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EP4588141A1 - Laser à solide court - Google Patents

Laser à solide court

Info

Publication number
EP4588141A1
EP4588141A1 EP23764607.0A EP23764607A EP4588141A1 EP 4588141 A1 EP4588141 A1 EP 4588141A1 EP 23764607 A EP23764607 A EP 23764607A EP 4588141 A1 EP4588141 A1 EP 4588141A1
Authority
EP
European Patent Office
Prior art keywords
doped yag
laser
solid
yag material
coating
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
EP23764607.0A
Other languages
German (de)
English (en)
Inventor
Daniel Kopf
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.)
Montfort Laser & Co Kg GmbH
Original Assignee
Montfort Laser & Co Kg 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 Montfort Laser & Co Kg GmbH filed Critical Montfort Laser & Co Kg GmbH
Publication of EP4588141A1 publication Critical patent/EP4588141A1/fr
Pending legal-status Critical Current

Links

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
    • H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
    • H01S3/06—Construction or shape of active medium
    • H01S3/0619—Coatings, e.g. AR, HR, passivation layer
    • H01S3/0621—Coatings on the end-faces, e.g. input/output surfaces of the laser light
    • 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
    • H01S3/0627—Construction or shape of active medium the resonator being monolithic, e.g. microlaser
    • 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
    • H01S3/08018—Mode suppression
    • H01S3/08022—Longitudinal modes
    • H01S3/08031—Single-mode emission
    • 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
    • H01S3/10—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
    • H01S3/11—Mode locking; Q-switching; Other giant-pulse techniques, e.g. cavity dumping
    • H01S3/1123—Q-switching
    • H01S3/113—Q-switching using intracavity saturable absorbers
    • 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
    • H01S3/14—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range characterised by the material used as the active medium
    • H01S3/16—Solid materials
    • H01S3/163—Solid materials characterised by a crystal matrix
    • H01S3/164—Solid materials characterised by a crystal matrix garnet
    • H01S3/1643—YAG
    • 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
    • H01S3/14—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range characterised by the material used as the active medium
    • H01S3/16—Solid materials
    • H01S3/1601—Solid materials characterised by an active (lasing) ion
    • H01S3/1603—Solid materials characterised by an active (lasing) ion rare earth
    • H01S3/1618—Solid materials characterised by an active (lasing) ion rare earth ytterbium

