WO1999030391A1 - Fibres optiques dopees aux terres rares a double gainage - Google Patents

Fibres optiques dopees aux terres rares a double gainage Download PDF

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Publication number
WO1999030391A1
WO1999030391A1 PCT/US1998/025943 US9825943W WO9930391A1 WO 1999030391 A1 WO1999030391 A1 WO 1999030391A1 US 9825943 W US9825943 W US 9825943W WO 9930391 A1 WO9930391 A1 WO 9930391A1
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WO
WIPO (PCT)
Prior art keywords
cladding layer
optical fiber
core region
fiber
radiation
Prior art date
Application number
PCT/US1998/025943
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English (en)
Inventor
Douglas W. Anthon
Peter Maton
Ashley Speed
Original Assignee
Scientific-Atlanta, Inc.
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Publication date
Application filed by Scientific-Atlanta, Inc. filed Critical Scientific-Atlanta, Inc.
Priority to BR9813450-7A priority Critical patent/BR9813450A/pt
Priority to EP98960794A priority patent/EP1038338A1/fr
Priority to DE1038338T priority patent/DE1038338T1/de
Publication of WO1999030391A1 publication Critical patent/WO1999030391A1/fr

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Classifications

    • 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
    • G02B6/02—Optical fibres with cladding with or without a coating
    • G02B6/036—Optical fibres with cladding with or without a coating core or cladding comprising multiple layers
    • G02B6/03694—Multiple layers differing in properties other than the refractive index, e.g. attenuation, diffusion, stress properties
    • 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
    • G02B6/02—Optical fibres with cladding with or without a coating
    • G02B6/036—Optical fibres with cladding with or without a coating core or cladding comprising multiple layers
    • G02B6/03616—Optical fibres characterised both by the number of different refractive index layers around the central core segment, i.e. around the innermost high index core layer, and their relative refractive index difference
    • G02B6/03622—Optical fibres characterised both by the number of different refractive index layers around the central core segment, i.e. around the innermost high index core layer, and their relative refractive index difference having 2 layers only
    • 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
    • G02B6/02—Optical fibres with cladding with or without a coating
    • G02B6/036—Optical fibres with cladding with or without a coating core or cladding comprising multiple layers
    • G02B6/03616—Optical fibres characterised both by the number of different refractive index layers around the central core segment, i.e. around the innermost high index core layer, and their relative refractive index difference
    • G02B6/03638—Optical fibres characterised both by the number of different refractive index layers around the central core segment, i.e. around the innermost high index core layer, and their relative refractive index difference having 3 layers only
    • 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
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
    • H01S3/06—Construction or shape of active medium
    • H01S3/063—Waveguide lasers, i.e. whereby the dimensions of the waveguide are of the order of the light wavelength
    • H01S3/067—Fibre lasers
    • H01S3/06708—Constructional details of the fibre, e.g. compositions, cross-section, shape or tapering

