CN104375355A

CN104375355A - Fiber-amplifiers with all-fiber optical isolator

Info

Publication number: CN104375355A
Application number: CN201410185257.9A
Authority: CN
Inventors: 蒋仕彬
Original assignee: Advalue Photonics Inc
Current assignee: Advalue Photonics Inc
Priority date: 2013-08-12
Filing date: 2014-05-05
Publication date: 2015-02-25

Abstract

Fiber-amplifier device the light-path of which is devoid of a free-space element. The system device an all-fiber-optic Faraday rotator and isolator. The device has a multicomponent glass optical fiber having a core having a first doping concentration of 55%-85% (wt./wt.) of a first rare-earth oxide and a the isolator includes at least three magnetic cells with throughout bores hosting an optical fiber, the same magnetic poles of two immediately neighboring cells facing each other. The first rare-earth oxide includes one or more of Pr2O3, Nd2O3, Pm2O3, Sm2O3, Eu2O3, Gd2O3, Tb2O3, Dy2O3, Ho2O3, Er2O3, Tm2O3, Yb2O3, La2O3, Ga2O3, Ce2O3, and Lu2O3.

Description

There is the fiber amplifier of Full optical fiber optical isolator

The cross reference of related application

The application is the U.S. Patent application No.13/708 being entitled as " Faraday Rotator andIsolator ", being disclosed as 2013/0129272 submitted on Dec 7th, 2012, the part of 787 continues, submit on June 29th, 2011, be entitled as " All Fiber Optical Isolator ", be disclosed as the continuation of the part of the U.S. Patent application 13/172,623 of 2013/0129272; And be that on May 12nd, 2010 is that submit, to be entitled as " Highly Rare-Earth Doped Fiber Array " be United States Patent (USP) 8 now, the part of the U.S. Patent application 12/778,712 of 374,468 continues; That be entitled as " the Highly Rare Earth Doped Fiber " submitted on Dec 1st, 2009 authorizes 12/628,914 parts of the U.S. Patent application for United States Patent (USP) 8,346,029 to continue.The application requires right of priority and the rights and interests of above application based on 35U.S.C. § 120.Disclosing in order to whole object is combined in here by reference of each above-mentioned application.

Technical field

The present invention relates generally to the fiber amplifier adopting Full optical fiber optical isolator, and is specifically related to the Faraday rotator based on optical fiber, more specifically, relates to high-power fiber amplifier system.

Summary of the invention

The embodiment provides optical fiber (FO) amplifier, it has input and output and comprises: at least one first optical fiber, and the light that the material composition of the first optical fiber is selected as making to pass from it can be exaggerated.In one embodiment, fiber amplifier comprises at least one pump laser source.

Embodiments of the invention also comprise (i) at least one Full optical fiber optical isolator, and it adopts second optical fiber with at least Part I, Part II and Part III separated from one another.The Part I of the second optical fiber is relevant to Faraday rotation with Part III and have the fibre core of 55% (wt./wt.) to first doping content of 85% (wt./wt.) of the first rare earth oxide separately.Embodiment also comprises at least three magnet units, and each magnet unit all has the hollow bulb (such as, axial hole) passed from it.The same pole that this magnet unit of more than three is disposed in order the unit for making direct neighbor is facing with each other.The described Part I of the second optical fiber and described Part III are arranged in the axial hollow bulb of the first magnet unit and the 3rd magnet unit separated by the second magnet unit.

The light path of the FO device between input and output limited by embodiment does not have freeboard region, makes this device can be all optical fibre structure thus.In one embodiment, the fiber optic component of the direct neighbor of embodiment is joined together by fusion.In a particular embodiment, second optical fiber of FO device comprises multicomponent glass optical fiber, and the first rare earth oxide selects from the group that following composition is formed: Pr2O3, Nd2O3, Pm2O3, Sm2O3, Eu2O3, Gd2O3, Tb2O3, Dy2O3, Ho2O3, Er2O3, Tm2O3, Yb2O3, La2O3, Ga2O3, Ce2O3 and Lu2O3.Second optical fiber has covering, this covering has second doping content of the 55%-85% (wt./wt.) of the second rare earth oxide alternatively, wherein, the second rare earth oxide is such as following at least one: Pr2O3, Nd2O3, Pm2O3, Sm2O3, Eu2O3, Gd2O3, Tb2O3, Dy2O3, Ho2O3, Er2O3, Tm2O3, Yb2O3, La2O3, Ga2O3, Ce2O3 and Lu2O3.The refractive index of covering is lower than the refractive index of fibre core.

Accompanying drawing explanation

When referring to the figures, by the following specific descriptions provided, embodiments of the present invention will become apparent, and key element similar is in the accompanying drawings represented by similar Reference numeral.

Fig. 1 is the schematic diagram of embodiment of the present disclosure.

Fig. 2 shows the figure of the free space embodiment of optical fiber pigtail Faraday rotation unit;

Fig. 3 shows the embodiment of All-fibre isolator device;

Fig. 4 is the figure of the transmission spectrum mixing terbium glass;

Fig. 5 schematically shows optional embodiment of the present invention;

Fig. 6 schematically shows another alternative embodiment of the invention;

Fig. 7 is the sectional view of the exemplary high rare-earth doped optical fibre for embodiments of the invention;

Fig. 8, Fig. 9, Figure 10, Figure 11 and Figure 12 show each subsystem of embodiments of the invention;

Figure 13 schematically illustrates another subsystem of embodiments of the invention;

Figure 14 and Figure 15 shows polarization maintaining fiber beam splitter/combiner;

Figure 16 depicts the stereographic map of an alternative embodiment of the invention of the beam splitter/combiner utilizing Figure 14 and Figure 15;

Figure 17 A and Figure 17 B schematically shows an alternative embodiment of the invention;

Figure 18 A, Figure 18 B and Figure 18 C schematically show the possible magnetic pole orientation of magnet unit of the present invention;

Figure 18 D schematically shows the cross section for the heavy magnet unit of the present invention;

Figure 19 A and Figure 19 B is the schematic diagram according to Faraday rotator of the present invention;

Figure 20 is the schematic diagram according to faraday isolator of the present invention.

