CN109818253A - A kind of Ramar laser compensating crystal astigmatism thermal lens - Google Patents
A kind of Ramar laser compensating crystal astigmatism thermal lens Download PDFInfo
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- CN109818253A CN109818253A CN201910147430.9A CN201910147430A CN109818253A CN 109818253 A CN109818253 A CN 109818253A CN 201910147430 A CN201910147430 A CN 201910147430A CN 109818253 A CN109818253 A CN 109818253A
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- thermal lens
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Abstract
The invention discloses a kind of Ramar lasers for compensating crystal astigmatism thermal lens, it include: that the first Raman crystal, the second Raman crystal material, geometric dimension, cut direction are all the same, and placement is rotated by 90 ° along optical direction, that is the optical axis of the two is orthogonal, to compensate the influence of Raman crystal thermal lens astigmatism generation；Resonator total reflective mirror resonant cavity outgoing mirror constitutes Stokes optical cavity；The basic frequency laser of fundamental frequency lasers transmitting is focused by condenser lens enters the first Raman crystal and the second Raman crystal, generates Raman gain, gain is proportional to fundamental frequency light light intensity, Raman crystal length and Raman gain coefficienct；After Raman gain is more than the loss of Stokes optical cavity, Stokes light generation is generated in resonant cavity, is exported through resonator outgoing mirror.The present invention compensates the astigmatism of Raman crystal thermal lens, so that laser is exported the circular light spot of high light beam quality, while circular light spot also contributes to improving the pattern match of laser, improves efficiency of laser.
Description
Technical field
The present invention relates to Ramar laser field more particularly to a kind of Ramar lasers for compensating crystal astigmatism thermal lens.
Background technique
Solid Roman laser based on nonlinear crystal stimulated Raman scattering (SRS) effect is to expand laser radiation wavelength
One of effective technology means of coverage area.Since SRS process is distinctive from phase matched and beam cleanup characteristic, raman laser
Device has the potential quality that the output of high light beam quality laser is realized in the entire light passing wave band of crystal, with important application prospects.
SRS the output of process inelastic scattering, there are Excited states between fundamental frequency light and stokes light, whenever generation one
One will be generated while Stokes (Stokes) photon and is excited phonon, be transferred in Raman crystal in the form of phonon,
Heat load is formed, the fuel factors such as thermal lens are generated.Currently used Raman crystal, such as vanadate, tungstates, diamond,
Substantially it is aeolotropic crystal or stress defect forms anisotropy, therefore different crystal axis side during the growth process
There are significant differences for upward thermal conductivity, thermo-optical coeffecient and thermal expansion coefficient, this will lead to the heat penetration in meridian plane and sagittal surface
Mirror focal length is different, i.e. the thermal lens of astigmatism.Such as document [G.M.Bonner et al., Measurement of thermal
lensing in a CW BaWO4 intracavity Raman laser,Opt.Express 20,9810-9818
(2012)] in report, BaWO4Thermal lens focal power of (barium tungstate) crystal on a axis and c-axis direction differs several times.Thermal lens
Astigmatism very big inconvenience can be brought to Resonator design, cause hot spot to become oval, Effect Mode matching and laser-conversion efficiency,
Deteriorate beam quality, even resulted in when serious resonant cavity generate non-gaussian mode hot spot, as document [A.Mckay et al.,
High power tungstate-crystal Raman laser operating in the strong thermal
Lensing regime, Opt.Express 22,6707-6718 (2014)] in, the heat penetration of KGW (potassium-gadolinium) crystal astigmatism
Mirror makes the Stokes hot spot in sagittal surface become high-order Hermite--Gaussian mode, seriously affects the performance of laser.
Therefore, Raman crystal thermal lens astigmatic compensation has become the factor that Ramar laser performance need to consider emphatically of improving,
For the thermal lens for compensating Raman crystal astigmatism, often also need to introduce astigmatism device or the astigmatism by fold resonator, such as on
Researcher improves beam quality in intracavitary insertion cylindrical lens to a certain extent in one document, but this way has standard
The disadvantages of straight difficulty, introducing insertion loss, actual effect is difficult to meet the requirements.
