WO2010130281A1 - Optical filter arrangement - Google Patents

Optical filter arrangement Download PDF

Info

Publication number
WO2010130281A1
WO2010130281A1 PCT/EP2009/055678 EP2009055678W WO2010130281A1 WO 2010130281 A1 WO2010130281 A1 WO 2010130281A1 EP 2009055678 W EP2009055678 W EP 2009055678W WO 2010130281 A1 WO2010130281 A1 WO 2010130281A1
Authority
WO
WIPO (PCT)
Prior art keywords
optical filter
polarisation
filter arrangement
narrow band
signal
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.)
Ceased
Application number
PCT/EP2009/055678
Other languages
French (fr)
Inventor
Lutz Rapp
Gernot Goeger
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.)
Nokia Solutions and Networks Oy
Original Assignee
Nokia Siemens Networks Oy
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 Nokia Siemens Networks Oy filed Critical Nokia Siemens Networks Oy
Priority to PCT/EP2009/055678 priority Critical patent/WO2010130281A1/en
Publication of WO2010130281A1 publication Critical patent/WO2010130281A1/en
Anticipated expiration legal-status Critical
Ceased 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 
    • G02F1/03—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 ceramics or electro-optical crystals, e.g. exhibiting Pockels effect or Kerr effect
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/28—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for polarising
    • G02B27/288—Filters employing polarising elements, e.g. Lyot or Solc filters
    • 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
    • G02F1/35—Non-linear optics
    • G02F1/355—Non-linear optics characterised by the materials used
    • G02F1/3558—Poled materials, e.g. with periodic poling; Fabrication of domain inverted structures, e.g. for quasi-phase-matching [QPM]
    • 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
    • G02F2203/00—Function characteristic
    • G02F2203/05—Function characteristic wavelength dependent
    • G02F2203/055—Function characteristic wavelength dependent wavelength filtering
    • 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
    • G02F2203/00—Function characteristic
    • G02F2203/06—Polarisation independent

