CN1406342A - Circularly polarized fiber in optical circuits - Google Patents

Circularly polarized fiber in optical circuits Download PDF

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Publication number
CN1406342A
CN1406342A CN 99810833 CN99810833A CN1406342A CN 1406342 A CN1406342 A CN 1406342A CN 99810833 CN99810833 CN 99810833 CN 99810833 A CN99810833 A CN 99810833A CN 1406342 A CN1406342 A CN 1406342A
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China
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light
optical fiber
circular polarisation
fiber
signal
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M·N·伊斯兰
D·A·诺兰
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Corning Co Ltd And Michigan University School Affairs Committee
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Corning Co Ltd And Michigan University School Affairs Committee
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    • 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
    • H04B10/2507—Arrangements specific to fibre transmission for the reduction or elimination of distortion or dispersion
    • H04B10/2543—Arrangements specific to fibre transmission for the reduction or elimination of distortion or dispersion due to fibre non-linearities, e.g. Kerr effect
    • 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
    • G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
    • G02B6/105—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type having optical polarisation effects
    • 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
    • H04B10/50—Transmitters
    • H04B10/516—Details of coding or modulation
    • H04B10/532—Polarisation modulation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J14/00—Optical multiplex systems
    • H04J14/02—Wavelength-division multiplex systems
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J14/00—Optical multiplex systems
    • H04J14/06—Polarisation multiplex systems

Abstract

The invention is directed to circularly polarized single mode waveguide fiber and to high data rate, multiplexed transmission systems that employ this fiber. The circularly polarized waveguide fiber attenuates the non-linear effects present in such high performance transmission links. In particular, self phase modulation is attenuated by more than 30 % and four wave mixing is essentially eliminated. This latter effect occurs because four wave mixing does not occur when a multiplexed link is made of a plurality of circularly polarized waveguide fibers which are arranged so that adjacent fibers have opposite circular polarization. The circularly polarized fiber enhances the non-linear effect of cross phase modulation, a feature that can be used in optical switching components associated with the transmission link. In addition, the strength of the XPM in CPF is independent of the relative polarization states of the signal and control pulses.

Description

Circular polarisation optical fiber in the light path
The related application of cross-reference
Have the U.S. Provisional Application No.60/100757 of application on September 17th, 1998 and the U.S. Provisional Application No.60/101282 of application on September 22nd, 1998 in the protection that the application requires.
Background of invention
1. Invention field
The present invention relates generally to use the system of optical fiber and Optical fiber component, be specifically related to comprise the system of circular polarisation waveguide fiber.
2. Technical background
The non-linear effects lightwave transmission system of light is divided into two classes usually.The 1st class is the stimulated scattering phenomenon, for example, is excited Brillouin scattering and stimulated Raman Scattering.They produce reciprocation between phonon in light signal and transferring material.The scattering type that the decision of phonon frequency occurs.In the 2nd class, nonlinear refractive index produces 3 effects, that is, and and from phase modulation (PM) (SPM), cross-phase modulation (XPM) and 4 wave mixings (4WN).According to long research apart from multi-wavelength system, find the 2nd quasi-nonlinear reciprocation to wavelength-division multiplex system (WDM), particularly to having the system of the electronics regenerative repeater that separates more than about 50km, maximum harm is arranged.The 2nd quasi-nonlinear effect is the application's a theme.
In SPM, nonlinear factor depends on pulse strength, and the pulse more than the threshold intensity is produced phase modulation (PM).This threshold intensity depends on material therefor in the waveguide generally in the 10mW magnitude.One of SPM consequence is their a spectral width broadening gradually when signal pulse is propagated in optical fiber.Because of being operated near the zero-dispersion wavelength of waveguide,, the spectrum of signal can not reduce system performance so widening.If there are enough group velocity dispersions, the spectrum of SPM is widened and can be caused temporarily widening of paired pulses so.In addition, at interval dense wdm system, if spectrum widens into and is enough to make the spectrum that adds bandwidth signals to appear at adjacent channel these channels to be overlapped, then crosstalk can occur.
In wdm system, Strength Changes can have influence on other channel by XPM in certain channel.In the linear polarization optical fiber, the XPM coefficient of expression influence size approximately is the twice of SPM coefficient, XPM depends on a kind of like this waveguide length, interpulse generation reciprocation on this length, so that interchannel arrives interactive length because of interval (dissociating) variable effect that group velocity dispersion takes place, thereby has influence on the size of XPM.In sufficiently long system, the group velocity of various channels can cause occurring passing through of interchannel.Thereby, under lossless state, got rid of the spectrum that XPM causes in fact and widened.
