CN87103899A - A kind of waveform regulating method for adjustable Q laser pulse - Google Patents
A kind of waveform regulating method for adjustable Q laser pulse Download PDFInfo
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- CN87103899A CN87103899A CN87103899.4A CN87103899A CN87103899A CN 87103899 A CN87103899 A CN 87103899A CN 87103899 A CN87103899 A CN 87103899A CN 87103899 A CN87103899 A CN 87103899A
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Abstract
A kind of waveform regulating method for adjustable Q laser pulse.This method is back along width by the compression adjustable Q laser pulse, and the adjustable Q laser pulse width is greatly reduced; And it is constant to obtain peak power, the continuously adjustable laser Q of pulse duration pulse; Can also guarantee to adjust the Q pulse peak power under the constant prerequisite of laser transverse mode continuously.The method is simple and reliable, is applicable to a merit Q-switched laser.
Description
The invention belongs to laser technology field.
Because Q-switched laser has the peak power height, the characteristics that pulse duration is narrow, thereby its application is extensive day by day.Meanwhile, also more and more high to the performance requirement of Q-switched laser, such as requiring pulse duration narrower, and require pulse durations to regulate continuously in many application scenarios, or the like.
The theory analysis of exchanging the Q process shows, the keying speed that the output peak power of Q-switched laser and pulse duration depend on Q switching, chamber gain and cavity loss.Therefore, the method for the compression pulse width that people adopt at first mainly comprises accelerates the Q switching opening speed, and selects high-quality working-laser material material for use, increases pump power and reduces cavity loss or the like.The advantage of these methods is to increase peak power in compression pulse width, and shortcoming then is to realize difficulty.In fact, using the said method compression pulse width has not had potentiality basically and can dig.Therefore, further compression pulse width just must on adjusting Q mechanism, carry out developmental research.
At present, the method of the external compression Q pulse duration that adopts mainly contains the method for US-4477905 and the described cavity dumping of US-4174504, and U.S.'s " optical communication ": the 298th page of magazine (Optics Communications) VoL.40. № .4 is described from method for implanting.These two kinds of methods say it all is effective in theory.The self-injection locking technology can also be regulated laser Q pulse duration continuously.But their shortcoming is too complicated and very easily is subjected to external interference, now impossible practical application.In addition, JP-61015384 has described a kind of method of regulating the acousto-optic Q modulation pulse duration, but this method can only obtain than the wideer pulse of common Q impulse width, promptly can not compressed pulse widths.
In sum, the objective of the invention is to study a kind of simple and easy to do compression and the technical method of the continuous Q of adjusting pulse duration.
Content of the present invention comprises:
The principle of common Q-switched laser is to make resonant cavity be in low reactance-resistance ratio state (closing Q switching) when pumping begins.Make interacvity gain be lower than loss, stop the formation of light generation, thereby pump energy is stored in the active medium.When energy storage reaches maximum, make resonant cavity be in high Q state of value (promptly opening Q switching) suddenly.At this moment, gain is far longer than loss, and the energy that is stored in the active medium is exported with the form of a giant pulse rapidly.
After Q switching is opened, close Q switching again in the Q pulse output procedure, thereby change the operating state of laser resonant cavity, make the waveform of Q pulse obtain adjusting.The moment that Q switching is closed again can be when the Q pulse reaches peak value, and makes Q switching be in the maximum possible closed condition again, along decay fast, reaches the purpose of compression Q pulse duration after the Q impulse waveform.The present invention can be regulated the Q pulse duration by the rate of decay of regulating the loss factor after Q switching is closed again or regulating the Q pulse back edge by the time that the adjusting Q switching is closed again continuously.The present invention can also regulate the peak power of Q pulse, before reaching peak value, the Q pulse just make Q switching return to high loss attitude, then the Q pulse just can not reach peak value, just can regulate the maximum that the Q pulse can reach by regulating the time that Q switching closes again, at this moment, under the pump power controlled condition, can adjust peak power continuously.The characteristics that adopt this kind method to regulate the Q pulse peak power are both to be convenient to automatic control, when regulating peak power, can regulate pump power again, this point is particularly useful for solid state laser, because just can guarantee that its horizontal output mode is constant like this.
