AU602251B2 - Creation of Inventions and Patents with Artificial Intelligence

AU602251B2 – Optical distributor
– Google Patents

AU602251B2 – Optical distributor
– Google Patents
Optical distributor

Download PDF
Info

Publication number
AU602251B2

AU602251B2
AU23054/88A
AU2305488A
AU602251B2
AU 602251 B2
AU602251 B2
AU 602251B2
AU 23054/88 A
AU23054/88 A
AU 23054/88A
AU 2305488 A
AU2305488 A
AU 2305488A
AU 602251 B2
AU602251 B2
AU 602251B2
Authority
AU
Australia
Prior art keywords
transflective
optical
outputs
plane mirror
input
Prior art date
1987-09-11
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.)

Ceased

Application number
AU23054/88A
Other versions

AU2305488A
(en

Inventor
Peter Healey
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.)

British Telecommunications PLC

Original Assignee
British Telecommunications PLC
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.)
1987-09-11
Filing date
1988-09-09
Publication date
1990-10-04

1988-09-09
Application filed by British Telecommunications PLC
filed
Critical
British Telecommunications PLC

1989-04-17
Publication of AU2305488A
publication
Critical
patent/AU2305488A/en

1990-10-04
Application granted
granted
Critical

1990-10-04
Publication of AU602251B2
publication
Critical
patent/AU602251B2/en

2008-09-09
Anticipated expiration
legal-status
Critical

Status
Ceased
legal-status
Critical
Current

Links

Espacenet

Global Dossier

Discuss

Classifications

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

G02F1/29—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 position or the direction of light beams, i.e. deflection

G02F1/31—Digital deflection, i.e. optical switching

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

G02B6/26—Optical coupling means

G02B6/28—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals

G02B6/2804—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals forming multipart couplers without wavelength selective elements, e.g. “T” couplers, star couplers

G02B6/2817—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals forming multipart couplers without wavelength selective elements, e.g. “T” couplers, star couplers using reflective elements to split or combine optical signals

Abstract

An optical distributor comprises an optical input (I1), and 2 optical outputs (01-08), where n is an integer greater than 1, one or more plane mirror surfaces (8) and transflective means (2, 4, 6). The plane mirror surface or surfaces (8) and the transflective means (2, 4, 6) are arranged to provide one optical path between the input (I1) and each of the outputs (01-08), each path making n transitions only at the transflective means. In a preferred embodiment the transflective means comprise n separate beam splitter stages, the effective lengths of the n separate splitter stages (2, 4, 6) being substantially in the ratio 1:2:…2. The beam splitters may be formed by transflective coatings on glass substrates.