4 wave mixings also can produce nonlinear refractive index, and are different with SPM and XPM, and 4WM has the phase matching requirement.For the signal of two different wave lengths, the intensity modulated of beat frequency meeting refraction index modulation in the waveguide, thus on the different frequency of two signals, produce phase modulation (PM).As a result, in 4WM, be created in the sideband frequency (sideband of lower frequency is called Stokes (Stokes) frequency, and the sideband of upper frequency is called anti-Stokes frequency) of plus-minus difference frequency on the primary frequency.The refractive index or the speed of two signal wavelengths must be consistent with the refractive index or the speed of Stokes and anti-Stokes ripple in other words in the phase matching requirement.Therefore, 4WM depends primarily on total chromatic dispersion.The total dispersion height, the propagation speed differential of different frequency will be big, and the effect of 4WM is just little.Have near signal wavelength in the optical fiber of zero-dispersion wavelength, near consistent, the 4WM process is extremely effective aspect refractive index and speed for all light waves.In wdm system, 4WM has two damaging effects.The 1st is the power attenuation that enters mixed product from signal wavelength.The 2nd is in the signaling channel that equates to separate, and Stokes is consistent with existing channel with anti-Stokes frequency, causes crosstalk.This mixed product is long mutually or disturb these existing channels mutually with disappearing, and this depends on the relevant phase place of signal.
Therefore, in high performance transmitting system, need a kind of system configuration that comprises the particular type optical waveguide fiber, this optical fiber makes work near zero-dispersion wavelength, thereby, make linear dispersion deterioration minimum, but this system has still limited nonlinear interaction, particularly 4WM.
Relational term
Following term definition is general in this area.
Quarter-wave delayer (QWR): linear polarization light is transformed to circularly polarized light, and vice versa.In order to act on the best, during linear polarization light incident QWR, with its 45 ° of right side or left sides of inciding the fast axle of QWR (fast axis) of polaxis.
Half wavelength retarder (HWR): the polarised direction of linear polarization light is revolved turn 90 degrees.In order to act on the best, during linear polarization light incident HWR, with its 45 ° of right side or left sides of inciding the fast axle of HWR (fast axis) of polaxis.HWR is transformed to the circularly polarized light (LHC) that is rotated counterclockwise with the circularly polarized light (RHC) that turns clockwise, and vice versa.
Therefore, in the input and output of CPF QWR being set is using among the application of CPF all linear polarization light to be applied.
Optical fiber QWR and HWR: in optical fiber, constitute by this optical fiber pack being built up also mutual relative these rings of rotation of many rings.33 have roughly shown a kind of optical fiber HWR among Fig. 7.The birefringence of rotating this optical fiber generation provides phase delay between two field vectors of this auroral poles state of definition on the mathematics.
The present invention's general introduction
One aspect of the present invention provides a kind of circular polarisation single-mode fiber (CPF).This CPF has little birefringence at least and in fact along the axial scroll of CPF length.This axial spiral pitch is less than the beat length among the CPF, makes among the CPF circular polarization effects greater than linear polarization effects.Beat length is the fiber lengths that repeats between given polarized state.
Be called CPF and be because its keeps with circular polarisation state propagation circularly polarized light, suppose that polarization type is complementary in the transmit direction of this light and the optical fiber.The emission of this requirement is all set in the application's front and back.CPF keeps the circular polarisation (clockwise or anti-clockwise circularly polarized light) of the circularly polarized light of injecting CPF.
In the embodiment of CPF, birefringence is equivalent to Δ n and is about 10 -5, Δ n is refractive index poor of two orthogonal polarization axles in the waveguide fiber.One of several method that utilizes known technology can be made optical fiber has birefringenct property.For example, fuse can be made the xsect ellipse, or fuse is applied non-homogeneous radial stress.
In another CPF embodiment, added helical is a right-hand pitch on a part of optical fiber, is left-handed pitch on another part.
On the other hand, the invention provides the optical transmission chain that a kind of high data rate multiplex system is used.This link uses CPF, is used for suppressing the nonlinear effect of using the high power signals system to occur, or uses the multi-wavelength channel.This transmission link is formed by a plurality of CPF of mutual optically-coupled.1CPF in the link couples light to the multi-wavelength transmitter module, and last CPF in the link couples light to the multi-wavelength receiver module.Alternate channel is changed pitch from dextrorotation to the left-handed rotation, can eliminate 4 wave mixings, i.e. nonlinear effect effectively.In multiplex system, this nonlinear effect can be brought the crosstalk of signal power loss and interchannel.
