EP0634025A1 - Ameliorations concernant le dephasage optique - Google Patents

Ameliorations concernant le dephasage optique

Info

Publication number
EP0634025A1
EP0634025A1 EP93907651A EP93907651A EP0634025A1 EP 0634025 A1 EP0634025 A1 EP 0634025A1 EP 93907651 A EP93907651 A EP 93907651A EP 93907651 A EP93907651 A EP 93907651A EP 0634025 A1 EP0634025 A1 EP 0634025A1
Authority
EP
European Patent Office
Prior art keywords
light
polarisation
paths
propagation
wavelength
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Withdrawn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
EP93907651A
Other languages
German (de)
English (en)
Other versions
EP0634025A4 (fr
Inventor
Steven James Friskin
Ralph Alexander Betts
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.)
Australian and Overseas Telecommunications Corp Ltd
Original Assignee
Australian and Overseas Telecommunications Corp 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 Australian and Overseas Telecommunications Corp Ltd filed Critical Australian and Overseas Telecommunications Corp Ltd
Publication of EP0634025A1 publication Critical patent/EP0634025A1/fr
Publication of EP0634025A4 publication Critical patent/EP0634025A4/fr
Withdrawn legal-status Critical Current

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
    • G02F1/01—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 
    • G02F1/09—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 magneto-optical elements, e.g. exhibiting Faraday effect
    • G02F1/093—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 magneto-optical elements, e.g. exhibiting Faraday effect used as non-reciprocal devices, e.g. optical isolators, circulators
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/25—Arrangements specific to fibre transmission
    • H04B10/2589—Bidirectional transmission
    • H04B10/25891—Transmission components