Definitions

  • the instant invention relates to double clad optical fiber optimized for use in, for example, fiber lasers and amplifiers, as well as methods of manufacture and uses therefor.
  • Optical amplifiers and in particular the optically-pumped erbium doped fiber amplifier (EDFA), are widely used in fiberoptic transmission systems (see, for example, E. Desurvire, Erbium Doped Fiber Amplifiers. Wiley, New York, 1994).
  • EDFA optically-pumped erbium doped fiber amplifier
  • a weak 1550 nanometer (nm) optical signal and a strong 980 nm pump signal, both propagating in single- mode optical fiber are combined by means of a fused dichroic coupler into one single-mode fiber. This fiber is then coupled to a single-mode erbium-doped fiber where the erbium ions absorb the pump radiation and provide gain at the signal wavelength.
  • the output of the EDFA is an amplified replica of the input signal.
  • the pump source consists of a laser diode operating in a single transverse mode coupled to single-mode optical fiber.
  • the amount of optical power that can be obtained from such devices is limited by the power density at the output facet of the pump laser.
  • To increase the diode output power it is necessary to increase the emitting area of the diode.
  • the transverse mode structure of the resulting broad area laser becomes multimode, and the laser output is no longer sufficiently coherent to be coupled into a single-mode fiber.
  • Such a diode output can, however, be coupled into a multimode fiber, to provide an essentially incoherent source for pumping the amplifier.
  • multimode fibers are typically round, since this shape is easier to fabricate than any alternative shape.
  • ytterbium may be added to the fiber (as taught in, for example, US patent no. 5,225,925, to Grubb, et al. issued Jul. 6. 1993).
  • energy absorbed by the ytterbium ions is efficiently transferred to the erbium ions. This results in a fiber with a much stronger, broader absorption than can be obtained in a singly-doped erbium fiber.
  • An amplifier made from such fiber can be pumped with longer wavelength sources, such as a diode-pumped neodymium laser (see Grubb, et al. Electronics Letters, 1991); output powers in excess of 4 watts (w) have been reported (Grubb, et al. paper TuG4 OFC 1996).
  • the wavelengths of neodymium lasers used for this purpose has varied from 1064 nm in Nd:YAG to 1047 nm in Nd:YLF. Over this range in a typical fiber, the Yb absorption varies from 2 to 7 dB/m.
  • Multimode pump sources and couplers are also optimized for round fiber.
  • the pump fiber diameter be less than or equal to the minimum inner diameter of the low-index silica outer cladding. Any radial perturbation in such fibers will be constrained to an annular region whose inner diameter is limited by the pump fiber diameter and whose outer diameter is limited by the fiber outer diameter and cladding thickness.
  • the constraints on actual fibers are such that the radial dimension of the waveguide can only vary by ⁇ 10%, with values as small as ⁇ 5% being preferable in some cases.
  • the enhanced fiber should retain the preferred round shape to remain compatible with other fiber components, as noted above.
  • the core of the fiber should preferably be substantially in the center of the fiber.
  • an optical fiber coupler comprises: a central glass core, doped to absorb radiation at a pump wavelength and to provide gain at a signal wavelength, a first glass cladding layer that, at the pump wavelength, is transparent and that, at the signal wavelength, optimizes coupling and amplification for the fundamental mode while minimizing coupling and amplification for other modes, and a second glass cladding layer with a noncircular outer boundary that is still near enough to round and concentric that a round outer cladding is possible.
  • the fiber may include a third cladding layer, that has an inner boundary that conforms to the outer boundary of the second cladding and that has a round outer diameter.
  • a method for making the optical fiber coupler according to the invention includes a sequence of procedures where the core and first cladding regions are fabricated using MCVD and solution doping in a fused silica preform, the non-circular interface between the second and third claddings is obtained by inserting a series of rods into holes drilled at the core-cladding interface of a silica preform with a fluorosilicate outer cladding layer, and a final preform is prepared by inserting the first preform into a hole in the second preform that is concentric with its outer diameter.
  • the fiber of the present invention is sufficiently asymmetric that it allows radiation propagating in the multimode waveguide to be efficiently absorbed in the core, yet sufficiently symmetric that it can be handled like conventional round fiber.
  • FIG. 1 is a cross sectional illustration of an optical fiber having a core and three claddings, in accordance with the present invention
