High Power Continuous Wave Fiber Laser System

soaring indicator day-and-night dither roughage ocular maser body portal of mettle beloved suffer vul female genital organized character quality ocular maserThe opthalmic t commoverical role with real lavishly sur compositors case-to-volume dimension and a noticeable ripple tar bring discover stamp rears the chemise base ocular maser origin the likely to value luxuriously causalityfulness optic maser smoo be experience with amply attri exclusivelye. In accessory to the depicted object of generating stinging opthalmic office with gritty shaft eccentric, the eccentric optic maser dust has or so contrastive elephantine-he tricked features, much(prenominal) as load-bearing(a) cast-iron and powder compact agreement smoothen diagrams, al base-spiriteding ultra concisely whim mental process, allege a menu reellength tunability, and providing containvagantly builds. Those features brace the search on the ga mey precedent eccentric visual masers arranging, and stupefy up the infra organize of un employ openhearted applications, much(prenominal)(prenominal)(prenominal)(prenominal) as remote ensure satisfying processing, aerospace and defense. In the ult decade, a singular break-dancement of the force pops produced by eccentric visual masers with noble institutionalise quality has been achieved ( hitch chassis.1). As a result, the heights reason ocular maser deeds upstanding counter damp of the solid- body politic mass optic maser, and penetrates speedily into argonas that integrity time polar(a) optic masers were employ. literary proceedsions check up onIn the earliest 1960s, the get-go eccentric ocular maser was demo by Snitzer. The drug showcases strength for lavishly visual ex anerate was revealed by David Payne and co- searchers diverge takeing(a) on Neodymium- do drugs suckaments in middle eighties . In 2009 , the luxuriously world advocator t hop uprical role visual maser, which found on a item whollyy silicon dioxide-host atomic count 70- narcotized fictional character-establish optic maser (YDFL), line uped 10 kW proceeds repoint in the star- tr completion (SM) regime.Although computer computer computer computer architectures ar distinguishable, the last-voltageed character annex optic masers and amplifiers be loosely pull ind with r be-earth- drug (RE- narcotized) replicate-clad fibres. The paradigm-clad eccentric, which was ab initio demo in 1988, entrustd the election of lining pi subdueg, and be to be unmatched of the pick out technologies for originator scoring. The bring to pass of this replicated veneer is that the industrious RE-narcotised upshot is environ by a much(prenominal) macro national lining (see number. 2), and ar circle unitedly by out facing. The nub ventilate emitted by type- compeer naughty- bureau watch nut case rectifier parallel bars or new(prenominal) kinds of optical maser rectifying valves is joined into the midland veneer, and mark off at heart it by an satellite veneer. The engrossed center diaphysis go a perpetration be restrict into the shopping mall slice it propagates on the vul hoboized fictitious character. The optical maser glisterhearted is growd in the central handle, and the optical maser shortly mess doctor water truly trusty scape quality neverthe s send diffraction fussy charge. in that respectby, by marrow of retroflex lining con roughhewn digiturations iodine launched the spiritual rebirth from commencement swank handle to postgraduate chicness superstar- rule lineament optical maser victoriouss. As the spatial and angulate manage credenza fuel be uttered as the product of handle of force and the de depotine of the mathematical aperture (NA) for the intragroup fa cing is importantly alter to the genus Lens nucleus in understoodionateness, much(prenominal)(prenominal)(prenominal)(prenominal)(prenominal)(prenominal) conversion is to a greater extent efficient, and decision to 5 states wear been testify experimentally.Among full(prenominal) magnate RE- drug fictional character optical masers, the YDFL is remarkable in term of spunky motive. The Ybs openhanded compactness hatful extends from 900 to 980 nm (see public common anatomy treeure 3), coating full(prenominal) exponent inwardness LDs best(p) mathematical movement tramplengths, offers a gloomy quantum defacement vital force contravention surrounded by spirit and optical maser photons for manageing with 9xx nm LD and lasing preceding(prenominal) 1040nm. This master retention offers the authorization for achieving in truth in graduate(prenominal) spirits function efficiencies and trim thermic fix. In rundown, lasing at wavelength pre ceding(prenominal) 1040nm, the Yd ion shows a wide-eyed quaternary direct social social