WO1992003858A1 - Systeme laser a tranche circulaire couple a un faisceau de fibres - Google Patents

Systeme laser a tranche circulaire couple a un faisceau de fibres Download PDF

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Publication number
WO1992003858A1
WO1992003858A1 PCT/AU1991/000379 AU9100379W WO9203858A1 WO 1992003858 A1 WO1992003858 A1 WO 1992003858A1 AU 9100379 W AU9100379 W AU 9100379W WO 9203858 A1 WO9203858 A1 WO 9203858A1
Authority
WO
WIPO (PCT)
Prior art keywords
iaser
medium
fibre bundle
tubular
output
Prior art date
Application number
PCT/AU1991/000379
Other languages
English (en)
Inventor
John Leonard Hughes
Original Assignee
Australian Electro Optics Pty. Ltd.
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 Australian Electro Optics Pty. Ltd. filed Critical Australian Electro Optics Pty. Ltd.
Publication of WO1992003858A1 publication Critical patent/WO1992003858A1/fr

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Classifications

    • 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
    • H01S3/09—Processes or apparatus for excitation, e.g. pumping
    • H01S3/091—Processes or apparatus for excitation, e.g. pumping using optical pumping
    • H01S3/094—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light
    • H01S3/0941—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light of a laser diode
    • 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
    • H01S3/02—Constructional details
    • H01S3/04—Arrangements for thermal management
    • H01S3/042—Arrangements for thermal management for solid state lasers
    • 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
    • H01S2301/00—Functional characteristics
    • H01S2301/20—Lasers with a special output beam profile or cross-section, e.g. non-Gaussian
    • H01S2301/203—Lasers with a special output beam profile or cross-section, e.g. non-Gaussian with at least one hole in the intensity distribution, e.g. annular or doughnut mode
    • 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
    • H01S3/02—Constructional details
    • H01S3/04—Arrangements for thermal management
    • H01S3/0404—Air- or gas cooling, e.g. by dry nitrogen
    • 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
    • H01S3/02—Constructional details
    • H01S3/04—Arrangements for thermal management
    • H01S3/0407—Liquid cooling, e.g. by water
    • 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
    • H01S3/0602—Crystal lasers or glass lasers
    • H01S3/0608—Laser crystal with a hole, e.g. a hole or bore for housing a flashlamp or a mirror
    • 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
    • H01S3/08—Construction or shape of optical resonators or components thereof
    • H01S3/08095—Zig-zag travelling beam through the active medium
    • 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
    • H01S3/09—Processes or apparatus for excitation, e.g. pumping
    • H01S3/091—Processes or apparatus for excitation, e.g. pumping using optical pumping
    • H01S3/0915—Processes or apparatus for excitation, e.g. pumping using optical pumping by incoherent light
    • H01S3/092—Processes or apparatus for excitation, e.g. pumping using optical pumping by incoherent light of flash lamp
    • H01S3/093—Processes or apparatus for excitation, e.g. pumping using optical pumping by incoherent light of flash lamp focusing or directing the excitation energy into the active medium