In an embodiment of transmission link, one or more image intensifers couple light to link to keep the signal noise ratio that needs.Transmission link can use part or distribute light amplifier, and they separate with proper spacing.
The transmitter that the present invention relates to or the embodiment of the required configuration of receiver module are discussed below.
In another embodiment of the present invention, but specific photoswitch or the delay circuit of transmission link adjunction.These circuit can for transmission link in several good configurations routing by or tandem signal.Especially, be described in detail in below and use the cross-phase modulation in the non-linear ring of light mirror (NOLM), or in polarization control system (PCS), use the coupling mechanism of polarization sensitive.The feature of these circuit is to use CPF in control signal and the interactive circuit part of light signal at least.This CPF has improved the reciprocation of two interpulse cross-phase modulation, makes to use lower gating pulse power or short interaction lengths of fiber.Use the advantage of CPF to be in the light member that uses XPM, XPM is irrelevant with the relative polarized state (comprising circular polarisation or linear polarization) of reciprocation signal.According to the launching condition that discloses above, the signal that is transmitted into CPF should be the eigenmodes that CPF supports, obtains polarization and the irrelevant benefit of XPM.
In detailed description subsequently, other features and advantages of the present invention will be described, Partial Feature and advantage are for those of skill in the art, can be apparent from described description, or comprise that by following description subsequently detailed description, claims and accompanying drawing put into practice when of the present invention, can recognize.
Should see, no matter be top general introduction or following detailed description, all be example of the present invention, total a kind of viewpoint or framework is provided, is used to understand the feature of requirement of the present invention.Accompanying drawing is used for further understanding the present invention, and the part of combined this instructions of formation.Accompanying drawing diagram shows and is used from principle of the present invention and the work of illustrating with instructions one by various embodiment of the present invention.
Summary of drawings
Fig. 1 is a general diagrammatic sketch of using the multichannel transmission link of CPF.
Fig. 2 and Fig. 3 are the general diagrammatic sketch of the optional structure of transmitter module.
Fig. 4,5 and 6 is general diagrammatic sketch of the optional structure of receiver module.
Fig. 7 is a general diagrammatic sketch of using the NOLM switch of CPF.
Fig. 8 is a general diagrammatic sketch of using the polarization coupled switch of CPF.
Fig. 9 is the general diagrammatic sketch of the experimental circuit used of the NOLM switch of Test Application CPF.
Figure 10 and 11 is curve maps of helical optical fiber and non-helical Experiments in Fibre Optical comparative result.
Figure 12 is the curve of the pitch of helical among the relative CPF of polarization sensitivity.
Detailed description of the present invention
Below, describing preferred embodiment of the present invention in detail, accompanying drawing illustrates each example.Situation whatsoever, to identical or similar portions, described accompanying drawing adopts identical label.Fig. 1 illustrates the exemplary embodiments of CPF circuit of the present invention.In this embodiment, multi-wavelength transmitter module 2 is transmitted into wavelength-division multiplex (WDM) signal pulse the 1st length of circular polarisation optical fiber 4.(be applicable to the wavelength division multiplexer of WDM network and demultiplexer device at present with the wave length grating router, the Littrow grating, or Fabry-Perot or Mach-Zehnder interferometer are the basis.) move by after this 1CPF length 4, amplify the WDM pulses by optional image intensifer 6, be sent to the 2nd length of CPF8.This WDM pulse continues by length C PF4 and CPF8 alternately, and both are optional by image intensifer 6 separately, until arriving multi-wavelength receiver module 10, produce the WDM demultiplexing at this, and signal allocation is given target ground.
The light path of Fig. 1 can comprise CPF, and near signal wavelength, this CPF has zero-dispersion wavelength λ 0, can not produce the loss of signal because of 4WM.Use CPF to reduce the SPM chromatic dispersion.This light path can be operated in non-return to zero system, return-to zero system, or orphan's transformat.
In one embodiment of this invention, transmitter module comprises the laser instrument of N shown in 12 among Fig. 2.These laser instruments are to N port emission line polarized light of WDM device 14.Between laser instrument and WDM14, be inserted with HWR18, change 90 ° in linear polarization direction every a passage 16.This polarization keeps by WDM14, and when making by QWR20, signal is transmitted into CPF with mutually despun polarization in the adjacent channel, and 4WM deterioration minimum.Though between adjacent channel, can not have 4WM, between alternate channel, may still have some 4WM.Yet, because the reciprocation wavelength channel separates far, so phase matching and reciprocation length obtain weak point.For the reciprocation of interchannel is little, but the channel density compromise selection.