Embodiment

The embodiment provides the fiber laser and fiber amplifier system that adopt All-fibre isolator, can operate under the output power level higher than the average power level of about 100W, wherein the average power level of about 100W is the limit of the fiber laser of traditional structure and the performance of fiber amplifier system (adopting the fibre optic isolater based on Faraday rotator of build).In order to the object of following discloses and claims, term " significantly more than " refer to the power level limiting fiber laser or fiber amplifier and exceed 100W average power, or alternatively or additionally, there is the output power of the peak power exceeding 5kW.As a comparison, the fiber laser of prior art and/or the output average power level of power amplifier are substantially limited to and are less than 50W.When level higher than 50W of the output power of the fiber amplifier (or fiber ring laser system) of prior art, the system of prior art does not use optical fiber pigtail isolator at its output terminal, instead, use large and operate insecure Free Space Optics isolator (for the following reason indirectly mentioned and explain).In some particular cases, the device of prior art does not use optical isolator under the output average power level exceeding about 50W.When in this case, the operation of laser instrument is very easily subject to the impact of bulk of optical feedback.Particularly, retroreflection may damage fiber amplifier/laser instrument, and therefore the operation of fiber laser (and/or fiber amplifier) becomes and is not easy.

In nearest 10 years, the service advantages of the solid-state free space laser instrument used relative to tradition due to it based on the laser instrument of optical fiber and amplifier and attracted a large amount of attention.By means of producing in the fibre core of optical fiber and propagating, the light produced by fiber laser and/amplifier can by using flexible fiberoptic elements easily long-distance communications.Fiber laser and amplifier can be encapsulated as little floor area compactly, because optical fiber can be bent and coil to save space.If necessary, the optical fiber for this object can be strict single-mode fiber, to guarantee the diffraction limited quality of output beam.Fiber laser shows high stability of operation under vibration and non-maintaining one-stop operation.

Light can directly produce in fiber laser cavity, and can be used directly afterwards or be amplified by least one fiber amplifier further.Fig. 1 shows typical fiber ring laser system 100, it comprises the fiber optic component 104 (gain fibre providing optical gain, it is shown as loop 104A here), this fiber optic component 104 is passed through at least one Fiber Bragg Grating FBG (FBG) 106 by pump laser 110 pumping.Pump laser source 110 is used to the active ions excited in the medium of gain fibre 104.Gain fibre 104 further with at least one FBG126 optical coupled of second group.Generally speaking, FBG106 and 126 forms fiber laser cavity 128.The different fiber assembly of embodiment 100 is engaged (being denoted as tie point 130) by fusion usually.Close to the FBG106 of pump laser 110 as high reflectance reverberator, and FBG126 is configured to operate as fiber laser output coupler.Pump laser 110 can be directly coupled to fiber laser cavity 128, or can be coupled in fiber laser cavity by pump combiner unit (not shown) alternatively, the object of pump combiner unit the pump light coming from more than one pump laser source can be coupled in fiber laser cavity simultaneously.Come from the light 136 of fiber laser cavity 128 at the fibre optic isolater 140 usually passing tail optical fiber in the path exported.Isolator 140 (alternatively) is used to stop that any light feeds back, due to puppet and/or parasitism reflection and produce or any bulk of optical feedback of turning back to fiber laser cavity 128, this bulk of optical feedback may make the fluctuation of service of fiber laser and even can damage pump laser 110 in some extreme environments.

The current free space embodiment 200 being used in the faraday isolator unit 140 of optical fiber pigtail of the prior art is shown in Figure 2.The operation of embodiment 200 is that polarization is correlated with, and this embodiment comprises the Faraday rotation apparatus be interposed between two optical polarizators.Embodiment 200 adopts free space build faraday rotator arrangements 204 (comprise produce the unit 204a in magnetic field by it and be appropriately selected to produce the material 104b with Verdet constants (Verdet constant)) as shown in the figure and has respectively by the input and output linear polarization 208 and 212 (being expressed as the forward-propagating direction of reference light, z-axis) of the respective axis of homology shown in arrow 208a, 212a.

The part 216 with the linear polarization parallel with vector 208A of input light 118 is being coupled to rotator arrangements 204 through collimation lens 214 and input polarization device 208 after being collimated.The polarization vector of light 216 is rotated usual 45 degree by Faraday rotator 204, and will export light 222 towards output polarizer (being also called analyzer) 212 transmission.Light 222 to have with the composition of the polarization of axis of homology 212A conllinear in the output of polarizer 212 as light 224 outgoing, on the fiber optic component (not shown) after this light 224 is converged to further by lens 228.In the opposite direction (namely, along-z direction) any light beam of transmitting, such as, back reflected laser, second time through Faraday rotator 204 time rotated in addition 45 (45) degree, thus from spinner 204 with the polarization vector outgoing orthogonal with the axis of homology 208A of polarizer 208.Therefore, polarizer 108 stops back reflected laser.When the polarization vector exporting light 220 is aligned to parallel with axis of homology 208A, and when axis of homology 212A is aligned to parallel with the polarization vector through rotating of light 222 (it is from Faraday rotator 204 outgoing), the decay of light when propagating through faraday isolator 200 is minimized, and the optics isolation of feedback is optimised.Usually, Faraday rotator (such as Faraday rotation apparatus 204) comprises terbium gallium garnet (TGG) crystal or mixes terbium glass.Terbium gallium garnet (TGG) has your moral of most higher-dimension of-40rad/Tm at 1064nm

When laser beam 224 is focused onto fiber end face, if the power of laser beam is higher, optical fiber may sustain damage due to mispairing or due to the change of the aligning caused by working temperature or vibration.Therefore, the output power of usual optical fiber pigtail isolator is limited to about 20W average power.Therefore, the fiber laser of optical fiber pigtail isolator and the output power of fiber amplifier is used also to be limited to the average power of about 20W.But, need much higher output power for comprising scientific research, intermediate application, military affairs and the various application such as defence application and materials processing.

