forthe optical fibre comprises electrical insulating material which in the present embodiment has embodied therein axially spaced apart pairs ofdiametrically- opposed sectors 4 and 5 of electrically conductive material of relatively high conductivity.These pairs of opposed sectors 4 and 5 allowforthe injection into the optical fibre 1 of data signals at pre-selected points along the cable and for this purpose the data signals may be applied to a pair of conductive sectorsthrough electrodes such as the electrodes 6 and 7which may be sprung on to the cable surface as shown in the drawing so that they make good electrical contact with the respective conductive sectors.
The alternating data signals applied to the conductive sectors 4 and 5 through the electrodes 6 and 7 will produce radial straining ofthe piezoelectric layer2 which in turn will produce phase modulation ofthe light propagating along the optical fibre 1 dueto radial compression and expansion of the fibre. This phase modulation will be detected by a demodulator at the far end of the optical fibre.
The optical fibre 1 may be of the polarisationmaintaining type so that straining of the piezoelectric layer causes phase modulation of one polarisation mode of the fibre relative to another mode.
As previousiy mentioned, the piezo-electric layer may comprise a strip orfilament extending along the optical fibre in close proximity to the optical fibre so that it is closely mechanically coupled thereto and the conductive sectors may be replaced by continuous regions of electrically conductive material having poor conductivity which extend over the entire length of the optical fibre, the necessaryelectri- cal isolation being provided by the naturally lossy nature of the electrically conductive material.
1. An optical fibre cable comprising an optical
**WARNING** end of DESC field may overlap start of CLMS **.

Claims (8)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Improvements relating to optical fibre cables This invention relates to optical fibre cables and relates more specifically to such cablesforuse in socalled non-invasive optical fibre communication systems in which data signals to be transmitted along an optical fibre highway of the cable may be applied non-invasivelyto the optical fibre highwayatdis- tributed points therealong.One such non-invasive communication system which forms the subject of our co-pending Patent Application No.216511 SA utilises piezoelectric transducers for imparting mechanical strains to the optical fibre highway at points therealong in response to electrical data signals applied thereto in order to produce phase modulation ofthe light propagating along the fibre which is arranged to be detected by a phase demo dulator at the far end of the fibre highway. The present invention is directed to an optical fibre cable construction eminently suitable for use in noninvasive optical fibre communication systems. According to the present invention an optical fibre cable comprises an optical fibre effectively mech anically coupled in radial directions along its length to piezoelectric material which is electrically in contact with axially extending electrically-conductive material embodied in the outer protective sheathing ofthecableforthe optical fibre whereby electrical signals applied to the electrically-conductive material at points along the length of the optical fibre cause mechanical strain to be produced in the piezoelectric material which in turn induces phase modulation in light propagating along the mechanically coupled optical fibre. The optical fibre cable construction according to the invention provides for non-invasive coupling of data signals into the optical fibre highwaywhilst providing good protection for the optical fibre against mechanical damage. In carrying outthe invention the piezoelectric material may be extruded overthe optical fibre or it may be provided in the form of a longitudinal strip orfilament of such material located in close proximity to the optical fibre so as to be closely mechanically coupled to itwherebythe expansion and contraction of the strip or filament in the radial direction ofthe optical fibre causes the latterto be mechanically strained for producing phase modulation of light propagating along the optical fibre highway. The electrically conductive material may take the form of diametrically-opposed conductive regions (e.g. sectors or strips) embodied in the cable protective sheathing. These opposed regions may be spaced at intervals along the length of the cable or if the electrically conductive regions are of relatively poor conductivity (e.g. electrically-conductive plastics material) they may extend over the entire length of the optical fibre cable without interruption so that the naturally lossy nature ofthe material is related upon to provide isolation between suitably spaced transmitter stations at which data is to be non-invasivelyinjected into the data highway. The mechanical strain induced in the optical fibre highway due to the electrical excitation of the piezoelectric material by data signals injected at trans mitterstations along the cable length may be merely radially symmetrical compressions or expansions providing identical phase shifts in the different modes of any polarisation. However, the excited piezoelectric material may be arranged to apply a radially anisotropic strain to a polarisation-maintaining optical fibre so that one polarisation mode in the optical fibre is phase-modulated with respect to an orthogonal polarisation mode thereby causing in effect a modulation of the polarisationtransmitted bythe fibre which may be detected by a polarisation analyser located at the far end ofthe optical fibre highway. Byway of example the present invention will now be described with reference to the accompanying drawing in which: Figures land 2 show radial and axial crosssectional views of an optical fibre cable constructed according to the present invention. Referring to the drawings the optical fibre cable construction illustrated comprises an optical fibre 1 having extruded over its length a layer of piezoelectric material 2. An outer protective sheathing 3 forthe optical fibre comprises electrical insulating material which in the present embodiment has embodied therein axially spaced apart pairs ofdiametrically- opposed sectors 4 and 5 of electrically conductive material of relatively high conductivity.These pairs of opposed sectors 4 and 5 allowforthe injection into the optical fibre 1 of data signals at pre-selected points along the cable and for this purpose the data signals may be applied to a pair of conductive sectorsthrough electrodes such as the electrodes 6 and 7which may be sprung on to the cable surface as shown in the drawing so that they make good electrical contact with the respective conductive sectors. The alternating data signals applied to the conductive sectors 4 and 5 through the electrodes 6 and 7 will produce radial straining ofthe piezoelectric layer2 which in turn will produce phase modulation ofthe light propagating along the optical fibre 1 dueto radial compression and expansion of the fibre. This phase modulation will be detected by a demodulator at the far end of the optical fibre. The optical fibre 1 may be of the polarisationmaintaining type so that straining of the piezoelectric layer causes phase modulation of one polarisation mode of the fibre relative to another mode. As previousiy mentioned, the piezo-electric layer may comprise a strip orfilament extending along the optical fibre in close proximity to the optical fibre so that it is closely mechanically coupled thereto and the conductive sectors may be replaced by continuous regions of electrically conductive material having poor conductivity which extend over the entire length of the optical fibre, the necessaryelectri- cal isolation being provided by the naturally lossy nature of the electrically conductive material. CLAIMS
1. An optical fibre cable comprising an optical fibre effectively mechanically coupled in radial directions along its length to piezoelectric material which makes electrical contact with axially extending electrically-conductive material embodied in the outer protective sheathing of the cable for the optical fibre whereby electrical signals applied to the electrically-conductive material at points along the length ofthe optical fibre cause mechanical strain to be produced in the piezoelectric material which in turn induces phase modulation in light propagating along the mechanically coupled optical fibre.
2. An optical fibre cable as claimed in claim 1, in which the piezoelectric material is extruded over the optical fibre so that it is located in close proximityto the fibre.
3. An optical fibre cable as claimed in claim 1, in which the piezoelectric material is in the form of a longitudinal strip orfilament located in close proximityto the optical fibre.
4. An optical fibre cable as claimed in any preceding claim, in which the electrically conductive material defines diametrically-opposed conductive regions (e.g. sectors) embodied in the protective sheathing ofthe cable.
5. An optical fibre cable as claimed in claim 4, in which the opposed regions of conductive material are spaced at intervals along the length of the cable.
6. An optical fibre cable as claimed in any preceding claim, in which the optical fibre is a polarisation maintaining fibre and the piezoelectric material when excited provides a radially anisotropic strain to the fibre.
7. An optical fibre cable substantially as here it before described with reference to the accompany ing drawing.
8. An optical fibre communications system com prising an optical fibre cable as claimed in any preceding claim, in which electrical data signals are app lied non-invasivelytothe cable at spaced points therealong through electrodes making contact with the conductive material embodied in the cable sheathing.
GB08614344A 1986-06-12 1986-06-12 Optical fibre cables Withdrawn GB2191596A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB08614344A GB2191596A (en) 1986-06-12 1986-06-12 Optical fibre cables