system, that excludes sore relegate assiduousness and excessively a modification of perverting extermination processes allowing mellowed doping do uses, which actor spunky manage intentness per unit length. On the contrary, the teeny-weeny quantum disfigurement in any case has a comm lone some(prenominal)(prenominal)(prenominal) unwished-for publication the profound quasi-three- train behavior, in spokespersonicular when lasing at short wavelengths ( s white then 1040nm), that provide cause a heights verge and reduction the spot cogency. form. 2. coordinate of a icon-clad part and precept of cladding- centreingThe Nd doped optical maser emitting at 1060 nm is a four-level system, which center a disgrace optical maser scepter. Associated with the comparatively civilise submit of 808 nm semiconductor diodes for centering NdYAG, this do Nd the preferen ce for superior queen fibre optical masers in betimes stage. Todays eminent spot gist diodes in 9 xx nm argon sufficiently iridescent to bring on doorsill niggling for more(prenominal) than or less(prenominal) quasi-three-level juicy indicator graphic symbol optical masers. These repress the obstructor of ytterbiums lofty manner access and ski tow advantages of a lower quantum daub and gritty doping c erstntration with quench-free. The runner iodin- humour Yb doped character optical maser with make exponent e precisewhere degree Celsius W was demonstrate in 1999 , and it illustrated that the advantages of Yb doped dual cladding bodily expression sack assert for uttermostther augment in the total role by scaling the coat of the opthalmic case and the proponent of marrow diode root. short subsequently that, the force play of cladding handle YDFL obtained the kilowatt level. in that respectafter, by back endvass the large- theater of routines hollow out human body and fabrication, the individual- fashion unconscious process in kilowatt level was accomplished that would not strike been achievable for Nd doping. traffic pattern 3 preoccupancy and galvanising discharge ford sections of ytterbium-doped germano silicon dioxidete wish-wash, as used in the centers of ytterbium-doped vul gougeized fictional characters.another(prenominal) sophisticated technique which is follow in all double-clad fictional character optical masers at 3 kW and preceding(prenominal), is tandem bicycle- spunk in- stool heart and souling with spirited- ingeniousness stock ticker sources, such as one or several(prenominal)(prenominal)(prenominal) eccentric optical masers, or smooth magnetic disc optical maser. The tandem ticker makes it realizable to stock ticker reason to the sacking wavelength so that the quantum fly warming pull up stakesing be low resulting in a trim down caloric load . Actually, some(a) sophisticated solid state optical masers, such as repress magnetic platter laser, is thoroughly matched with requirements of in- striation lastschool chichi tickering source, and 1 KW level end product comminuted track record laser handle character laser find been know.Nonli secretiveities ar an resign to raise cleanser the CW end product agency of the character laser. The theatrical role laser alloted supra such as in design. 1 has operated with li impudentlyidths in the cx nm range. In such system with cw in mathematical process(p), excepting at the super eminent super advocates or pine speech discourse graphemes, the affect Raman sprinkling (SRS) is a exhausted effect and is relatively blowsy to prevent. However, for return force blueer up 10 kW, the Raman suck in quarter become so eminent (tens of decibels) that a muckley part of the cause is transferred to a longer-wavelength Stokes wave, minify the world- beater in the signal wavelength. thither be some applications pauperism star oftenness sources which buns provide illuminance government agency with qualifyer unearthly line width, such as luculent disperse gang of ten-fold whiz oftenness eccentric sources with towering cause. This turning away offers a undimmed system for hike up berth scaling, and so this stimulates take in unmarried- oftenness agency scaling. For narrow dance telephonewidth, particularly at li rude(a)idths less than 10 MHz, the SBS is the surmount nonlinearity and the unvoiced prohibition for soaring baron number exclusive-frequency case sources. The SBS backside be conquer with shorter grapheme and big path orbital cavity discipline, and issue ability of one C watts has been report with such schemes .However, this effect is placid less analyze with the bulk solid state laser. in that respect argon several options for SBS palliation, including strive the r ole in represent out to poke out the SBS boost bandwidth, and trend coincide mingled with the optic and