Fig. 3 illustrates another transmitter module embodiment.In this embodiment, N laser instrument 12 is circularly polarized light through a plurality of QWR 22 with the linear polarization laser beam transformation, and connects the port of WDM14.Because the fast axis of another QWR is with respect to the half-twist of adjacent QWR, so the circular polarisation direction of signal is opposite in the adjacent channel.The result is that multi-wavelength signals is transmitted in fact and CPF link identical shown in Fig. 2.If wavelength coverage is wide, then use the have advantage of Fig. 3 scheme than Fig. 2.The bandwidth of QWR among Fig. 2 is not enough to launch all wavelengths.The real advantage of Fig. 2 and Fig. 3 two schemes is that QWR also provides isolation between transmitter (for example, laser diode) and the reflection that comes of optical fiber components thereafter.
QWR and HWR can be a large amount of tabula rasa as known in the art or other device.But QWR comprises the optical fiber that forms mutual relative swivel eye with HWR in the preferred embodiment.This fiber device is easy to be combined in the light path, and reflection and absorption loss minimum.
Fig. 4,5 and 6 roughly illustrates alternative receiver module embodiment.In Fig. 4 embodiment, light last CPF24 from link enters WDM demultiplexer 14.The demultiplexer signal is through waveguide 16 connecting band bandpass filters 26.Wave filter is delivered to each corresponding receiver 28 with one of N signal.
Fig. 5 embodiment uses the receiver 28 of polarization sensitive, further improves signal to noise ratio (S/N ratio).Circularly polarized light passed through QWR20 before entering WDM demultiplexer 14.Thus, circularly polarized signal is transformed to the linear polarization signal.At 28 of the receivers of wave filter 26 and polarization sensitive HWR18 is set every a passage.This HWR makes the polaxis half-twist, makes adjacent channel that the linear polarization of quadrature be arranged.
Use QWR in the optical channel of the receiver module of Fig. 6 between the receiver 28 of wave filter 26 and polarization sensitive.The mutually relative half-twist of the fast axis of QWR in the adjacency channel.So alternately the signal of receiver reception has opposite circular polarisation, thereby the channel crosstalk that has further reduced between receiver is disturbed.
Mentioned when transmitter module embodiment is discussed, the receiver module structure of Fig. 5 and Fig. 6 has the advantage that isolation is provided between transmission line and receiver.
Fig. 7 roughly illustrates the switching member that uses NOLM.All optical fiber structures of NOLM and the transmission link compatibility of Fig. 1.Basically at any position along the conveying link, NOLM can be used to switch selected wavelength.
NOLM is made of 4 port orientations coupling mechanisms 30, and wherein, the two-port 32 of a side connects fiber optic loop 34.NOLM plays interferometer, this interferometer have with around ring two corresponding arms of two-phase anti-spread direction.This structure is very stable because of two arms all comprise accurately identical light path.
When coupling mechanism with input signal 36 timesharing such as grade, NOLM is equivalent to a desirable catoptron.Go up the control signal 38 of quadrature by being increased in frequency or polarization, make NOLM be equivalent to 3 end switch.Particularly, utilize coupling mechanism 38 that control signal 38 is coupled to NOLM and in the direction of NOLM, propagating.Control signal 38 utilizes non-linear XPM that the input signal 36 that moves in this direction is carried out phase shift.Therefore, when gating pulse and signal pulse homophase incided coupling mechanism, NOLM produced an output.This output produces maximum π phase shift by XPM.This output square becomes with the trigonometric function of angle of phase displacement.By using CPF44 to increase the effect of NOLM at least a portion of gating pulse and signal pulse reciprocation ring.As discussed above XPM is enhanced in CPF like that, and the corresponding polarity of each reciprocation signal is irrelevant among this enhancing and the CPF.Therefore, ring length can amplitude shorter or gating pulse can be littler.
