EP3695257A1 - Dispositif et procédé de soudage de fibres de verre à un réseau de microlentilles pour fabriquer un réseau de collimateurs de fibres - Google Patents

Dispositif et procédé de soudage de fibres de verre à un réseau de microlentilles pour fabriquer un réseau de collimateurs de fibres

Info

Publication number
EP3695257A1
EP3695257A1 EP19742231.4A EP19742231A EP3695257A1 EP 3695257 A1 EP3695257 A1 EP 3695257A1 EP 19742231 A EP19742231 A EP 19742231A EP 3695257 A1 EP3695257 A1 EP 3695257A1
Authority
EP
European Patent Office
Prior art keywords
fiber
lens array
glass fiber
light
wavelength
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP19742231.4A
Other languages
German (de)
English (en)
Inventor
Peter Schmidt
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Schleifring GmbH
Original Assignee
Schleifring GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Schleifring GmbH filed Critical Schleifring GmbH
Publication of EP3695257A1 publication Critical patent/EP3695257A1/fr
Pending legal-status Critical Current

Links

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
    • G02B6/24—Coupling light guides
    • G02B6/26—Optical coupling means
    • G02B6/32—Optical coupling means having lens focusing means positioned between opposed fibre ends
    • 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
    • G02B6/24—Coupling light guides
    • G02B6/42—Coupling light guides with opto-electronic elements
    • G02B6/4201—Packages, e.g. shape, construction, internal or external details
    • G02B6/4219—Mechanical fixtures for holding or positioning the elements relative to each other in the couplings; Alignment methods for the elements, e.g. measuring or observing methods especially used therefor
    • G02B6/422—Active alignment, i.e. moving the elements in response to the detected degree of coupling or position of the elements
    • G02B6/4225—Active alignment, i.e. moving the elements in response to the detected degree of coupling or position of the elements by a direct measurement of the degree of coupling, e.g. the amount of light power coupled to the fibre or the opto-electronic element