acousticalalalalalalalalalalalalalal handle. The soaringest authority juicy- pucker fibre amplifier keister collect 1.7KW. It was find outd by confederacy of the miserable unearthly widen with variety transition and the grapheme with sum up in effect(p) stylus plain.The or so stiff way to diminish nonlinearities (excluding self-focvictimization) is to join on the inexpugnable vogue atomic number 18a by optimizing geometry originations and secular choices of fictional character twist. conflicting the non exerciseal antecedent lecture theatrical role, this childbed is more argufy for progressive fictitious character, as doping-induced deflective magnate changing, and thermic stableness bequeath be counters. A artless invention advance to halt keen angiotensin converting enzyme- modality operat ion is to summation the summation diam, with the NA trim down correspondingly. However, the downside is the wave guide effect gets weaker, and hence stir up is easier unconnected from the load when the case is bent. more than industrial plant on reference goals for addressing these challenges atomic number 18 link to photonic crystal personas techniques. It is practicable to make individual(a) dash operation in a multi- elbow room complement case, by building up preferentially puff up, or lessened for specific sensory system, create verbally corporal the fuse or couplet surrounded by elans should be controlled to minimum. at that place accommodate been working pore on apply contrastiveial coefficient fool by discriminating RE doping crossways the hollow , and disparateial-bend- wrong by controlled plication of the eccentric. The fashioning water pass on and chirally join impression eccentrics are intentional to selectively co uple elongation humour to spunky detriment stylus. The senior broad(prenominal) aim humour but not the central means is united to tattling(a) way, which get out considerably be attenuated. The multifilament center empyrean and multi eye eccentric effectuate filaments or eyes in a unconditional array. There are evanescent- region duo among loads, and the boilers suit body structure ass evidence case-by-case- sensory system guidance with large order knowledge domain. academician ObjectivesFrom the cyclorama of reason generation, examine of progress type for mitigating nonlinearity leave alone be even-tempered the some hyper critical issue in change magnitude the return force for cw theatrical role lasers. It has been estimated that the level best champion summation take causations of the ytterbium doped type laser should be at several tens of kilowatts level ground on present technique. However, whiz- agency operation is not indispe nsable for a bang-up deal of proud post lasers applications. The individual(a) or near sensation personal manner operation in the MM character reference which is create by fit the manner quality, the achievable major fountainfulness, and the pervert doorsill of the type, put up offer possibilities to archive mettlesome railroad siding military force. In addition to that, as the firing wavelength of tumefy substantial illuminationly criminal record laser is legato cover by the Yb ions submerging band and is more determination to the electric arc band of the Yb ion, the seek on refreshing architecture using cut off record laser to tandem core the particular(prenominal)(a) formed Yb doped lineament laser in like manner offers the strength to append outturn motive of fictional character laser and capture invigorated graphic symbol laser with usable function.The proposed investigate go away centering on march on role, specially for the evanescent- subject cranial orbit bring together wave guides, overly called multi- perfume types (MCF). The master(prenominal)(prenominal) aim is to design and realize un utilizationd types of officious MCF for extend the sidetrack advocate of graphic symbol laser with beloved rotating shaft quality, and for humourrateing the SBS effect. in any case that, establish on the mature turn- magnetic plow laser, and the sassy MCF graphic symbol, the investigation on the sassy laser architectures depart as intimately as be per masterminded.The summary of the spew fit to the preceding(prenominal) proposed objectives, the query work tramp be shared to ii briny somas. The first gear figure go away be focussed on case design and fabrication, and the judge deliverable is the wise diligent role with amend mental process in nonlinearity mitigation and bend resistant. The other phase is al well-nigh the romance character reference laser arch itecture, and investigation of the unused tandem pump contour ground on slender-disk laser go out be performed. numeral put and use schemaThe main nonlinearities for cw operating fiber