Fig. 8 illustrate with Fig. 1 in another embodiment of transmission link compatible switch.Linear polarization pulse 36 becomes circular polarisation by QWR20 before injecting CPF4.CPF keeps polarization, so that 2QWR20 is transformed to it linear polarization pulse before pulse 38 enters polarization sensitive coupling mechanism 46.Coupling mechanism 46 transmits a polarization components of this linear polarization signal pulse 36 and Coupling Control pulse 38.Two pulses are transformed to the circular polarisation pulse by the QWR20 that is positioned at coupling mechanism 46 optical path downstream.Signal and gating pulse produce reciprocation by the XPM in the coupling mechanism 46 downstream CPF length 4.The circular polarisation direction of signal and gating pulse can be selected on the contrary, makes that just the QWR before polarization sensitive wave filter 48 is the linear polarization pulse of polaxis quadrature with two signal transformations.Then, polarization sensitive wave filter 48 is selected, allowed signal pulse pass through and gating pulse is reflected.Fig. 8 side view shows the reciprocation of XPM, has wherein shown output signal pulses 50 on time shaft 52.The reciprocation of XPM is enough to signal pulse 50 is shifted out specific clock window, therefore, can in digital display circuit 1 bit be become 0 bit.
The CPF waveguide can be made with one of known several method.For example, can be 09/117,280 with reference to the U.S. application number, (application artificial " Hawk "), all be attached among the application by it is quoted, this application has proposed the method for a kind of CPF of manufacturing substantially, promptly begins design production from preform and has appropriate birefringent optical fiber.In drawing operation, by preform or the twisting of optical fiber own are made helical.For example, the major axis of drawing machine around optical fiber rotated back and forth and optical fiber can be made helical, fiber axis is introduced sinusoidal twisting.In order to allow circular birefringence surpass linear birefringence, pitch must be done shortlyer than the beat length of optical fiber.
Has appropriate its Δ of birefringent optical fiber n ≌ 10 -5, Δ n is the refringence between fast axle and slow axis.Da Xiao birefringence is easy to generate like this, for example, can obtain by core slightly being made ellipse or optical fiber being applied radial stress heterogeneous.
The example of the NOLM switch of combination helical optical fiber
Use the predetermined action of CPF in NOLM switch testing optical communication circuit shown in Figure 9 and the device.The signal pulse 38 of 1535nm is by the emission of 50/50 coupling mechanism, around encircling mirror reversal to propagation.Utilize polarization sensitive coupling mechanism 40 with gating pulse polarization and be transmitted in the ring, the polarization sensitive coupling mechanism 40 by the downstream extracts again.This extracting method is the most useful to be because signal does not influence the XPM reciprocation with the relative polarized state of gating pulse.Control and signal pulse are to be undertaken interactive by the XPM in the top of waveguide fiber lengths 54 contained rings.By measuring intensity, measure the effect of this switch through the 1535nm of NOLM switching output pulse.Regulate with Fig. 7 discussed above in 33 roughly the same folded fiber polarization controllers 56 make signal output maximum.
Use helical and non-helical to experimentize as fiber lengths 54, its result is presented in the curve map of Figure 10.The situation that output signal strength became with the polarization of input signal 38 when curve 58 showed fiber lengths 54 coiled helicals, switch was irrelevant with polarization basically when its showed optical fiber coiled helical.On the gamut that polarization from 0 to 200 degree changes, visual intensity changes has only 0.6dB.When fiber lengths 54 not during coiled helical optical fiber, output intensity is followed curve 60 among Figure 10.On the gamut that polarization from 0 to 200 degree changes, the signal output intensity variation is about 5dB.Use CPF to make the size of NOLM effect improve an order of magnitude.Multiplication among the irrelevant and CPF of this polarization and XPM can be applicable to optical transmission chain and with the light path of this link association.
The centigrade of the nonlinear transport that the curve of Figure 11 provides the input signal polarized state when changing by helical and non-helical optical fiber.Top and bottom at curve show polarized state, and arrow is represented the linear polarization signal up and down, and a left side and right hand ring are represented two types of circular polarisation.Curve 62 shows that CPF has 8 circle helical/m, and the variation of transmitting for all polarized state nonlinear properties is about 0.05%.Curve 64 is measured under input signal polarized state identical change for non-helical optical fiber among Figure 11, and what record is changed to about 0.3%.This shows, compare that CPF is improving an order of magnitude to amplitude aspect the polarization insensitivity with non-helical optical fiber.
Empirical curve Figure 12 shows that with solid side's point 66 the polarization insensitivity depends on the situation of every meter axial helical number of turn.By and large, helical rate (twist rate) can obtain good result greater than 6/ meter.