By theory analysis, we find to transfer the back of Q giant pulse always to be far longer than the forward position half width along half width.In fact, transfer the pulse duration of Q giant pulse mainly to form along half width by the back.This is that we always do very for a short time loss in the chamber (not comprising the outgoing mirror transmission loss) as far as possible because big as far as possible in order to guarantee to transfer the peak power of Q giant pulse.Though this helps the increase of pulse peak power, can make and transfer the forward position of Q giant pulse to rise as quickly as possible, be unfavorable for the decay of pulse back edge simultaneously, make and transfer the back edge of Q giant pulse to drag very longly.In fact, this part energy of pulse back edge does not have any use in many instances.Especially under occasions such as laser processing, be very disadvantageous during it have.Therefore, it is necessary the back edge of transferring the Q giant pulse being attenuated.And adopt compression pulse width method of the present invention can reach this purpose, but also can in a big way, regulate the Q pulse duration continuously, it is constant to guarantee to transfer the peak power of Q giant pulse simultaneously again.In addition, adopt method of the present invention, can also be in the peak power that guarantees to adjust continuously under the constant prerequisite of laser transverse mode the Q pulse.
The invention has the advantages that:
The compression pulse width scope is big.Because transferring the back edge of Q giant pulse width is the major part of forming its pulsewidth, method of the present invention then can decay rapidly thereafter along part, thus in a big way compression pulse width;
Solved after the accent Q giant pulse along with the contradiction of forward position (Main Ingredients and Appearance of peak power).Because Q pulse front edge and peak power require cavity loss as far as possible little, along then requiring cavity loss big as far as possible, the present invention had both kept the forward position part, had compressed back edge again partly, had properly solved this contradiction thereafter;
Can keep peak power constant in the time of compression pulse width, because the present invention just makes Q switching close again after pulse reaches peak value.Therefore, the forward position forming process of Q pulse is had no effect, so can not influence maximum output;
Easy, easy row, reliable, adaptability is strong.The present invention goes for all and transfers the Q form, and is particularly better in field effects such as Laser Micro-Machining and laser rangings.
Description of drawings and embodiment
Fig. 1 is a schematic representation of apparatus of the present invention.Q-switched laser is by working-laser material (1), total reflective mirror (2), outgoing mirror (3), pump supply source (4), Q switched element (5) and transfer Q control power supply (6) to form.Wherein, working-laser material (1) is any laser material that can transfer Q, and it should have sufficiently high energy storage characteristic, can guarantee to transfer finishing of Q work.For example, solid Nd: YAG crystal, neodymium glass, ruby and gas Co
2Or the like.
Total reflective mirror (2) and outgoing mirror (3) are formed resonant cavity.Suppose among Fig. 1 that it is two level crossings, in fact, they can be any optical mirrors that can form laserresonator.For example, spherical mirror, Ni Xiaosuo mirror, corner reflector or the like.
Pump supply source (4) can be continuous pumping, also can be pulse pump, and this depends on laser material and transfers the Q mode.For example, acousto-optic Q modulation mostly is continuous pumping, and electric-optically Q-switched pulse pump or the like always.
Q switched element (5) is to finish the Primary Component of transferring the Q action, generally requires extinction ratio enough high.Only be schematic form among Fig. 1, its concrete structure will be decided on the accent Q form that is adopted.For example, adopt when electric-optically Q-switched, it generally is made up of a crystal and (or a pair of) polarizer.Unique requirement for Q-switching device is that it must be the active Q switched element that can control, rather than a passive Q-adjusted element of being made up of saturated absorbing body.
Transfer Q control power supply (6) supporting with Q-switching device (5).For different accent Q forms, desired power supply output difference is very big.To electric light KD
*P Q-switching device, power supply (6) must can output map 2 in (a) or high-voltage square-wave (b), good as much as possible for making q-effect, the rising edge of square wave and trailing edge all should try one's best suddenly (promptly trying one's best) near the perfect condition shown in the dotted line.For the present invention, the rising behind the △ t interval is particularly important, and it directly has influence on the minimum value that pulse duration can be compressed.To A-O Q-switch device, the output of power supply (6) should be the waveform of figure (2) shown in (c), and wherein, the rising and falling edges of the envelope of radiofrequency signal also should be steep as best one can, especially rising edge.Radio frequency signal frequency is 40-100MH, and pulse repetition frequency is 0～24KHz.No matter be electric-optically Q-switched or the acousto-optic Q modulation power supply, continous-stable is adjustable at interval all to require △ t.In fact, we adjust the Q pulse duration by adjusting △ t size.
Figure (2) is the output waveform of power supply among Fig. 1 (6).Wherein (a) and (b) are electric-optically Q-switched output waveform, (c) are the output waveform of acousto-optic Q modulation.
Fig. 3 is the forming process of common adjustable Q laser pulse.Wherein, δ is a cavity loss, and △ n is an inverted population density, and φ is a vibration photon number density in the chamber, t
1Be laser pulse forward position half width, t
2For behind the laser pulse along half width, △ no is the initial inversion population density, △ n
ThBe the threshold inversion population density.