Summary of the invention
The present invention provides a kind of Ramar lasers for compensating crystal astigmatism thermal lens, by the present invention in that identical with two pieces
Raman crystal, and be rotated by 90 ° placement along optical direction, i.e., both optical axis is orthogonal so that in sagittal surface and meridian plane etc.
It is consistent to imitate thermal lens, generates ellipse light spot to solve Raman crystal thermal lens astigmatism, influences laser beam quality and mode
With the problem of, it is described below:
A kind of Ramar laser compensating crystal astigmatism thermal lens, the Ramar laser include: fundamental frequency lasers, focus
Lens, resonator total reflective mirror, the first Raman crystal, the second Raman crystal and resonator outgoing mirror；
First Raman crystal, the second Raman crystal structure, material are all the same, and are rotated by 90 ° placement along optical direction,
That is the optical axis of the two is orthogonal, for compensating the influence of Raman crystal thermal lens astigmatism generation；
The resonator total reflective mirror resonant cavity outgoing mirror constitutes Stokes optical cavity；The base of fundamental frequency lasers transmitting
Frequency laser is focused by condenser lens enters the first Raman crystal and the second Raman crystal, generates Raman gain, gain is proportional to
Fundamental frequency light light intensity, Raman crystal length and Raman gain coefficienct, when Raman gain is more than the loss of Stokes optical cavity
Afterwards, Stokes light generation is generated in resonant cavity, is exported through resonator outgoing mirror.
Preferably, the condenser lens plates basic frequency laser anti-reflection film, and the resonator total reflective mirror plating basic frequency laser is anti-reflection, draws
Graceful stokes light high reflectivity film stack；First Raman crystal and the second Raman crystal plate basic frequency laser and stokes light increases
Permeable membrane system, resonator outgoing mirror plating stokes light part penetrate membrane system.
Both further, first Raman crystal, the second Raman crystal and be rotated by 90 ° placement along optical direction, i.e.,
Optical axis it is orthogonal, it is identical with the equivalent thermal lens of sagittal surface in meridian plane as a whole, avoid the astigmatism of thermal lens to laser beam
The influence of quality and pattern match.
Preferably, first Raman crystal and the second Raman crystal are that Raman gain coefficienct is consistent in polarization direction
Crystal so that the placement direction of crystal will not have an impact the gain of Ramar laser, and guarantees heat load in two pieces of crystal
With the consistency of corresponding thermal lensing effect.
Preferably, the resonator total reflective mirror, first Raman crystal and the second Raman crystal and the resonant cavity
Outgoing mirror, which is also coated with, corresponds to Stokes wavelength counnter attack membrane system to high-order stokes light and Raman secondary peak, other wavelength is avoided to rise
Vibration.
When specific implementation, the Ramar laser is continuous wave, adjusts Q, modulation or mode locking operating.
The beneficial effect of the technical scheme provided by the present invention is that:
1, the astigmatism of present invention compensation Raman crystal thermal lens, enables laser to export the circular light of high light beam quality
Spot, while circular light spot also contributes to improving the pattern match of laser, efficiency of laser is improved, without additionally introducing cylindrical lens
Etc. astigmatism devices, it is easy to accomplish, and Insertion Loss is smaller；
2, the present invention increases the length of Raman crystal by the use of bicrystal, to improve Raman gain.
Detailed description of the invention
Fig. 1 is a kind of structural schematic diagram of Ramar laser for compensating crystal astigmatism thermal lens；
Fig. 2 is a kind of another structural schematic diagram of Ramar laser for compensating crystal astigmatism thermal lens.
In attached drawing, parts list represented by the reference numerals are as follows:
1: fundamental frequency lasers；2: condenser lens；
3: resonator total reflective mirror；4-1: the first Raman crystal；
4-2: the second Raman crystal；5: resonator outgoing mirror.
Specific embodiment
To make the object, technical solutions and advantages of the present invention clearer, embodiment of the present invention is made below further
Ground detailed description.