Definitions

  • This invention relates to a fiber bundle coupled hybrid laser system consisting of a circular slab of laser medium in the form of an annular, fluid cooled rod optically coupled to an optical fibre bundle both ends of which are optically polished which effectively converts the annular output beam emitted by said hybrid laser system into a laser beam of uniform cross-section, said slab of laser medium having both of its end faces optically polished, one being mirrored for 100% reflection at the laser wavelength whilst the other is anti-reflection coated at the lasing wavelength, said slab medium being fluid cooled via a tube inserted into its hollow centre, the surface of said tube being reflective at the excitation wavelengths of said annular rod which is optically excited via the outer surface via the output of arc lamps, flashtubes or diode laser arrays.
  • the free end of the fibre bundle of the invention is mirrored to partially transmit at the lasing wavelength.
  • the invention has applications in the industrial, medical and defence fields.
  • This invention overcomes the defects of prior art rod lasers firstly by being of an annular rod construction which allows much more effective cooling, thus minimising the "thermal lensing" effect at a given level of excitation. Secondly, the invention overcomes a defect of the prior art rod lasers by allowing for larger output aperture operative areas, hence more output power. Thirdly, the invention allows for both the excitation and the cooling of the Iaser medium over a larger surface area than is the case with rod lasers. Fourthly, the output beam of the invention can be of circular, rectangular of any desired format simply by configurating the output face of the phase-locked fibre bundle to generate the said format. Fifthly, the invention has relatively small optically polished faces which do not have to be fluid cooled, thus overcoming a major problem with prior art slab lasers.
  • Slab lasers have significant advantages over rod lasers in that the slab thickness may be as little as three millimetres so that effective cooling becomes possible. The better the cooling of the Iaser medium, the lower is the thermal lensing effect. Also, if the Iaser beam to be amplified is propagating as parallel as possible to ti. ⁇ direction of minimal thermal gradients in the slab, very little thermal lensing effect occurs so that near diffraction limited Iaser beams can be generated in slab lasers at high power levels.
  • the present invention represents a compromise between a rod and slab Iaser because it has many of the thermal advantages of the slab Iaser yet retains the large ratio of unpolished excitation surface to output surface of rod lasers, which represents a major saving in cost of optical polishing compared to slab lasers of similar power capability.
  • the present invention it is necessary to consider the present invention as a rod/slab/fibre bundle hybrid Iaser. Not only does the phase locked fibre bundle allow for high output beam quality and iow beam divergences but, importantly, it also allows the conversion of the annular output beam of such a tubular laser medium to be converted directly into an output beam of circular or rectangular apertures.
  • the said fibre bundle also acts as an integral beam delivery system significantly simplifying the task of delivering the high power Iaser beam generated with the said tubular Iaser medium into the industrial workstation.
  • the same fibre bundle also allows for several such tubular laser media to be effectively combined into a single Iaser so that it becomes possible to assemble solid state lasers of very high power in the 10-100 kilowatt range mean power, which was unattainable with prior art rod and slab systems.
  • Another object of the invention is to use an annular rod Iaser medium to realise a Iaser medium which is thin enough to allow adequate cooling so as to minimise thermally induced distortions of the said laser medium.
  • Another object of the invention is to provide an integral Iaser beam delivery system in the form of the flexible fibre bundle section of said Iaser oscillator. It is an object of the invention to provide an efficient means of exciting the laser medium using arc lamps, flashtubes and Iaser diode arrays.
  • Another object of the invention is to provide a relatively large outside surface area of the Iaser medium for its direct excitation, using any excitation sources and a smaller reflector area positioned inside the tubular structure so as to reflect any excitation light traversing said medium back into said medium.
  • Iaser system as a whole emits a phased locked Iaser beam output of low beam divergence.
  • Another object of the invention is to end pump the said annular Iaser medium with a fibre bundle coupled, switchable diode array.
  • Figure 1 shows a schematic layout of an arc lamp/flashtube excited configuration of the invention.
  • the central portion of the circular slab allows for water cooling whilst the annular output beam is coupled into a phase-locked, single mode fibre bundle whose output face may be either of circular or other cross-section, depending on the required output beam parameters.
  • Figure 2 shows a schematic layout of a fibre bundle coupled, switchable Iaser diode end pumped configuration of the invention.
  • Figure 3 shows a schematic layout of the cross-section of the arc lamp/flashtube pumped version of the invention with an array of arc lamps surrounding the outside surface of the cooled annular Iaser rod.
  • Figure 4 shows a side pumping arrangement
  • numeral 1 indicates i e circular slab Iaser medium.
  • Numeral 2 indicates a Iaser mirror which is fully reflecting at the lasing wavelength whilst numeral 3 indicates a mirror which transmits at the lasing wavelength but is fully reflecting at the pump wavelength.
  • Numeral 4 indicates a microlens array which couples the laser output beam into a phase-locked array of single mode optical fibres indicated by numeral 5.
  • Numeral 6 indicates the fibre bundle coupler whose mirrored output aperture indicated by numeral 7 emits the output Iaser beam indicated by numeral 8.
  • Numeral 9 indicates an arc lamp used to excite laser medium 1 whilst numeral 10 indicates a reflector to enhance the said excitation process.
  • numeral 11 indicates a fluid which passes through the tube indicates by numeral 12 which emerges as indicated by numeral 13 in front of the plug indicated by numeral 14 to pass through the annulus in rod 1 as indicated by numeral 15. It should be noted that the outside surface of tube 12 may be mirrored to reflect at the excitation wavelength of medium 1.
  • numeral 16 indicates a reflector to reflect any straying excitation light back into Iaser medium 1.
  • Numeral 17 indicates the annular end of a fibre bundle used to convey the Iaser medium 1 excitation light from a remote site, the other end of such a fibre bundle indicated by numeral 18 being connected to a switchable Iaser diode array indicated by numeral 19 and powered by the supply indicated by numeral 20.
  • numeral 1 indicates the circular slab Iaser medium
  • numeral 3 indicates the transmitting Iaser mirror which is fully reflecting at the pump wavelength
  • numeral 9 indicates the excitation lamps.
  • Numeral 10 indicates the reflectors used to redirect some of the excitation light emitted by 9 into 1 whilst numeral 14 indicates the plug used to seal the end of the circular slab from cooling fluid leakage.
  • numeral 1 indicates the circular slab Iaser of the invention.
  • Numeral 21 indicates a fibre coupled laser array output, the output of said fibre bundle 21 being indicated by numeral 22.
  • Numeral 23 indicates an optically polished entrance window on 1 which allows the propagating pump beam to be internally reflected off the inner face indicated by numeral 24 and off the outer face indicated by numeral 25.
  • the invention has applications for the generation of intense laser beams for industrial, medical and defence applications. It should also be noted that the output beam may be frequency shifted as it propagates through the fibre bundle coupler 6.
  • fibre bundle coupler can be used to combine the outputs of several circular slab lasers into a single output Iaser beam.