  • FIG. 2 illustrates the propagation of light rays in a conventional round optical fiber
  • FIG's. 3a - 3c are a series of cross sectional illustrations demonstrating steps for producing a noncircular waveguide embedded in a round glass fiber.
  • the optimum area for the multimode waveguide depends on the pump wavelength and the desired performance. For 1047 nm-like performance with a 950 nm pump the area ratio would have to be 60. For 1064 nm-like performance with a 975 nm pump an area ratio of 1250 would be acceptable.
  • a typical value of 100 is consistent with typical pump diodes, single-mode core diameters, and multimode fiber numerical apertures. For example, the core diameter of a typical single-mode fiber at 1550 nm (Corning SMF-28) is 8.3 ⁇ m, leading to a multimode waveguide diameter of 83 mm.
  • a typical 1 Watt (W) laser diode has an aperture of 100 mm and a numerical aperture of 0.13; assuming a (typical) silica multimode fiber numerical aperture of 0.22, this can be focused into a 60 ⁇ m fiber.
  • the difference between 60 ⁇ m and 83 ⁇ m can be used to accommodate any mechanical tolerances and aberrations in the coupling optics.
  • the choice of core size is dependent upon which one of many attributes one wishes to emphasize in a particular application.
  • D the core diameter
  • D the core diameter
  • the input signal is usually much larger than the amplifier saturation power, and the issue of core size is less important.
  • the optimum core size is then limited by the bending losses associated with large, low numerical aperture (NA) fibers.
  • FIG. 1 there is illustrated therein a cross-sectional view of an optical fiber 10 having a core 12, and three claddings 14, 16, and 18 respectively.
  • a layer of doped material corresponding to cladding 14 may be deposited between cladding 16, such as a silica starting tube, and the YbEr doped core 12. If this layer of doped material is thick enough, and is fabricated of the right materials, then the properties of the fundamental radiation mode will be determined only by the core index and the surrounding index pedestal.
  • the core 12 may be fabricated of any of a number of core materials known in the art, preferred materials being Yb-Er doped optical fibers which may further include a doping material such as phosphorous and/or cesium, among others.
  • the first cladding region 14, also referred to as the pedestal, is as described above, one or more layers of doped material.
  • cladding 14 may include a first doped layer 20 and a second doped layer 22.
  • One preferred function of the first cladding 14 is to have a higher index of refraction than the silica starting tube (cladding 16), though less than the core 12.
  • layer 22 may be fabricated of any one or more materials well known in the art, an example of which is germanium.
  • Layer 20 may likewise have a reflective property or may be adapted to perform other functions.
  • layer 20 may be fabricated of a material which absorbs or strips undesirable modes of light. Accordingly, layer 20 may be fabricated of a cobalt containing material. Other functions (and materials) may be employed as both layers 20 and 22.
  • cladding 14 may also be eliminated in certain applications. Disposed about cladding 14 is second cladding 16, which is typically fabricated of a layer of pure or modified silica material 24, or other material as is well known in the art.
  • the third cladding layer 18 is disposed about the outside of the second cladding layer 16, and is typically fabricated of a fluorine doped silica material 26, and is the outer covering for the optical fiber.
  • Typical refraction index profiles for the core and claddings are also shown in FIG. 1, and below.
  • the optical modes typical of the structure of FIG. 1 can be calculated from the usual Bessel functions, and the effective indices and power densities can be calculated for each mode.
  • the modes can be labeled by their effective indices as core modes (ni > n e ff > n_), pedestal modes (n 2 > n e ff > n 3 ), and waveguide modes (n 3 > n e f > n ).
  • core modes ni > n e ff > n_
  • pedestal modes n 2 > n e ff > n 3
  • waveguide modes n 3 > n e f > n
  • Table 1 gives the effective indices and the distribution of the modal power or modes (HE) in both the core and pedestal modes, as well as the region defined by layer 20. The fraction of the power in this region can be used to estimate how losses in this region will affect the various modes.
  • HE modal power or modes
  • Table 1 Properties of the core and pedestal modes at 1550 nm for the fiber shown in FIG. 1.
  • the fiber is single-mode only in the sense that there is only one guided core mode, and that its n e ff is sufficiently different from the other modes that any direct form of mode coupling is unlikely. It is not a true single-mode fiber because of the existence of guided cladding modes. The fact that some of these modes have appreciable overlap with the core 12 can complicate the performance of an amplifier using this fiber.