Definitions

  • the invention relates to a device and a method for welding a glass fiber to a lens to manufacture fiber optic collimators or fiber optic collimator arrays.
  • Such fiber collimators or fiber collimator arrays are able to transmit a high optical power, have a very low pointing error and a high channel density and may be used in in optical rotary joints. Description of the related art
  • Optical transmission systems and specifically optical rotary joints must meet a high level of requirements on precision, transferrable power, insertion loss and return loss.
  • US 9,726,824 B1 discloses an optical circuit switch collimator, where a plurality of fibers is held in a fiber array matching to a lens array.
  • the lens array and the fiber array must match precisely, which requires a complex and expensive manufacturing process.
  • the precision of such a fiber array is limited by mechanical tolerances, the maximum power handling is limited by the damage threshold of the glue between fiber array and lens array.
  • the maximum transferable power of such glued collimators is limited to a few lOOmW.
  • Advanced fiber collimator arrays for high power applications with glass fibers directly welded to a micro lens array suffer from increased optical losses caused by relatively low precision of the lateral fiber position.
  • a method for welding glass fibers in a 2D-arrangement and a high package density is described in DE10204012B4. The welding increases the reliability of the connection and addi- tionally allows the transmission of optical power up to some watts over a single mode fiber, which is an advantage over a glued connection.
  • the above men tioned relatively low precision of the fiber position relative to the lens is in the range of some micrometers and results in a pointing error of every single colli- mator, which in turn leads to an increased insertion loss of the collimators.
  • At greater working distances, as typical for fiber optic rotary joints not only the insertion loss increases, above all the variation of the insertion loss during rota tion. This is a disadvantage of collimators or collimator arrays manufactured by means of this existing process.
  • the problem to be solved by the invention is to provide a device and a method for welding of glass fibers to a lens or a micro lens array, which allows to minimize the positioning error of the glass fiber relative to a lens down to the sub-micrometer range and to minimize the pointing error of every single collimator of a fiber collimator array resulting from this process.
  • a collimator is a lens with an attached fiber.
  • a fi ber collimator array also called FCA may comprise one or a plurality of lenses, preferably comprising glass or any other optical transparent material with at least one optical fiber, preferably glass fiber attached to the at least one lens. Normally, one fiber is attached to one lens.
  • the collimator and/or collimator array has a fiber side to which the fibers are connected and oposing thereto an output side.
  • the embodiments disclosed herein are alternatively usable for fiber collimators and fiber collimator arrays.
  • the fibers may be attached by welding of individual fibers each and preferably one fiber at one time. For welding an individual glass fiber may be selected.
  • the glass fiber is positioned into close proximity of the lens to which it has to be welded by a fiber positioning device.
  • Welding of the glass fiber may be done by heating up the fiber and/or lens or MLA (micro lens array) laterally with a high- power laser producing high-power laser pulses of a first wavelength.
  • a laser may be a C02 Laser or any other appropriate laser source with a wavelength that is absorbed sufficiently to heat up the used materials.
  • the first wavelength may be in a range of 9,4 to 10,6 pm.
  • low power light of a second, different wavelength e.g. 1550nm, 1310nm, 850nm or any value in between
  • a second, different wavelength e.g. 1550nm, 1310nm, 850nm or any value in between
  • This light is forwarded by the lens associated with the glass fiber to a mirror mounted at the output side of the lens array and distant to the lens array at a first distance.
  • the distance may be half of the operational distance of the lens array.
  • the light reflected by the mirror may be coupled back through the lens and the fiber to a detector.
  • the detector provides an output signal indicating the optical power received by the detector.
  • a perfect alignment of fiber results in a maximum detector output signal whereas the signal decreases with position (lateral or along the optcal axis of the fiber) or angular displacement of the fiber.
  • the detector and the second wavelength light source may be coupled by a coupler which may be a 3 dB coupler to the glass fiber.
  • a wavelength selective filter configured for selectively blocking the first wavelength may be provided between the coupler and the glass fiber.
  • the detector output signal may be used to control the fiber positioning device, which may further be a closed loop control.
  • the fiber positioning device may be configured to adjust the fiber position for maximum detector output signal which results in a minimum insertion loss. Such an adjustment of the glass fiber may be done before and/or during the welding until the weld is mechanically stable.
  • all fiber collimators of an FCA fiber collimator array manufactured with the described process resulting in parallel optical axis.
  • a reference fiber collimator may be used.
  • This reference fiber collimator has at least one reference fiber which is coupled to the light detector.
  • a wavelength selective filter configured for selectively blocking the first wavelength may be provided between the at least one reference fiber and the light detector.
  • the MLA can be positioned relatively to the fiber kept static.
  • Another advantage of the present invention is the compensation of the devia tions of the lens shape between the single lenses of a micro lens array as well as the deviation from the ideal lens shape. Differences within the fiber or the quali ty of the fiber end faces are compensated as well.
  • the pointing error angular deviation
  • the pointing error is therefore no longer limited by the absolute position accuracy of the used machine, but rather by the smallest increment of the positioning unit itself.
  • the material of the each component used to manufacture a welded FCA can be different, e.g. fused silica and Pyrex or Borofloat or any other optically and / or near infrared transparent material e.g. silicon.
  • the softening point of the lens material is lower than that of the fiber.
  • an insertion loss profile of each lens of an MLA can be recorded before welding.
  • the optical axis of a fiber preferably a referential fiber
  • the fiber is moved in x-, y- and z- direction.
  • the stored relationship between position of the fiber and the insertion loss can be used to optimize the adjustment during welding, e.g. by moving the fiber to a position where slight variations does not affect the insertion loss.
  • the fiber endface can be optionally held in direct contact, at a defined distance or alternatively coupled with an index matching gel to the surface of the micro lens array.
  • the laser energy of the high-power laser is not coupled into the core of the fiber directly, a part of the energy might be coupled into the fiber and manipulate measurement results or even destroy the detector.
  • the detector may be protected from the high-power laser by a wavelength selective filter which may allow light of the second wavelength to pass and blocks light of the first wavelength.
  • the mirror, reflecting the light back into the currently processed fiber can be coated to absorb any stray light of the first wavelength but be transparent for the second wavelength.
  • the embodiments enables the manufacturing of fiber collimators or fiber collimator arrays simultaneously having a high channel density, a low insertion loss and the capability to transmit high optical power.
  • Such fiber collimators or fiber collimator arrays may be used in areas in which not only a reliable transmission of high optical power and low insertion loss is required but also a temporarily or permanent contact with fluids is present.