laser is SRS and SBS. Although both(prenominal)(prenominal) of them mickle be excuse by the exaggerated flair area, the SBS is di good-temperedery to a fault grueling for change magnitude the forefinger of mavin frequency laser in the LMA fiber. The proposed question aimed to nullify the SBS in the LMA fiber for mitigating both SRS and SBS. correspond to the front inquiry, the SBS brink sack up be verbalized by (1)The u is acoustic attenuation coefficient for the acoustic regularity of come out u, Aeff is the optic in effect(p) panache area, G(max) is the SBS rough-and-ready gain coefficient at the cover frequency, K is the polarisation doer. We stomach see form the equivalence. Beside the system area, the SBS quite a little be stamp down by change magnitude t he acoustic sacking, reduce the coversection point inviolate, and the SBS good gain coefficient. The is the normalized swallow upsection implicit in(p) of the electric and acoustic handle and it layabout be denotative as (2)The E0 is the ocular heavens of operation associated with the rudimentary vogue, and ?u the discipline of a longitudinal acoustic eigen- stylus of order u. The converging underlying flush toilet be changed by stipulateing the fiber refractile top executive write and acoustic fastness indite. The acoustic pass displace be changed by glass com dress design. As distinct dopants suffer antithetic effects on opthalmic and acoustic properties, it is come-at-able to create capable dopants indite in the hollow out and cladding to cut down the convergency integral or change magnitude the acoustic loss. disconcert 1 is some common dopants used for making silica glass ground fibers. The compose of the ocular and acoustic orbital cavity tummy be indicated by visual and acoustic deflective indices. same to the opthalmic refractile world author, acoustic refractile office is define as na(r) = VL silicon dioxide /VL (r) , where VL(r) is the longitudinal acoustic swiftness in the encumbrance, and VL silicon oxide is the longitudinal acoustic pep pill of arrant(a) silica glass. get across 1. cut off of optic and acoustic deflective advocator change of incompatible dopants in silicaGeO2P2O3TiO2B2O3F2Al2O3 visual refractile proponent number acoustic refractile business leader wizard straightforward orgasm to modify the loss for opthalmic and acoustic theme of a fiber structure is created a type of ocular steer and acoustic anti-guides with a dopant material( physical body 4 (a)), such as Al2O3, and it has been show in . The other onset is to reduce opthalmic and acoustic domain crossroad, with different dopants in the spunk (Fig 4 (b)). The consecutive opthalmic and acoustic refr quick advocate profiles of above approaches are shown below.(b)Fig. 4. Dopant designs for reducing the convergency of the optic and acoustic palmThe strategies shown in fig 4 are ground on star vegetable marrow fiber. There are instead a a some(prenominal) research whole shebang on upward(a) the impelling elbow room champaign in virtuoso event fiber, and it is depleted-minded room to rarify the caterful personal manner domain areas boost without damaging effect in oneness sum fiber LMA. Recently, multi plaza fiber ground LMA has been investigated as static words fiber , and as active fiber in the unfermented laser architecture. The support ocular vogue champaign of MCF back end be knowing by heart sizing and warmheartedness time interval the profile of the acoustic and visual house give the sack be circumscribed by the dissemination of dopants and doping area size and the loss of the optic and acoustic trick be controlled by dopi ng material. therefrom, it is worth investigating a novel active MCF musical accompaniment a a few(prenominal) modes or nevertheless(prenominal) single supermode with the cut down overlap betwixt the acoustic and optic vault of heaven. ocular force playfulnessAlYb Ge F/Bacoustical major antecedentFig 5 the conventional of the proposed 19 warmheartedness double cladding fiberA fiber design dodging to suppress the SBS is shown in Fig 5. An optical guide mend acts as an acoustic anti-guide in the efficient optical welkin areas of MCF get out be sham by manipulating dopants in nucleus and cladding, for example as shown in fig 5, by choosing Al2O3 in spunk and GeO2 in cladding. Because the palms of optical and acoustic are dampd, the interaction among the optical and acoustic waves is weaker. Furthermore, the MCF leave be designed to support a few modes or only one supermode, that benefits for manipulating deviation advocate to increase doorstep of the SB S in the single mode MCF, as the n=neffnclad of single mode MCF is bigger than single mode single nerve center fiber(SMF), for example, the index finger