Description

YU~ur~uaM u/000011 Nnilil AU-AI-230 54 88 PCT WORLD INTELLECTUAL PROPERTi JANZATIO_ INTERNATIONAL APPLICATION PUB LD)E IN^R TifN P NT OPERATION TREATY (PCT) (51) International Patent Classification 4 (11) International Publication Number: WO 89/ 02680 HO4B 9/00, G02B 6/28 H04Q 3/52 Al (43) International Publication Date: 23 March 1989 (23.03.89)
I
(21) International Application Number: PCT/GB88/00746 (22) International Filing Date: 9 September 1988 (09.09.88) (31) Priority Application Number: 8721472 (32) Priority Date: (33) Priority Country: 11 September 1987 (11.09.87) (71) Applicant (for all designated States except US): BRIT- ISH TELECOMMUNICATIONS PUBLIC LIMIT- ED COMPANY [GB/GB]; 81 Newgate Street, London ECIA 7AJ (GB).
(72) Inventor; and Inventor/Applicant (for US only) HEALEY, Peter [GB/ GB]; 31 Norbury Road, Ipswich, Suffolk IP4 4RQ
(GB).
(74) Agent: KENNINGTON, Penelope, Anne; British Telecommunications Public Limited Company, Intellectual Property Unit, 151 Gower Street, London WCIE 6BA (GB).
(81) Designated States: AU, JP, US.
Published With international search report.
r amndum i:-s rI1:’e und r j for I i p.
RO.JP. 25 MAY 1989
AUSTRALIAN
17 APR 1989 PATENT OFFICE (54) Title: OPTICAL DISTRIBUTOR (57) Abstract An optical distributor comprises an optical input and 2 n optical outputs (01-08), where n is an integer greater than 1, one or more plane mirror surfaces and transflective means 4, The plane mirror surface or surfaces and the transflective means 4, 6) are arranged to provide one optical path between the input (II) and each of the outputs (01-08), each path making n transitions only at the transflective means. In a preferred embodiment the transflective means comprise n separate beam splitter stages, the effective lengths of the n separate splitter stages 4, 6) being substantially in the ratio n The beam splitters may be formed by transflective coatings on glass substrates.
-1- OPTICAL DISTRIBUTOR The present invention relates to devices for distributing optical signals. Such devices are needed in fields such as optical communications and signal processing. They may be required to split only one input signal amongst 2n output devices or alternatively may interconnect 2 input devices with 2 output devices, n being an integer greater than i. Known devices used for this purpose have typically been formed from arrays of 4-port optical couplers interconnected by links of optical fibres in a star network configuration. These devices o require large numbers of separate components, as many as 12 different couplers being required in the case of an 8 port star network. The physical complexity of such systems makes them expensive to manufacture and difficult to instal in-line in optical systems. Moreover, insertion losses associated with each individual coupler have a cumulative effect which significantly degraded the performance of the network as a whole.
oo FR-A-2,341,873 and DE-A-2454,996 disclose a method of n 210 forming a 1 to 2 optical distributor which uses n successive stages of optical beam splitters, each beam 4.splitter stage having one or more individual transflective beam splitters to split an optical path into two further paths, and mirrors to realign the optical paths as necessary.
The term “transflective” as used herein describes a characteristic of a device or surface which provides for both transmission and reflection of optical beams.
L -1 -7-*41I I WO 89/02680 PCT/GB88/00746 -2- {1 Such devices are capable of splitting an optical signal equally among many outputs and of distributing intact all the components of a signal which is multidimensional in the optical rsgime, having spacial, colour, time and polarisation components but it uses an arrangement which requires 2 k separate beam splitters components for the kth stage and associated mirrors which means the number of beam splitters elements increases rapidly with increasing n.
According to a first aspect the present invention an optical distributor has at least one optical input, 2 n optical outputs, where n is an integer greater than 1, one or wore plane mirror surfaces and at least one transflective means, the plane mirror surface or surfaces and the transflective means being arranged to provide one optical path between the input and each of the outputs, each path making n transitions only at the transflective means, at least two of the transflective means being portions of a single transflective surface.
A device in accordance with the present invention is more compact, and may be formed using a smaller and sometimes the minimum number of different components than with previously known arrangements and can therefore be simpler and cheap to manufacture and instal. The two transflective means may be part of the same or different beam splitter stages.
The present invention is applicable to distributors having a single input to provide a 1 to 2 n distributor, which is functionally equivalent to known such distributors as previously described, as well as to distributors where the above optical input is one of 2 n optical inputs, for example star couplers.
The transflective means may, for example, be formed by a transflective coating on a glass substrate or by a cube
P
SUBSTITUTE SHEET I- WO 89/02680 PCT/GB88/00746 3 beam splitter. They have the property that light incident upon the transflective means is divided into two beams of equal power, a reflected beam and a transmitted beam. The transflective means are substantially insensitive to the presence of different polarisation components in the incident light.