CPF is except having the advanced aspect non-linear phenomena, and also has many favourable linear features, and they have important practicality.At first, the CPF that is wrapped is very convenient, and this is because it can prevent numerous external disturbances.For example, the experience that optical fiber is made cable shows with linear birefringence to be compared, and the disturbance that CPF introduces is little.Be restricted as under situation about sealing for a short time in the space, this feature can be used in the light path.Secondly, people such as Jeunhomme are at " electronics wall bulletin " (Electron.Lett.16,921,1980) show that CPF can engage and can not introduce mode coupling between the polarization type in " Polarization-maintaining single-mode cable design (polarization keeps the single mode fiber cable the design) " literary composition in.Particularly, linear birefringent fiber requires the birefringence axis of contained two optical fiber of joint accurately consistent, to keep high polarization extinction ratio.The cross-couplings and the overlap integral between required polarized state of Incoming optical fiber and the unwanted polarized state of out optical fiber that engage the knot place are proportional.For CPF, regardless of two optical fiber directions, the cross-couplings of joint is always zero, and this is because the overlap integral between right and left circularly polarized light is always zero.Therefore, polarization is kept transmission line and can be made up of various CPF sections, and need be in the joint to fiber orientation.
In sum, the following describes the advantage of CPF in transmission link and relative photo member.Two wavelength light signals solve by the most handy CPF of general considerations that the nonlinear refractive index reciprocation produces, and wherein, a kind of ripple applies phase shift to another ripple.Non-linear interaction and wave polarization input state are irrelevant, this be since XPM at the parallel or identical (XPM of two wave polarizations #) under the situation with the input state of two wave polarizations vertical or quadrature (XPM mutually ) identical under the situation.
In addition, be interferometer if use the device of non-linear interaction, two light beams by each arm of interferometer must terminate in identical polarized state so, realize interfering at output coupler or beam separator.Usually, use polarization controller (PC) can satisfy above-mentioned situation to one or two light beam.But, use a plurality of PC just not all right, because they need periodic adjustment to come compensate for ambient to change.Keep identical polarized state if guarantee two arms of interferometer with CPF, then can a plurality of PC.
Use circular polarisation waveguide fiber (CPF) to show with linear polarization optical fiber and compare, the SPM effect has reduced about 1/3.There is not 4WM between the rightabout light wave (left side and right hand circular polarisation).In fact, there is not non-linear 4WM signal with the emission of reverse direction circular polarisation.Owing to this reason, do not have 4WM so be operated in zero-dispersion wavelength.
Because CPF is a kind of polarization-maintaining fiber (polarization maintaining optical fibre), so polarization mode dispersion (PMD:poiarizationmode dispersion) also reduces.
Use its XPM effect of the relative linear birefringence optical fiber of CPF to increase about 1 times.The enhancing of XPM is very valuable in switchgear, but can produce crosstalk in the WDM transmission link.Yet, channel is suitably separated, that is, according to the XPM chromatic dispersion channel is arranged to mutually and passes through fully, can make the harmful XPM minimum in this link.
The example that can more effectively utilize CPF to make switch has non-linear ring of light mirror or optical soliton towing and optical soliton to subside logic grating (soliton-dragging and soliton-trapping logic gates).Because these switches utilize XPM to carry out signaling transfer point, thereby the switching of using CPF to provide in these devices compares with using linear polarization optical fiber, and the switching energy reduces half or waveguide fiber lengths shortens half.
CPF is one of technical key that can reach Ya Pijiao switching energy, and this switching energy is all photoswitch needs in the high performance system.
Obviously, those of skill in the art can make various modifications and variations to the present invention under the situation that does not break away from spirit scope of the present invention.Therefore, the present invention includes the interior modifications and variations of appended claims and its equivalent scope.

Claims (20)

1. circular polarisation monomode optical waveguide optical fiber comprises:
By encompasses and the core district that contacts with this covering, wherein, core district and covering have index distribution separately, are used for direct light, and,
Wherein,
Circular polarisation single mode waveguide optical fiber has birefringence and along the axial scroll of its length, it is characterized in that, beat length is greater than the axial pitch of helical.
2. single mode waveguide optical fiber as claimed in claim 1 is characterized in that, wherein, birefraction is expressed as the refractive indices n between fast axis and slow axes, and this Δ n is about 10 -5
3. single mode waveguide optical fiber as claimed in claim 1 is characterized in that, wherein, the xsect in core district for ellipse so that birefringence to be provided.
4. single mode waveguide optical fiber as claimed in claim 1 is characterized in that, wherein, the core district is applied asymmetric radial stress so that birefringence to be provided.
5. single mode waveguide optical fiber as claimed in claim 1 is characterized in that, wherein, axially the pitch of helical changes to left-handed with the length of preliminary election at interval along waveguide fiber from dextrorotation.