Definitions

  • the invention refers an optical filter arrangement which is especially suited for compensation of spectral hole burning
  • Optical communication systems employ EDFAs (Erbium Doped Fiber Amplifiers) to amplify optical WDM (Wavelength Division Multiplex) signals.
  • EDFAs Erbium Doped Fiber Amplifiers
  • WDM Widelength Division Multiplex
  • SHB Spectral Hole Burning
  • the EDFA' s gain spectrum does not originate from the transition of one single homogeneously broadened level, but consist of an ensemble of different homogeneously broadened levels. Furthermore, the broadening varies from ion to ion since the energy levels of an ion depend on the environment.
  • the va ⁇ a- tion stems from the amorphous nature of the glass host. Different transitions affect the population probabilities for a metastable level of the ions in a different way.
  • the gain spectrum depends on signal powers which may induce depletion of ions resulting in gain saturation at the corre- sponding signal frequency. Typically, this becomes apparent in a gain reduction around the saturating signal resembling a spectral hole. Therefore, this effect is named "Spectral hole burning" .
  • fix transmission filters are inserted to flatten the gain spectrum across the e.g. C-band for specific operating points.
  • it is de ⁇ sirable to compensate for SHB induced spectral changes dy- namically and adaptively. Then, channel performance, i.e. its signal-to-noise ratio, can be kept with minimum penalty.
  • optical filter arrangement for fast gain spectrum correction.
  • the optical filter should be suited for adaptive compensation of spectral hole burning.
  • An additional object of the invention is to provide a polarisation independent optical filter. The main object is achieved by an optical filter arrangement comprising
  • This filter has an ideal transmission characteristic for the compensation of SHB because only a single wavelength range, e.g. one channel or a wider SHB band, is less attenuated than the remaining broadband/WDM signal. More precisely: This fil ⁇ ter can be designed to equalize SHB-induced gain reduction across one or more spectral bands.
  • the tuning is based on the electro-optic effect, it would have a much faster response than those based on thermal or UV-illummation effects.
  • the rotatable polarization analyzer enables the setting of the ratio between the amplification of the narrow band signal and the broadband signal.
  • FIG 1 shows a transmission characteristic of a known PPLN filter
  • FIG 2 shows a filter arrangement according to the invention
  • FIG 3 shows a transmission characteristic of the inventive filter arrangement.
  • FIG 1 illustrates the transmission characteristic of the PPLN-fliter as described by G. Zheng and W. She and shown in Figure 1 of their article.
  • the transmission wavelength is tuneable and the filter width is suited for a narrow band signal NBS, which bandwidth is marked.
  • a normalized transmis ⁇ sion characteristic, the transmission factor as a function of the wavelength, is shown in FIG 1 for three different tuning values .
  • the amount of a maximum transmission value should be tune ⁇ able, the ratio of a narrow transmission band and the broad- band should be settable, and the filter should be polarisation independent because the channels (more exact the optical signals) of received WDM signals have general different po ⁇ larisations .
  • Fig 2 shows the inventive filter arrangement.
  • the narrow band PPLN periodic poled LiNbO 3
  • Sole-filter described by G.
  • a polarisation adjuster 2-6 is inserted which sets the polarization state of arbitrarily polarized incident light along a z-axis.
  • a broadband signal e.g. a WDM (wavelength division multiplex) signal WMS, is fed to a polarisation beam splitter 2 and divided into vertical components ZC and horizontal polarized components ZY.
  • the z-polarized components ZC are transmitted along the x-axis whereas the perpendicularly polarized components YC are rotated after a first mirror 3 in a lambda-half plate 4 by ⁇ /2 into the z-direction and reflected by a second mir ⁇ ror 5.
  • Different optical elements like Faraday rotators, twisted fibers, optically active elements and free-space rotation etc. can be applied for the rotation of the polarization. Both components are then recombmed in a beam combiner 6 and optical signals having the same linear polarization are output marked as WMSP.
  • the polarisation configuration has to be stabilized interferometrically .
  • the filter stack 7 is traversed by linear pola ⁇ rized optical signals.
  • z-polarized light propagating along the x-axis is incident on a stack of periodically alternated poled LiNbO3 crystal layers (or other birefringent crystals) .
  • the thicknesses of the layers and the length of the LLPN filter stack 7 determine the transmission characteristics.
  • the transmission width depends on the number of layers and is chosen for a narrow band signal e.g. accord- ing to the channel width of a WDM signal. The width might be chosen to equal the bandwidth of a SHB band, i.e. a few nm.
  • a first variable DC control voltage U 2 applied to first elec ⁇ trodes 71, 72 allows adjustment of the spectral position of maximum intensity of the narrow band signal NSB.
  • a second variable DC control voltage Uy applied to second electrodes 73, 74 allows adjustment of the amplitude of the narrow band signal.
  • the fraction of z- parallel and perpendicular components is set.
  • Applying the second control voltage U y along the y-axis causes a rotation of refractive index ellipsoids in the layers around the x- axis.
  • the polarization of a spectral component is rotated.
  • the vertical polarized input beam is converted into a horizontal polarized output beam which can pass a horizontal aligned polarization analyzer with minimum loss of intensity. Therefore U y allows setting the maximum transmission value of the narrow band signal.
  • the first control voltage applied along the z-axis has no in ⁇ fluence on the orientation of the index ellipsoids but on the amount of refractive index difference between alternating poled LiNbO3 layers.
  • an adjustable polarization analyzer 8 is arranged downstream of the filter stack 7. By rotation of the polari- zation analyzer 8 the ratio of the narrow-band signal compared to the broadband transmitted spectrum is set.
  • FIG 3 illustrates examples of the transmission characteristic.
  • the wavelength ⁇ 0 of the narrowband transmission width (solid line) of the Sole-filter device 7,8 is varied by U z (dashed line) and in addition the transmission values are varied by U ⁇ (dotted line) while the position of the pola ⁇ - zation analyzer 8 remains.
  • the polarization analyzer 8 is rotated by ⁇ /2 the transmission characteristic is inversed.
  • the polarization analyzer 8 may also be controlled automatically; in some cases it might be sufficient to set it manu- ally.
  • the narrow band transmission wavelength and the transmission factor are always controlled electronically so that a compensated WDM signal WMSC is output at output 9 comprising optical signals with almost the same intensity.
  • a measurement and control unit (not shown) is nec ⁇ essary to measure the intensity of the channels and to sec the filter control voltages.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Nonlinear Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Ceramic Engineering (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Optical Communication System (AREA)

