EP0225737A2
Expired / Lapsed
EP
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Optical state of polorisation modulator
Assignee: STC PLC
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Filing: 1986-11-12
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Granted: —
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Expires: 2006-11-12
Abstract
Abstract A tandem pair of two variable birefringence half-wave elements (18) provided with an intervening invariant quarter-wave birefringent element can be used in a polarisation sensitive optical system, such as a coherent light optical fibre reflectometer, for modulating the light in a manner enabling the derivation of a polarisation independent electrical signal from a photodetector (25).
Inventors
- 👤 Jonathan Paul King
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-10 02:03
CPC Classifications
G; G01; G01M; G01M11/00; G01M11/30; G01M11/31; G01M11/3172; G01M11/3181; G02; G02B; G02B26/00; G02B5/00; G02B5/30; G02B5/3083; G02F; G02F1/00; G02F1/01; G02F1/0136; G02F1/09
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
66 words
A state of polarisation (SOP) modulator possessing an input port and an output port which modulator is characterised in that it is operable between a set of states possessing the property that, for any given input SOP to the input port, the output SOP's from the output port form a set whose members, when represented on a Poincaré sphere, sum to the centre of that sphere.
Claim 2
Dependent Claim
66 words
A state of polarisation (SOP) modulator possessing an input port and an output port which modulator is characterised in that it is operable between a set of states possessing the property that, for any given input SOP to the input port, the output SOP's from the output port form a set whose members, when represented on a Poincaré sphere, sum to the centre of that sphere.
Claim 3
Dependent Claim
16 words
An SOP modulator as claimed in claim 1, wherein the members of the set number four.
Claim 4
Dependent Claim
98 words
An SOP modulator as claimed in claim 2, which modulator includes a tandem arrangement of two variable birefringence elements and an intervening invariant birefringence element, wherein each variable birefringence element is operable between a pair of states affording a nett half-wave change in birefringence, wherein the invariant birefringence element affords a quarter-wave birefringence, and wherein the birefringences of the three elements are such that they are represented on the Poincaré sphere by birefringence axes having the property that those of the two variable elements lie in a common direction to which that of the invariant element is normal.
Claim 5
Dependent Claim
18 words
An SOP modulator as claimed in claim 3, wherein the two variable birefringence elements exhibit variable circular birefringence.
Claim 6
Dependent Claim
20 words
An SOP modulator as claimed in claim 4, wherein the two variable birefringence elements are constituted by Faraday effect elements.
Claim 7
Dependent Claim
18 words
An SOP modulator as claimed in claim 3, wherein the two variable birefringence elements exhibit variable linear birefringence.
Claim 8
Dependent Claim
65 words
An SOP modulator as claimed in claim 2, which modulator includes a tandem arrangement of two variable birefringence elements with no intervening birefringence element, wherein each variable birefringence element is operable between a pair of states affording a nett half-wave change in birefringence, and wherein the birefringence elements are such that they are represented on the Poincaré sphere by birefringence axes that are mutually orthogonal.
Claim 9
Dependent Claim
18 words
An SOP modulator as claimed in claim 7, wherein the two variable birefringence elements exhibit variable linear birefringence.
Claim 10
Dependent Claim
36 words
An SOP modulator as claimed in any claim of claims 3 to 8, wherein each variable birefringence element is constituted by a device operable between a state affording no birefringence and a state affording half-wave birefringence.
Claim 11
Dependent Claim
38 words
An optical heterodyne or homodyne system in which there is included in the light path of one of the coherent light beams that are coherently mixed by the system an SOP modulator as claimed in any preceding claim.
Claim 12
Dependent Claim
11 words
An reflectometer including an optical system as claimed in claim 10.
References Cited (Backward Citations)
No citation records indexed.
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