CN1021717C - Automatic tracking method for selecting longitudinal mode, adjusting Q and locking mode - Google Patents
Automatic tracking method for selecting longitudinal mode, adjusting Q and locking mode Download PDFInfo
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- CN1021717C CN1021717C CN 91107359 CN91107359A CN1021717C CN 1021717 C CN1021717 C CN 1021717C CN 91107359 CN91107359 CN 91107359 CN 91107359 A CN91107359 A CN 91107359A CN 1021717 C CN1021717 C CN 1021717C
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Abstract
The invention relates to a method for automatically tracking selection of longitudinal modes, Q regulation and mode locking in the technical field of laser, wherein a photoconductive switch receives irradiation of a laser beam, generates current pulses, forms feedback voltage VR through a resistor R connected with the photoconductive switch in series, and is added on an electro-optical switch Pockels cell to form a feedback loop. The invention realizes the integration of moving single longitudinal mode Q-switching and mode locking. The device has the advantages of simple structure, strong anti-interference capability, long-time stable operation, low cost and the like.
Description
The present invention is single longitudinal mode selection, Q switching and the mode-locking technique in the laser technology.
In the prior art, the laser single longitudinal mode is selected with resonance reflector in U.S.'s Lawrence Livermore (Livemoce) laboratory, acoustooptic Q-switching transfers Q, constantly revise chamber length with the long automatic feedback compensation in chamber system guarantees long-time single longitudinal mode running, see figure-(D.J.Kuizenga, IEEE J.Quant.Eletcon, Vol.QE-17, NO.9.P1694-1708,1981).Its shortcoming is a complex structure, and the chamber automatic feedback compensation of the length system that it adopts is a kind of high sensitivity, the electronic system of fast-response.It is the cost height not only, and anti-electrical interference ability.It is the locked mode element that present mode-locking technique still adopts saturated absorbing body or acousto-optic modulator, the major defect of saturated absorbing body is stability and poor reliability, the characteristic of its molecule random fluctuation, determined mode locking pulse poor stability of poor quality, and under high light radiation, its molecule decomposes easily, so the mode-locked laser that is difficult to carry out is reliably and with long-term exported, the major defect of acousto-optic mode-locking modulator then is that modulation depth is too low, requires the long matching precision height in chamber.
Purpose of the present invention is invented a kind of method from motion tracking menu mould, accent Q and locked mode for overcoming above-mentioned shortcoming.
Method of the present invention is to adopt photoconductivity switching (high voltage source that comprises its needs), and electrooptical switching (or claiming Pockers cell) and resistance constitute a kind of feedback loop fast, see figure two.
When the laser beam irradiation photoconductivity switching, the resistance value of photoconductivity switching reduces rapidly, at this moment will produce a current impulse, and this current impulse forms feedback voltage V through the resistance R of connecting with photoconductivity switching
R, this feedback voltage V
RBe added on the electrode of electrooptical switching-Pockers cell, at this moment be added in the effective voltage V on the Pockers cell
EfTo reduce.Because be added in the effective voltage V on the Pu Jiaer box
EfEqual to be added in the bias voltage V on the Pockers cell
b(being added on another electrode) deducts feedback voltage V
R, be and be added in Pu Keer and close two voltage differences on the electrode, V
Ef=V
b-V
RIf irradiates light is strong more, the resistance value of photoconductivity switching will be more little, and the current impulse of generation will be big more, feedback voltage V
RAlso just big more, be added in the effective voltage V on the Pockers cell
EfWill be more little, suppose that irradiation photoconductivity switching light intensity is identical, change the resistance of resistance R, the resistance that then resistance is big more produces feedback voltage V
RAlso big more, the effective voltage that is added on the Pockers cell switch is also more little, if electrooptical switching is placed in the resonant cavity of laser, and the rayed photoconductivity switching that goes out with reflective polarizer, said system can realize that single longitudinal mode is selected automatically and accent Q, can also realize locked mode in addition.
The present invention preferably is applied in the solid state laser, and the end face of its bar-shaped operation material is vertical with rod axle, and the both ends of the surface depth of parallelism poor＜α
n(both ends of the surface are not preferably plated anti-reflection film), when making laser works like this, each oscillation longitudinal mode has different gains and initial duration of oscillation (such operation material is equivalent to the F-P etalon), when the maximum longitudinal mode of gain at first vibrates, because the reflection of polarizer, part light will shine on the photoconductivity switching, and it produces feedback voltage V
R, the feasible effective voltage V that is added on the Pockers cell
EfReduce.Because V
EfReduce, the laser cavity internal loss also reduces, intracavity medicine gain increases, the light intensity of this oscillation longitudinal mode is exaggerated; After its light intensity was exaggerated, the light intensity of reflective polarizer also increased, and the light that at this moment is radiated on the photoconductivity switching is stronger, feedback voltage V
RBigger, be added in the effective voltage V on the Pockers cell
EfLittler, cavity loss further reduces, and this longitudinal mode light intensity is amplified byer force.So circulation is gone down, and a positive feedback loop forms.Because material response time of the selected photoconductivity switching of the present invention fast (less than 10ns), so the laser generation longitudinal mode that positive feedback loop can produce at this moment from motion tracking, so far single longitudinal mode is selected to finish.Along with this longitudinal mode power constantly increases, work as feedback voltage V
RMake effective voltage V on the Pockers cell
EfBeing reduced to " zero " voltage (is V
R=V
b) time, this longitudinal mode flash-up is to its maximum P
MexThen Q impulse forms, the Q impulse width can be realized by the speed of change in gain in the resistance control chamber that changes resistance R, if laser bar is become the low-angle cutting, chamber length is set goes up synchronously laser pulse and whole feedback control system time, and further reduce the resistance of resistance R, can realize locked mode.