Abstract

A periodically poled LiNo3 filter device (7,8) has a first pair of electrodes (71, 72) to control the transmission range and a second pair of electrodes (73, 74) to control the amplitude of a transmitted narrow band signal (NBS). A rotatable polarisation analyser (8) determines the ratio of the narrow band signal (NBS) and the broadband signal (WMS). Further a polarisation adjuster (2-6) at the input of the filter arrangement converts received signals into signals having the same linear polarisation.

Description

OPTICAL FILTER ARRANGEMENT
FIELD OF THE INVENTION
The invention refers an optical filter arrangement which is especially suited for compensation of spectral hole burning,
BACKGROUND OF THE INVENTION
Optical communication systems employ EDFAs (Erbium Doped Fiber Amplifiers) to amplify optical WDM (Wavelength Division Multiplex) signals. The communication systems are becoming more reconfigurable which leads to more variations of the in¬ put signal load. At the same time the amplifier should provide constant gain of all individual channels.
But, due to spectroscopy of the erbium doped fiber, namely to the Spectral Hole Burning (SHB) effect, the gain spectrum of the EDFA depends on the input load. SHB results in a decrease of gain for individual channels.
The EDFA' s gain spectrum does not originate from the transition of one single homogeneously broadened level, but consist of an ensemble of different homogeneously broadened levels. Furthermore, the broadening varies from ion to ion since the energy levels of an ion depend on the environment. The vaπa- tion stems from the amorphous nature of the glass host. Different transitions affect the population probabilities for a metastable level of the ions in a different way. Thus the gain spectrum depends on signal powers which may induce depletion of ions resulting in gain saturation at the corre- sponding signal frequency. Typically, this becomes apparent in a gain reduction around the saturating signal resembling a spectral hole. Therefore, this effect is named "Spectral hole burning" .
In commercial EDFAs, fix transmission filters are inserted to flatten the gain spectrum across the e.g. C-band for specific operating points. To assure a gain spectrum with minimum gain ripple for a wider range of operating conditions, it is de¬ sirable to compensate for SHB induced spectral changes dy- namically and adaptively. Then, channel performance, i.e. its signal-to-noise ratio, can be kept with minimum penalty.
M. Bolshtyansky and G. Cowle, describe in "Spectral hole burning compensation in Raman/EDF hybrid amplifier", JWA15, OFC/NFOEC 2008 the SHB problems and suggests a solution by adjusting a Dynamic Gain Equalizer.
G. Zheng and W. She describe in ,,Fast and wide-range continuously tunable Sole-type filter based on periodically poled LiNbO3", Appl. Phys . B, vol. 88, no. 4, 545-549 (2007) a fil¬ ter formed by applying a biased DC (direct current) electric field along the y-axis, and the tuning of a transmitted central wavelength is realized by applying another DC electric field along the z-axis.
OBJECTS AND SUMMERY OF THE INVENTION
It is an object of the invention to provide an optical filter arrangement for fast gain spectrum correction. The optical filter should be suited for adaptive compensation of spectral hole burning. An additional object of the invention is to provide a polarisation independent optical filter. The main object is achieved by an optical filter arrangement comprising
- a periodically poled Lithiumniobat filter stack,
- first electrodes controlled by a first control voltage de- termining the wavelength of a transmitted narrow band signal, and
- second electrodes controlled by a second control voltage (UY) determining the amplitude of the transmitted narrow band signal, and - a rotatable polarization analyzer arranged downstream the filter stack determining the ratio of the narrow band signal.
This filter has an ideal transmission characteristic for the compensation of SHB because only a single wavelength range, e.g. one channel or a wider SHB band, is less attenuated than the remaining broadband/WDM signal. More precisely: This fil¬ ter can be designed to equalize SHB-induced gain reduction across one or more spectral bands.
Since the tuning is based on the electro-optic effect, it would have a much faster response than those based on thermal or UV-illummation effects.
The rotatable polarization analyzer enables the setting of the ratio between the amplification of the narrow band signal and the broadband signal.
It is advantageously when the arrangement further comprises
- a polarization beam splitter splitting a received signal into a fist component and a perpendicular component,
- means for rotating one of these components by π/2, and
- a beam combiner adding both components and outputting signals having the same aligned polarization, which are inserted into the filter stack. Further advantageous features are described in the pending claims .
BRIEF DESCRIPTION OF THE DRAWINGS
An example of a presently preferred embodiment is described below with reference to accompanying drawing, where
FIG 1 shows a transmission characteristic of a known PPLN filter,
FIG 2 shows a filter arrangement according to the invention, and FIG 3 shows a transmission characteristic of the inventive filter arrangement.
DETAILED DESCRIPTION OF THE INVENTION
FIG 1 illustrates the transmission characteristic of the PPLN-fliter as described by G. Zheng and W. She and shown in Figure 1 of their article. The transmission wavelength is tuneable and the filter width is suited for a narrow band signal NBS, which bandwidth is marked. A normalized transmis¬ sion characteristic, the transmission factor as a function of the wavelength, is shown in FIG 1 for three different tuning values .