The or each plane mirror surface may be formed by a conventional metal or multiplayer dielectric coating on a glass substrate, by a totally reflecting prism or by any other surface arranged to reflect substantially all of the power of any incident beam.
The or each plane mirror surface may be formed by a conventional metal or multilayer dielectric coating on a glass substrate, by a totally reflecting prism or by any other surface arranged to reflect substantially all of the power of any incident beam.
A distributor according to the present invention having one input and 2 n outputs can be arranged to n beam splitter stages each of which includes a single separate transflective surface and a first plane mirror surface arranged such that the or each beam incident on each beam splitter stage is split into a reflected beam and a transmitted beam, one of the beams passing directly to any subsequent beam splitter stage, the other of the two beams being reflected at the first plane mirror surface before passing to any subsequent beam splitter stage.
Preferably the transflective surfaces are arranged to lie at substantially 450 to the incident beams and the plane mirror surface is parallel to the transflective surfaces.
This arrangement provides a 1 to 2 n optical distributor using one mirror and only n beam splitter elements.
K
i SUBSTITUTE
SHEET
.i i-1 ir WO 89/0: :j 2680 PCT/GB88/00746 -4- Preferably the splitter stages are arranged in order of beam splitter effective length, with the shortest stage closest to the optical input. In such a device the effective length of the beam splitter is determined by the physical length of the transflective surface.
According to a second aspect of the present invention there is provided an optical distributor having 2 n optical inputs according to the first aspect of the invention, each of the transflective means being in the optical paths originating from at least two distinct inputs.
A first arrangement of such an optical distributer may comprise n beam splitter stages in which each kth beam splitter stage has 2 n k spatially separate transflective surfaces arranged between a first plane mirror surface and a second opposing plane mirror surface parallel to the first plane mirror surface.
In this case each of the 2 n k transflective surfaces of the kth beam splitter stage form 2 of transflective means of that beam splitter stage.
The stages are not necessary in order as will be discussed later.
In another arrangements the transflective means from different stages can be formed from a single transflective element.
In such arrangements the transflective surfaces of the beam splitter stages each act as beam splitters for beam originating from two or more inputs.
A further redundancy in transflective means can be obtained in a reflective star coupler according to the present invention as each transflective means can form the transflective means necessary for the optical path of at least four inputs.
SUBSTITUTE SHEET i .I ii i WO 89/02680 PCT/GB88/00746 Alternatively the transflective means of all the necessary beam splitter stages can comprise portions of a single transflective surface in which case the plane mirror surfaces include separate mirror surfaces of different lengths arranged on either side of the single transflective surface.
Preferably the beam splitters extend in the direction at right angles to a first plane containing the optical input and outputs and one or more further independent sets of optical inputs and outputs are provided in a plane or planes parallel to the first plane.
A distributor in accordance with present invention has the properties of a star-network in the case with 2″ inputs and 2″ outputs or a tree-network in the simoler case of a single input going to 2 outputs. It is readily constructed because all the beam splitters may be identical in form, differing only in scale for the different stages. This enables the use of a minimum number of components to achieve the desired power distribution. Since there is only one path between each input and output port, multipath propagation and the resultant degradation in signal handling cannot occur.
The ratio of the device endface size to its length is 2n/(2n-l) and tends to unity for large n. The power distributor is therefore well proportioned and compact, facilitating its insertion in line in optical systems.
A device in accordance with the present invention is now described in detail with reference to the accompanying drawings, in which: Figure 1 is a side elevation of a first embodiment of the present invention having a single input; Figure 2 is a side elevation of an alternative embodiment of the present invention having a single input; SUBSTITUTE SHEET i i _:i WO 89/02680 PCT/GB88/00746 6- Figure 3 is a side elevation of a further alternative embodiment of the present invention in the form of a star coupler; Figures 4 and 5 are side elevations of a star coupler functionally equivalent of Figure 3 with the beams splitting stages in different orders; Figure 6 is a diagram illustrating growth-rules for the beam splitter networks shown in Figures 1, 2 and 3; Figure 7a to 7c are diagrams illustrating the multiplexing functions of devices in accordance with the present invention; Figures 8a and 8b are side elevations of reflective networks in accordance with the present invention; Figure 9 is a side elevation of a four by four coupler according to the present invention in which transflective elements of different stages are formed on a common element; Figure 10 is a diagram illustrating a 4 input common transflector network in accordance with the present I invention; Figure 11 is a diagram illustrating an 8 input common transflector network in accordance with the present invention; Figure 12 is a diagrammatic perspective view showing the transmission properties of a device in accordance with the present invention; Figure 13 is a perspective view of a further embodiment of the present invention; and Figure 14 is a perspective view of an alternative embodiment of a switch incorporting a device in accordance with the present invention.