Feedback voltage V on photoconductivity switching
RBe higher than bias voltage V
bThe time, whole feedback loop will carry out the transition to the negative feedback state automatically by the positive feedback state, and then be the positive feedback state by the negative feedback state-transition, and so positive negative feedback is alternately conversion constantly, finally make whole feedback loop clamp down on, realized the stable state locked mode a stable state.
Its resistance value of material of photoconductivity switching that the present invention adopts is inversely proportional to the light intensity that is received, and promptly its received light intensity is strong more, and resistance value descends manyly more, otherwise its received light intensity light current resistance more descends fewly more.Require the response time fast, be preferably less than 10ns, highly sensitive, normally working as light intensity is 1 μ j/mm
2Rayed the time, its resistance value descends and is at least 10
4Doubly.And requirement can be born a kilovolt above high direct voltage.This is also relevant with the receiving plane size of photoconductivity switching except relevant with the performance of selected material own, and after material was selected, its receiving plane size was big, bear the voltage height, but sensitivity has reduced relatively; If receiving plane size hour, sensitivity improves, but it is low to bear voltage, so receiving plane will be chosen appropriately.
Above-mentioned resistance R of connecting with photoconductivity switching should optionally (be transferred Q or locked mode) and be decided, and generally, the resistance of resistance R is chosen as greater than 10 Ω.
Major advantage of the present invention:
Adopt method of the present invention, can realize the menu longitudinal mode simultaneously, transfer Q, locked mode and quasi-continuous outgoing laser beam.
The first, realize modeling (single longitudinal mode) accent Q
The present invention realizes modeling (single longitudinal mode) accent Q integrated (process is finished simultaneously on modeling, the accent Q two), and from motion tracking menu longitudinal mode and accent Q.Do not need the long automatic feedback compensation system in chamber and the energy long-term stable operation.
The Q impulse width-adjustable, the working point of laser can be away from the laser threshold values, to the long no specific (special) requirements of laser chamber.
There is not special-purpose modeling element (as resonance reflector, the F-P etalon) in the laser cavity.Whole laser does not adopt complicated electronic circuit, and antijamming capability is strong, simplifies the structure.
The second, realize quasi-continuous laser output
The present invention can easily realize the output of negative feedback quasi-continuous lasing, and does not need (about gigahertz) the electronics control circuit or the high-precision quasi-continuous power supply of super fast response, and the precision of paired pulses pump supply source and working point do not have specific (special) requirements yet.
Three, realize locked mode
The present invention can realize the positive feedback locked mode; this locked mode mechanism; the statistics and the chemical instability of non-linear saturated absorbing body have promptly been overcome; overcome acousto-optic active mode locking modulators modulate depth as shallow again; the too high shortcoming of the long matching precision in driving power and chamber; and entire device forms by durable element, so can long-term stability turn round reliably.
This locked mode also further transition be quasi-continuous stable state locked mode, the mode locking pulse width of output can be narrower.
Owing to the menu longitudinal mode, transfer Q, locked mode, quasi-continuous control to realize that by same feedback loop so simple in structure, implementation cost is extremely low, and to compare with the conventional laser of performance complexity, cost can reduce more than 10 times.
Description of drawings:
Fig. 1 is that U.S.'s Lawrence Livermore (Livemoce) Nd:YAG single longitudinal mode is transferred Q oscillator structure figure.Wherein:
1-total reflection chamber mirror, 2-laser works medium Nd:YAG rod, 3-smallcolumn diaphragm, the 4-acoustooptic Q-switching, 5-2mm heavy sheet glass flat board, 6-9mm heavy sheet glass flat board, the thick air-gap of 7-6mm, 8-8mm heavy sheet glass flat board, 9-piezoelectric ceramic (meeting the chamber automatic feedback compensation of length system).
Fig. 2 is of the present invention from motion tracking menu longitudinal mode, Q-switch and mode-locking method structural representation.Wherein:
The high-voltage DC power supply of 10-photoconductivity switching (or pulse power), 11-photoconductivity switching, 12-resistance R, 13-polarizer, the high-voltage DC power supply 15-Pockers cell of 14-Pockers cell, 16-laser output cavity sheet.