Embodiment 1
A kind of Ramar laser compensating crystal astigmatism thermal lens, referring to Fig. 1, comprising: fundamental frequency lasers 1, condenser lens
2, resonator total reflective mirror 3, the first Raman crystal BaWO44-1, the second Raman crystal BaWO44-2, resonator outgoing mirror 5.
Wherein, fundamental frequency lasers 1 are continuous wave Nd:YVO4Laser, wavelength 1064nm；Condenser lens 2 is plano-convex lens,
Focal length 100mm, two-sided plating 1064nm anti-reflection film；Resonator total reflective mirror 3 is plano-concave mirror, radius of curvature 100mm, two-sided plating 1064nm
Anti-reflection, 1180nm high reflectivity film stack is plated in concave surface；First Raman crystal BaWO44-1 and the second Raman crystal BaWO44-2 is that a is cut
Cut BaWO4Crystal, size are 5 × 5 × 15mm3, two-sided plating 1064nm, 1180nm anti-reflection film, the first Raman crystal BaWO4 4-
1 c-axis is parallel to table top, the second Raman crystal BaWO4The c-axis of 4-2 is perpendicular to table top；Resonator outgoing mirror 5 is also plano-concave
Mirror, radius of curvature 100mm, concave surface plating is high to 1064nm basic frequency laser anti-, 1% membrane system of 1180nm Stokes light transmission rate.
The Stokes optical cavity that 3 resonant cavity outgoing mirror 5 of resonator total reflective mirror is constituted is symmetric design, geometrical length
180mm, the first Raman crystal BaWO44-1 and the second Raman crystal BaWO44-2 is at a distance of 40mm.
The design compensation of Ramar laser in embodiment of the present invention BaWO4The astigmatism of thermal lens, 1064nm fundamental frequency light
When average output power 30W, the 1180nm Stokes light output of 8.3W can get.
Embodiment 2
A kind of Ramar laser compensating crystal astigmatism thermal lens, referring to Fig. 1, comprising: fundamental frequency lasers 1, condenser lens
2, resonator total reflective mirror 3, the first Raman crystal YVO44-1, the second Raman crystal YVO44-2, resonator outgoing mirror 5.
Wherein, fundamental frequency lasers 1 are to adjust Q Nd:YVO4Laser, wavelength 1064nm；Condenser lens 2 is plano-convex lens, burnt
Away from 100mm, two-sided plating 1064nm anti-reflection film；Resonator total reflective mirror 3 is plano-concave mirror, radius of curvature 300mm, two-sided plating 1064nm increasing
Thoroughly, 1176nm high reflectivity film stack is plated in concave surface；First Raman crystal YVO44-1 and the second Raman crystal YVO44-2 is a cutting
YVO4Crystal, size are 3 × 3 × 10mm3, two-sided plating 1064nm, 1176nm anti-reflection film, the first Raman crystal YVO4The c of 4-1
Axis is parallel to table top, the second Raman crystal YVO4The c-axis of 4-2 is perpendicular to table top；Resonator outgoing mirror 5 is flat mirror, single side plating pair
1064nm basic frequency laser is high anti-, 5% membrane system of 1176nm Stokes light transmission rate.First Raman crystal YVO44-1 and second is drawn
Graceful crystal YVO44-2 is placed close to resonator total reflective mirror 3, the stoke that 3 resonant cavity outgoing mirror 5 of resonator total reflective mirror is constituted
This optical cavity geometrical length 80mm.
The design compensation of Ramar laser in embodiment of the present invention YVO4The astigmatism of thermal lens, 1064nm fundamental frequency light are defeated
Out when power 15W, pulse recurrence frequency 30kHz, the 1176nm Stokes light output of 6.2W can get.
The embodiment of the present invention to the model of each device in addition to doing specified otherwise, the model of other devices with no restrictions,
As long as the device of above-mentioned function can be completed.
It will be appreciated by those skilled in the art that attached drawing is the schematic diagram of a preferred embodiment, the embodiments of the present invention
Serial number is for illustration only, does not represent the advantages or disadvantages of the embodiments.