The embodiment provides a kind of fiber laser and fiber amplifier system, its use All-fibre isolator with can exceed 100W average power level or be greater than about 5kW peak power output power level under carry out work.

Turn to Fig. 3 now, show the embodiment 300 of All-fibre isolator device.Propagate across along z-axis the order that device 300 runs into according to light, embodiment 300 comprises the first polarizer 302 based on optical fiber, Faraday rotator based on optical fiber 306 and second based on the polarizer 310 of optical fiber, and Faraday rotator 306 has the optical fiber component 306B be arranged in magnet unit 306A (being such as configured as tubulose).The end of optical fiber component 306B is joined to the corresponding end (being schematically connected 320A and 320B by optical fiber fusion to illustrate) of polarizer 302 and 310 by fusion, thereby produce a kind of device based on all-fiber, it does not relate to the element in free-space light propagation region from the input end of embodiment 300 to output terminal.Because device avoids free space element, so do not relate to light by free space coupling to optical fiber from the output that is input to of device.Therefore, compared to the device adopting optical fiber pigtail isolator, this device has much higher laser induced damage threshold.Output power can be in the level of the average power of kilowtt for each optical fiber.When whole fiber optic components is joined together by fusion, laser induced damage mainly will be included in the damage of the optical fiber in some optical fiber and hot effect of bringing out.For the optical fiber of about 20 micron core diameter, under optical fiber damage occurs in the average power level of about 5kW or higher.Propagation loss for Faraday rotation fiber optic component of the present invention is more much higher than the propagation loss of usual commercial commercially available silicon optical fiber.Based on the absorption of the laser power in Faraday rotation fiber optic component, estimate that damage threshold is higher than 1kW.This adopts the combination of the passage of multiple optical fiber or fiber laser (amplifier) to distinguish to the contrast beyong contemplation of the device realizing this high merit output power level with some of prior art.

The optical fiber component 306B be used in Faraday rotator 306 has been doped rare earth oxide, such as Pr ₂o ₃, Nd ₂o ₃, Pm ₂o ₃, Sm ₂o ₃, Eu ₂o ₃, Gd ₂o ₃, Tb ₂o ₃, Dy ₂o ₃, Ho ₂o ₃, Er ₂o ₃, Tm ₂o ₃, Yb ₂o ₃, La ₂o ₃, Ga ₂o ₃, Ce ₂o ₃and Lu ₂o ₃in at least one.In a particular embodiment, assembly 306B can comprise and mixes terbium glass.Fig. 4 shows the Tb doped with 55 massfractions ₂o ₃the transmitted spectrum of glass, although it illustrates Tb ₂o ₃show Verdet constant the highest in the Verdet constant corresponding with rare earth oxide, but absorb light in the SPECTRAL REGION of this material also near 1.5 microns and 2 microns.

With further reference to Fig. 3, in one embodiment, the material being used in the optical fiber component 306B in Faraday rotator 306 has been doped La ₂o ₃, Ga ₂o ₃, Yb ₂o ₃and Ce ₂o ₃in at least one.The embodiment of Faraday rotator use to work under the wavelength of the fiber laser of high power levels work preferably near 1.5 microns or 2 microns.

With further reference to Fig. 3, in another related embodiment, optical fiber component 306B comprises multicomponent glass.Particularly, the fibre core of this multicomponent glass optical fiber 306B and/or covering can comprise such as silicate glass, germanate glass, phosphate glass, borate glass, tellurate glass, bismuth glass and/or aluminate glass.Additionally or alternatively, the multicomponent glass of optical fiber component 306 can comprise glass network formers, intermediate agent and correctives.In a particular embodiment, the network structure of glass comprises the atom that obviously can change the particular type of the characteristic of glass.Kation as network adjustment agent, thus can destroy the continuity of network, or as contributing to the forming agent forming network.Network former has the quantivalency being more than or equal to three, and is not more than the coordination number of four.Network intermediate agent has the quantivalency lower than network former and higher coordination number.In a particular embodiment, one or more glass network formers of the multicomponent glass of the optical fiber component 306B of Fig. 3 comprise SiO ₂, GeO ₂, P ₂o ₅, B ₂o ₃, TeO ₂, Bi ₂o ₃and Al ₂o ₃. at least one.

Prior art does not openly adopt this All-fibre isolator and produces fiber laser or the fiber amplifier system of kilowtt levels of transmission power output.This may be that it corresponds to low Verdet constant because the fiber optic component doped with rare earth material has the doping content of the even lower order of magnitude of several mass percent usually.Such as, the silex glass that 2% (wt. (quality)) is adulterated has the Verdet constant of about 1rad/T.m.Before the rotation of the linear polarization vector of the light guided by this optical fiber component arrives 45 degree, adopt the Faraday rotation apparatus of this optical fiber component optical fiber component will be needed extremely long, with one meter for the order of magnitude.Therefore, realize the size of the magnet unit needed for performance of this spinner and weight will become on cost and in operation and make us hanging back.Compared with prior art, present invention employs the optical fiber component of the rare earth material doped with the obvious increase level being greater than 55% (wt.).In a particular embodiment, doping content is greater than 65% (wt.).In other embodiments, doping content is greater than 70% (wt.).In certain embodiments, doping content is between 55%-85% (wt.).These highly doped levels ensure that the Verdet constant of produced about 30rad/T.m contributes to manufacturing the Faraday rotator based on optical fiber of the 5cm order of magnitude.