One kind the transmission multiplexed light signal optical transmission chain, comprise:
Have beat length and along the 1st circular polarisation monomode optical waveguide optical fiber of the axial helical of its length distribution, wherein, axially the pitch ratio beat length of helical is short, this pitch is along fiber lengths dextrorotation or left-handed;
Transmitter module produces light signal, with the 1st circular polarisation waveguide fiber optically-coupled a plurality of light signals is injected this circular polarisation waveguide fiber, and wherein, each light signal has unique wavelength;
Some additional circular polarisation monomode optical waveguide optical fiber, the end-to-end in regular turn optically-coupled from an additional optical fiber to another additional optical fiber, one of these additional circular polarisation optical fiber couple light to the 1st circular polarisation waveguide fiber, wherein, additional circular polarisation waveguide fiber have separately beat length and along they axial pitches of length separately, wherein, axially the pitch ratio beat length of helical is short in each additional optical fiber, and each pitch is along fiber lengths dextrorotation or left-handed;
Receiver module receives a plurality of light signals, couples light to circular polarisation waveguide fiber last in the additional optical fiber series, and wherein, wavelength is separately separately according to them for signal.
7. optical transmission chain as claimed in claim 6 is characterized in that, further comprises at least one image intensifer that inserts and be optically coupled between two circular polarisation waveguide fibers.
8. optical transmission chain as claimed in claim 6 is characterized in that, further comprises at least one image intensifer that inserts in regular turn and be optically coupled between every pair of circular polarisation waveguide fiber.
9. optical transmission chain as claimed in claim 6 is characterized in that, wherein,
Transmitter module comprises: N light source, each light source have linear polarization and unique wavelength so that N signaling channel to be provided,
WDM with N input port and at least one output port,
N corresponding light source light is coupled to N the N root optical fiber that the WDM input port is corresponding one,
N/2 half wavelength retarder, each connect respectively couple light in N the channel every one, make adjacent wavelength-channels have each with the linear polarization of other channel quadrature and
Be coupled to the optical transmission chain the 1st circular polarisation waveguide fiber so that the linear polarization signal of each channel is varied to the photo-coupler of circular polarisation by quarter wave plate from least one WDM output port.
10. optical transmission chain as claimed in claim 6 is characterized in that, wherein,
Transmitter module comprises: N light source, and each light source has unique wavelength,
Have N input port and at least one output port WDM and
N corresponding light source light is coupled to N the N root optical fiber that the WDM input port is corresponding one,
N quarter-wave delayer, each is connected respectively and couples light in the N root optical fiber corresponding one, wherein
In the adjacent signals wavelength channel the fast axle quadrature of quarter-wave delayer and
Be coupled to the photo-coupler of the 1st circular polarisation waveguide fiber the optical transmission chain from least one WDM output port.
11. optical transmission chain as claimed in claim 6 is characterized in that, wherein,
Receiver module comprises: have the WDM demultiplexer of at least one an input port and N output port, wherein, described at least one port couples light to circular polarisation optical fiber last in the circular polarisation optical fiber series,
The 1st group of N root waveguide fiber has the 1st end and the 2nd end, and each the 1st end of N root waveguide fiber couples light to of correspondence of N output port in the WDM demultiplexer respectively,
N wave filter, each transmits in N the signal wavelength corresponding one, couples light to of correspondence in N the waveguide fiber,
N receiver, receive respectively in N the signal separately one and
The 2nd group of N waveguide fiber, be coupling in respectively in N the wave filter corresponding one with N receiver between corresponding one.
12. optical transmission chain as claimed in claim 11 is characterized in that, wherein, the receiver in the described receiver module is a polarization sensitive, and this receiver module further comprises:
Quarter-wave delayer, series connection be optically coupled in the WDM demultiplexer at least one with circular polarisation optical fiber series at last between the circular polarisation optical fiber so that with circularly polarized light signal transformation be the linear polarization light signal and
N/2 half wavelength retarder, each is connected respectively and couples light in the 2nd group of N root optical fiber correspondingly on one, makes adjacent wavelength-channels center line polarized signal quadrature.
13. optical transmission chain as claimed in claim 11 is characterized in that, wherein, the receiver in the described receiver module is a polarization sensitive, and this receiver module further comprises:
N quarter-wave delayer, each is connected respectively and couples light to one of the 2nd group of correspondence in the N root optical fiber, and wherein, the fast axle of quarter-wave delayer is directed in the adjacent wavelength-channels, makes the circular polarisation direction of adjacent channel signal opposite.