  • the heat, resulting from unavoidable losses, can be dissipated much better with welded than with glued fibers as the thermal conductivity of a welded joint by far exceeds that of a glued joint.
  • fiber collimators or fiber collimator arrays is the improved stability of the return loss during the temperature changes compared to a glued connection.
  • high precision 2D-fiber arrays may be manufactured.
  • a spacer may be inserted temporarily between the fibers and a micro lens array, whereas the latter functions as a reference micro lens array.
  • the pitch of the manufactured 2D-fiber array corresponds to that of the reference micro lens array.
  • the Precision of such 2D-fiber arrays outperforms conventionally produced ID- and 2D-fiber arrays that are manufactured by grinding, sawing or drilling. They can be used in applications or with micro lens arrays of the same pitch.
  • Double clad fi brers in contrast to standard optical fibers provide two optical paths, a higher power in the outer channel (cladding) and a measurement or communication signal in the core.
  • a double-clad fiber may be used where the inner channel serves as a measurement channel for providing the signal necessary for the adjustment of the fiber relative to a lens.
  • a plurality of fibers may be positioned simultaneously and welded simultaneously and/or without repositioning individual fibers.
  • a plurality of fibers is temporarily clamped in a holder comprising a plurality of V-grooves. After the fibers have been positioned and welded, the holder is removed.
  • the holder may be produced in a way that all fiber cores are on a straight line and the pitch of the V-grooves corresponds to that of the micro lens array.
  • a higher channel density compared to conventional glued 1-D fiber arrays can be achieved as the V-groove holder is removed after welding and only the fibers remain on the micro lens array.
  • fiber collimators or fiber collimator arrays produced using the process of the present invention is not limited to optical rotary joints. They may also be used in applications, requiring single- or multi-mode fibers in the wavelength range of 800nm...l700nm and, at the same time, high optical power in the range of a few watt, such as (D)WDM based long haul connections, status scans of fiber Bragg-sensors or antennas and status scans at offshore oil exploration.
  • the embodiments may be applied to micro lens arrays with similar or varying lens shapes or materials.
  • a combination of different fibers, e.g. single-mode fi bers, multi-mode fibers and / or other fiber types in a single fiber collimator ar ray is also possible.
  • a method comprises the steps of:
  • Further optional steps are welding of the fiber to the MLA by using light of a second wavelength.
  • Figure 2 shows a further embodiment with a reference collimator
  • Figure 3 shows a fiber holder module
  • a collimator 100 comprises a lens array 110 and at least one fiber 121, 122, 123.
  • the lens array 110 may be monothithic or may include a lens arry with a spacer (113) which may be attached by glueing or optical contact bonding or any other suitable method.
  • the bodies 110 and 113 are one part.
  • the lens array 110 has a fiber side 111 for attaching fibers and opposing thereto an output side 112, where light leaves or enters the lens array.
  • a glass fiber 121 has been selected to be connected to the lens array. There may be further fibers which have already been connected or will be connected in the future.
  • the collimator or lens array may be held by a support 200.
  • the support 200 may comprises at least one lens array base 210, a main spacer 220, which may be a tube or a hollow cylinder, and a mirror 230.
  • the distance 221 from the mirror 230 to the lens array may be defined by the main spacer 220.
  • the total first distance between the lens array and the mirror is determined by the main spacer 220 and the lens array base 210.
  • the length of the main spacer 220, distance 221 may be about one half of the operating distance of the fiber collimator.
  • the mirror 230 is parallel to the output side 112 of the lens array and/or parallel to the lens array 110.
  • An attenuation measurement device 300 may comprise asecond wavelength light source 310 connected to a coupler 320 which further is connected to glass fiber 121.
  • the fiber may be connected by means of a fiber connector 131.
  • a wavelength selective light filter 330 for passing the second wavelength may be in the light path between the glass fiber 121 and the second wavelength light source 310 and/or the light detector 340.
  • Light from the second wavelength light source 310 is coupled via coupler 320, which may be a 3dB coupler, and the wavelength selective light filter 330 into the glass fiber 121.
  • this fiber 121 is with one end in close proximity to a lens of the lens array 110 and therefore may couple light into the fiber cited 111 of the lens array 110.
  • This light is guided to the output side 112 of the lens array 110 and propagates along the light path 380 towards the mirror 230 from which it is reflected back to the output side 112 of the lens array 110.
  • This light further propagates back through the lens and the glass fiber 121 into coupler 320 and light detector 340, which generates a light detector output signal 341 indicating the optical power received.
  • a fiber positioning device 400 comprises an actuator 410 for moving the glass fiber, preferably with high precision. Such movements may comprise
  • the fiber positioning device device 400 may position the fiber before or during welding dependent on predetermined and/or preprogrammed position values and/or detector output signal 341.
  • the fiber positioning device 400 may further comprise a control unit 420 which may be configured for a closed-loop control of the fiber position based on the detector output signal 341 such that the detector output signal 341 reaches its optimum or maximum value.
  • the fiber may be kept stationary in a welding apparatus and the positioning device 400 with the micro lens array fixed to it may be moved in relation to the fibre.
  • a first wavelength, high-power light source 500 which may be a laser is focused on a lens of the lens array or a surface of the lens array close to a lens and/or the glass fiber for welding the glass fiber to the lens array.
  • the first wavelength, high- power light source 500 may radiate light while or after the glass fiber was put in place by the fiber positioning device 400.
  • FIG. 2 shows a further embodiment.
  • a reference collimator 610 is provided.
  • Such a reference collimator is preferably the same as the collimator 100.
  • the reference collimator is arranged opposing to the collimator with a second distance of a second length of spacer 222 and lens array base 210.
  • a different spacer may be provided.
  • This second length of spacer preferably is the full operating distance of the collimator.
  • At the fiber side one reference fiber 611 or a plurality of fibers is connected to a light detector 340.
  • a filter 330 may be provided.
  • a reference fiber 611 may be selected at a lens of reference collimator 610 which corresponds to the lens of the glass fiber 121 of lens array 110.
  • a plurality of fibers 611 of the reference collimator may be connected at the same time.
  • the lens array 110 may be monothithic or may include a lens array with a spacer (113) attached.
  • the second wavelength light is guided through a first lens array and a second lens array to the light detector, instead of reflecting the light emitted from the first lens array by a mirror back through the first lens array.
  • a fiber holder module 700 is disclosed. Such a module may be used to hold a plurality of fibers at the same time for welding. This may significantly increase the welding speed in a 2D (2-dimensional) collimator array.
  • the module comprises a fiber holder base 701, the base comprising a plurality of V-grooves 711, 712, and a fiber holder plate 702 which holds fibers 721, 722 in place in their V-grooves.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Optical Couplings Of Light Guides (AREA)

