WO2007054737A1 - Timing of a q-switch to suppress pre-lasing of the laser - Google Patents
Timing of a q-switch to suppress pre-lasing of the laser Download PDFInfo
- Publication number
- WO2007054737A1 WO2007054737A1 PCT/GB2006/050336 GB2006050336W WO2007054737A1 WO 2007054737 A1 WO2007054737 A1 WO 2007054737A1 GB 2006050336 W GB2006050336 W GB 2006050336W WO 2007054737 A1 WO2007054737 A1 WO 2007054737A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- laser
- switch
- lase
- pump pulse
- pulse
- Prior art date
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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
- H01S3/094076—Pulsed or modulated pumping
-
- 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
- H01S3/102—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating by controlling the active medium, e.g. by controlling the processes or apparatus for excitation
- H01S3/1022—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating by controlling the active medium, e.g. by controlling the processes or apparatus for excitation by controlling the optical pumping
-
- 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
-
- 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
- H01S3/0804—Transverse or lateral modes
-
- 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
- H01S3/0804—Transverse or lateral modes
- H01S3/08045—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
- H01S3/09—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
- H01S3/10—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
- H01S3/10038—Amplitude control
-
- 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
- H01S3/1611—Solid materials characterised by an active (lasing) ion rare earth neodymium
-
- 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
Definitions
- the invention relates generally to laser arrangements and methods. More specifically, but not exclusively it relates to a Q-switched laser resistant to beam seeding, whilst retaining pre-lase characteristics, and a method of achieving the same.
- any Q-switched laser there is a possibility that a very small amount of continuous wave (CW) or quasi-continuous wave (QCW) laser radiation is emitted prior to the main Q-switch pulse. This is termed pre-lase.
- CW continuous wave
- QCW quasi-continuous wave
- This is normally used for spectral seeding of single frequency lasers to finely control output frequency within the Q-switch pulse.
- Pre-lase can also happen by accident, if the resonator is not "closed” enough or when a parasitic resonator is formed from reflective surfaces outside the laser. This may occur in very high gain systems where hold-off is difficult to maintain.
- One of the unfortunate side-effects is that, particularly when the high gain laser is multi-transverse mode, serious spatial (as well as spectral) seeding occurs, causing the beam to fragment and often become excessively "peaky". This is termed spatial beam seeding.
- the fragmentation and excessive peaking of the laser beam resulting from the spatial beam seeding can cause damage to sensitive optics in the system. This is because the peak power density can significantly increase as a result of the spatial beam seeding associated with the pre-lase.
- the standard method in which to prevent spatial beam seeding, and hence protect the sensitive optics of the system, is to try to prevent pre-lase occurring at all. This can be accomplished by under-pumping the laser, or by attempting to detect conditions pre-requisite to the onset of pre-lase. Under- pumping the laser reduces output energy, whilst detection of pre-lase is rarely achievable in practice.
- a method of preventing spatial or spectral beam seeding in a pumped Q-switch laser comprising the step of delaying the Q-switch trigger by an integer number of laser resonator lifetimes after the end of the pump pulse, such that pre-lase does not result in the onset of beam seeding.
- a method of preventing spatial or spectral beam seeding in a laser comprising the step of delaying the initial pulse of energy to the laser by an integer number of laser resonator lifetimes after the end of the pump pulse, such that pre-lase does not result in the onset of beam seeding.
- a laser system comprising a diode laser for pumping using a defined pump pulse, a trigger for triggering the pumped pulse and control means for delaying the trigger by an integer number of laser resonator lifetimes after the end of the pump pulse, such that pre-lase does not result in the onset of beam seeding.
- the laser in question can be designed much closer to the damage threshold of the optics, either in the laser itself or in associated systems, completely eliminating the risk that pre-lase will cause the dramatic increase in peak power density associated with spatial seeding. This therefore prevents catastrophic damage to optical coatings and/or substrates, and also permits removal of pre-lase detectors from laser systems thereby simplifying the optics of the system.