Definitions

  • the present invention relates to optical systems, including phase shifters, isolators, circulators and bi-directional communication systems, particularly but not exclusively for optical fibre communication systems.
  • An optical isolator is an important component in many optical systems, including communications applications and bulk lasers.
  • the role of the isolator is to allow transmission of light in only one direction.
  • Isolators are used in communications systems to prevent feedback resulting from reflections returning to a laser diode, and are used in conjunction with optical amplifiers to ensure there is no lasing or noise degradations due to feedback.
  • a typical amplifier may have a conventional isolator at its input, its output or both input and output. It is not practically possible to operate a very high gain amplifier without isolation because of residual reflections and scattering.
  • a single polarisation isolator can be constructed as shown in Figure 1. Light travelling from left to right is polarised in the vertical direction, then rotated by 45 degrees by the Faraday rotator. A second polariser is placed at this angle, allowing the light to pass undisturbed.
  • One technique for achieving polarisation independent isolation is to split incident light into two polarisation components, isolating each of the components, and then recombining the two polarisation components.
  • the polarisation splitters themselves may act as the polarisers for the isolators, so a polarisation independent isolator can be constructed as shown in Figure 2.
  • the present invention provides a non- reciprocal phase shifter, comprising at least one first polarisation rotating means, the direction of polarisation rotation being dependant on the direction of propagation of transmitted light, and at least one second means for altering polarisation, the direction of polarisation alteration being independent of the direction of propagation of transmitted light, characterised in that substantially half of any light propagating from either end of the phase shifter having an arbitrary polarisation travels through each of the first polarisation rotating means and second means for altering polarisation.
  • the invention comprises a non- reciprocal optical phase shifter, comprising means for transmitting incident light through first and second optical paths and recombining said paths at an output, said paths including respectively first and second means for altering the polarisation of incident light having arbitrary polarisation, at least one of said means for altering polarisation having a first rotation in one direction of propagation and another rotation in a second direction of propagation, and the other or one of said means for altering having a polarisation change independent of the direction of propagation, the arrangement being such that a first relative phase shift between the paths occurs for light propagating in one direction, and a second relative phase shift between the paths occurs for light propagating in a second direction.
  • the invention comprises a non- reciprocal optical phase shifter, comprising means for transmitting incident light through first and second optical paths and recombining said paths at an output, said first path including in a first propagation direction successively first polarisation rotating means having a rotation dependent on propagation direction and second polarisation altering means having a change independent of the direction of propagation, said second path including in said first propagation direction successively third polarisation altering means having a change independent of the direction of propagation and fourth polarisation rotating means having a rotation dependent on propagation direction, the arrangement being such that substantially half of the incident light travels through each of said first and second paths, and the relative phase shift of output light is dependent on the direction of propagation of the incident light.
  • a further aspect of the present invention provides a non- reciprocal phase shifter, comprising means for transmitting substantially half of incident light into two optical paths each having arbitrary polarisation, and recombining the paths to produce an output, each of said paths comprising means for altering the polarisation of the transmitted light, characterised in that in a first direction of propagation the paths have outputs which are have a first relative phase shift, and in the reverse direction the paths have outputs which have a different relative phase shift.
  • an optical isolator comprising a non-reciprocal phase shifter characterised in that for a selected wavelength, in a first propagation direction the output light is substantially transmitted, and in the reverse direction the output light is substantially attenuated.
  • a further aspect of the present invention provides bidirectional optical isolator, comprising means for transmitting substantially half of incident light through each of first and second optical paths, at least said first path including polarisation rotating means having a rotation dependent on propagation direction and at least said second path including second polarisation altering means having a rotation independent of the direction of propagation, said first and second paths having a path length difference, and means for recombining said first and second paths, the arrangement being such that for light having a first wavelength propagating in a first direction total attenuation occurs, while for light having said first wavelength propagating in a second reverse direction substantial transmission occurs; and for light having a second wavelength propagating in said first direction substantial transmission occurs, while for light having said second wavelength propagating in said second reverse direction substantial attenuation occurs.