14. the photoswitch that uses in the described transmission link of claim 6 is characterized in that, comprises:
One or more smooth phase-shift circuits couple light to circular polarisation waveguide fiber in the transmission link, and transmitting signal correspondence in the transmission link one or more are carried out phase shift, wherein,
Control signal utilizes the cross-phase modulation to change the light signal phase place, and
This cross-phase modulation occurs on the length of circular polarisation waveguide fiber.
15. photoswitch as claimed in claim 14, it is characterized in that, wherein, phase-shift circuit further is included in and propagates before control signal and the light signal device that described control signal and light signal is applied circular polarisation in the circular polarisation waveguide fiber lengths that the cross-phase modulation takes place.
16. photoswitch as claimed in claim 14 is characterized in that, wherein, phase-shift circuit further comprises the device that light signal is passed through and reflect or absorb control signal.
17., it is characterized in that wherein, phase-shift circuit comprises the non-linear ring of light mirror that has circular polarisation optical fiber as claim 15 or 16 described photoswitches, the cross-phase modulation take place at least a portion of this ring.
18. photoswitch as claimed in claim 17 is characterized in that, wherein, the 1st polarization sensitive WDM coupling mechanism is used for gating pulse is inserted non-linear ring of light mirror, and the 2nd polarization sensitive WDM coupling mechanism is used for extracting gating pulse from non-linear ring of light mirror.
19. as claim 15 or 16 described photoswitches, it is characterized in that wherein, phase-shift circuit comprises,
Propagate gating pulse and control the gating pulse link of its polarized state,
Signal pulse is coupled to the polarization sensitive coupling mechanism of gating pulse link,
Take place on the circular polarisation waveguide fiber cross-phase modulation reciprocation length and
Couple light to the polarization sensitive wave filter that circular polarisation optical fiber reciprocation length end is used to transmit signal pulse and reflection gating pulse.
20. photoswitch as claimed in claim 14 is characterized in that, wherein, the polarized state among the light signal CPF is at random with respect to the polarized state among the gating pulse CPF.
CN 99810833 1998-09-17 1999-09-07 Circularly polarized fiber in optical circuits Pending CN1406342A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113196692A (en) * 2018-12-29 2021-07-30 华为技术有限公司 Optical transmission apparatus and method

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1356333A2 (en) * 2000-12-28 2003-10-29 PIRELLI S.p.A. Method for producing an optical fibre telecommunications cable with reduced polarization mode dispersion
EP1463966A4 (en) * 2001-12-06 2005-08-10 Chiral Photonics Inc Chiral in-fiber adjustable polarizer apparatus and method
JP2005173530A (en) 2003-11-17 2005-06-30 Osaka Industrial Promotion Organization Light signal processing method and device, nonlinear optical loop mirror and its design method, and light signal conversion method
WO2005100274A1 (en) * 2004-04-07 2005-10-27 Fujikura Ltd. Process for producing optical fiber and optical fiber
US8111957B2 (en) * 2008-07-10 2012-02-07 Corning Incorporated +cylindrical polarization beams
CN106169950B (en) * 2016-07-21 2023-08-18 西南大学 Long-distance laser chaos synchronous device based on all optical fibers
TW202235938A (en) * 2020-11-13 2022-09-16 美商爾雅實驗室公司 Mitigation of polarization impairments in optical fiber link

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2515693B1 (en) * 1981-11-03 1985-10-11 Thomson Csf METHOD FOR MANUFACTURING AN OBJECT HAVING A CHIRAL STRUCTURE ARISING FROM A SOURCE OF FORMABLE MATERIAL AND DEVICE USING THE SAME
US4515436A (en) * 1983-02-04 1985-05-07 At&T Bell Laboratories Single-mode single-polarization optical fiber
US5298047A (en) * 1992-08-03 1994-03-29 At&T Bell Laboratories Method of making a fiber having low polarization mode dispersion due to a permanent spin
EP0635739B1 (en) * 1993-07-21 2000-03-22 AT&T Corp. Improved fiber loop mirror for time division demultiplexing
US5452394A (en) * 1994-02-24 1995-09-19 Huang; Hung-Chia Practical circular-polarization maintaining optical fiber
US5587791A (en) * 1994-09-27 1996-12-24 Citeq Optical interferometric current sensor and method using a single mode birefringent waveguide and a pseudo-depolarizer for measuring electrical current

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113196692A (en) * 2018-12-29 2021-07-30 华为技术有限公司 Optical transmission apparatus and method
CN113196692B (en) * 2018-12-29 2022-11-25 华为技术有限公司 Optical transmission apparatus and method

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