Fig. 4 is an adjustable Q laser pulse forming process schematic diagram of the present invention.Among the figure, make cavity loss δ return to α when photon number density reaches maximum in the chamber immediately
2Thereby, pulse back edge is decayed rapidly, dotted line is represented common Q impulse waveform among the figure.
Fig. 5 adopts the method with the regulation loss rate to reach adjusting Q pulse duration purpose, wherein, and the proportion of goods damageds height that solid line is represented, i.e. α
2＞α
1, therefore, fast behind the laser pulse that solid line is represented among Fig. 5 along decay.
Fig. 6 regulates the Q pulse duration for adopting the method for regulating Q switching opening time interval τ.Wherein, the time interval τ that represents of solid line
1The time interval τ that represents less than dotted line
2, i.e. τ
2＞τ subtracts thereby begin sorrow the more morning that the pulse ratio dotted line that solid line is represented is represented, therefore, and △ t
2＞△ t
1
More than the analysis showed that, transfer the back of Q giant pulse to depend on cavity loss along the rate of decay.And cavity loss depends on the proportion of goods damageds of Q switching.Therefore, need only the loss factor of suitably adjusting after Q switching is closed again (be actually and adjust correspondent voltage in the accompanying drawing 2), can reach the purpose of continuous adjusting Q pulse duration.As shown in Figure 5, loss factor α
2＞α
1So, △ τ
2＜△ τ
1But this control method also has shortcoming, promptly must adopt three electric pressures, because when pumping begins in order fully to close resonant cavity, need make the loss factor of Q switching big as far as possible, then require the proportion of goods damageds adjustable when closing Q switching again, so the complicated design of power supply.Therefore, the method that adopts Fig. 6 of the present invention to represent is more simple and reliable, also promptly can regulate time that Q switching closes again and just can realize the purpose (as Fig. 2, regulating the time interval that Q switching is opened exactly) of compression pulse width.As long as to drop to two/for the moment (be the t behind the peak value among Fig. 3 on the edge behind the common Q impulse after the Q pulse reaches peak value
2In time), during this period of time in any moment close Q switching, can reach the purpose of compression pulse half width, just the degree difference of compression.Facts have proved that this method is more reliable than the method for regulation loss rate α, and is easier.As shown in Figure 6, time interval t
2＞t
1Thereby, obtain △ τ
2＞△ τ 1 can find out that thus it is practicable regulating the method that the Q switching opening time regulates pulsewidth at interval.
Specific implementation method of the present invention is very simple, and the Q-switched laser of any practicality can directly adopt through suitable adjustment.
Can see that from the above description unique difference of the present invention and common Q-switched laser is exactly to transfer the Q power supply to return to high loss attitude again after unlatching after a while.In fact, the Q-switched laser of any practicality all should have such function.Because we know that the Q-switched laser of any practicality all must repeated application.Also has certain repetition rate.For example, electric-optically Q-switched repetition rate is 0～100Hz, and the repetition rate of acousto-optic Q modulation is 0～20KHz.Owing to this reason, the Q switching of the Q-switched laser of any practicality all must return to high loss closed condition after pulse of emission, otherwise, just can not carry out the energy storage of next pulse.But the opening time of common laser Q switch all is that long enough is unhinderedly launched to guarantee whole Q impulse.In addition, it is all slow that general accent Q power supply recovers the speed of high loss closed condition again, because common Q-switched laser does not also require that This move is enough fast, therefore, we if from these two aspects in addition suitable adjustment Q switching power supply just can finish practical application of the present invention, these two aspects are: the Q switching opening time is transferred at interval with the formation time of Q laser pulse is mated mutually; Accelerate the speed that Q switching recovers high loss again as far as possible.Cause this 2 point as long as do, the logical Q-switched laser of any Daepori can adopt the present invention.In fact, will as above improve not difficultly for any accent Q mode, and mode is a lot, does not have certain specific pattern.
Fig. 7 is embodiment, the acousto-optic Q modulation power principle figure of a practical application of expression.By regulating W
1Be the time that the scalable Q switching is closed again, with this power supply, accomplished in fact acousto-optic Q modulation YAG laser pulse width by 200ns to adjustable continuously the 100ns, guarantee that simultaneously peak power is constant, output transverse mode constant.
Claims (4)
1, a kind of Q impulse Waveform regulating method.When the Q-switched laser pumping began, Q switching was closed, and when energy storage reached maximum in the laser medium, Q switching was opened.The invention is characterized in Q switching unlatching back, Q pulse output procedure and close Q switching again, thereby change the operating state of laser resonant cavity, make the waveform of Q pulse obtain adjusting.
