GB2211956A - Optical switch - Google Patents
Optical switch Download PDFInfo
- Publication number
- GB2211956A GB2211956A GB8825205A GB8825205A GB2211956A GB 2211956 A GB2211956 A GB 2211956A GB 8825205 A GB8825205 A GB 8825205A GB 8825205 A GB8825205 A GB 8825205A GB 2211956 A GB2211956 A GB 2211956A
- Authority
- GB
- United Kingdom
- Prior art keywords
- phase shifter
- couplers
- arms
- optical
- polarisation
- 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.)
- Granted
Links
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
- G02F1/313—Digital deflection, i.e. optical switching in an optical waveguide structure
- G02F1/3131—Digital deflection, i.e. optical switching in an optical waveguide structure in optical fibres
Landscapes
- Physics & Mathematics (AREA)
- Nonlinear Science (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Mechanical Light Control Or Optical Switches (AREA)
Abstract
An optical switch comprises a pair of single mode optical waveguides coupled together at two spaced locations to form couplers to mix equally light from each waveguide, the arms of the waveguides between the couplers being of substantially equal length, so as to form a Mach Zehnder interferometer 4; a polarization-dependent phase shifter 5 associated with one of the arms; and a polarization-independent phase shifter associated with the other arm. The phase shifter 5 comprises a piezo-electric devices which in use compress the optical fibre in one direction only. <IMAGE>
Description
Optical Switch
This invention relates to optical switches of the type which comprise a pair of single mode optical waveguides, preferably fibres, which are coupled at two spaced locations, known as couplers, so as to mix equally light from each waveguide such that the two arms between the couplers are of substantially equal length, forming a
Mach Zehnder interferometer. In particular the invention relates to a polarisation splitter/switch.
Generally, all optical fibre polarisation splitters are formed by fusing and tapering two single mode fibres side by side.
The tapering process is continued through the duration of many more power transfer cycles between the coupler arms than for a standard 3 dB coupler, until a further modulation is superimposed onto these power oscillations. Usually, polarisation splitters are formed at the first minimum of this superimposed modulation. As a result of this lengthened tapering, the performance of the splitters formed is in general highly dependent on the wavelength of the light to be analysed.
It is an object of this invention to provide an optical polarisation splitter which is switchable and can also be used over a wider range of wavelengths than conventional polarisation splitters.
According to the invention, an optical switch comprises a
Mach Zehnder interferometer, as hereinbefore described, wherein a phase shifter is mounted on each of the interferometer arms, one of said shifters being polarisation-dependent, the other being pol ari sati on-Independent.
There is no longer any need for a lengthy interaction region, and each coupler is preferably a standard 3 dB coupler, so that wavelength dependence is substantially reduced.
In this way, it is possible to vary the optical power of light of either linear polarisation emerging from the switch.
Conveniently, where the waveguides are optical fibres, transducers in the form of piezo-electric squeezers are used to compress the optical fibre forming a polarisation-dependent phase shifter in which the relative phase difference between orthogonal polarisations may be electrically varied.
Each transducer acts on one light path so that the phase relationship between light of one polarisation in one lightpath may be altered relative to light of the same polarisation in the other light path. Light of the orthogonal polarisation is not affected.
To reduce the wavelength dependence of the coupling ratio still further, where the waveguides are fibres, one fibre at each coupler is pretapered to alter the propagation constant of the light guided by the fibre in the pretapered region.
The invention will now be described by way of example only, with reference to the accompanying drawings of which
Figure 1 is a perspective view of a polarisation-dependent phase shifter for an optical fibre; and
Figure 2 is a plan view of a fibre-optic Mach Zehnder interferometer incorporating the phase shifter of Figure 1.
As shown in Figure 1 a change in the phase of light in the optical fibre 1 is induced by compressing the fibre using piezo-electric squeezers 2 mounted on a U-shaped block 3. A bias force adjustment screw 7 is used to adjust the fibre compression.
The phase difference between light polarized in the x direction and light polarised in the y direction is induced in light travelling along the z-axis if the force exerted by the squeezers 2 is along the x-axis. A pair of insulating clamps 8 with inset electrodes is mounted on the block 3.
The interferometer 4 is formed in the normal way by forming two standard single mode optical fibre 3 dB couplers in series on a pair of single mode fibres using the fused biconical technique.
Each of the two arms of the interferometer 4 has a phase shifter 5, 6 mounted thereon, as shown in Figure 2. One of the phase shifters is a standard non-birefringent phase shifter 6, but the other is constituted by a piezo-electric squeezer 5 which induces a phase shift in light of one polarisation relative to light of the orthogonal polarisation.
Thus a switchable polarisation splitter is formed, which may be used to maintain either of two constant specified states of linear polarisation at both outputs.
An active device which may offer better long term stability of operation may be achieved by monitoring the state of polarisation at one output and using a feed back control system to optimise the phase shifts applied by the two transducers. This may be realised by dithering the control signals to the two transducers and detecting improvement in the polarisation match at the output.
It is envisaged that an integrated optic implementation of the invention would also be feasible, in which the phase shifters take one of the forms conventional in integrated optics.
Claims (5)
1. An optical switch comprising : a pair of single mode optical waveguides coupled together at two spaced locations to form couplers to mix equally light from each waveguide, the arms of the waveguides between the couplers being of substantially equal length, so as to form a Mach Zehnder interferometer; a polarization-dependent phase shifter associated with one of the arms; and a polarization-independent phase shifter associated with the other arm.