  • a further aspect of the present invention provides an optical circulator, comprising at least one input to an non-reciprocal isolator , and means for coupling the isolator to two outputs, the arrangement being such that light having one wavelength is output through one output, and light having a second wavelength is output through the second output.
  • a further aspect of the present invention provides bidirectional optical fibre communications system, in which signals travelling in a first direction have a first wavelength, and signals travelling in the other direction have a second wavelength, both signals travelling in the same optical fibre, characterised in that the system includes one or more wavelength selective bidirectional isolators.
  • a further aspect of the present invention provides a bidirectional optical amplifier for allowing amplification of signals at a first wavelength in a first direction, and at a second wavelength in the second, reverse direction, comprising means for inducing gain at said first and second wavelengths, and bidirectional wavelength dependent isolation means arranged such that signals at said first wavelength travelling in said first direction, and signals at said second wavelength travelling in said second direction, are transmitted, and signals at said first wavelength travelling in said second direction, and signals at said second wavelength travelling in said first direction, are attenuated, and such that undesired feedback at said first and second wavelengths is substantially suppressed.
  • a further aspect of the present invention provides an optical isolator, comprising means for transmitting substantially half of incident light into two optical paths each halving arbitrary polarisation, and recombining the paths to produce an output, each of said paths comprising means for altering the polarisation of the transmitted light, characterised in that in a first direction of propagation the paths have outputs which are in phase, and so transmit the incident light, and in the reverse direction the paths have outputs which are 180° out of phase, and so do not transmit the incident light.
  • Figure 1 is a schematic view of a prior art isolator
  • Figure 2 is a schematic view of another prior art isolator;
  • Figure 3 is a schematic view of an optical circulator;
  • Figure 4 illustrates a first technique for bi-directional isolation in a wavelength diversity transmission system
  • Figure 5 illustrates a second technique for bi-directional isolation in a wavelength diversity transmission system
  • Figure 6 illustrates conceptually a technique for bi-directional isolation in a wavelength diversity system
  • Figure 7A and 7B illustrate interference within the system of figure 10
  • Figure 8 illustrates one implementation of the system of figure 10
  • Figure 9 illustrates another implementation of the system of figure 10
  • Figures 10A and 10B illustrate a preferred implementation of a non-reciprocal phase shifter
  • Figure 11 illustrates a polarisation dispersion free isolator
  • Figure 12 illustrates a balanced polarisation dispersion free design
  • Figure 13 illustrates an integrated implementation of a circulator/isolator according to the present invention
  • Figure 14 is a graph showing wavelength dependence in an experimental device;
  • Figure 15 illustrates a preferred implementation of the system of figure 10;
  • Figure 16 illustrates schematically a bidirectional amplifier.
  • Figure 17 illustrates schematically a fibre embedded circulator according to the present invention
  • Figure 18 illustrates an implementation of the device of Figure 17
  • Figure 19 illustrates a mode-converting circulator
  • Figure 20 illustrates a fused Mach-Zender implementation of an isolator/circulator according to the present invention
  • Figure 21 illustrates a filtered isolator according to the present invention
  • Figure 22 illustrates a high isolation device
  • Figure 23 illustrates a network utilising a bi-directional amplifier
  • Figure 24 illustrates schematically a low polarisation dispersion amplifier. • Detailed description
  • This aspect of the present invention is particularly adapted to be implemented in bi-directional networks.
  • transmission in one direction takes place at one wavelength, and in the opposite direction at a second wavelength, as is illustrated in principle in Figure 23.
  • a particular difficulty in this arrangement is in constructing a simple isolator which achieves wavelength selective isolation. If such an isolator could be constructed, it is clear that the amplifier would be adequately isolated from reflections, as such reflections would in general maintain the wavelength of the light and so be passed out of the system upon meeting an isolator.
  • a first embodiment of this type of isolator depends upon splitting the light into the two wavelengths using a grating or wavelength division multiplexer 34, isolating each wavelength separately in each direction using isolators 32, 33, then recombining the light afterwards 31, as shown in Figure 4.
  • a slightly more refined approach can be constructed with an optical circulator 42 and a single wavelength multiplexing element 41 as shown in Figure 5.
  • This aspect of the present invention is based on a new approach to isolation which is inter. erometric instead of being polarisation dependent.
  • One immediate advantage that arises from this is that all of the embodiments described are in general polarisation independent, without the need to split and recombine polarisations.
  • a general form of this aspect of the invention is shown in Figure 6.
  • a single beam of light entering at point 1 is split by beamsplitter 51 into two paths formed using mirrors 54, 55.
  • a 90 degree Faraday rotator 53 is placed, and in the second path a pair of half-wave retardation plates 52 at a relative angle of 45 degrees is placed.
  • the pair of retarders 52 rotates the polarisation of any arbitrary polarisation of incident light by 90 degrees.