2, Q impulse Waveform regulating method as claimed in claim 1, it is characterized in that: the moment that Q switching is closed again is when the Q pulse reaches peak value, and make Q switching be in the maximum possible closed condition again, along decay fast, make the compression of Q pulse duration after the Q impulse waveform.
3, as claim 1,2 described methods, it is characterized in that: can the Q pulse duration be regulated continuously by the rate of decay of regulating the loss factor after Q switching is closed again or regulating the Q pulse back edge by the time that the adjusting Q switching is closed again.
4, the method for claim 1, it is characterized in that: before the Q peak value of pulse reaches, close Q switching, thereby make the Q pulse can not reach peak power, regulate the maximum that the Q pulse can reach by regulating the time that Q switching closes again, at this moment, under the pump power controlled condition, can adjust peak power continuously, and guarantee that the transverse mode of laser output is constant.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 87103899 CN1013329B (en) | 1987-05-27 | 1987-05-27 | Waveform regulating method for adjustable q laser pulse |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 87103899 CN1013329B (en) | 1987-05-27 | 1987-05-27 | Waveform regulating method for adjustable q laser pulse |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN87103899A true CN87103899A (en) | 1988-12-14 |
| CN1013329B CN1013329B (en) | 1991-07-24 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 87103899 Expired CN1013329B (en) | 1987-05-27 | 1987-05-27 | Waveform regulating method for adjustable q laser pulse |
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102224337A (en) * | 2008-11-21 | 2011-10-19 | 罗伯特·博世有限公司 | Laser-induced spark ignition for an internal combustion engine |
| CN102430855A (en) * | 2011-09-21 | 2012-05-02 | 长春理工大学 | Energy time domain accumulating method for multiple laser pulse sequences |
| CN106992425A (en) * | 2017-06-12 | 2017-07-28 | 中国原子能科学研究院 | With pulse incoherent quasi-molecule laser source is induced from compression property without ladder |
| CN108155555A (en) * | 2016-12-04 | 2018-06-12 | 中国科学院大连化学物理研究所 | A kind of impulse type rubidium steam blue laser of adjustable pulse width |
| CN108963746A (en) * | 2017-05-24 | 2018-12-07 | 中国科学院理化技术研究所 | Laser using method, pulse width adjustable laser and using method thereof |
| CN111864517A (en) * | 2020-07-29 | 2020-10-30 | 中国科学院长春光学精密机械与物理研究所 | Laser pulse waveform purification method and system |
| CN112271543A (en) * | 2020-09-29 | 2021-01-26 | 北京卓镭激光技术有限公司 | Active Q-switched laser and pulse width modulation method thereof |
-
1987
- 1987-05-27 CN CN 87103899 patent/CN1013329B/en not_active Expired
Cited By (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102224337A (en) * | 2008-11-21 | 2011-10-19 | 罗伯特·博世有限公司 | Laser-induced spark ignition for an internal combustion engine |
| US8783221B2 (en) | 2008-11-21 | 2014-07-22 | Robert Bosch Gmbh | Laser-induced spark ignition for an internal combustion engine |
| CN102224337B (en) * | 2008-11-21 | 2016-03-16 | 罗伯特·博世有限公司 | For the spark ignition device of the induced with laser of internal-combustion engine |
| CN102430855A (en) * | 2011-09-21 | 2012-05-02 | 长春理工大学 | Energy time domain accumulating method for multiple laser pulse sequences |
| CN108155555A (en) * | 2016-12-04 | 2018-06-12 | 中国科学院大连化学物理研究所 | A kind of impulse type rubidium steam blue laser of adjustable pulse width |
| CN108155555B (en) * | 2016-12-04 | 2019-11-15 | 中国科学院大连化学物理研究所 | A kind of impulse type rubidium steam blue laser of adjustable pulse width |
| CN108963746A (en) * | 2017-05-24 | 2018-12-07 | 中国科学院理化技术研究所 | Laser using method, pulse width adjustable laser and using method thereof |
| CN108963746B (en) * | 2017-05-24 | 2020-06-26 | 中国科学院理化技术研究所 | Laser using method, pulse width adjustable laser and using method thereof |
| CN106992425A (en) * | 2017-06-12 | 2017-07-28 | 中国原子能科学研究院 | With pulse incoherent quasi-molecule laser source is induced from compression property without ladder |
| CN111864517A (en) * | 2020-07-29 | 2020-10-30 | 中国科学院长春光学精密机械与物理研究所 | Laser pulse waveform purification method and system |
| CN112271543A (en) * | 2020-09-29 | 2021-01-26 | 北京卓镭激光技术有限公司 | Active Q-switched laser and pulse width modulation method thereof |
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| Publication number | Publication date |
|---|---|
| CN1013329B (en) | 1991-07-24 |
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