A plurality of problems arises when this filter has to be adapted for compensation of spectral hole burning.
The amount of a maximum transmission value should be tune¬ able, the ratio of a narrow transmission band and the broad- band should be settable, and the filter should be polarisation independent because the channels (more exact the optical signals) of received WDM signals have general different po¬ larisations .
Fig 2 shows the inventive filter arrangement. The narrow band PPLN (periodic poled LiNbO3) Sole-filter described by G.
Zheng and W. She is extended in the following way to allow usage as a polarization independent broadband tuneable optical filter: At an input 1 of the filter arrangement a polarisation adjuster 2-6 is inserted which sets the polarization state of arbitrarily polarized incident light along a z-axis. At the input 1 a broadband signal, e.g. a WDM (wavelength division multiplex) signal WMS, is fed to a polarisation beam splitter 2 and divided into vertical components ZC and horizontal polarized components ZY. After the polarization beam splitter the z-polarized components ZC are transmitted along the x-axis whereas the perpendicularly polarized components YC are rotated after a first mirror 3 in a lambda-half plate 4 by π/2 into the z-direction and reflected by a second mir¬ ror 5. Different optical elements like Faraday rotators, twisted fibers, optically active elements and free-space rotation etc. can be applied for the rotation of the polarization. Both components are then recombmed in a beam combiner 6 and optical signals having the same linear polarization are output marked as WMSP. The polarisation configuration has to be stabilized interferometrically .
Subsequently the filter stack 7 is traversed by linear pola¬ rized optical signals. When using this setup, z-polarized light propagating along the x-axis is incident on a stack of periodically alternated poled LiNbO3 crystal layers (or other birefringent crystals) . The thicknesses of the layers and the length of the LLPN filter stack 7 determine the transmission characteristics. The transmission width depends on the number of layers and is chosen for a narrow band signal e.g. accord- ing to the channel width of a WDM signal. The width might be chosen to equal the bandwidth of a SHB band, i.e. a few nm. A first variable DC control voltage U2 applied to first elec¬ trodes 71, 72 allows adjustment of the spectral position of maximum intensity of the narrow band signal NSB.
A second variable DC control voltage Uy applied to second electrodes 73, 74 allows adjustment of the amplitude of the narrow band signal. By means of the second control voltage Uy applied to second electrodes 73, 74 the fraction of z- parallel and perpendicular components is set. Applying the second control voltage Uy along the y-axis causes a rotation of refractive index ellipsoids in the layers around the x- axis. Depending on the refractive index difference between a y-polarized and a z-polarized beam and on the thickness of the respective poled LiNbCG layers the polarization of a spectral component is rotated.
If rotated by π/2, the vertical polarized input beam is converted into a horizontal polarized output beam which can pass a horizontal aligned polarization analyzer with minimum loss of intensity. Therefore Uy allows setting the maximum transmission value of the narrow band signal.
The first control voltage applied along the z-axis has no in¬ fluence on the orientation of the index ellipsoids but on the amount of refractive index difference between alternating poled LiNbO3 layers.
In addition an adjustable polarization analyzer 8 is arranged downstream of the filter stack 7. By rotation of the polari- zation analyzer 8 the ratio of the narrow-band signal compared to the broadband transmitted spectrum is set.
FIG 3 illustrates examples of the transmission characteristic. According to different tunings of the Sole-filter device 7,8 the wavelength λ0 of the narrowband transmission width (solid line) of the Sole-filter device 7,8 is varied by Uz (dashed line) and in addition the transmission values are varied by Uγ (dotted line) while the position of the polaπ- zation analyzer 8 remains. If the polarization analyzer 8 is rotated by π/2 the transmission characteristic is inversed. The polarization analyzer 8 may also be controlled automatically; in some cases it might be sufficient to set it manu- ally. The narrow band transmission wavelength and the transmission factor are always controlled electronically so that a compensated WDM signal WMSC is output at output 9 comprising optical signals with almost the same intensity.
Of course a measurement and control unit (not shown) is nec¬ essary to measure the intensity of the channels and to sec the filter control voltages.
The present invention is not limited to the details of the above described principles. The scope of the invention is defined by the appended claims and all changes and modifications falling within the equivalents of the scope of the claims are therefore to be embraced by the invention.
REFERENCE SIGNS and ABBRIVATIONS
1 input
2-6 polarisation adjuster
2 polarisation beam splitter
3 mirror
4 λ/2-plate
5 second coupler
6 beam combiner
7 filter stack
8 polarisation analyzer
7,8 Sole-filter device
9 output
WMS received WDM signal
WMSP linear polarised WMS signal
WMSC compensated WDM signal
ZC z-component
YC y-component uz first control voltage second control voltage