  • the device created is related to a Mach-Zender interferometer. It will be apparent that wavelength dependence in the isolation can be achieved. If an optical path length difference is introduced between the two arms of the Mach-Zender, then there will be only certain wavelengths for which the interference will be constructive in light travelling from port 1 to port 4. This will give a sin2 dependence to the intensity of light emerging in port 4 as a function of ⁇ , with a periodicity proportional to
  • a device can be constructed to be forward propagating at 1535 nm (corresponding to the first gain peak of the erbium-doped fibre amplifier) and reverse propagating at 1555 nm (the second gain peak of the erbium doped fibre amplifier). Isolation is provided for both wavelengths.
  • the main obstacle to be overcome is the stability of the device to external perturbations. As an interferometric device it is potentially much more sensitive to any thermally or mechanically induced variations in the relative path lengths. Although thermal and mechanical stabilisation is possible, it is unlikely that any bulk device built according to Figure 6 would have the required stability for a field device.
  • a second solution is to physically split the beam into the top half and bottom half and to use the same rotators and birefringent plates as before ,as shown in Figure 9.
  • Lens 73, 71 collimate/focus the incident light to and from beam 75 and project the light onto mirror set 70. It is now much less obvious that this should work as an isolator, or even that there should be any interference at all. In fact this will no longer act as a bulk isolator, and it is only when the input 74 and output 72 are both single mode fibres that the interference or isolation will take place. This is because of the quantum nature of the modes of a fibre.
  • a qualitative theoretical understanding can be obtained by considering the device as a black box, which provides two paths of equal probability and the same phase for photons travelling in the forward direction.
  • the expectation value of a photon arriving at a point in the second fibre is the sum of ⁇ the different possible wave functions times the probability of that wave function ⁇ .
  • the wave functions will be in phase for a given wavelength photon and the normalised expectation value will be 1 (100% probability of the photon arriving).
  • the wave functions will be opposite sign and so the probability of the photon arriving will be 0.
  • Insertion loss should be negligible ( ⁇ 0.5 dB) with good beam expansion optics, and stability is maximised because there is only a small length of crystal ( ⁇ 1 mm) generating the path difference.
  • One disadvantage of the embodiments described is that the construction of the non-reciprocal phase shifter used different materials to act upon each half of the beam which is split. The device is therefore susceptible to temperature dependence as the thermal expansion coefficients and thermal refractive index coefficients for each half will be different, thus shifting the wavelength of maximum isolation.
  • Figures 10A, 10B illustrate a preferred stable design for the non- reciprocal phase shifting element.
  • This implementation uses a 45 degree Faraday rotator 101 in both halves and a half-wave plate 100, 102 in both halves.
  • the half waveplate 100 is to the left of the Faraday rotator 101, and in the second half, the half waveplate 102 is to the right of the Faraday rotator 101.
  • the second waveplate 102 is orientated to have its optic axis at 45 degree relative to the first waveplate 100.
  • the isolator described with reference to Figure 10 has a very small (yet finite) polarisation dispersion of one wavelength difference between the two polarisation states in the forward direction. This is because one polarisation travels in the fast axis (top and bottom halves) and the other polarisation travels in the slow axis of the half wave plates.
  • the resultant polarisation dispersion is for 1.5 ⁇ m light equal to 5 fs.
  • the bottom half consists for both polarisations of an optical path length equivalent to fast axis + Faraday rotator + slow axis. There is no intrinsic polarisation dispersion.
  • Figure 12 is equivalent to Figure 11 except that the design is entirely balanced again.
  • a simple optical circulator using the beam splitting isolator as the basis may be readily implemented as shown in Figure 19.
  • the light which is rejected in the non-transmission direction is antisymmetric about the axis of the interface and so cannot excite the fundamental mode of a single mode fibre. It can however excite the first higher order mode of a multimode fibre 110 which can have the same symmetry.
  • a fibre which supports this higher order mode and then producing a coupler 115 which couples the higher order mode to a second fibre we can perform the function of a three or four port circulator.
  • Single mode fibres 116 are coupled 114, 115 to multimode fibre 118, 110.
  • Lens 111, 113 and phase shifter 112 form a beam-expanded isolator as described above.
  • Such a coupler can couple light from the correct symmetry higher order mode to the fundamental mode of a single mode fibre, where the propagation coefficients are matched in the coupling region.
  • Either fused or polished coupling techniques can be used. Note that with the crystal interface in the parallel expanded beam, non-optimal excitation of the higher order mode is achieved with the remaining light lost to the system. This can be improved by having the interface where the beam of light is in transition from the near-field to far- field image. This is achieved by focussing the light between the lenses and placing the non reciprocal phase shifting crystals at an appropriate position. Referring to Figure 13, in this implementation a Mach-Zender wave guide is made in integrated optics. These are commercially available.