Referring to Figure 1 a device for distributing an optical signal among eight outputs comprises an optical SUBSTITUTE SHEET j
I
WO 89/02680 PCT/GB88/00746 7 input 1 and three splitter stages 2, 4, 6. Each splitter stage includes a transflective surface lying at 450 to the direction of incidence of light from the input 1. A mirror 6 extends across the device parallel to the transflective surfaces of the splitter stages 2, 4, 6.
The transflective surface of the second splitter stage 4 is twice the length of the surface of the first splitter stage 2 and the surface of the final splitter stage 6 is in turn twice the length of the surface of the ::Cznd splitter stage 4.
In use, a single beam is input at the optical input 1 which follows the optical paths shown by the dotted lines to the outputs 01 to 08. The beam strikes the first beam splitter 2 and is divided into two beams of equal power by a portion of the 50:50 transflective surface of the beam splitter (constituting a transflective means). One of the two resultant beams is transmitted through the beam splitter 2 and passes directly to the second beam splitter 4. The other beam is reflected from the transflective surface at 900 to the one beam and is reflected through a further 90° at the mirror sides so that after reflection the other beam propagates parallel to the one beam but separated from it in space. If losses at the mirror are neglected then since each beam has undergone a single transition at a 50:50 transflective surface each of the two beams reaching the second splitter stage 4 has half of the power of the original input beam. The beams are similarly subdivided at the subsequent splitter stages 4, 6 giving a total of eight beams at the optical outputs i- 01-08. Each of the paths from the input 1 to the outputs 01-08 involves three transitions at 50:50 transflective surfaces. The power of the input beam is therefore equally divided with one eighth going to each of the outputs 01-08.
U78T TUTE S HEET i 1-I- WO 89/02680 PCT/GB88/00746
-B-
The transflective means of each stage are form a single transflective element corresponding to that stage.
The device may conveniently be constructed as a “sandwich” of optical glass substrates. Transflective coatings are applied to the substrates using masks to give the required coating geometry. The coating used is chosen to have transmission and reflection coefficients which are equal for light of different polarisation states incident at 450 and for a wide range of wavelengths. The device is therefore polarisation and wavelength insensitive. The substrates are then aligned by the outer edges and bonded with optical epoxy resin. A mirror coating is then applied or a separate mirror attached. Finally the “sandwich” is cut and polished to give optical quality end faces.
An alternative construction shown in Figure 2 uses an ensemble of beam splitter cubes 12 of graded sizes packed with 45° prisms 14. This construction requires more sub-assemblies but is physically suited to the fabrication of simple tree-networks with only one input. In place of beam splitter cubes polarising beam splitters followed by quarter wave plates may be used if the input and output states of polarisation of the light are known to be fixed.
In constructing the device the transflective coatings may be made colour selective to give a wavelength responsive routing function. In this case one or more of the beam splitting surfaces is arranged to function as a dichroic mirror. At a given wavelength substantially all of the light incident on the dichroic mirror is reflected whilst light of a significantly differing wavelength is transmitted. With a distributor including such wavelength selective surfaces a signal may be wavelength encoded to determined at which output or outputs it leaves the device.
SUBSTITUTE
SHEET
WO 89/02680 PCT/GB88/00746 i-9 The beam splitters may be made active to allow the interconnect pattern to be rearranged dynimically. The splitters may, for example, comprise polarising beam splitters and associated electro-optic polarisers such as liquid crystal cells arranged to function as half-wave plates. The input to the distributor is then linearly polarised in a given direction and the optical axes of the polarisers and beam splitters arranged at such an angle to the direction of polarisation of the light that an incident beam is transmitted or reflected according to the state of the electro-optic polariser. Alternatively, active 1/4-wave plates maybe used to produce circularly polarised components from the incident plane polarised beam.