  • One potential difficulty with having higher order guided modes is coupling loss.
  • the pedestal region has been designed to produce a fundamental mode that very closely resembles that of conventional single-mode fiber.
  • Mode overlap arguments suggest that most of the incident power will be coupled to the fundamental mode. Nonetheless, fiber misalignments and imperfections will always result in some power being coupled into other guided modes.
  • This power likely to be concentrated in modes such as the HE22 mode which, as can be seen in Table 2, has appreciable overlap with the core region. In an amplifier, these modes are likely to experience appreciable gain. The difficulty with this is that the amplified pedestal signal can be remixed with the fundamental mode signal by imperfections in the output splice.
  • One way of avoiding this problem is to selectively attenuate the pedestal modes at the signal wavelength.
  • the fundamental mode intensity decreases rapidly outside the core region, and is almost negligible in the edge regions of the pedestal. Most of the higher order modes have significantly higher power density in this region. If the edge region, i.e., layer 20, is doped, as described above, to be absorbing at 1550 nm, then the higher order modes will be attenuated without perturbing the fundamental mode. This absorbing region will act like the mode stripping coatings on conventional single-mode fiber, and will make the double clad fiber effectively single-mode at 1550 nm.
  • Dopants with the correct spectroscopic properties include Tb 3+ , Co 2+ , OH- and B2O 3 . To minimize the doping level, and resulting index perturbation, a strongly absorbing dopant is desirable. Of the dopants listed, either Co 2+ or Tb 3+ appear to have the strongest contrast ratio (see Ainslie, et al. J_
  • Co 2+ is the most strongly absorbing.
  • Co 2+ is the ion used in filter glasses such as Schott BG-3, which attenuate at 1550 nm with negligible loss at 950 nm. In fused silica, the absorption has a value of 0.4 dB/m/ppmw. (P.C. Schultz, J. Am. Ceram. Soc. 57, 309, 1974).
  • a Co 2+ concentration of approximately 100 ppmw in the edge region would give a loss of approximately 0.2 dB/m for the fundamental mode, 3.8 dB/m for the HE21 mode and much higher losses for the other modes.
  • Co 2+ -induced loss at 950 nm is expected to be less than 0.01 dB/m.
  • Co 2+ can be introduced into the preform using conventional solution doping techniques. The existence of volatile compounds like Co(CO) 3 NO suggests that MCVD may ultimately be possible.
  • a solution doped fiber would presumably be made by depositing a germanosilicate or aluminosilicate frit on the inside of the starting tube. After solution doping and sintering, this layer would have, for example, a Co 2+ concentration of approximately 100 ppmw and a refractive index equal to that of the germanosilicate layers that are then added to make the remainder of the pedestal region.
  • the Yb Er core is deposited by conventional means. Note that this technique can be used in any double clad fiber, and need not be limited to round or silica clad designs. Potential problems would be variations in the Co 2+ doping, index mismatches between the Co 2+ doped region and the rest of the pedestal, and the possibility of Co 2+ migration into regions where it will attenuate the fundamental mode.
  • the Co 2+ doped absorbing region of layer 20 can be used to eliminate problems at the signal wavelength, but there are also potential problems at the pump wavelength.
  • the pedestal forms a waveguide with radial symmetry, and the higher order modes do not interact strongly with the core. This problem is minimized by keeping the pedestal small. All the modes in Table 1 have more than 1% of their power in the core region, so their absorption efficiency is no worse than for an average cladding mode.
  • any further increase in the pedestal diameter would result in a group of modes with greatly reduced core interactions.
  • This solution may not be possible for the waveguide modes, where a much larger waveguide area is required. Instead it is necessary to eliminate the radial symmetry of the waveguide.
  • FIG. 2a and 2b illustrates propagation of the waveguide modes in a round outer cladding fiber 32, and forms the starting point for analyzing the nonsymmetric geometries as described below.
  • the two angles q z and qf are defined in the drawing and are conserved on reflection.
  • n c r cos qf .
  • ray propagation can be characterized by a ray trace in the projection plane where it can be seen in Fig. 2b that for a round fiber, n c is invariant.
  • the allowable variation in fiber radius is limited by the need to have a round fiber that can be spliced to a round multimode pump fiber.
  • An inner radius ro is chosen to be greater than or equal to the radius of the pump fiber.