2. A switch according to Claim 1, in which each coupler is a standard 3 dB coupler.
3. A switch according to Claim 1 or 2, in which each waveguide is an optical fibre, the fibres being fused at the couplers.
4. A switch according to Claim 3, in which one of the fibres is pretapered at each coupler.
5. A switch substantially as described herein with reference to the accompanying drawings.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB8825205A GB2211956B (en) | 1987-11-05 | 1988-10-27 | Optical switch |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB878725945A GB8725945D0 (en) | 1987-11-05 | 1987-11-05 | Optical switch |
GB8825205A GB2211956B (en) | 1987-11-05 | 1988-10-27 | Optical switch |
Publications (3)
Publication Number | Publication Date |
---|---|
GB8825205D0 GB8825205D0 (en) | 1988-11-30 |
GB2211956A true GB2211956A (en) | 1989-07-12 |
GB2211956B GB2211956B (en) | 1991-12-18 |
Family
ID=26292997
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB8825205A Expired - Fee Related GB2211956B (en) | 1987-11-05 | 1988-10-27 | Optical switch |
Country Status (1)
Country | Link |
---|---|
GB (1) | GB2211956B (en) |
Cited By (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2234828A (en) * | 1989-08-09 | 1991-02-13 | Stc Plc | Optical polarisation state controllers |
DE4418751A1 (en) * | 1994-05-28 | 1995-11-30 | Sel Alcatel Ag | Refractive index changer for planar waveguide in optical switch for telecommunication |
EP0622650B1 (en) * | 1993-04-29 | 1998-06-24 | Corning Incorporated | Narrow band Mach-Zehnder filter |
EP1181585A1 (en) * | 1999-02-26 | 2002-02-27 | Corning Incorporated | Wideband polarization splitter, combiner, isolator and controller |
US6366709B1 (en) * | 1997-06-23 | 2002-04-02 | Chiaro Networks Ltd. | Integrated optics beam deflectors and systems |
US6427036B1 (en) * | 1998-12-31 | 2002-07-30 | Oni Systems Corp. | Fiber optic interferometer based switch |
US6956985B2 (en) * | 2003-01-07 | 2005-10-18 | Agilent Technologies, Inc. | Semiconductor-based optical switch architecture |
US11733460B2 (en) | 2018-11-02 | 2023-08-22 | Teknologian Tutkimuskeskus Vtt Oy | Devices and methods for polarization splitting |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4291939A (en) * | 1978-03-24 | 1981-09-29 | The United States Of America As Represented By The Secretary Of The Navy | Polarization-independent optical switches/modulators |
WO1988003278A1 (en) * | 1986-10-24 | 1988-05-05 | British Telecommunications Public Limited Company | Optical signal modulation device |
-
1988
- 1988-10-27 GB GB8825205A patent/GB2211956B/en not_active Expired - Fee Related
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4291939A (en) * | 1978-03-24 | 1981-09-29 | The United States Of America As Represented By The Secretary Of The Navy | Polarization-independent optical switches/modulators |
WO1988003278A1 (en) * | 1986-10-24 | 1988-05-05 | British Telecommunications Public Limited Company | Optical signal modulation device |
Non-Patent Citations (1)
Title |
---|
IEEE Journal of Quantum * |
Cited By (12)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2234828A (en) * | 1989-08-09 | 1991-02-13 | Stc Plc | Optical polarisation state controllers |
GB2234828B (en) * | 1989-08-09 | 1994-02-16 | Stc Plc | Optical polarisation state controllers |
EP0622650B1 (en) * | 1993-04-29 | 1998-06-24 | Corning Incorporated | Narrow band Mach-Zehnder filter |
DE4418751A1 (en) * | 1994-05-28 | 1995-11-30 | Sel Alcatel Ag | Refractive index changer for planar waveguide in optical switch for telecommunication |
US6366709B1 (en) * | 1997-06-23 | 2002-04-02 | Chiaro Networks Ltd. | Integrated optics beam deflectors and systems |
US6542648B2 (en) | 1997-06-23 | 2003-04-01 | Chiaro Networks Ltd. | Integrated optics beam deflectors and systems |
US6556730B2 (en) | 1997-06-23 | 2003-04-29 | Chiaro Networks Ltd. | Integrated optics beam deflectors and systems |
US6427036B1 (en) * | 1998-12-31 | 2002-07-30 | Oni Systems Corp. | Fiber optic interferometer based switch |
EP1181585A1 (en) * | 1999-02-26 | 2002-02-27 | Corning Incorporated | Wideband polarization splitter, combiner, isolator and controller |
EP1181585A4 (en) * | 1999-02-26 | 2005-04-20 | Corning Inc | Wideband polarization splitter, combiner, isolator and controller |
US6956985B2 (en) * | 2003-01-07 | 2005-10-18 | Agilent Technologies, Inc. | Semiconductor-based optical switch architecture |
US11733460B2 (en) | 2018-11-02 | 2023-08-22 | Teknologian Tutkimuskeskus Vtt Oy | Devices and methods for polarization splitting |
Also Published As
Publication number | Publication date |
---|---|
GB8825205D0 (en) | 1988-11-30 |
GB2211956B (en) | 1991-12-18 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 19941027 |