Referring now to Figure 3, a device according to the present invention configured as a star network is arranged to connect eight optical inputs Il to 18 with eight optical outputs 01 to 08. As before there are, by way of example only, three splitter stages. However in this example first splitter stage includes four separate beam splitters 16 the second splitter stage two beam splitters 18 and the final splitter stage a single beam splitter In general for a star network with 2 n outputs and 2 n inputs then if the ensemble of splitter stages are considered in order of increasing splitter lengths the kth splitter stage has with this specific arrangement 2 n-k separate beam splitters. It should be noted that the splitter stages do not need to be physically ordered in order of splitter length but may, for example, be arranged in configurations such as those of Figures 4 and In use each input of the star-network effectively sees a tree network which functions in the same manner as that -e WO 89/02680 PCT/GB88/00746 10 described above according to the first aspect of the invention. For clarity paths from just one of the inputs is shown in Figure 3. A light beam from input 14 strikes a lower mirror 22 at 450 and is reflected upwards to the uppermost of the beam splitters of the first stage 16.
Here it is split in two by the 50:50 transflective surface, the reflected beam passing directly to the upper beam splitter of the second stage 18 and the transmitted beam being reflected at an upper mirror 24 before travelling parallel to the reflected beam to the same upper beam splitter of the second splitter stage 18. A beam can be traced in similar fashion each of the other input and can be seen to be split in a manner precisely analogous to that described above for the tree-network.
As with the tree network each path between the inputs 11-18 and the outputs 01-08 undergoes the same number of transitions at 1:1 transflective means and so the power from any one of the inputs 11-18 is divided equally between the eight outputs 01-08. The star-network is bi-directional: light may be input from either end.
The tree networks for different inputs II to 18 have transreflective portions in common because the two :i parallel mirror 22 and 24 provide that optical paths from different inputs approach them from two orthogonal directions.
By increasing the number of beam splitter stages a Idevice in accordance with the present invention can be made for distributing power from one or many inputs independently between a selected number of 2 n outputs.
Growth rules for both tree and multiple input star networks of the arrangements shown in Figures 1, 2 and 3 are shown in Figure 6.
The propagation delay through the star network of Figure 3 is a linear function of input position with light from input 18 following the shortest path and hence emerging first and light from input II following the SUBSTITUTE
SHEET
c i i i l; -‘rr 1:r 1 1: WO 89/02680 PCT/GB88/00746 11 longest path and hence emerging last. This property may be exploited to give spatially-parallel to time-serial or time-serial to spatially-parallel multiplexing operations. Consider the 8×8 star couplers shown in Figures 7a to 7c. In ja a simultaneous but spatially split input to the device is output as a signal which is spatially identical i.e. the same from each of the spatially separated ports, but time-serial i.e. the output from the lowermost port precedes that from the port immediately above it and so on signal A being the first to exit from each. As shown in Figure 7b the device may be used to carry out the inverse operation in an analogous manner by inputting at input 18 a time serial signal (in which A enters the distributor first) and simultaneously sampling the outputs as signal A exits output 08.
Either of the end faces of the device may be coated with a mirror surface to give a distributor with the properties of a reflective-star-network but with 2 n multiple paths. However since each multiple path has a propagation delay that is a linear function of position this feature enables the use of the device as a single-ended spatially-parallel to time-serial multiplexer as shown in Figure 7c. A plane wave pulse 26 is fed into the input port 18 which is distributed to the eight output ports. The output pulses impinge on a spatial modulator 28 in serially, A which therefore feeds back into the distributor time-serial inputs A to H which then pass back to the input 18 to exit as a time-serial signal 29.
Referring now to Figures 8a and 8b there are shown reflective 4×4 star couplers and an illustrative beam path for an input at 14 which have transflective elements 28, mirrors 20 and 22 corresponding to those of Figure 2 and SUBSTITUTE
SHEET
Li WO 89/02680 PCT/GB88/00746 12 additional mirrors 30 which introduce additional redundancy in that the 4×4 coupler requires only two transflective means each on each on one transflective element.
In the embodiments described with reference to Figures 1 to 5 means the transflective which were formed by common transflective elements were from the same beam splitter stage. This need not be the case: in some configurations transflection means from different stages can be combined, according to the present invention, on one transflective surface to obtain a component reduction. This is shown in the 4×4 star coupler of Figure 9 in which stage one and stage two means (I and II respectively) are combined on one element. This enables a 4×4 coupler to be constructed from only two transflective elements.