Definitions

  • the invention relates to a solid-state laser with a resonator, which has a first doped YAG material as an active laser medium for forming laser radiation, a second doped YAG material as a saturable absorber, a first end mirror which is composed of a coating of the first doped YAG material on the side remote from the second doped YAG material, and having a second end mirror formed by a coating of the second doped YAG material on the side remote from the first doped YAG material, pump radiation for pumping the laser medium through the
  • the first end mirror can be irradiated, with a coating arranged between the first doped YAG material and the second doped YAG material being provided, which is at least 50% reflective for the pump radiation and at least partially transparent for the laser radiation, the reflection of the laser radiation being caused by the Coating is at least 5%.
  • Short solid-state lasers are usually designed in the form of microchip lasers, which have a monolithic resonator, i.e. H .
  • the components of the resonator are connected to one another in a materially coherent manner.
  • These are usually passive Q-switched lasers to produce pulsed laser radiation, with the saturable absorber often being formed by a SESAM.
  • Microchip lasers are usually pumped using laser diodes. The dimensions of such a microchip laser depend on the materials used and the configuration. Examples of possible laser mediums include Yb:YAG, Nd:YVO 4 or Nd:YAG.
  • the length of the laser medium is 1 mm and the Length of the saturable absorber is also 1 mm, giving a pulse width of 169 ps and a pulse energy of 29 pj.
  • the resonator is designed as a stable resonator, the length of the resonator being less than 2 mm and the length of the second doped YAG material forming the saturable absorber being more than twice as long as the length of the first doped YAG material forming the active laser medium .
  • the pulse width is increased by such a coating between the first doped YAG material and the second doped YAG material can be further reduced.
  • Pre-saturation of the saturable absorber formed by the second doped YAG material due to irradiation of pump light is at least reduced.
  • the solid-state laser is preferably designed in the form of a microchip laser.
  • the laser therefore has a monolithic resonator, i.e. H .
  • the components of the resonator are connected to one another in a materially coherent manner.
  • Purely pulsed operation of the solid-state laser is understood to mean that essentially no laser radiation is emitted between the individual pulses, i.e. H .
  • the intensity of the laser radiation in the middle between two Pulsing is in any case less than 0.1 b of the intensity of the laser radiation at the maximum of a respective pulse.
  • the first doped YAG material forms a kind of “sub-cavity” with this coating and the first end mirror. This means that an increase in the intensity of the laser radiation can be achieved in the laser medium. This results This creates an effect like a higher amplification of the laser medium or an increase in the emission cross section c.
  • the pulse rate can thus be increased. With a certain desired total energy, the energy emitted per pulse can be reduced, which reduces damage problems caused by the laser radiation This is particularly advantageous for Yb:YAG, since this laser medium has a comparatively very low emission cross section.
  • the reflection of the laser radiation through the coating were to be too large, a continuous emission of laser radiation could form in the laser medium, which is undesirable.
  • the length of the saturable absorber being more than twice as long as the length of the laser medium, especially in connection with the Forming the previously mentioned sub-cavity, a certain wavelength selection for the laser light can be achieved, as will be explained in more detail below.
  • pump radiation 1 which is indicated by an arrow in the figure, is irradiated into a resonator 2 of the solid-state laser.
  • the resonator 2 has a first doped YAG material 3 as the active laser medium.
  • the resonator 2 has a second doped YAG material 4 as a saturable absorber.
  • the first doped YAG material 3 is provided with a coating on the side remote from the second doped YAG material 4, which forms a first end mirror 5 of the resonator 2.
  • the pump radiation 1 is passed through this first end mirror 5 into the first doped YAG material 3 irradiated.
  • the first end mirror 5 is designed to be highly transparent for the pump radiation.
  • the first end mirror 5 is designed to be highly reflective for the laser radiation formed.
  • the second doped YAG material 4 is provided with a coating on the side remote from the first doped YAG material 3, which forms a second end mirror 6 of the resonator 2.
  • this second end mirror 6 is used to decouple the laser radiation 7, which is indicated by an arrow in the figure.
  • the second end mirror 6 for the laser radiation 7 is designed to be approximately 50% reflective and approximately 50% transmissive.
  • An advantageous range for the transmission can be between 30 to 70%, preferably between 40 to 60%.
  • the first doped YAG material 3 in the exemplary embodiment is Yb:YAG.
  • Other doped YAG materials can also be used as an active laser medium, as is known per se, for example Nd:YAG or Er:YAG.
  • the wavelength of the continuously irradiated pump radiation is 940 nm, which is particularly useful for Yb:YAG.
  • the pump radiation is also laser radiation. To distinguish it from the laser radiation emitted by the solid-state laser, the radiation used to pump the laser is always referred to as pump radiation in this document.
  • the second doped YAG material 4 in the exemplary embodiment is Cr 4+ :YAG.
  • Other doped YAG materials can also be used as a saturable absorber, as is known per se, for example V:YAG.
  • V:YAG the combination of Nd:YAG with V:YAG or Cr 4+ :YAG is useful.
  • a coating 8 which is at least 50%, preferably at least 75%, particularly preferably at least 90% reflective for the pump radiation. A value of more than 95% is even more preferred. In the exemplary embodiment, the reflection of the coating 8 for the pump radiation is approximately 98%.
  • the coating 8 is partly transparent and partly reflective for the laser radiation.
  • the reflection of the coating 8 for the laser radiation is at least 5%, preferably at least 10%, in the exemplary embodiment approximately 15%.
  • a “sub-cavity” is formed for the laser radiation between the first end mirror 5 and the coating 8. There is therefore no saturable absorber in this sub-cavity.
  • the laser begins to laser even with a lower excitation of the active laser medium. The pulse rate therefore becomes higher. At a certain desired output energy of the laser, the energy per laser pulse can be lower. This means that the Problems caused by damage reduced.
  • the reflection of the laser radiation through the coating 8 should be small enough so that purely pulsed operation of the solid-state laser is maintained. If the reflection were too high, continuous lasing could be triggered in the active laser medium.
  • the reflection of the laser radiation through the coating in order to achieve such purely pulsed operation of the solid-state laser is less than 50% or less than 30% or less than 20%. In the exemplary embodiment, the reflection is approx. 15%.
  • T R is the round-trip time in the cavity and is therefore proportional to the length of the resonator 2.
  • AR is the modulation depth e of the saturable absorber, related to the intensity and therefore corresponds to the absorption of the saturable absorber (if other losses in the absorber material are neglected).
  • the length s of the resonator, measured parallel to the axis of the laser beam, from the outer surface of the first end mirror 5 to the outer surface of the second end mirror 6, is less than 2 mm, particularly preferably less than 1.5 mm.
  • the length of the first doped YAG material 3 is, particularly when using Yb:YAG, advantageously more than 0.05 mm, preferably more than 0.1 mm.
  • the length of the second doped YAG material 4 is, particularly when using Cr 4+ :YAG, advantageously more than 0.3 mm, preferably more than 0.5 mm.
  • the doping of the first doped YAG material 3 is approximately 10% in the exemplary embodiment and the doping of the second doped YAG material 4 in the exemplary embodiment is such that the transmission T o is 68%.
  • the coating 8 is designed in the manner of a Bragg coating, i.e. H .
  • Two materials with different refractive indices are alternately applied in a large number of layers, for example 24, as is known per se.
  • silicon dioxide and hafnium oxide can be used.
  • the absorption of the laser radiation when passing through the coating 8 is advantageously less than 1 k».
  • the resonator is therefore designed to be monolithic, i.e. H .
  • the components of the resonator are connected to one another in a materially coherent manner. It is therefore a microchip laser.
  • a laser according to the invention can achieve pulse lengths of less than 200 ps, preferably less than 150 ps or even less than 100 ps (the pulse length being determined as usual as the FWHM of the power).
  • pulse energies of more than 10 pj, preferably more than 30 pj, can be achieved.
  • a coupling out of the laser radiation at the first end mirror could also be provided, with the pump radiation and the laser radiation subsequently being able to be separated from one another by a dichroic mirror.