The foregoing is merely presently preferred embodiments of the present invention, is not intended to limit the invention, it is all in spirit of the invention and
Within principle, any modification, equivalent replacement, improvement and so on be should all be included in the protection scope of the present invention.
Claims (6)
1. a kind of Ramar laser for compensating crystal astigmatism thermal lens, which is characterized in that the Ramar laser includes: that fundamental frequency swashs
Light device, condenser lens, resonator total reflective mirror, the first Raman crystal, the second Raman crystal and resonator outgoing mirror；
First Raman crystal, the second Raman crystal material, geometric dimension, cut direction are all the same, and revolve along optical direction
Turn 90 ° of placements, i.e. the optical axis of the two is orthogonal, to compensate the influence of Raman crystal thermal lens astigmatism generation；
The resonator total reflective mirror resonant cavity outgoing mirror constitutes Stokes optical cavity；The fundamental frequency of fundamental frequency lasers transmitting swashs
Light is focused by condenser lens enters the first Raman crystal and the second Raman crystal, generates Raman gain, gain is proportional to fundamental frequency
Light light intensity, Raman crystal length and Raman gain coefficienct；
After Raman gain is more than the loss of Stokes optical cavity, Stokes light generation is generated in resonant cavity, through humorous
The chamber outgoing mirror that shakes exports.
2. a kind of Ramar laser for compensating crystal astigmatism thermal lens according to claim 1, which is characterized in that
The condenser lens plates basic frequency laser anti-reflection film, and the resonator total reflective mirror plating basic frequency laser is anti-reflection, Raman Stokes
Light high reflectivity film stack；
First Raman crystal and the second Raman crystal plate basic frequency laser and stokes light anti-reflection film system, the resonant cavity
Outgoing mirror plates stokes light part and penetrates membrane system.
3. a kind of Ramar laser for compensating crystal astigmatism thermal lens according to claim 1 or 2, which is characterized in that institute
State the first Raman crystal, the second Raman crystal is rotated by 90 ° placement, as a whole in meridian plane and the equivalent thermal lens phase of sagittal surface
Together, influence of the astigmatism of thermal lens to laser beam quality and pattern match is avoided.
4. a kind of Ramar laser for compensating crystal astigmatism thermal lens according to claim 1 or 2, which is characterized in that institute
The first Raman crystal and the second Raman crystal are stated as the consistent crystal of Raman gain coefficienct in polarization direction.
5. a kind of Ramar laser for compensating crystal astigmatism thermal lens according to claim 1 or 2, which is characterized in that institute
It states resonator total reflective mirror, first Raman crystal and the second Raman crystal and the resonator outgoing mirror is also coated with to high-order
Stokes light and Raman secondary peak correspond to Stokes wavelength counnter attack membrane system, avoid other wavelength starting of oscillations.
6. according to a kind of Ramar laser for compensating crystal astigmatism thermal lens described in claim 1, which is characterized in that the Raman
Laser is continuous wave, adjusts Q, modulation or mode locking operating.
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5093838A (en) * | 1990-05-23 | 1992-03-03 | Sony Corporation | Laser apparatus |
| US5148445A (en) * | 1989-04-24 | 1992-09-15 | Quantronix Corp. | High power Nd:YLF solid state lasers |
| WO2006058381A1 (en) * | 2004-12-01 | 2006-06-08 | Macquarie University | External cavity raman laser |
| CN108988114A (en) * | 2018-07-19 | 2018-12-11 | 中国科学院上海光学精密机械研究所 | The compensation method of high power laser light thermal lensing effect |
-
2019
- 2019-02-27 CN CN201910147430.9A patent/CN109818253A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5148445A (en) * | 1989-04-24 | 1992-09-15 | Quantronix Corp. | High power Nd:YLF solid state lasers |
| US5093838A (en) * | 1990-05-23 | 1992-03-03 | Sony Corporation | Laser apparatus |
| WO2006058381A1 (en) * | 2004-12-01 | 2006-06-08 | Macquarie University | External cavity raman laser |
| CN108988114A (en) * | 2018-07-19 | 2018-12-11 | 中国科学院上海光学精密机械研究所 | The compensation method of high power laser light thermal lensing effect |
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