In alternative embodiments of the present invention shown in Figures 10 and 11, a single transflective surface forms the transflective means for all the splitters stages. Figure 10 is a 4×4 star coupler utilising this configuration. Another such configuration is shown in Figure 11 is an 8×8 star coupler having a transflective element 38, two common mirrors 40, 42 and three double sided mirrors 44. In general for an NxN network where N equals 2 n, (N/2 1) mirrors are required including two mirrors common to all stages. There are (log 2 N)-l stages, the first stage having (N/4 2) mirrors, including the mirror common to all stages. The second stage has (N/8 2) mirrors and so on, the jth stage having (N/ 2 (j 2) mirrors. The internal mirrors, which are double sided, are arranged about a point spaced mid-way between the transflective surface and one of the common mirrors. The common mirrors are placed on opposite sides of the transflective surface and spaced from it by a distance proportional to N/4. The common mirrors can if a s. -i:f i i- j,:i.
iSI Is;.
-I I r ;1 ii .i ;1- :i L: 1 :”r S1J7S1,1_;T11 “E-E L 1 1- 1 WO 89/02680 PCT/GB88/00746 13 desired be extend laterally from the positions shown in Figures 10 and 11 to intersect the upper input and output beams so all the inputs and outputs are on the same side of the device.
By increasing the number of beam splitters in the splitter stages a device in accordance with the present invention can be made for distributing power from one or many inputs independently between many outputs. Growth rules for both tree and multiple input star-networks of the form shown in Figure 1, 2 and 3 are shown in Figure 6.
By extending the transflective surfaces of the above embodiments in the direction orthogonal to the plane of the inputs 11-18 and outputs 01-08 the device may be depth-multiplexed with further independent sets of inputs and outputs at intervals along the X-direction as shown in Figure 12, each independent set of inputs and outputs lying parallel to the Y-Z plane. Such a depth-multiplexed device my be used in combination with a un-multiplexed network of the type described above in order to distribute a single input or inputs over a two-dimensional array.
Such an arrangement is as shown schematically for a simple 4-output tree-network in Figure 13. A depth-multiplexed set of four tree-networks 61-64 is placed at the output of a single tree-network 60. The depth-multiplexed networks are rotated through 900 with respect to the input tree-network and arranged so that each output of the input tree-network 60 goes to the input of a respective one of I the networks 61-64 of the depth-multiplexed set.
Similarly a depth-mulLiplexed set of star networks may be i arranged to receive the output of a single star network.
Alternatively star networks may be combined with tree networks in a similar fashion according to the distribution characteristics required.
SUBSTITUTE
SHEET
L An optical aIlstroutor comprises an opticat input anu L- upmL’1 VULULo kVt-v-u) &Lo a -1 11- I than 1, one or more plane mirror surfaces and transflective means 4, The plane mirror surface or surfaces and the transflective means 4, 6) are arranged to provide one optical path between the input (II1) and each of the outputs (01-08), each path making n transitions only at the transflective means. In a preferred embodiment the transflective means comprise n separate beam splitter stages, the effective lengths of the n separate splitter stages 4, 6) being substantially in the ratio The beam splitters may be formed by transflective coatings on glass substrates.
WO 89/02680 PCT/GB88/00746 14 Devices in accordance with the present invention may advantageously be used in the construction of broadband digital electro-optic space switches are described in our co-pending UK application no. 8701996. The low-loss and high optical quality of a device in accordance with the present invention allows switch dimensions as high as 300 x 300 to be achieved. A further advantage of the use of these devices in this context is that the switch throughput can be increased with no loss penalty by using the two spatial dimensions of the signal paths. For example, the signal may consist of a 32-bit data bus or even a complete page of data transmitted in parallel. An architecture for a two-dimensional image switching system is shown in Figure 14. For simple 1-D serial transmission the output optical elements may be replaced by a simple clyindrical lens. Since inter-crosspoint signals are collimated optical beams, the entire switch traffic can be routed in many ways. It is, for example, possible to switch between M cross point arrays in order to provide a fail-proof backup.
An alternative embodiment of a switch including a distributor in accordance with the present invention, is shown in figure 15. The outputs of a depth multiplexed set of N tree networks TI to TN are input to N digitally indexed light deflectors DI to DN spacially multiplexed in the direction at right angles to the depth multiplexed tree-networks. The light deflectors comprise birefingent crystals interspersed with electro-optic polarisers: such deflectors are disclosed in the paper by Kulcke et al on pages 64 67 of the IBM Journal, January 1964. In the optical switch of figure 14 the deflectors are used in an N input to 1 output configuration so that the switch as a whole has N outputs extending in a direction at right angles to the N inputs Such a switch has an inherent loss of 10 logo 0 N dB.
SUBSTITUTE SHEET