  • a radially varying positive perturbation dr(f) is added to the diameter such that its maximum value, dr ma ⁇ , gives a value of ro + dr m a ⁇ less than the outside fiber radius, minus the cladding thickness.
  • the modes are of the form f(x)g(y), where f and g are sines or cosines. Because of the cosine terms, 25% of the modes have maxima at the fiber center. This is not ideal, because the remaining 75% of the modes have minima at the center and will not be absorbed without additional mode mixing. However, this shows that fibers with lower symmetry can have stronger absorption.
  • the propagation of rays can be characterized by a two dimensional ray trace in the projection plane, with the appropriate figure of merit being related to the pathlength in this plane normalized to r 0 .
  • Practical evaluation of fiber shapes can be achieved by considering an ensemble of rays launched with large r lc (for example, r_ c > 0.9 ro) and then propagating these rays in the plane until a large fraction (for example, 90% of the rays) has passed at least once along a trajectory with a small value of r*. c (for example, r- c ⁇ 0.1 ro).
  • the figure of merit L ⁇ o/ro for the perturbation is then the normalized pathlength in the projection plane required to achieve this.
  • the first shapes to consider are regular polygons.
  • One observation is that the performance of the triangular and pentagonal shapes are nearly identical.
  • a second observation is that while L90/1O increases with the number of sides, it is not a smooth quadratic function. The even and odd values larger than 4 do scale approximately quadratically, but the even-sided polygons appear to be twice as efficient as their odd-sided counterparts. Furthermore, the calculated values for the three and four sided figures are significantly larger than the values extrapolated from larger polygons.
  • Polygons are not especially well adapted to the problem of making all- silica nearly-round fibers with small values of dr max .
  • the first polygon to have dr ma ⁇ /ro ⁇ .1, for example, is an octagon. This is a potentially useful shape, since it gives a figure of merit only slightly worse than that of the triangular fiber.
  • the fiber has a centered core and has equal radii across any two perpendicular directions.
  • Polymer clad rectangular fibers have been made by grinding the preform to the desired shape and then drawing the fiber near enough its softening point that the shape is preserved. The polymeric cladding is then coated onto the fiber where it conforms to the existing shape.
  • the equivalent fabrication process for an octagon is greatly complicated by the larger number of sides to be ground. It is also difficult to make all-silica polygonal fibers, since there is no readily apparent process analogous to the low-index organic coating that produces a conforming low index silica cladding.
  • FIG. 3A shows a conventional preform for an all silica multimode fiber.
  • the silica core 40 is overlaid with a layer of fluorine doped silica 42.
  • Such preforms are available commercially from Hereus.
  • the vias 44- 58 may be circular holes as illustrated in FIG. 3B, or some other shape.
  • the vias are simply present to introduce irregularities into the shape of preform 40. Undoped silica rods may then inserted into these holes to produce the profile shown in FIG. 3C. Thereafter, the core and pedestal region such as described hereinabove with respect to Fig. 1, may be introduced into the preform of FIG. 3C.
  • an optical fiber having a central core region appropriately doped to absorb radiation and provide gain at preselected wavelengths.
  • Disposed around the core may be a first region adopted to modify or strip modes in light introduced into the core.
  • a first cladding layer found of for example, silica, and having a radially constrained, substantially non-circular outer boundary.
  • radially constrained substantially non-circular it is meant that the outside surface of the first cladding layer is generally round in cross-section and tubular overall, but due to the pattern of predefined irregularities manufactured into the cladding the outer boundary does not define a smooth, regular circle or tube.
  • a second cladding layer having an inner boundary which conforms to the outer boundary of the first cladding layer, and a regular round outer boundary.
  • the effectiveness of this design illustrated in FIG. 3 is determined by both the size and number of holes. Accordingly, the instant invention is not limited either by the number of holes deposited herein, nor by the hole sizes. Rather, any number of variably sized holes may be appropriate for a given fiber application.
  • Table 4 gives calculated figures of merit for different hole arrangements. For a given hole size, the figure of merit decreases almost linearly with the number of holes. This is to be expected, since any reflection from the original round surface causes no change in r-c.
  • each new hole or irregularity reduces the amount unperturbed surface, it also reduces the time that each ray spends "idling" at a particular value of r ⁇ c .