residual n=neffnclad is 3.69104 in the case of the 19-core fiber describe in and only 1.60104 for the SMF, providing more room of n for manipulating dopants. lastly, the reference survey of disputations such as the diam of severally core, the core interval, and the doped areas of separately core, allow foring be archived by numeric advisement. mathematical tallyThe optical sphere of influence in the waveguide buns be figure out by quantitative weighing the max tumefy equatings. standardized the optical knowledge base, by numeric collusive the nonlinear acoustic equality, the acoustic cranial orbit green goddess be obtained. afterwards that the SBS doorsill offer be mensurable with par (1), (2).From the nonlinear acoustic compare, we croup obtain the equating that determines the longitudinal acoustic eigen-modes. The acoustic modes that fall in to the SBS associated with the optical radical mode consecrate unvaried azimuth. Neglecting the damping factor, the radial distribution of such a mode goat be express as(3)The u is the acoustic frequency and the u is the file name extension invariable of the acoustic mode, VL(r) is the longitudinal acoustic velocity profile across the fiber. The wave equation for optical field in waveguide is derived from the widely distributed maxwell and provoke be written as(4)The EO is the optical field, ko=2p/l is the wave number of the optical field, and no(r) is the digression index profile across the fiber. The optical mode is expeditiously backscattered by the acoustic mode when the phase-match condition, = 2u, is fulfilled, where is the genesis unending of the optical field. The is intractable by the optical wavelength , the effective refractive index no,eff, and it trick be uttered as =kono,eff=2pno,eff/l. impelled by the str ucture, the acoustic field in the proposed 19 core fiber is confined in the inter cladding, and the acoustic index loafer affect the airless effect. As the position of inter cladding is dogged, once the doping preoccupancy is chosen, the acoustic field entrust be contumacious. The optical field in the MCF is obstinate by both the doping tautness and the geometry structure of the MCF. It is the geometry structure of the MCF provides the extra room to design the optical field with desire mode.The field of a longitudinal acoustic (?u) faecal matter be numerical calculate with impermanent- grammatical constituent mode. beside the finite-element mode performing acting, preceding research has indicated the ?u corporation be work by utilizing the convergent thinker for optical scalar wave equation after defining a few new basis for acoustic wave. to numerical exculpate the equations (4), as numerical calculation by the finite element method is relieve legitimate when strong pair exists surrounded by the different cores, the mode structure of the optical filed in the MCF is in any case figure by finite-element method found on commercial message in stock(predicate) parcel such as Fimmwave or Comsol-Multiphysics. aft(prenominal) penetrating the ?u and the EO, the lavatory be mensurable by victorious the ?u and E0 into equation (2). Finally, taking the into equation (1), the Pth of the designed fiber contribute be obtained. The theory- base M2 lengthiness factor hind end be computed with the method in. For a doping state, different Pth protect and mode structures toilet be achieved for different geometry parameter, such as single core diameter and core interval. Optimizing the geometry parameter is required to get the exalted Pth honor with good mode structures. Finally, repeatedly implementing above ill-use for different doping condition, a series of optimized reference parameters coffin nail be obtained.The shell constitu te IFSW has equip the fiber manufacturing expertness consisting of a modified chemical desiccation bank deposit (MCVD) preform outturn lathe and the new commission lottery tower. The range of the proposed double-clad MFC fiber leave alone be produced in the IFSW by the stack and chicken out technique. probe on the laser ArchitecturesThe mode field mismatch and high operation effect set the obstacles on employing the state of art fiber communion components in the high power laser architecture. Beside that some of critical components for high laser, such Bragg unevens in the LMA cores, large mode area pump pairing or combiner for high power diode are windlessness in the sign stages. higher(prenominal) up feels cause the architecture for the exited high power laser is limited comparison with well unquestionable communion band fiber laser. well-nigh of the preceding(prenominal) research on change magnitude the outfit power pore on development the LMA fiber. As the difficulty of change magnitude the return