EP0277779A1
Expired / Lapsed
EP
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Optical space switch
Assignee: British Telecommunications PLC
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Filing: 1988-01-28
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Granted: —
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Expires: 2008-01-28
Abstract
Abstract A bidirectional optical space switch for selectively coupling an input signal to a selected output comprises two arrays of inputs (1, 8), two arrays of outputs (5, 9), polarising beam splitters (2, 4), and a matrix of cells (3) each of which is selectively capable of varying the polarisation state of light passing through it in response to an applied control signal. A first optical system (6) couples each of inputs (1) and a corresponding one of outputs (9) with a corresponding column of cells while a second optical system (7) couples each of inputs (8) and a corresponding one of outputs (5) with a corresponding row of cells. One of inputs (1) is switched to one of outputs (5) by activating the appropriate cell so that it rotates the polarisation of light passing through it by 90°. This also couples one of inputs 8 to one of outputs (9) thereby providing bidirectional switching. Use of combined beam splitters and polarisers (2, 4) provides bidirectionalily at substantially no loss of light additional to that lost on discrimination of the polarisation states.
Inventors
- 👤 Peter Healey
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-04 13:12
CPC Classifications
G; G02; G02F; G02F1/00; G02F1/29; G02F1/31; G02B; G02B27/00; G02B27/28; G02B27/283; G02B27/285; G02B6/00; G02B6/24; G02B6/26; G02B6/27; G02B6/2706; G02B6/35; G02B6/351; G02B6/353
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
216 words
A bi-directional optical space switch comprising - a first and a second array of inputs for emitting optical signals to be switched; a first and a second array of outputs for receiving switched optical signals from the first and second array of inputs, respectively; an active array of cells having first and second sides each cell being selectively capable of varying the polarisation state of light passing through from one side of the cell to the other in response to an applied control signal; a first optical coupling means for optically coupling the first sides of each of a plurality of groups of cells with a corresponding input of the first array of inputs and with a corresponding output of the second array of outputs; a second optical coupling means for optically coupling the second sides of each of a plurality of groups of cells with a corresponding input of the second array of inputs and with a corresponding output of the second array of outputs; the first and second optical coupling means including a respective first and second polarising beam splitter each arranged both to polarise light travelling from an input to the array of cells and to direct appropriately polarised light, only, passing through a cell away from the inputs and to the outputs.
Claim 2
Dependent Claim
216 words
A bi-directional optical space switch comprising - a first and a second array of inputs for emitting optical signals to be switched; a first and a second array of outputs for receiving switched optical signals from the first and second array of inputs, respectively; an active array of cells having first and second sides each cell being selectively capable of varying the polarisation state of light passing through from one side of the cell to the other in response to an applied control signal; a first optical coupling means for optically coupling the first sides of each of a plurality of groups of cells with a corresponding input of the first array of inputs and with a corresponding output of the second array of outputs; a second optical coupling means for optically coupling the second sides of each of a plurality of groups of cells with a corresponding input of the second array of inputs and with a corresponding output of the second array of outputs; the first and second optical coupling means including a respective first and second polarising beam splitter each arranged both to polarise light travelling from an input to the array of cells and to direct appropriately polarised light, only, passing through a cell away from the inputs and to the outputs.
Claim 3
Dependent Claim
22 words
An optical space switch as claimed in claim 1 in which each polarising beam splitter is located adjacent the array of cells.
Claim 4
Dependent Claim
27 words
An optical space switch as claimed in claim 1 in which each polarising beam splitter is located adjacent an array of inputs and an array of outputs.
Claim 5
Dependent Claim
29 words
An optical space switch as claimed in any preceding claim in which the optical means includes optical waveguides to couple the inputs and outputs to the array of cells.
Claim 6
Dependent Claim
55 words
An optical space switch as claimed in any preceding claim in which the active array of cells has the form of a matrix array and the optical means is arranged to couple each input to a respective row or column of cells, and to couple each row and column of cells to a respective output.
Claim 7
Dependent Claim
18 words
An optical space switch as claimed in claim 5 in which the optical means are formed by lenses.
Claim 8
Dependent Claim
22 words
An optical space switch as claimed in claim 6 in which the optical means includes a spherical lens and a plano-convex lens.
Claim 9
Dependent Claim
28 words
An optical space switch as claimed in any preceding claim in which the active array of cells comprises an array of liquid crystal devices of the twisted-nematic type.
Claim 10
Dependent Claim
25 words
An optical space switch as claimed in claim 8 in which the twisted-nematic liquid crystal cells are each cascaded with a liquid crystal scattering cell.
Claim 11
Dependent Claim
21 words
An optical space switch as claimed in any preceding claim in which the inputs comprise the ends of optical fibre waveguides.
Claim 12
Dependent Claim
42 words
An optical space switch as claimed in any one of claims 1 to 9 in which the arrays of inputs are formed by a plurality of optical devices the outputs of which are modulated to provide the optical signals to be switched.
Claim 13
Dependent Claim
20 words
An optical space switch as claimed in any preceding claim in which the outputs comprise the ends of optical waveguides.
Claim 14
Dependent Claim
25 words
An optical space switch as claimed in any one of claims 1 to 12 in which the outputs comprise photodetectors which detect switched optical signals.
References Cited (Backward Citations)
FR2385266A1
Cited
EP0161683A2
Cited
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