  • Larger vias or holes also contribute to this effect because each via hole occupies a larger fraction of the fiber circumference. However, for a given circumference, a larger number of smaller holes is more effective, as can be seen by comparing the bracketed values in Table 4.
  • parentheses 0 cannot be fabricated by rod-in-tube methods due to interference between adjacent rods.
  • Values in brackets _ ⁇ represent shapes with approximately equal unperturbed circumferences. Smaller values correspond to better performance.
  • the combinations involving fewer, larger holes may be easier to fabricate, simply because there are fewer holes to make.
  • a rod of radius rb that has a focal length rb / 2 as a reflector has a focal length of (rb / 2)(n/ ⁇ n) as a refractive rod with index n + ⁇ n, where n is the refractive index of the original material. Since in most practical cases, ⁇ n « n, the reflector will be much more strongly focusing than the lens, and effectiveness of the refractive technique will be much lower than that of the reflective technique. Nonetheless, it may provide a practical alternative in some cases, especially if large values of ⁇ n are achievable.
  • a second related technique is to introduce stresses into the first cladding region so that the stress-induced index changes perturb the skew ray trajectories.
  • Stresses could be introduced by adding stress members such as inserted borosilicate rods to the region outside the waveguide. This has the advantage that the perturbations are all external to the guiding region, so that no extra losses will be introduced. Stress introduces both index changes and birefringence, and both can perturb the ray trajectories. The index changes will produce lensing analogous to that produced by the rod lenses, although shapes of the index distortions are unlikely to be conveniently round and lens-like, so the exact deflections will be difficult to calculate.
  • Birefringence can cause the reflections to occur at angles different from the usual law of reflection. This is analogous to double refraction.
  • the magnitude of the index changes that can be achieved by stress is quite small, as distortions large enough to change the material density appreciably also tend to cause fracture in a brittle material like glass.
  • it is unlikely that the perturbations achieved by this technique will be as effective as those created by the reflective technique. Nonetheless, it may be a useful technique in some cases, especially when loss is an important issue.
  • a 1 watt laser diode at 950 nm (model 6360 from SDL Inc., San Jose, CA) can be coupled to 60/125, 0.22 NA, all-silica multimode fiber with an efficiency approaching 100%; an actual coupling efficiency of at least 80% is reported using a lens system sold by LIMO-Lissotschenko Mikrooptik, GmbH, Dortmund, Germany.
  • the increase in fiber diameter is required to accommodate spherical aberration in the GRIN lenses.
  • FWDM filter wavelength division multiplexer
  • a multimode preform can be obtained from Hereus-Amersil, Inc, (Duluth, GA) where a fused silica rod with a diameter of 20 mm is surrounded by a 5.6 mm thick layer of a fluorosilicate material with a refractive index 0.017 lower than the undoped fused silica.
  • a fused silica rod with a diameter of 20 mm is surrounded by a 5.6 mm thick layer of a fluorosilicate material with a refractive index 0.017 lower than the undoped fused silica.
  • 5 holes 6 mm in diameter are drilled parallel with the axis of the rod. One is centered on the axis, and the other four are symmetrically arranged with their centers 9 mm from the axis.
  • the rods to be inserted in the 4 radial holes are made from fused silica.
  • the rod to be inserted in the central hole is a preform made by MCVD and solution doping techniques.
  • a 0.5 mm thick germanosilicate frit is prepared and solution doped with Co 2+ from an aqueous solution.
  • This layer will have a Co 2+ concentration of 100 ppmw and a refractive index 0.008 larger than pure fused silica.
  • This layer is dried and sintered as usual and then a 1 mm thick germanosilicate layer with the same refractive index is applied over it. A phosphosilicate frit is then applied and solution doped with Yb and Er.
  • This layer is dried and sintered, and then the preform is collapsed to its final 6 mm outer diameter.
  • This tube is then inserted in the central hole and the entire preform is heated to fuse the rods into the holes.
  • This preform is then drawn to a 125 mm outer diameter using conventional techniques.
  • a length of 2 to 10 meters will be sufficient to absorb a 950 nm pump and will provide gain in excess of 50 dB.
  • a second example would be a higher power laser pumped at the absorption maximum of 975 nm to yield performance similar to a 1064 nm- pumped device. In this case, an area ratio of 1250 combined with an 8.3 mm core would permit the use of a 290 mm outer waveguide.