Abstract

La présente invention concerne un procédé de fabrication de collimateurs de fibres optiques. Les fibres sont fixées à une lentille ou à un réseau de microlentilles sans avoir besoin de réseaux de fibres préfabriqués avec des rainures en v ou des trous. Un dispositif de soudage d'une fibre de verre à une lentille comprend un rétroréflecteur réfléchissant la lumière dans le collimateur, un détecteur couplé à la fibre actuellement traitée pour recevoir la lumière provenant du collimateur et générer une sortie indiquant la puissance lumineuse reçue et un moyen de positionnement destiné à positionner la fibre de verre par rapport à la lentille sur la base de la sortie du détecteur. La quantité de lumière reçue par le détecteur est une mesure pour l'atténuation du collimateur. La sortie de signal du détecteur est utilisée pour déplacer la fibre dans la position comportant l'atténuation la plus faible et la souder en cette position à la lentille. Toutes les irrégularités et la déviation des lentilles individuelles à partir d'une lentille parfaite provoquées par les tolérances de fabrication sont compensées par ledit procédé.
EP19742231.4A 2018-07-30 2019-07-25 Dispositif et procédé de soudage de fibres de verre à un réseau de microlentilles pour fabriquer un réseau de collimateurs de fibres Pending EP3695257A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP18186401 2018-07-30
PCT/EP2019/070030 WO2020025438A1 (fr) 2018-07-30 2019-07-25 Dispositif et procédé de soudage de fibres de verre à un réseau de microlentilles pour fabriquer un réseau de collimateurs de fibres

Publications (1)

Publication Number Publication Date
EP3695257A1 true EP3695257A1 (fr) 2020-08-19

Family

ID=63108430

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19742231.4A Pending EP3695257A1 (fr) 2018-07-30 2019-07-25 Dispositif et procédé de soudage de fibres de verre à un réseau de microlentilles pour fabriquer un réseau de collimateurs de fibres

Country Status (2)

Country Link
EP (1) EP3695257A1 (fr)
WO (1) WO2020025438A1 (fr)

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH04146411A (ja) * 1990-10-09 1992-05-20 Sumitomo Electric Ind Ltd ファイバコリメータの製造方法
US6587618B2 (en) * 2001-03-16 2003-07-01 Corning Incorporated Collimator array and method and system for aligning optical fibers to a lens array
US6404955B1 (en) * 2001-07-03 2002-06-11 Corning, Incorporated System and method for fabricating arrayed optical fiber collimators
DE10204012B4 (de) 2001-12-20 2005-01-27 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Verfahren zum stoffschlüssigen Verbinden mikrotechnischer Bauteile
US9726824B1 (en) 2016-09-15 2017-08-08 Google Inc. Optical circuit switch collimator

Also Published As

Publication number Publication date
WO2020025438A1 (fr) 2020-02-06

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