Embodiments of the invention have employed single mode doped with (one or more) rare earth material or multimode optical fiber, are used for structure optical fiber faraday rotor element.In one embodiment, the Faraday rotator based on optical fiber is fused the polarizer (hereinafter referred to as being fibre optic polarizer) joined to based on optical fiber, to form All-fibre isolator system.As known in the art, fusion is bonded to and helps use thermal treatment to be combined by two end-to-end conllinear of optical fiber component, make through the first optical fiber component light when not through free space and optical loss is minimum (that is, engage position scattering and reflection optimised) enter the second assembly.In a particular embodiment, the power stage of Faraday rotator element is greater than 100 watts.In addition, embodiments of the invention have employed complete optical fiber polarization element, it is when combined all-fiber Faraday rotator embodiment uses, and provides structure and is determined to be in kilowtt or the full-optical-fiber laser of novelty more worked under high power levels or amplifier system.

The light output of fiber laser can be strengthened by fiber amplifier.Fig. 5 schematically show with All-fibre isolator 510 (such as, the isolator 300 of such as Fig. 3) and the juxtaposed typical fiber amplifier 500 of output of pump combiner (allowing the light output such as coming from more than one pump laser source merged, as optical fiber tail 520A, 520B schematically show).Fig. 6 shows the related embodiment of fiber amplifier 600 with two paired All-fibre isolator 610A, 610B.

Pump laser can be single-mode laser or multimode laser.Pumping can be the pumping simultaneously of forward pumping, backward pump or forward and backward.In many cases, remaining pump power must use high refractive index adhesives material to remove.(as will be understood by the skilled person in the art, when multimode laser and multimode pump laser, while propagating in fibre core at gain fibre of the light of fiber laser, the light of pump laser is also propagated in its covering.Low refractive index polymer material or air as extramural cladding material so that the light of pump laser is guided in covering.When the material of more high index of refraction is applied on gain fibre, for the light of pump laser, covering no longer can as waveguide, and therefore the light of pump laser leaks out from optical fiber.) for fiber amplifier, usual needs at the optical isolator (such as isolator 510,610A) of the input end of gain fibre 104, to guarantee the good optical fractionation (unless seed laser combines the output optical isolator unit of himself) between fiber amplifier and seed laser.Owing to using All-fibre isolator, input (seed) laser instrument may have high-average power or high-peak power.In many cases, input isolator and output both isolators (see Fig. 6) are all used, to guarantee not having to be fed to the retroreflection getting back to amplifier.

In order to realize higher output power, multi-stage fiber amplifier can be used.

Table 1

Composition	SiO ₂	Al ₂O ₃	B ₂O ₃	CeO ₂	Tb ₂O ₃
						wt％	9.9	0.9	7.4	0.1	72.7

						Composition	SiO ₂	Al ₂O ₃	B ₂O ₃	CeO ₂	Tb ₂O ₃
wt％	13.3	13.9	10.7	0	62.2

Composition	SiO ₂	Al ₂O ₃	B ₂O ₃	CeO ₂	Tb ₂O ₃
						wt％	12.2	13.3	10	0	64.5

						Composition	SiO ₂	Al ₂O ₃	B ₂O ₃	CeO ₂	Yb ₂O ₃
wt％	14.8	16.5	10.3	0.1	58.3

Composition	SiO ₂	Al ₂O ₃	B ₂O ₃	CeO ₂	Er ₂O ₃
						wt％	15.1	16.8	10.5	0.1	57.6

						Composition	SiO ₂	Al ₂O ₃	B ₂O ₃	CeO ₂	Yb ₂O ₃
wt％	16	17.8	11.1	0.1	55

Table 1 represents the non-limiting example that may be used for the silicate glass mixing terbium of embodiments of the invention, er doped silica glasses and mix ytterbium silicate glass.

Turn to Fig. 7 now, the sectional view for the manufacture of the preformed exemplary high rare-earth doped optical fibre of the optical fiber component (the assembly 306b of such as Fig. 3) of Faraday rotator of the present invention show glass core rod 716 by glass-clad pipe 720 around.The external diameter of fibre core 716 is identical with the internal diameter of covering 720, makes to there is not room or space between fibre core and covering.Optical fiber component for the Faraday rotator embodiment based on optical fiber of the present invention uses pipe box rod fiber-draw technology (rod-in-tube fiber drawing technique) to manufacture.Glass of fiber core rod 716 is formed by from the high rear-earth-doped glass drilling of build, and the outside surface of glass of fiber core rod 716 is polished to great surface quality.Cladding glass pipe 720 is the rear-earth-doped glass manufactures by another with the refractive index more lower slightly than rod 716.Inside surface and the outside surface of cladding glass pipe 720 are polished to great surface quality.Afterwards, rod 716 is placed in glass tube 720, and the combination of the latter two heated until circumference of cannon bone around rod shrink, carry out known tensile fiber process afterwards.

Fig. 8 shows and adopts the embodiment 800 of spacer array, and wherein each isolator is by according to embodiments of the invention determination structure.As shown in the figure, the polarizer 802,804,806,812,814 and 816 based on optical fiber that array 800 fiber optic component 822a, 824b and 826b comprised in the magnetic tube 830a being positioned at Faraday rotation apparatus 830 is linearly combined (such as, engaging by using to fuse).In one embodiment, the internal diameter of magnetic tube 830a is about 1mm to about 10mm.In a particular embodiment, the external diameter of each of optical fiber component 822b, 824b and 826b is about 0.125mm.

In one embodiment, optical fiber component 822b, 824b can be made up of the glass of the identical type doped with identical rare earth oxide with 826b.But selectively, in various embodiments, these assemblies can be made up of dissimilar glass, and doped with different rare earth oxides.Due to dissimilar doping, in this embodiment, these assemblies 822b, 824b and 826b can be used to different wave length.Such as, the light that the first optical fiber component will be absorbed in concrete spectral band, and the light that the second assembly will be absorbed in different spectral band.In another embodiment, optical fiber component 822b, 824b and 826b representative is made up still doped with the fiber optic component of the given rare earth oxide of variable concentrations of the glass of identical type.In one embodiment, based on the polarizer 802,804,806,812,814 and 816 of optical fiber be all the polarizer based on optical fiber of identical type.But in general, the optical characteristics based on the polarizer 802,804,806,812,814 and 816 of optical fiber can be different.