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  • Optics & Photonics (AREA)
  • General Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
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  • Optical Fibers, Optical Fiber Cores, And Optical Fiber Bundles (AREA)

Abstract

L'invention concerne une fibre optique (10) comprenant un coeur central (12), une première couche de gainage (16) ainsi qu'une seconde couche de gainage (18) présentant une série de perturbations ou d'irrégularités formées dans la limite extérieure circulaire de la première couche de gainage. Les irrégularités dans la première couche de gainage arrêtent la propagation de rayons obliques et favorisent le couplage à l'intérieur du coeur. Les irrégularités sont formées par perçage de trous (44-58) dans la préforme de fibres, lesquelles sont parallèles à son axe longitudinal, puis insertion de tiges dans lesdits trous. Une couche de gainage intermédiaire (14) est prévue pour supprimer les modes de coeur d'ordre supérieur. On utilise les fibres optiques dans le gainage de lasers et d'amplificateurs à fibres optiques pompés.
PCT/US1998/025943 1997-12-09 1998-12-07 Fibres optiques dopees aux terres rares a double gainage WO1999030391A1 (fr)

Priority Applications (3)

Application Number Priority Date Filing Date Title
BR9813450-7A BR9813450A (pt) 1997-12-09 1998-12-07 Fibras ópticas indutadas com terras raras com duplo revestimento
EP98960794A EP1038338A1 (fr) 1997-12-09 1998-12-07 Fibres optiques dopees aux terres rares a double gainage
DE1038338T DE1038338T1 (de) 1997-12-09 1998-12-07 Doppelt ummantelte, mit seltenen erden dotierte optische faser

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US98786297A 1997-12-09 1997-12-09
US08/987,862 1997-12-09

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WO1999030391A1 true WO1999030391A1 (fr) 1999-06-17

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BR (1) BR9813450A (fr)
DE (1) DE1038338T1 (fr)
ES (1) ES2154251T1 (fr)
WO (1) WO1999030391A1 (fr)

Cited By (17)

* Cited by examiner, † Cited by third party
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EP1182475A2 (fr) * 2000-08-25 2002-02-27 Agere Systems Optoelectronics Guardian Corporation Réseaux à fibre optique avec gaine rugueuse pour réduire les pertes aux modes de gaine de courte longueur d'onde
EP1241744A1 (fr) * 2001-03-12 2002-09-18 Alcatel Amplificateur à fibre optique à double gainage
US6477307B1 (en) 2000-10-23 2002-11-05 Nufern Cladding-pumped optical fiber and methods for fabricating
US6625363B2 (en) 2001-06-06 2003-09-23 Nufern Cladding-pumped optical fiber
US6687445B2 (en) 2001-06-25 2004-02-03 Nufern Double-clad optical fiber for lasers and amplifiers
US6950586B2 (en) 2001-03-02 2005-09-27 Ocg Technology Licensing, Llc Fiber for enhanced energy absorption
US6959022B2 (en) 2003-01-27 2005-10-25 Ceramoptec Gmbh Multi-clad optical fiber lasers and their manufacture
WO2006089999A1 (fr) * 2005-02-23 2006-08-31 Liekki Oy Methode de traitement de faisceaux de fibres optiques
US7116887B2 (en) 2002-03-19 2006-10-03 Nufern Optical fiber
US7317857B2 (en) 2004-05-03 2008-01-08 Nufem Optical fiber for delivering optical energy to or from a work object
GB2444091A (en) * 2006-11-24 2008-05-28 Gsi Group Ltd A Laser Amplifier
US7483610B2 (en) 2004-05-03 2009-01-27 Nufern Optical fiber having reduced defect density
US7839902B2 (en) 2006-06-23 2010-11-23 Gsi Group Ltd. Fibre laser system
US8213758B2 (en) 2006-09-20 2012-07-03 Imra America, Inc. Rare earth doped and large effective area optical fibers for fiber lasers and amplifiers
US8902493B2 (en) 2008-12-04 2014-12-02 Imra America, Inc. Highly rare-earth-doped optical fibers for fiber lasers and amplifiers
WO2017143429A1 (fr) * 2016-02-26 2017-08-31 Coractive High-Tech Inc. Fabrication de fibres optiques à saillies longitudinales rompant la symétrie
DE10059314B4 (de) 2000-11-29 2018-08-02 Tesat-Spacecom Gmbh & Co.Kg Lichtleitende Faser und Verfahren zum Herstellen einer lichtleitenden Faser