Claims

1. Optical filter arrangement comprising - a periodically poled birefπngent crystal, preferable Li- thiumniobat, filter stack (7) ,
- first electrodes (71, 72) controlled by a first control voltage (Uz) determining the wavelength (λ0) of a transmitted narrow band signal (NBS) , and - second electrodes (71, 72) controlled by a second control voltage (Uγ) determining the amplitude of the a transmitted narrow band signal (NBS) , and
- a rotatable polarization analyzer (8) arranged downstream the filter stack (7) determining the ratio of the narrow band signal (NBS) and the broadband signal (WMS) .
2. The optical filter arrangement according to claim 1, further comprising a polarisation adjuster (2-6) arranged upstream of the filter stack (7) outputting signals (WMSP) with the same linear polarisation.
3. The optical filter arrangement according to claim 2, further comprising a polarisation adjuster (2-6)
- a polarization beam splitter (2) splitting a received sig- nal into a fist component (ZC) and a perpendicular component
(YC) ,
- means for rotating one of these components (ZC, ZY) by π/2, and
- a beam combiner (6) adding both components and outputting signals with a same aligned polarization, which are inserted into the filter stack (7) .
4. The optical filter arrangement according to claim 3, comprising a λ/2 plate for polarisation rotation.
5. The optical filter arrangement according to one of the claims 1-4, being adapted for compensation of spectral hole burning of a received wavelength division multiplex signal (WMS) .
PCT/EP2009/055678 2009-05-11 2009-05-11 Optical filter arrangement Ceased WO2010130281A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/EP2009/055678 WO2010130281A1 (en) 2009-05-11 2009-05-11 Optical filter arrangement

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/EP2009/055678 WO2010130281A1 (en) 2009-05-11 2009-05-11 Optical filter arrangement

Publications (1)

Publication Number Publication Date
WO2010130281A1 true WO2010130281A1 (en) 2010-11-18

Family

ID=41050473

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP2009/055678 Ceased WO2010130281A1 (en) 2009-05-11 2009-05-11 Optical filter arrangement

Country Status (1)