- FIG 1 shows the typical timing of pump, pre-lase and Q-Switch outputs for optimised output energy, in accordance with one form of the invention.
- Figure 2 shows the beam seeding fragmentation caused by varying amounts of pre-lase energy showing that the worst effects are for the smallest amounts of pre-lase energy.
- a Q-switched laser system when pumping the laser using a defined pump pulse, from say a diode laser, the timing of the Q-switch relative to the pump pulse is normally chosen to maximise the output energy, or optimise the output pulse duration. In this configuration, a pre-lase event will cause spatial beam seeding to occur.
- Seeding of the main Q-switch output pulse can be completely eliminated by delaying the Q-switch trigger by at least several laser resonator lifetimes (typically 10 to 20ns) after the end of the pump pulse. Indeed, by delaying the Q-switch by up to 1 % of the active laser medium spontaneous emission lifetime (230 ⁇ s for Nd:YAG) after the end of the pump pulse, spatial seeding can be completely eliminated, no matter how much pre-lase is present, for almost no loss in final output power/energy.
- the diode pump pulse is indicated by reference numeral 10.
- Numerals 20 and 30 indicate the pre-lase on energy monitor and fast photodiode respectively.
- the Q-Switch output is indicated by reference numeral 40.
- the pre-lase energy would cause beam seeding, as indicated in Figure 2.
- the Q-switch timing By delaying the Q-switch timing by an additional 4 to 5 ⁇ s on the above trace, all beam seeding is eliminated whilst in the presence of the illustrated level of pre-lase.
- the Q-Switch pulse By delaying the Q-Switch pulse in the manner described above all the transverse beam profiles shown in Figure 2 look homogeneous and similar to that shown for the 14OmJ case.
- a short pump pulse fall time of less than or equal to 2% of lasing medium upper state lifetime is required.
- a Q-switch firing delay of an additional 1 % of lasing medium upper state lifetime subsequent to the fall of - A - the pump pulse is preferable.
- the Q-switch firing point must be for pump pulse levels at least below the threshold level, preferably with no pump present at all.
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- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Engineering & Computer Science (AREA)
- Plasma & Fusion (AREA)
- Optics & Photonics (AREA)
- Lasers (AREA)
Abstract
Description
Claims
Priority Applications (5)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AU2006313535A AU2006313535B2 (en) | 2005-11-14 | 2006-10-18 | Timing of a Q-switch to suppress pre-lasing of the laser |
EP06794993A EP1949511A1 (en) | 2005-11-14 | 2006-10-18 | Timing of a q-switch to suppress pre-lasing of the laser |
CA2628143A CA2628143C (en) | 2005-11-14 | 2006-10-18 | Timing of a q-switch to suppress pre-lasing of the laser |
US11/629,516 US9373929B2 (en) | 2005-11-14 | 2006-10-18 | Q-switched laser system and method to prevent seeding from pre-lasing |
IL191419A IL191419A (en) | 2005-11-14 | 2008-05-13 | Timing of a q-switch to suppress pre-lasing of the laser |
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB0523128.7 | 2005-11-14 | ||
GB0523128A GB0523128D0 (en) | 2005-11-14 | 2005-11-14 | Laser arrangements and methods |
EP05270080 | 2005-11-14 | ||
EP05270080.4 | 2005-11-14 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2007054737A1 true WO2007054737A1 (en) | 2007-05-18 |
Family
ID=37546878