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EP1182475A2 (fr) * 2000-08-25 2002-02-27 Agere Systems Optoelectronics Guardian Corporation Réseaux à fibre optique avec gaine rugueuse pour réduire les pertes aux modes de gaine de courte longueur d'onde
EP1626296A3 (fr) * 2000-08-25 2006-02-22 Agere Systems Optoelectronics Guardian Corporation Réseaux à fibre optique avec gaine ayant des hauteurs structurées pour réduire les pertes des modes de gaine aux courtes longueurs d'ondes
EP1626296A2 (fr) * 2000-08-25 2006-02-15 Agere Systems Optoelectronics Guardian Corporation Réseaux à fibre optique avec gaine ayant des hauteurs structurées pour réduire les pertes des modes de gaine aux courtes longueurs d'ondes
EP1182475A3 (fr) * 2000-08-25 2003-08-06 Agere Systems Optoelectronics Guardian Corporation Réseaux à fibre optique avec gaine rugueuse pour réduire les pertes aux modes de gaine de courte longueur d'onde
US6779364B2 (en) 2000-10-23 2004-08-24 Nufern Cladding-pumped optical fiber and methods for fabricating
US6477307B1 (en) 2000-10-23 2002-11-05 Nufern Cladding-pumped optical fiber and methods for fabricating
US7003206B2 (en) 2000-10-23 2006-02-21 Nufern Cladding-pumped optical fiber and methods for fabricating
DE10059314B4 (de) 2000-11-29 2018-08-02 Tesat-Spacecom Gmbh & Co.Kg Lichtleitende Faser und Verfahren zum Herstellen einer lichtleitenden Faser
US6950586B2 (en) 2001-03-02 2005-09-27 Ocg Technology Licensing, Llc Fiber for enhanced energy absorption
EP1241744A1 (fr) * 2001-03-12 2002-09-18 Alcatel Amplificateur à fibre optique à double gainage
US6625363B2 (en) 2001-06-06 2003-09-23 Nufern Cladding-pumped optical fiber
US6687445B2 (en) 2001-06-25 2004-02-03 Nufern Double-clad optical fiber for lasers and amplifiers
US7116887B2 (en) 2002-03-19 2006-10-03 Nufern Optical fiber
US6959022B2 (en) 2003-01-27 2005-10-25 Ceramoptec Gmbh Multi-clad optical fiber lasers and their manufacture
WO2004070431A3 (fr) * 2003-01-27 2005-12-08 Ceramoptec Ind Inc Lasers a fibres optiques a gaines multiples et leur fabrication
US7317857B2 (en) 2004-05-03 2008-01-08 Nufem Optical fiber for delivering optical energy to or from a work object
US7483610B2 (en) 2004-05-03 2009-01-27 Nufern Optical fiber having reduced defect density
WO2006089999A1 (fr) * 2005-02-23 2006-08-31 Liekki Oy Methode de traitement de faisceaux de fibres optiques
US7839902B2 (en) 2006-06-23 2010-11-23 Gsi Group Ltd. Fibre laser system
US8213758B2 (en) 2006-09-20 2012-07-03 Imra America, Inc. Rare earth doped and large effective area optical fibers for fiber lasers and amplifiers
US8542968B2 (en) 2006-09-20 2013-09-24 Imra America, Inc. Rare earth doped and large effective area optical fibers for fiber lasers and amplifiers
US9151889B2 (en) 2006-09-20 2015-10-06 Imra America, Inc. Rare earth doped and large effective area optical fibers for fiber lasers and amplifiers
GB2444091A (en) * 2006-11-24 2008-05-28 Gsi Group Ltd A Laser Amplifier
US8902493B2 (en) 2008-12-04 2014-12-02 Imra America, Inc. Highly rare-earth-doped optical fibers for fiber lasers and amplifiers
WO2017143429A1 (fr) * 2016-02-26 2017-08-31 Coractive High-Tech Inc. Fabrication de fibres optiques à saillies longitudinales rompant la symétrie
CN109071312A (zh) * 2016-02-26 2018-12-21 科拉克蒂夫高科技公司 制造具有破坏对称性的纵向突起的光纤

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DE1038338T1 (de) 2001-02-08

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