  • a slot is cut through both arms of the Mach-Zender 113 and the two halves of the non-reciprocal phase shifter 112 are inserted into the slot so that light from one arm passes through one half and light from the second arm passes through the second half.
  • Beam expansion techniques can be used if necessary to reduce the loss due to the non- waveguiding propagation through this region.
  • a magnetic field must be supplied around the Faraday rotator. This device could be combined with other integrated optic devices in a useful fashion, such as combining it with an integrated splitter.
  • Figure 20 illustrates a further Mach-Zender implementation involving two fibres using fused coupler technology.
  • the implementation illustrated insert two fibres 115 into a glass tube 114 of lower refractive index than the fibre cladding index, and taper the tube down in two closely spaced regions 113 to form two 50:50 couplers.
  • the device With the fibres 115 held firmly in place by the surrounding collapsed glass tubing 114, the device can be cut and polished, before the non-reciprocal phase shifting elements 112 are placed between the fibre waveguides.
  • a slot 116 can be used as for the integrated optic implementation shown in Figure 13.
  • This implementation has the potential to provide low loss coupling of the light through the non- reciprocal phase shifter.
  • Beam expansion is achieved through using a tapered region of the fibre, or by core diffusion techniques.
  • a single polarisation fibre embedded isolator has been described in the scientific literature. The application of single polarisation devices is, however, extremely limited.
  • the device shown in Figure 15 provides a polarisation insensitive isolator.
  • Light from a single mode fibre 74 is expanded via lens 73 into an expanded beam.
  • Non-reciprocal phase shifter 112 is formed from a Faraday rotator 76 in one half of beam 75, and a pair of half wave plates 77 in the other half.
  • Lens 71 conveys the light into fibre 72. It will be appreciated that the principle of operation is analogous to the device of Figure 6. These could be potentially made into isolating connectors.
  • Such devices can be either wavelength independent or wavelength selective.
  • Another feature which can be incorporated into a isolator of the split beam type (or a standard isolator for that matter) is filtering using the split beam technique.
  • a non-birefringent reciprocal element for instance a non-birefringent wave plate 117
  • a sinusoidal filtering can be applied. This can be seen in Figure 21.
  • This is particularly useful in amplifier applications to equalise the gain over a certain band width.
  • the interface of the reciprocal filtering element should be orthogonal to the interface of the non-reciprocal phase shifter 112.
  • Two non- reciprocal phase shifters, 112, 122 can be cascaded in the same beam expander by ensuring that the interfaces of the devices are perpendicular to each other. This is shown in Figure 22. Some tuning of the characteristics of the device can also be achieved with small variations from 90 degree relative orientation. Two identical devices can be cascaded to increase the peak isolation and isolation bandwidth of the device, or two devices with slightly different central wavelengths can be cascaded to achieve a broader isolation bandwidth. Peak isolation wavelength tuning
  • a separate tuning mechanism is possible.
  • a small phase shift in half of the Fourier plane i.e. in the expanded beam
  • a lateral displacement in the direction perpendicular to the interface in the image plane is equivalent to a lateral displacement in the direction perpendicular to the interface in the image plane.
  • This tuning mechanism can incur some small losses, but is useful for fine tuning.
  • Figure 17 illustrates a circulator using the principle of the devices described earlier, for instance Figure 6, except that the beam splitting will be done in fibre using an optical coupler.
  • a 90 degree Faraday rotator 88 is embedded in one arm of the Mach-Zender and a 90 degree birefringent rotator 88 in the other arm (or other combinations as described earlier), to form a circulator.
  • a fused silica V-grove 90, 92 is used to align each of the fibres, and a 90 degree Faraday rotator 93 is embedded into one fibre 130 half way along the fused silica and a 90 degree polarisation rotating birefringent plate 94 is embedded into the other fibre 131.
  • the silica V-grooves are then used to make a polished coupler, by continually polishing until 100 percent coupling is achieved in the forward direction. This should correspond to 50% coupling before and after the rotating devices.
  • the device is now identical in operation to that shown in Figure 17, but is extremely compact and resistant to the environment. The device will behave as a circulator and is capable of mass production.
  • FIG 24 illustrates an amplifier arrangement using an isolator according to the present invention .
  • This arrangement is low polarisation dispersive.
  • Pump source 131 and input signal 142 enter wavelength division multiplexer 135, pass through low birefringence erbium doped fibre 132, and enter polarisation dispersion isolator 138 (as described with reference to figures 11 and 12 for example).
  • the signal then passes through low birefringence erbium doped fibre 134, wavelength division multiplexer 136, and is output 143.
  • Pump source 137 drives the erbium fibre amplifier.
  • Figure 25 illustrates a bidirectional amplifier, of the type which enables bidirectional communications down a single fibre, utilising the same amplifiers for both wavelengths.
  • the arrangement is similar to figure 24, but incorporates a bidirectional wavelength dependant isolator 133 (as described, for example, with reference to figure 6).
  • the isolator 133 is positioned between two erbium doped fibre amplifiers 132, 134.
  • signals at ⁇ r are input, and at ⁇ 2 are output.
  • signals at ⁇ 2 are