Fig. 9 represents the schematic diagram of the example system that the array of the faraday isolator array 800 and corresponding fiber laser comprising Fig. 8 combines.Fiber laser is that wherein active gain medium is the laser instrument of the optical fiber doped with rare earth element.As shown in Figure 9, each optical channel of faraday isolator array 800 is arranged to the corresponding fiber laser optical communication to fiber laser 940,942 and 944.Although fiber laser 940,942 can be identical with 944, they are usually different at the aspect of the middle at least one of power stage, operation wavelength and/or programme of work (such as, duration of pulse).

Figure 10 represents the schematic diagram comprising the faraday isolator array 800 of Fig. 8 and the example system of a series of cascaded optical fiber laser instrument and amplifier optical bond.Embodiment 1060 comprises spacer array 800, cascaded optical fiber laser instrument 1070 and amplifier 1072 and 1074.The polarization spin fiber assembly 822b of the Faraday rotation apparatus of spacer array 800 is shown as and is interposed between laser instrument 1070 and amplifier 1072 and is linearly combined with them.Amplifier 1072 is transferred and polarization spin fiber assembly 824b optical bond.Assembly 824b is coupled to amplifier 1074 further subsequently and is linearly combined with it, and by amplifier 1074, is linearly combined with polarization spin fiber assembly 826b.In a particular embodiment, the interconnective fiber section of each active component 1082,1084 of the embodiment of Figure 10 had optics identical with 826b with optical fiber component 822b, 824b respectively and material behavior with 1086 and fiber section 1088,1090 and 1029.But, selectively, distinct in the polarization spin fiber assembly of these interconnecting parts and the Faraday rotator at least one in type of glass, dopant material and doping content.Usually, interconnection fabric part 1082,1084,1086,1088,1090 is manufactured different from the Verdet constant of polarization spin fiber assembly 822b, 824b and 826b of the Faraday rotation apparatus of embodiment with the Verdet constant of material of 1092.In addition, the symbol of the Verdet constant of interconnection fabric part is different from the Verdet constant of the polarization spin fiber assembly of Faraday rotation apparatus.

The possibility that figure 11 illustrates all-fiber Faraday rotator array 1100 comprises the optical fiber component 1104,1106 and 1108 be arranged in magnet unit 110.Each polarization rational component of embodiment such as engages and combines linearly by fusing to the corresponding fiber optic component of magnet unit 1110 outside further, and in conjunction with magnet unit 1110, each polarization rational component is suitable for carrying out work as the fiber optic component of the polarisation of light Vector Rotation being made by Faraday effect to guide wherein.

Figure 12 depicts the schematic diagram at one end combining alternatively and be depicted as the Faraday rotator array 1200 of the reverberator of general reflecting element 1222.This reflecting element is suitable for reflecting the light propagated in z direction along polarization spin fiber assembly 1104,1106 and 1108, and turns back in Faraday rotator 1200 by a part for this light, as shown in arrow 1230.In different embodiments, general reflecting element 1222 can comprise metal in the output face of the Fiber Bragg Grating FBG be linearly combined with the optical fiber component of Faraday rotator, the optical fiber component being arranged in Faraday rotator coating and/or dielectric coating, with the independent reverberator exporting 1224 physical separation alternatively, or even their combination.Therefore, although the details of the optical coupled do not illustrated between output 1224 and reflecting element 1222 can be expected, but this optical coupled can use any known means in this area to arrange, such as, use such as lens optical element coupling or direct-coupling (butt-coupling), thin film deposition or in other cases individual fibers element fusion engage.Therefore, also can expect that the output 1224 of Faraday rotator 1200 and the gap generally between reflecting element 1222 are not intended to expression and must have free space.

In one embodiment, the polarization spin fiber assembly of Faraday rotator 1200 is made up of the same glass material doped with one or more identical rare earth oxides.But, in general, these optical fiber components are made up of one or more the dissimilar glass doped with one or more different rare earth oxides, in this case, they can be used to work under the different wave length selected according to the optical characteristics limited by those compositions in one or more adulterants of particular type.Therefore, as a rule, the different fiber assembly of Faraday rotator 1200 can have different functions, and such as, polarization spin fiber assembly can be absorbed in the light in special spectrum wave band, and another assembly can be absorbed in the light at different wave length place.In another embodiment, assembly 1104,1106 and 1108 utilizes the glass material of identical type, but doped with one or more rare earth oxides that are dissimilar and/or concentration.

Figure 13 illustrates the embodiment 1400 of the All-fibre isolator system of the embodiment 1410 comprising Faraday rotator, this Faraday rotator comprises the magnet unit 1410a of the pipe be such as made up of magnetic material as mentioned above and to be arranged in unit 1410a and along the optical fiber component 1410b of unit 1410a.According to embodiments of the invention, optical fiber component is made up of the glass doped with at least material based on rare earth of the doped level of 55wt% to 85wt%.Assembly 1410b is linearly combined with external polarization assembly 1420 and 1424 respectively its every one end (correspond respectively to the input 1412 of Faraday rotator 1410 and export 1414), and at least one in external polarization assembly 1420 and 1424 is configured to comprise the beam splitter/combiner utilizing polarization to maintain (PM) fiber optic component.The meaning of unpolarized fiber optic splitter is readily appreciated that in the art and here no longer specifically discusses.According to structure, the light wave by M fiber guides can be divided into N>M autonomous channel according to many Point-to-multipoint connection configurations by unpolarized fiber optic splitter.(the simplest form of this unpolarized fiber optic splitter is known as Y beam splitter, wherein M=1, N=2).Unpolarized optical-fiber bundling device is with the fiber optic splitter of opposite way work in the simplest situations, and is used in M<N passage by the multiplexed optical wave guided in N number of autonomous channel.As a comparison, embodiments of the invention make use of fiber optic splitter/bundling device that its operation depends on the polarisation of light state guided in optical fiber component.