Country Link
WO (1) WO2010130281A1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2019133623A1 (en) * 2017-12-28 2019-07-04 Tetravue, Inc. Wide field of view electro-optic modulator and methods and systems of manufacturing and using same

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4678287A (en) * 1985-11-04 1987-07-07 Gte Laboratories Incorporated Methods of and apparatus for tuning a birefringent optical filter
US20040165808A1 (en) * 2003-02-20 2004-08-26 Institut National D'optique Optical repolarizing devices

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4678287A (en) * 1985-11-04 1987-07-07 Gte Laboratories Incorporated Methods of and apparatus for tuning a birefringent optical filter
US20040165808A1 (en) * 2003-02-20 2004-08-26 Institut National D'optique Optical repolarizing devices

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
GUOLIANG ZHENG ET AL: "Wave coupling theory of quasi-phase-matched linear electro-optic effect", OPTICS EXPRESS, OSA (OPTICAL SOCIETY OF AMERICA), WASHINGTON DC, (US), vol. 14, no. 12, 1 June 2006 (2006-06-01), pages 5535 - 5540, XP009123747, ISSN: 1094-4087 *
ZHENG G ET AL: "Fast and wide-range continuously tunable Solc-type filter based on periodically poled LiNbO3", APPLIED PHYSICS B ; LASERS AND OPTICS, SPRINGER, BERLIN, DE, vol. 88, no. 4, 7 July 2007 (2007-07-07), pages 545 - 549, XP019540573, ISSN: 1432-0649 *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2019133623A1 (en) * 2017-12-28 2019-07-04 Tetravue, Inc. Wide field of view electro-optic modulator and methods and systems of manufacturing and using same
US10437082B2 (en) 2017-12-28 2019-10-08 Tetravue, Inc. Wide field of view electro-optic modulator and methods and systems of manufacturing and using same

Similar Documents

Publication Publication Date Title
US6429962B1 (en) Dynamic gain equalizer for optical amplifiers
CN103443701B (en) Optical parameter amplifier, optical amplifying system, wavelength converter, optical amplification method, and optical communication system
US6646789B2 (en) Single parameter gain slope adjuster for an optical system
EP1072937B1 (en) Optical filter
US20080296481A1 (en) Chirp measurement method, chirp measurement apparatus and their application
US6268954B1 (en) Method and system for controlling the slope of an output response
Muridan et al. Effect of polarization adjustment towards the performance of SOA-based multiwavelength fiber laser
Li et al. Switchable multi-wavelength thulium-doped fiber laser using a cascaded or two-segment Sagnac loop filter
US6760149B2 (en) Compensation of polarization dependent loss
US7620274B2 (en) Optical protection switch and method for optical protection switching
EP2185968B1 (en) An optical filter
Jazayerifar et al. Impact of SBS on polarization-insensitive single-pump optical parametric amplifiers based on a diversity loop scheme
US6614572B2 (en) Apparatus and method for controlling optical gain profiles in a temperature independent manner
EP1410100B1 (en) Fiber optical gain equalizer
Lu et al. A liquid crystal-based Fourier optical spectrum analyzer
Cai et al. Equalization of nonuniform EDFA gain using a fiber-loop mirror
Takasaka et al. Polarization insensitive arbitrary wavelength conversion in entire C-band using a PM-HNLF
JP2001318354A (en) Gain equalizer, and optical amplifier and WDM optical transmission system using the same
US6747774B2 (en) Apparatus and method for controlling optical gain profiles
Sulaiman et al. Effect of PMF length to channel spacing tunability by temperature in multiwavelength fiber laser
Wang et al. A tunable Lyot birefringent filter with variable channel spacing and wavelength using nonlinear polarization rotation in an SOA
CN1322690C (en) A method of polarization mode dispersion compensation
Westbrook et al. Application of self-phase modulation and optical filtering to measurement of residual chromatic dispersion
Mimura et al. PMD compensator and PMD emulator
Mack et al. Polarization insensitive wavelength conversion by FWM of multiformat DWDM signals using birefringent PCF

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 09779442

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 09779442

Country of ref document: EP

Kind code of ref document: A1