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Nonlinear Science (AREA)
  • Electromagnetism (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Power Engineering (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)

Abstract

On décrit un déphaseur optique du type à mouvement non alternatif, avec différentes applications. Ce déphaseur optique comprend des dispositifs rotatifs de polarisation (52, 53) dépendants et indépendants de la direction qui sont placés dans des trajectoires optiques parallèles qui sont recombinées de manière à ce que le déphasage relatif du signal de sortie dépende de la direction de propagation. Le dispositif peut être utilisé pour former des isolateurs simples, des isolateurs bidirectionnels dépendants de la longueur d'onde, des circulateurs, et il permet des communications bidirectionnelles par une fibre unique à différentes longueurs d'onde sans sélection de la polarisation. On décrit des utilisations dans le domaine de l'optique générale et dans celui des fibres optiques.
EP93907651A 1992-04-03 1993-04-02 Ameliorations concernant le dephasage optique. Withdrawn EP0634025A4 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
AU1713/92 1992-04-03
AUPL171392 1992-04-03
PCT/AU1993/000146 WO1993020475A1 (fr) 1992-04-03 1993-04-02 Ameliorations concernant le dephasage optique

Publications (2)

Publication Number Publication Date
EP0634025A1 true EP0634025A1 (fr) 1995-01-18
EP0634025A4 EP0634025A4 (fr) 1995-05-17

Family

ID=3776073

Family Applications (1)

Application Number Title Priority Date Filing Date
EP93907651A Withdrawn EP0634025A4 (fr) 1992-04-03 1993-04-02 Ameliorations concernant le dephasage optique.

Country Status (4)

Country Link
EP (1) EP0634025A4 (fr)
JP (1) JPH07508355A (fr)
CA (1) CA2133556A1 (fr)
WO (1) WO1993020475A1 (fr)

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0793130B1 (fr) * 1996-02-28 2002-08-28 Nippon Telegraph And Telephone Corporation Dispositif optique non réciproque insensible à la polarisation
DE19653276A1 (de) * 1996-12-20 1998-06-25 Bosch Gmbh Robert Bidirektionaler optischer Verstärker mit optischem Isolator
JP2000066137A (ja) * 1998-08-19 2000-03-03 Fujitsu Ltd 光アイソレータとして使用可能な光デバイス並びに該光デバイスを含む光増幅器及びシステム
EP1315007A1 (fr) * 2001-11-09 2003-05-28 Corning Incorporated Compensation de la dépendence à la polarisation
DE102010019134B4 (de) 2010-04-30 2019-08-08 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. THz-Messsystem und Sensoranordnungen sowie deren Verwendung
CN104917040B (zh) * 2015-06-08 2018-03-09 湖北航天技术研究院总体设计所 一种环形多波长光纤放大器
CN106019617B (zh) * 2016-07-28 2018-11-06 中国工程物理研究院应用电子学研究所 一种光隔离合束装置

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Publication number Priority date Publication date Assignee Title
US1252512A (en) * 1916-12-12 1918-01-08 Hilger Ltd Adam Method and apparatus for finishing prisms or lenses or combinations of the same.
US4627731A (en) * 1985-09-03 1986-12-09 United Technologies Corporation Common optical path interferometric gauge
JPH0367231A (ja) * 1989-08-07 1991-03-22 Oki Electric Ind Co Ltd 光中継伝送方式
US5033830A (en) * 1989-10-04 1991-07-23 At&T Bell Laboratories Polarization independent optical isolator
NL9100292A (nl) * 1991-02-19 1992-09-16 Nederland Ptt Optisch zend- en ontvangsysteem met optische circulator.

Non-Patent Citations (2)

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Title
No further relevant documents disclosed *
See also references of WO9320475A1 *

Also Published As

Publication number Publication date
JPH07508355A (ja) 1995-09-14
CA2133556A1 (fr) 1993-10-14
WO1993020475A1 (fr) 1993-10-14
EP0634025A4 (fr) 1995-05-17

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