Claims (9)

1. An optical distributor having at least one optical input, 2 n optical outputs, where n is an integer greater than 1, one or more plane mirror surfaces and transflective means, the plane mirror surface or surfaces and the transflective means being arranged to provide one optical path between the input and each of the outputs, each path making n transitions only at the transflective means, at least two of the transflective means being portions of a single transflective surface.

2. A distributor as claimed in claim 1 having n beam splitter stages each of which includes a single separate transflective surface and a first plane mirror surface arranged such that the or each beam incident on each beam splitter stage is split to a reflected beam and a transmitted beam, one of the beams passing directly to any subsequent beam splitter stage, the other of the two beams being reflected at the first plane mirror surface before passing to any subsequent beam splitter stage.

3. A distributor according to claim 3, in which the transflective surfaces are arranged to lie at substantially 450 to the incident beams and the first plane mirror surface is parallel to the transflective surfaces.

4. A distributor according to claims 3 or 4, in which the splitter stages are arranged in order of beam splitter effective length, with the shortest stage closest to the optical input. An optical distributor comprising 2 n optical inputs, 2 n optical outputs, where n is an integer greater than 1, two or more plane mirror surfaces and transflective means, the plane mirror surfaces and the transflective SUBSTITUTE SHEET i.

WO 89/02680 PCT/GB88/00746 16 means being arranged to provide one optical path between each input and each of the outputs, each path making n transitions only at the transflective means, at least two of the transflective means being portions of a single transflective surface and each transflective means being in optical paths originating from at least two inputs.

6. A distributor according to claim 5 including 2 n optical inputs 2 n optical outputs and k beam splitter stages, each kth beam splitter stage having 2 (nk) spatially separate transflective surfaces arranged between the first plane mirror surface and a second opposing plane mirror surface parallel to the first plane mirror surface.

7. A distributor according to any one of the previous claims, in which the transflective surfaces extend in the direction at right angles to a first plane containing the optical input and outputs and one or more further independent sets of optical inputs and outputs are provided in a plane or planes parallel to the first plane.