Landscapes

  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Optics & Photonics (AREA)
  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Lasers (AREA)

Abstract

L'invention concerne un laser à solide qui comporte un résonateur stable (2) qui comprend un premier matériau YAG dopé (3) en tant que milieu laser actif, un second matériau YAG dopé (4) en tant qu'absorbeur saturable, un premier miroir d'extrémité (5), qui est formé par un revêtement du premier matériau YAG dopé (3) sur le côté distant du second matériau YAG dopé (4), et un second miroir d'extrémité (6), qui est formé par un revêtement du second matériau YAG dopé (4) sur le côté distant du premier matériau YAG dopé (3), un rayonnement de pompe (1) pour pomper le milieu laser pouvant être émis à travers le premier miroir d'extrémité (5). Un revêtement (8) disposé entre le premier matériau YAG dopé (3) et le second matériau YAG dopé (4) est fourni, lequel est réfléchissant d'au moins 50 % pour le rayonnement de pompe (1) et réfléchissant d'au moins 5 % pour le rayonnement laser (7). Le rayonnement laser (7) présente au moins sensiblement un seul mode longitudinal.
EP23764607.0A 2022-09-12 2023-08-31 Laser à solide court Pending EP4588141A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
AT1762022 2022-09-12
PCT/EP2023/073893 WO2024056390A1 (fr) 2022-09-12 2023-08-31 Laser à solide court

Publications (1)

Publication Number Publication Date
EP4588141A1 true EP4588141A1 (fr) 2025-07-23

Family

ID=87929179

Family Applications (1)

Application Number Title Priority Date Filing Date
EP23764607.0A Pending EP4588141A1 (fr) 2022-09-12 2023-08-31 Laser à solide court

Country Status (2)

Country Link
EP (1) EP4588141A1 (fr)
WO (1) WO2024056390A1 (fr)

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5394413A (en) * 1994-02-08 1995-02-28 Massachusetts Institute Of Technology Passively Q-switched picosecond microlaser
US9236703B2 (en) * 2011-11-07 2016-01-12 Raytheon Company Laser system and method for producing a linearly polarized single frequency output using polarized and non-polarized pump diodes
AT515789B1 (de) * 2014-07-07 2015-12-15 Daniel Dr Kopf Microchip-Laser
US11367990B2 (en) * 2018-08-29 2022-06-21 Luminar, Llc Lidar system operating at 1200-1400 NM
AT521942B1 (de) 2018-12-14 2022-09-15 Daniel Kopf Dr Gütegeschalteter Festkörperlaser
AT522108B1 (de) 2019-01-31 2022-09-15 Montfort Laser Gmbh Passiv gütegeschalteter Festkörperlaser
CN115280608B (zh) 2020-03-13 2025-10-28 大学共同利用机关法人自然科学研究机构 光振荡器、光振荡器的设计方法和激光装置

Also Published As

Publication number Publication date
WO2024056390A1 (fr) 2024-03-21

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