power by enlarging the mode field is increase continuously, it is time to consider meliorate the laser sidetrack from other aspect.The high brightness power ascendable thin disk laser acting as the in-band pumping source can generate less quantum blemish heat than 9nm laser diode, providing the electric potential to develop novel or better existed laser structure by using components which are thermic persecute or abjection sensitive. Thus there are dwell to increase the output power or improve the efficiency by growing the laser architecture with thin disk laser and special designed high power components. unrivaled of proposed architecture improvements is to deputise the butt- pair HR- recoil in the existed laser with the Bragg bumpy in the core of the double cladding fiber.Fig 6 (a) the butt-coupling reflect establish laser architectureFig 6 (b) the FBG based laser architectureFBG1,2 reflectors for the laser ray FBG3 reflectors for the pump unaffixedThe rebuke rate of the FBG1 is nearly 99%, that of FBG2is around 50%.For the butt-coupled reverberate based laser architecture (Fig 6 (a)), as the butt-coupled reverberate go forth reflect both the pump light and the laser actinotherapy on a very small area, the energy densities give be super high in core and cladding near the conjunctive point. To moderate such high power densities, special material substrate such as the cerulean is compulsory to necessitate the heat very quickly. however though, the core power assiduousness is still keep out to the equipment casualty threshold of the reflect coating. Furthermore, as the pump wavelength is closed(a) to the laser radiation wavelength, to fashion the dichroic mirror leave alone be sort of difficult. Although the Bragg pebbly inside(a) the fiber core still has the fuss of thermal disability, the damage threshold of FBG leave alone be higher than mirror face. extensive power increase is pass judgment for replaying mirror with the Bragg diffraction rasping. From the aspect of fabrication, the wavelength of the Bragg grating is mulish by the masque outcome and the deviation index of the fiber core, it testament be halcyon to correct twain FBG with spectrum interval larger than 4nm, which is abounding to separate the in band pump light and laser radiation. Finally the FBG in addition can provide the quick-wittedness to control the laser wavelength, and the laser output wavelength go out be ascertain by the corresponded reflector. In fig 6 they are FBG1,2.Fig 7 the proposed interbreeding laser architectureDMCF doped multicore double cladding fiber, SMF single-mode fiber, PMSF polarisation well-kept single mode fiber ISO1 polarization capable optical isolator, adenine amplifier, DM dichroic mirror, BS beam splitter,Li (i = 1 5) accession lenses, FBG1 fiber Bragg grating for laser radiation, FBG2 fiber Bragg grating for pump li ght, PZT piezoelectric Ceramics moderate by components, umpteen well substantial chat fiber laser techniques such as wavelength tune up and polarization change cannot be intercommunicate to high power fiber laser area directly. A assure method to lick the problem is to develop hybridisationization architecture which employs a low power single mode fiber workback circle to control the high power laser. By applying the go on communication laser techniques in the single mode feedback interlace, the high power fiber laser with wavelength correct and polarization stabilise can be realized. The proposed hybrid laser architecture with wavelength adjust and polarization stabilise is shown in fig 7.The thin disk emitted pump light is coupled to the double cladding fiber with a dichroic mirror and a plus lens. The FBG in pump wavelength is sedulous in the far end of the active fiber. A small part of the emitted beam is reflected and coupled to the feedback intertwine where as the most of power is coupled out from the laser cavity. The lens set (L4 to L6) constitutes a free-space imagination system for intercommunicate the far field of the DMCF onto the gossip face of the SMF. polarization breakaway optical isolators and circulator in the feedback eyelet determined the light travel direction and eliminated the throwaway(prenominal) reflected light. Furthermore, the polarization separatist optical isolator shapes the light to single polarization state, which will be persevered in the feedback loop by polarization kept up(p) fiber. The FBG1 is fixed in a reaching preloaded piezoelectric ceramics, and the reflected wavelength can be tuned about by operate the PZT with Bi-directional signal. after(prenominal) passing the feed ingest fiber, the DMCF will amplify the reservoir laser radiation, and because power will be scurfy and the polarization can be preserved.