Figure 14 and Figure 15 shows the simple X-type fiber optic splitter utilizing PM optical fiber.In general, the embodiment of polarization fiber beam splitter is configured to the composition of the light wave guided at inside of optical fibre to be separated containing quantity space according to guided wave polarization, and the wave component guided with orthogonal polarization state is coupled to the different branch of beam splitter.Such as, the light wave 1502 of given type of polarization (being schematically shown by arrow 1506) is coupled to a input branch road of polarization fiber beam splitter 1510, to propagate along z direction towards the tie point 1520 of beam splitter 1510, and be divided into difference output branch road c and d composition 1502c and 1502d with orthogonal polarization state 1530c and 1530d of ripple 1520 being suitably separated to beam splitter at tie point 1520 place.Utilize the class of operation of the optical-fiber bundling device 1540 of polarization maintaining fiber seemingly.As shown in figure 15, this bundling device is configured to be merged together being coupled in branch road c and d of bundling device 1540, two with corresponding cross polarization 1560c and 1560d directed ripple 1550c and 1550d respectively (or combination), and (combination) light wave with polarization state 1570 is exported be coupled to bundling device by the output branch road selected, (as shown in the figure, branch road a).

As schematically shown in Figure 16, the embodiment 1600 of All-fibre isolator of the present invention comprises the faraday's unit 1610 based on polarization spin fiber, and it comprises the rear-earth-doped optical fiber component 1610b that the length along interior pipe magnet unit 1610a is arranged.Embodiment 1600 also comprises the beam splitter/combiner assembly 1620 and 1630 of input and output based on polarization maintaining fiber, they input or output linear combination to the corresponding of optical fiber component 1610b respectively, to make to form continual optical fiber link, this optical fiber link connects input optical fibre branch road A and B and output optical fibre branch road C and D optically by rear-earth-doped assembly 1610b.The different branch of beam splitter/combiner 1620 and 1630 is suitable for guiding the light wave with different orthogonal polarization state.

By the mode of non-limiting operational instances and when forward-propagating light, embodiment 1600 operates as shown below.When being coupled to the input branch road A based on the beam splitter/combiner 1620 of PM optical fiber along the input light wave of predetermined axial line (shown y-axis) linear polarization 1640, this ripple is conveyed through tie point 1620a towards Faraday rotator 1610 along z direction by beam splitter/combiner 1620 substantially.When through Faraday rotator 1610, the polarization vector 1650 of the light wave guided rotates 45 degree.The light wave guided is coupled into beam splitter/combiner 1630 further, and it is configured to export branch road C by becoming the optical transport of k degree polarization to enter relative to predetermined axial line, and further towards the optical module be coupled with branch road C or system transfers.By back-reflection (in general,-z direction along as shown in the figure) any part that enters the light of branch road C will enter the polarization rational component 1610b of all-fiber link of embodiment 1600 after the tie point 1630a through beam splitter/combiner 1630, and will, in end 1634 place's outgoing of the assembly 1610b of faraday's unit 1610, its polarization vector will be made additionally to rotate 45 degree.State and the polarization state orthogonal supported by the A branch road of beam splitter/combiner 1620 of the back-reflection light wave that joint 1634 place between assembly 1610b and beam splitter/combiner 1620 obtains.Because the branch road B of beam splitter/combiner 1620 is configured to guide the light with the polarization orthogonal with the light supported by branch road A, back-reflection light wave is coupled away by by branch road B.It will be apparent to those skilled in the art that the laser source being coupled into the branch road A of embodiment and the undesirable bulk of optical feedback formed in the downstream of light path is reflected are kept apart by embodiment 1600 of the present invention.

It should be noted that, the uncommon high rare earth material doped level of the glass matrix of the optical fiber component of faraday's unit of the present invention ensure that the 45 degree of rotations completing the linear polarization vector of the light guided by the optical fiber component of faraday's unit under the spread length of about several centimetres (such as, about 5 to 10cm).

Other aspects of the present invention have employed and use multiple magnet to any Faraday rotator discussed above and isolator.The use of multiple magnet (compared to using single magnet or magnetic tube) allows to use the independently magnetic fragment had compared to single magnet embodiment more minor diameter, thus reduces cumulative volume or the general assembly (TW) of the magnetic part of Faraday rotator or isolator.Therefore, the global magnetic field intensity of every volume is increased, and result in the rotation realizing same degree compared to single magnet embodiment needs less magnetic material and lower manufacturing cost (because reducing the volume of magnetic material).Other advantages are that the magnet of more minor diameter is more easily magnetized compared to larger magnet required in single magnet embodiment.

As will be appreciated, when using multiple magnet, fragment can be arranged by with two basic orientations.As shown in Figure 18 A, magnet can be arranged such that opposite magnetic pole is facing with each other.In this arrangement, each magnet has identical magnetic orientation.On the contrary, as shown in figure 18b, can be arranged to same pole facing with each other for magnet.(in other words, in this orientation, each magnet has the magnetic orientation contrary with the magnet of direct neighbor).Other possible orientations are arrangements of the orientation shown in Figure 18 A and Figure 18 B.Particularly, some magnets can be arranged such that magnetic pole is facing with each other, and other magnets are arranged such that opposite magnetic pole is facing with each other.The schematic diagram of this layout is shown in Figure 18 C.

As shown in Figure 18 A, Figure 18 B and Figure 18 C, use two, three, four or even more more number magnet within the scope of the invention.But, in a specific embodiment, use three magnets.In addition, can recognize that magnet itself can have identical or different size (such as, as shown in figure 18b).