Embodiment 1: be applied in the Nd:YAG single longitudinal mode q-spoiled laser.The laser structure schematic diagram as shown in Figure 2.The long L=50cm of laser chamber; The reflectivity R ≈ 100%(wavelength 1.053 μ m of total reflection chamber mirror 1); The aperture of smallcolumn diaphragm is φ 1.5mm; Laser working medium is the Nd:YAG rod, φ 4 * 50mm, and plane rod end is vertical with the rod axle, the poor＜α of the both ends of the surface depth of parallelism
n; The operating voltage of photoconductivity switching high-voltage DC power supply is 3000V; The material of photoconductivity switching receiving plane is a GaAs, and the response time, sensitivity was 1 μ j/mm for working as intensity less than 10ns
2Laser radiation it the time, its resistance descends 10
6Doubly, receiving plane is of a size of 2 * 3 * 0.5mm
3; The resistance of resistance R is 100K Ω; Polarizer is the plated film polarizer; The operating voltage of the DC high-voltage power supply of electrooptical switching Pockers cell is 2000V; The material of Pockers cell is KDP, is of a size of φ 8 * 15mm, laser output cavity sheet reflectivity R=50%(wavelength 1.053 μ m).
This laser output parameter is: Q impulse width 35ns, and energy 30 μ j, output pulse width and fluctuation of energy≤± 5%, output single longitudinal mode probability is 100%, can long-term stable operation.
Embodiment 2: be applied in the Nd:YAG quasi-continuous laser.The laser structure schematic diagram is shown in figure two.The long L=150cm of laser chamber; Working-laser material is the Nd:YAG rod, φ 5 * 50mm, and the operating voltage of the DC high-voltage power supply of electrooptical switching Pockers cell is 3900V, and the resistance of resistance R is 5K Ω, and other parameter is substantially the same manner as Example 1.
This laser output parameter is: the width of quasi-continuous impulse waveform is that the discharge waveform of 100 μ s(pump supply sources only is 150ns) but long-term stable operation.
Embodiment 3: be applied in the Nd:YAG mode-locked laser.Fig. 2 laser structure schematic diagram, Nd:YAG are working-laser material, and rod is of a size of φ 5 * 50mm, low-angle (2 °) cutting, and the resistance of resistance R is 50 Ω, and other parameter is all identical with embodiment 1, and it is long synchronous with feedback loop that the chamber is set.
The laser output parameter is: the locked mode probability is similar to 100%, mode locking pulse width～100Ps, mode locking pulse sequence energy～10mj, sequence energy stability ± 5%, but long-term stable operation.
Claims (4)
1, a kind of from motion tracking menu longitudinal mode, transfer Q and locked mode method, it is characterized in that photoconductivity switching, produce the resistance R formation feedback voltage V of current impulse after receiving laser beam irradiation through connecting with photoconductivity switching
R, be added on electrooptical switching-Pockers cell, constitute feedback loop.
2, according to claim 1 a kind of from motion tracking menu longitudinal mode accent Q and locked mode method, it is characterized in that the effective voltage V of electrooptical switching-Pockers cell
Ef=V
b-V
R, V wherein
bBy the magnitude of voltage that is called bias voltage that the Pockers cell high-voltage DC power supply is supplied with, V
R-be that the resistance R of connecting with photoconductivity switching has current impulse through out-of-date, the feedback voltage value of generation.
3, according to claim 1 a kind of from motion tracking menu longitudinal mode accent Q and locked mode method, it is characterized in that the resistance value of the photoelectric material of photoconductivity switching is inversely proportional to the light intensity that is received, the response time, it was 1 μ j/mm that receiving light power is worked as in sensitivity less than 10nS
2Illumination the time, resistance value descends and to be at least 10
4Doubly.
4, according to claim 1 a kind of from motion tracking menu longitudinal mode accent Q and locked mode method, the resistance that it is characterized in that the resistance R that photoconduction is connected is greater than 10 Ω.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 91107359 CN1021717C (en) | 1991-04-04 | 1991-04-04 | Automatic tracking method for selecting longitudinal mode, adjusting Q and locking mode |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 91107359 CN1021717C (en) | 1991-04-04 | 1991-04-04 | Automatic tracking method for selecting longitudinal mode, adjusting Q and locking mode |
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| Publication Number | Publication Date |
|---|---|
| CN1065558A CN1065558A (en) | 1992-10-21 |
| CN1021717C true CN1021717C (en) | 1993-07-28 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 91107359 Expired - Fee Related CN1021717C (en) | 1991-04-04 | 1991-04-04 | Automatic tracking method for selecting longitudinal mode, adjusting Q and locking mode |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100495834C (en) * | 2004-12-31 | 2009-06-03 | 中国科学院西安光学精密机械研究所 | Cavity-emptying laser |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100375345C (en) * | 2004-12-31 | 2008-03-12 | 中国科学院西安光学精密机械研究所 | Cavity-dumped laser |
| CN102944931A (en) * | 2012-11-19 | 2013-02-27 | 中国电子科技集团公司第十一研究所 | Precise compensator for optical path |
-
1991
- 1991-04-04 CN CN 91107359 patent/CN1021717C/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100495834C (en) * | 2004-12-31 | 2009-06-03 | 中国科学院西安光学精密机械研究所 | Cavity-emptying laser |
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| Publication number | Publication date |
|---|---|
| CN1065558A (en) | 1992-10-21 |
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