8. A distributor according to claim 1, in which the transflective means comprise a single common transflective surface and 2 n- 1 mirror stages, the 2 n- 1 mirror stages being positioned on the other side of the common transflective surface to a common plane mirror surface.

9. An optical space switch incorporating a distributor according to any of of the preceding claims. SUBSTITUTE SHEET -tW 1

AU23054/88A
1987-09-11
1988-09-09
Optical distributor

Ceased

AU602251B2
(en)

Applications Claiming Priority (2)

Application Number
Priority Date
Filing Date
Title

GB878721472A

GB8721472D0
(en)

1987-09-11
1987-09-11
Optical distributor

GB8721472

1987-09-11

Publications (2)

Publication Number
Publication Date

AU2305488A

AU2305488A
(en)

1989-04-17

AU602251B2
true

AU602251B2
(en)

1990-10-04

Family
ID=10623677
Family Applications (1)

Application Number
Title
Priority Date
Filing Date

AU23054/88A
Ceased

AU602251B2
(en)

1987-09-11
1988-09-09
Optical distributor

Country Status (8)

Country
Link

EP
(1)

EP0307243B1
(en)

JP
(1)

JP2848836B2
(en)

AT
(1)

ATE83102T1
(en)

AU
(1)

AU602251B2
(en)

CA
(1)

CA1322287C
(en)

DE
(1)

DE3876344T2
(en)

GB
(1)

GB8721472D0
(en)

WO
(1)

WO1989002680A1
(en)

Families Citing this family (2)

* Cited by examiner, † Cited by third party

Publication number
Priority date
Publication date
Assignee
Title

DE19904592C2
(en)

1999-02-05
2001-03-08
Lavision Gmbh

Beam splitter device

FR2886416A1
(en)

2005-05-24
2006-12-01
Breizhtech Sas

MATRIX HEAD FOR ROUTING LUMINOUS BEAMS WITH FREQUENCY ADDRESSING

Family Cites Families (2)

* Cited by examiner, † Cited by third party

Publication number
Priority date
Publication date
Assignee
Title

DE2454996A1
(en)

1974-11-20
1976-05-26
Siemens Ag
Coupling device for guide elements AND single light source – has amplifiers inform of sequential light splitters

CA1077606A
(en)

1976-02-23
1980-05-13
Robert S. Congleton
System for combining laser beams of diverse frequencies

1987

1987-09-11
GB
GB878721472A
patent/GB8721472D0/en
active
Pending

1988

1988-09-09
WO
PCT/GB1988/000746
patent/WO1989002680A1/en
unknown

1988-09-09
DE
DE8888308380T
patent/DE3876344T2/en
not_active
Expired – Fee Related

1988-09-09
JP
JP63507247A
patent/JP2848836B2/en
not_active
Expired – Lifetime

1988-09-09
AT
AT88308380T
patent/ATE83102T1/en
not_active
IP Right Cessation

1988-09-09
EP
EP88308380A
patent/EP0307243B1/en
not_active
Expired – Lifetime

1988-09-09
AU
AU23054/88A
patent/AU602251B2/en
not_active
Ceased

1988-09-12
CA
CA000577155A
patent/CA1322287C/en
not_active
Expired – Fee Related

Also Published As

Publication number
Publication date

JPH02501433A
(en)

1990-05-17

DE3876344T2
(en)

1993-04-01

JP2848836B2
(en)

1999-01-20

DE3876344D1
(en)

1993-01-14

WO1989002680A1
(en)

1989-03-23

EP0307243B1
(en)

1992-12-02

GB8721472D0
(en)

1987-10-21

ATE83102T1
(en)

1992-12-15

AU2305488A
(en)

1989-04-17

CA1322287C
(en)

1993-09-21

EP0307243A1
(en)

1989-03-15

Información de contacto