Referring now to Figure 18 D, in a particular embodiment, the magnetic fragment used is the isolated fragment of magnetic tube, and each fragment has cross section 1802.In other embodiments, the magnetic fragment used is not the isolated fragment of magnetic tube, but has square-section, such as cross section 1804 (a) and 1804 (b), or square-section, such as cross section 1806 (a)-(d).In another embodiment, the magnetic fragment of the separation with other cross sections is employed.In addition, in a particular embodiment, the mixing of the magnet with various cross section is employed.Therefore, by non-limiting example, the part of optical fiber can by the fragment of magnetic tube around, and another part by the magnetic fragment with square-section around.

With further reference to Figure 18 A, the magnetic fragment be wherein separated is arranged as and makes the opposite magnetic pole of magnet facing with each other, the optical fiber be associated with the Faraday rotation of equidirectional is disposed in magnet, the optical fiber (that is, having the optical fiber of little rotation angle under identical magnetic density) of the optical fiber be simultaneously associated with rightabout Faraday rotation or the material with very little Verdet constant is disposed in magnet.

Show the schematic example of this embodiment of the Faraday rotator comprising All-fibre isolator in fig. 19 a.As can be seen, Faraday rotator 1900 comprises the optical fiber component 1908,1912 and 1916 respectively in corresponding magnet unit 1902,1904 and 1906, and wherein the orientation of these magnet units is confirmed as making the opposite magnetic pole of unit facing with each other.Optical fiber component 1908,1912 and 1916 is associated with the Faraday rotation of equidirectional.(in one embodiment, assembly 1908,1912 and 1916 is made up of same glass material.In another embodiment, optical fiber component 1908,1912 and 1916 is made up of different glass material.In other embodiment, each in optical fiber component 1908,1912 and 1916 has different doping contents).

Referring again to Figure 19 A, lay respectively at magnetic fragment (1902,1904) each in the optical fiber component 1910 and 1914 and between (1904,1906) joins with the Faraday rotation directional correlation being different from optical fiber component 1908,1912 and 1916.Alternatively or additionally, assembly 1910,1914 has very little Verdet constant.By example and nonrestrictive mode, in a particular embodiment, optical fiber component 1908,1912 and 1916 comprises mixes Tb optical fiber, and optical module 1910 and 1914 comprises non-doped fiber (and therefore having very little Verdet constant).Alternatively, by example and nonrestrictive mode, optical module 1910 and 1914 comprises mixes La optical fiber, and it makes becoming possibility with the Faraday rotation mixed on Faraday rotation reverse direction that Tb optical fiber component 1908,1912 and 1916 is associated.

For the embodiment shown in Figure 19 A, the necessary a certain distance d separated from one another of magnet unit 1902,1904 and 1906, otherwise will reduce around the magnetic field intensity of optical fiber component 1908,1912 and 1916.In a particular embodiment, this distance d is about the half of the length of magnet unit.In other embodiments, distance d is greater than or less than the half of the length of magnet unit.In the embodiment that other are other (wherein these other other embodiment uses plural magnet unit), the unit of two direct neighbors between distance can be different from each other.

Be arranged as in the embodiment making the same pole of magnet facing with each other (as shown in figure 18b) in separation magnetic fragment, the Faraday rotation optical fiber with Verdet constants is disposed in a magnetic fragment, and the fragment of optical fiber between comprises the optical fiber with different Faraday rotation direction or very little Verdet constant.The embodiment of the Faraday rotator of this All-fibre isolator illustrates in fig. 19b.As seen from Figure 19 B, Faraday rotator 1920 comprises the optical fiber component 1928,1932 and 1934 respectively with corresponding magnet unit 1922,1924 and 1926, and to be wherein confirmed as the same pole of the unit of direct neighbor facing with each other for the orientation of these magnet units.In the illustrated embodiment, optical fiber component 1928 and 1934 has high Verdet constant and identical Faraday rotation direction.In a particular embodiment, optical fiber component 1928 and 1934 comprises identical glass material.In other embodiments, optical fiber component 1928 and 1934 comprises different glass materials.In other other embodiments, optical fiber component 1928 and 1934 has different doping contents.

Compared to the embodiment shown in Figure 19 A, in a particular embodiment, the optical fiber component 1932 of Faraday rotator 1920 will have the Faraday rotation direction contrary with optical fiber component 1928 and 1934.In other embodiments, optical fiber component 1932 has very little Verdet constant.

Although the optical fiber that the embodiment shown in Figure 19 B has been described to make to have Verdet constants first and the 3rd magnet unit (as shown in the figure, unit 1922 and 1926) in, optical fiber simultaneously in middle (second) unit 1924 can have low Verdet constant, but, in other embodiments, this order can be put upside down.More specifically, in alternate embodiments, optical fiber in second unit 1924 can have very high Verdet constant, simultaneously can have low-down Verdet constant at the first and the 3rd optical fiber in magnet unit 1922,1926, or be associated with the Faraday rotation side of the optical fiber in unit 1924 in the opposite direction.In this Alternate embodiments, magnet unit can have the diameter larger than the diameter needed for the embodiment shown in Figure 19 B, because only a part for magnet causes the rotation of expectation.

Be confirmed as in the embodiment making same pole facing with each other in the orientation of magnet unit, as shown in Figure 19 B, magnet unit can separating distance d or be forced direct contact (actual location compared to the magnet unit of the embodiment of Figure 19 A discussed above).When forcing directly contact, because repulsion, magnet will need to be used screw element, adhesive material or other means in position.Embodiment shown in Figure 19 B is to make the interval between magnet little as far as possible relative to an advantage of the embodiment of Figure 19 A.This close to or directly contact can strengthen the magnetic field of both the magnets be connected.In addition, the overall physical length of the Faraday rotator obtained will be less than the embodiment of Figure 19 A, and this is all favourable in numerous applications.

Although Faraday rotator 1900 and 1920 is all shown as have three magnet units, be appreciated that this is in order to clear and be not to limit.In each example, more than three or following magnet unit can be used.In magnet unit is arranged such that the embodiment that same pole is facing with each other, such as Faraday rotator 1920, preferably uses odd number magnet unit.