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/GB2006/050336 WO2007054737A1 (en) | 2005-11-14 | 2006-10-18 | Timing of a q-switch to suppress pre-lasing of the laser |
Country Status (6)
Country | Link |
---|---|
US (1) | US9373929B2 (en) |
EP (2) | EP1949511A1 (en) |
AU (1) | AU2006313535B2 (en) |
CA (1) | CA2628143C (en) |
IL (1) | IL191419A (en) |
WO (1) | WO2007054737A1 (en) |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
KR101254246B1 (en) | 2012-09-12 | 2013-04-12 | (주) 블루코어컴퍼니 | Nd-yag laser high pulse controll device with igbt |
JP6242917B2 (en) | 2013-02-08 | 2017-12-06 | カール・ツァイス・エスエムティー・ゲーエムベーハー | Beam reversing module and optical power amplifier having such a beam reversing module |
JP6296927B2 (en) * | 2014-07-03 | 2018-03-20 | キヤノン株式会社 | Subject information acquisition device and laser device |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2000049407A (en) * | 1998-07-27 | 2000-02-18 | Sony Corp | Laser beam generator |
US6038241A (en) * | 1997-10-24 | 2000-03-14 | Coherent, Inc. | Pulsed-laser with first-pulse control |
Family Cites Families (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3577097A (en) * | 1967-11-28 | 1971-05-04 | Trw Inc | Laser with combined q-switch and synchronized cavity dump circuit |
US3711791A (en) * | 1971-05-03 | 1973-01-16 | A Erickson | Frustrated total internal reflection laser q-switch |
GB2149199A (en) | 1983-10-28 | 1985-06-05 | Bausch & Lomb | Laser system |
US5355383A (en) * | 1992-12-03 | 1994-10-11 | The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration | Method and apparatus for detection and control of prelasing in a Q-switched laser |
-
2006
- 2006-10-18 AU AU2006313535A patent/AU2006313535B2/en not_active Ceased
- 2006-10-18 US US11/629,516 patent/US9373929B2/en active Active
- 2006-10-18 CA CA2628143A patent/CA2628143C/en not_active Expired - Fee Related
- 2006-10-18 EP EP06794993A patent/EP1949511A1/en not_active Ceased
- 2006-10-18 EP EP15020020.2A patent/EP2985843A3/en not_active Withdrawn
- 2006-10-18 WO PCT/GB2006/050336 patent/WO2007054737A1/en active Application Filing
-
2008
- 2008-05-13 IL IL191419A patent/IL191419A/en active IP Right Grant
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6038241A (en) * | 1997-10-24 | 2000-03-14 | Coherent, Inc. | Pulsed-laser with first-pulse control |
JP2000049407A (en) * | 1998-07-27 | 2000-02-18 | Sony Corp | Laser beam generator |
Non-Patent Citations (3)
Title |
---|
GEORGIOU E ET AL: "50 mJ/30 ns FTIR Q-switched diode-pumped Er:Yb:glass 1.54 mum laser", OPTICS COMMUNICATIONS, NORTH-HOLLAND PUBLISHING CO. AMSTERDAM, NL, vol. 198, no. 1-3, 15 October 2001 (2001-10-15), pages 147 - 153, XP004308636, ISSN: 0030-4018 * |
PATENT ABSTRACTS OF JAPAN vol. 2000, no. 05 14 September 2000 (2000-09-14) * |
XIE W ET AL: "FLUORESCENCE FEEDBACK CONTROL OF AN ACTIVE Q-SWITCHED DIODE-PUMPED ND:YVO4 LASER", APPLIED OPTICS, OSA, OPTICAL SOCIETY OF AMERICA, WASHINGTON, DC, US, vol. 39, no. 6, 20 February 2000 (2000-02-20), pages 978 - 981, XP000928335, ISSN: 0003-6935 * |
Also Published As
Publication number | Publication date |
---|---|
EP1949511A1 (en) | 2008-07-30 |
US9373929B2 (en) | 2016-06-21 |
CA2628143C (en) | 2016-04-12 |
AU2006313535B2 (en) | 2012-06-07 |
CA2628143A1 (en) | 2007-05-18 |
IL191419A (en) | 2013-06-27 |
EP2985843A2 (en) | 2016-02-17 |
EP2985843A3 (en) | 2016-03-02 |
AU2006313535A1 (en) | 2007-05-18 |
US20080291947A1 (en) | 2008-11-27 |
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