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB08614344A GB2191596A (en) 1986-06-12 1986-06-12 Optical fibre cables

Publications (2)

Publication Number Publication Date
GB8614344D0 GB8614344D0 (en) 1986-07-16
GB2191596A true GB2191596A (en) 1987-12-16

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
GB08614344A Withdrawn GB2191596A (en) 1986-06-12 1986-06-12 Optical fibre cables

Country Status (1)

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GB (1) GB2191596A (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5221989A (en) * 1991-11-13 1993-06-22 Northrop Corporation Longitudinal plzt spatial light modulator
WO1996027121A1 (en) * 1995-03-01 1996-09-06 Nizhny Novgorod Center For High Technology Incubation (Nchti) Optical fibre interferometer and optical fibre piezo-electric modulator

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1175855A (en) * 1966-08-25 1970-01-01 American Optical Corp Improvements in or relating to information processors
EP0084736A1 (en) * 1982-01-21 1983-08-03 Minnesota Mining And Manufacturing Company Optical fibers having piezoelectric coatings
EP0144190A2 (en) * 1983-11-30 1985-06-12 The Board Of Trustees Of The Leland Stanford Junior University Single mode fiber optic single sideband modulator

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1175855A (en) * 1966-08-25 1970-01-01 American Optical Corp Improvements in or relating to information processors
EP0084736A1 (en) * 1982-01-21 1983-08-03 Minnesota Mining And Manufacturing Company Optical fibers having piezoelectric coatings
EP0144190A2 (en) * 1983-11-30 1985-06-12 The Board Of Trustees Of The Leland Stanford Junior University Single mode fiber optic single sideband modulator

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5221989A (en) * 1991-11-13 1993-06-22 Northrop Corporation Longitudinal plzt spatial light modulator
WO1996027121A1 (en) * 1995-03-01 1996-09-06 Nizhny Novgorod Center For High Technology Incubation (Nchti) Optical fibre interferometer and optical fibre piezo-electric modulator
US5835642A (en) * 1995-03-01 1998-11-10 Optical Coherence Technologies, Inc. Optical fiber interferometer and piezoelectric modulator
US5867268A (en) * 1995-03-01 1999-02-02 Optical Coherence Technologies, Inc. Optical fiber interferometer with PZT scanning of interferometer arm optical length

Also Published As

Publication number Publication date
GB8614344D0 (en) 1986-07-16

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WAP Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1)