Landscapes

  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Optics & Photonics (AREA)
  • Lasers (AREA)

Abstract

Système oscillateur laser hybride à faisceau de barres/tranche/fibres, dans lequel une tige annulaire (1) est couplée à un faisceau de fibres de blocage de phase (6) à l'aide d'un réseau de microlentilles (4), le résonateur laser étant défini par le miroir arrière (2) réfléchissant à 100 % sur la longueur d'onde du laser et ayant une transmission totale à la longueur d'onde de pompage et à l'extrémité du faisceau de fibres (7) réfléchissant. Le milieu laser (1) peut être excité à l'aide de lampes (9) et refroidi à l'aide d'un fluide (11). On peut mettre à l'échelle le faisceau de sortie (8) par couplage de plusieurs des inventions à l'aide des fibres de sortie (6).
PCT/AU1991/000379 1990-08-23 1991-08-23 Systeme laser a tranche circulaire couple a un faisceau de fibres WO1992003858A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
AUPK190090 1990-08-23
AUPK1900 1990-08-23

Publications (1)

Publication Number Publication Date
WO1992003858A1 true WO1992003858A1 (fr) 1992-03-05

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ID=3774909

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/AU1991/000379 WO1992003858A1 (fr) 1990-08-23 1991-08-23 Systeme laser a tranche circulaire couple a un faisceau de fibres

Country Status (1)

Country Link
WO (1) WO1992003858A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2007084111A3 (fr) * 2005-01-12 2008-03-06 Raytheon Co Laser a semi-conducteurs a haute energie avec pompage deporte et geometrie d'extraction
CN109378693A (zh) * 2018-12-11 2019-02-22 中国工程物理研究院激光聚变研究中心 激光增益结构及激光器

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1919821A1 (de) * 1969-04-18 1970-11-05 Siemens Ag Molekularverstaerker fuer hohe Leistungen
JPS62199080A (ja) * 1986-02-27 1987-09-02 Toshiba Corp 固体レ−ザ発振装置
EP0306248A1 (fr) * 1987-08-28 1989-03-08 General Electric Company Appareil laser pour minimiser la distorsion du front d'onde

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1919821A1 (de) * 1969-04-18 1970-11-05 Siemens Ag Molekularverstaerker fuer hohe Leistungen
JPS62199080A (ja) * 1986-02-27 1987-09-02 Toshiba Corp 固体レ−ザ発振装置
EP0306248A1 (fr) * 1987-08-28 1989-03-08 General Electric Company Appareil laser pour minimiser la distorsion du front d'onde

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
DERWENT ABSTRACT, Accession no. 87-287125/41, Class V08; & JP,A,62 199 080 (TOSHIBA K.K.), 2 September 1987 (02.09.87). *
IEEE JOURNAL OF QUANTUM ELECTRONICS, Volume QE-20, No. 3, issued March 1984, J.M. EGGLESTON et al., "The Slab Geometry Laser - Part I: Theory", see pages 289-300. *
IEEE JOURNAL OF QUANTUM ELECTRONICS, Volume QE-21, No. 8, issued August 1985, THOMAS J. KANE et al., "The Slab Geometry Laser - Part II: Thermal Effects in a Finite Slab", see pages 1195-1210. *

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2007084111A3 (fr) * 2005-01-12 2008-03-06 Raytheon Co Laser a semi-conducteurs a haute energie avec pompage deporte et geometrie d'extraction
US7346091B2 (en) * 2005-01-12 2008-03-18 Raytheon Company High energy solid-state laser with offset pump and extraction geometry
US7760789B2 (en) 2005-01-12 2010-07-20 Raytheon Company High energy solid-state laser with offset pump and extraction geometry
EP2284966A1 (fr) * 2005-01-12 2011-02-16 Raytheon Company Laser à semi-conducteurs haute énergie avec géometrie de pompage et géometrie d' extraction déportées
CN109378693A (zh) * 2018-12-11 2019-02-22 中国工程物理研究院激光聚变研究中心 激光增益结构及激光器
CN109378693B (zh) * 2018-12-11 2024-02-20 中国工程物理研究院激光聚变研究中心 激光增益结构及激光器

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