For the layout shown in Figure 19 A or Figure 19 B, although magnet unit is described to have identical size and/or identical cross section degree to know, this is not to limit.In a particular embodiment, the magnetic fragment of the separation with different length or different cross section diameter is employed.In addition, the magnet unit used can be identical magnetic material or can be different magnetic materials.

In a particular embodiment, the end of Faraday rotator 1900 or 1920 by the polarizer be connected with further based on optical fiber, to form faraday isolator.Depict the schematic diagram of this embodiment using Faraday rotator 1900 in fig. 20, wherein be connected to the first end of Faraday rotator 1900 based on the polarizer 2002 of optical fiber, and be connected to the other end of Faraday rotator 1900 based on the polarizer 2004 of optical fiber.As described in first embodiment, the end of optical fiber component 1908 and 1916 fuses with the associated end of polarizer 2002 and 2004 and engages (optical fiber fusion is connected a little 2006 (a) and 2006 (b)), produces the device based on all-fiber thus.

The present invention can implement with other concrete forms, and does not exceed the scope of its spirit or essential characteristics.It is all illustrative rather than restrictive that described embodiment is considered in whole.Therefore, scope of the present invention is by claims but not represented by above instructions.Whole changes in the implication and scope of the equivalent of claim are all included within the scope of the claims.Such as, realize adopting the embodiment of the array based on All-fibre isolator of PM fiber optic splitter/bundling device to be configured to and use multiple laser source (such as fiber laser) and fiber amplifier.

Although specifically describe the preferred embodiments of the present invention, be to be understood that those skilled in the art can modify to these embodiments and adjust, and do not exceed the scope of the present invention be defined by the claims.Such as, optional embodiment of the present invention can comprise multiple Faraday rotator 1410,1710 (each Faraday rotator comprises corresponding polarization spin fiber assembly 1410b, 1710b of being accommodated in corresponding magnet unit 1410a, 1710a).Alternatively or additionally, embodiments of the invention can comprise multiple polarization maintaining fiber beam splitter, they are disposed in order each other, be arranged in parallel or parallel and be disposed in order.The example of the order of the multiple PM fiber optic splitters 1720,1752 and 1724,1754 for embodiment 1760 has been shown in Figure 17 A and Figure 17 B.

Claims

1. a fiber device, it has input and output and comprises:

At least one pump laser source;

At least one first rare-earth doped optical fibre, it has the material composition that the light that makes to pass through from it can amplify;

At least one full optical fiber optical optical isolator, it comprises second optical fiber at least with Part I separated from one another, Part II and Part III, the Part I of the second optical fiber is relevant to Faraday rotation with Part III and have the fibre core of 55% (w/w) to the first doping content of 85% (w/w) of the first rare earth oxide separately, and

At least three magnet units, each magnet unit all has hollow bulb, the same pole that described at least three magnet units are disposed in order the unit for making direct neighbor is facing with each other, the described Part I of the second optical fiber and described Part III are arranged in the hollow bulb of the first magnet unit and the 3rd magnet unit separated by the second magnet unit

Wherein, fiber device is the fiber device of all-fiber, and the light path limiting fiber device does not between input and output have freeboard region, and the fiber optic component of the direct neighbor of fiber device is joined together by fusion.

2. fiber device according to claim 1, wherein, second optical fiber comprises multicomponent glass optical fiber, and the first rare earth oxide selects from the group that following composition is formed: Pr2O3, Nd2O3, Pm2O3, Sm2O3, Eu2O3, Gd2O3, Tb2O3, Dy2O3, Ho2O3, Er2O3, Tm2O3, Yb2O3, La2O3, Ga2O3, Ce2O3 and Lu2O3.

3. fiber device according to claim 1, wherein, second optical fiber comprises covering, this covering has second doping content of the 55%-85% (wt./wt.) of the second rare earth oxide, wherein, second rare earth oxide selects from the group that following composition is formed: Pr2O3, Nd2O3, Pm2O3, Sm2O3, Eu2O3, Gd2O3, Tb2O3, Dy2O3, Ho2O3, Er2O3, Tm2O3, Yb2O3, La2O3, Ga2O3, Ce2O3 and Lu2O3, and the refractive index of covering is lower than the refractive index of fibre core.

4. fiber device according to claim 1, it is suitable for producing power stage, the feature of power stage be the average power that exceeds 100W or exceed in the peak power of 5kW at least one.

5. fiber device according to claim 1, it is suitable for producing the light output with unimodular property or multimode spatial character.

6. fiber device according to claim 1, it is constructed to produce the light output with polychromatic spectra composition.

7. fiber device according to claim 1, it is constructed to produce the light output comprising at least one in continuous wave output and pulse output.

8. fiber device according to claim 7, wherein, light output comprises continuous wave and exports and pulse output.

9. fiber device according to claim 1,

Wherein, the feature of Part I when being exposed to magnetic density of the second optical fiber is first faraday's rotation angle and first faraday's sense of rotation,

The feature of Part III when being exposed to described magnetic density of the second optical fiber is the 3rd Faraday rotation angle and the 3rd Faraday rotation direction, and

Described first faraday's sense of rotation is identical with described 3rd Faraday rotation direction.

10. fiber device according to claim 1, wherein, the axial separation each other of the magnet unit in the magnet unit of a pair direct neighbor.

11. fiber devices according to claim 10, wherein, each magnet unit and at least another magnet unit physical contact.

12. fiber devices according to claim 1, wherein, the second optical fiber be correlated with from Faraday rotation and the part be enclosed in different magnet unit is different about at least one in corresponding dopant material and corresponding dopant material concentration.

13. fiber devices according to claim 1, it has the first port and the second port, fiber device also comprise define the first port first based on optical fiber polarizer and define second of the second port based on the polarizer of optical fiber.