CN110858699A - Q-switched laser - Google Patents
Q-switched laser Download PDFInfo
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- CN110858699A CN110858699A CN201810977528.2A CN201810977528A CN110858699A CN 110858699 A CN110858699 A CN 110858699A CN 201810977528 A CN201810977528 A CN 201810977528A CN 110858699 A CN110858699 A CN 110858699A
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- 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
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- 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
- H01S3/13—Stabilisation of laser output parameters, e.g. frequency or amplitude
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Abstract
The invention discloses a Q-switched laser which comprises a gain cell, a Q-switched element, an optical polarization element, an optical phase delay element and an optical reflection element, wherein the optical polarization element is positioned between the gain cell and the Q-switched element, the gain cell is positioned between the optical phase delay element and the optical polarization element, and the optical reflection element is used for reflecting laser processed by the Q-switched element and enabling the laser to enter the gain cell for primary amplification. The Q-switched laser disclosed by the invention has a simple and compact structure, and can realize laser output with high average power, high repetition frequency and high peak power by utilizing the ingenious combination of the optical polarization element and the optical phase delay element under the condition of ensuring that the Q-switched element works in a safe state.
Description
Technical Field
The invention relates to the field of lasers, in particular to a Q-switched laser.
Background
With the development of the optoelectronic industry, glass, quartz, and other composite materials are used in large quantities. In the process of manufacturing corresponding materials, the requirement for laser superfinishing is more urgent, and common continuous wave lasers and low-repetition-frequency pulse lasers cannot meet the requirement for laser superfinishing, namely the laser superfinishing requires that a heat affected zone as small as possible is formed in the interaction process of laser and substances, so that the laser must operate in a high-repetition-frequency narrow-pulse mode.
At present, the main vibration power amplification (MOPA) technology is generally adopted to realize high average power, high repetition frequency and narrow pulse laser output. In the MOPA system, a low-power Q-switched laser is used as a master oscillator to generate a high-repetition-frequency narrow-pulse laser seed signal, and the high-repetition-frequency narrow-pulse laser seed signal is injected into an amplifier to form high-average-power high-repetition-frequency narrow-pulse laser output. Thus, at least a low power, high repetition frequency, narrow pulse Q-switched laser oscillator and a high power laser amplifier are required for MOPA systems, with both lasers operating simultaneously. In order to achieve efficient amplification of the laser light, strict synchronization triggering and perfect laser light mode matching between the oscillator and the amplifier are required, and a transmission device is required to be provided between the oscillator and the amplifier.
Therefore, the existing MOPA system for realizing high average power and high repetition frequency narrow pulse laser output has the defects of large device, high cost, high technical realization difficulty and the like, is generally used in large engineering devices such as extreme ultraviolet lithography and nuclear fusion, and is not convenient to apply in the field of industrial superfinishing.
Disclosure of Invention
The invention aims to provide a Q-switched laser which is simple in structure, realizes high average power, high repetition frequency and narrow pulse laser output and can be applied to the field of industrial superfinishing.
An embodiment of the present invention provides a Q-switched laser, including a gain cell and a Q-switched element, wherein the Q-switched laser further includes:
an optical polarizing element located between the gain cell and the Q-switching element;
an optical phase retarding element, the gain cell being located between the optical phase retarding element and the optical polarizing element; and
and the optical reflection element is used for reflecting the laser processed by the Q-switching element so that the laser enters the gain cell to be amplified for the first time.
Further, the laser light primarily amplified by the gain cell enters the gain cell again for secondary amplification after the polarization direction of the laser light is changed by the optical phase delay element.
Further, the optical phase delay element includes:
a total reflection mirror;
the quarter wave plate is arranged between the total reflection mirror and the gain cell;
after the polarization direction of the laser light which is amplified by the gain cell for the first time is changed by the quarter-wave plate for the first time, the laser light is reflected to the quarter-wave plate by the full-reflection mirror, and the polarization direction of the laser light is changed for the second time; and the laser after primary amplification and secondary polarization direction change enters the gain cell for secondary amplification.
Further, the quarter-wave plate is arranged perpendicular to an optical axis of the resonant cavity of the Q-switched laser and is rotatable about a rotation axis perpendicular to the optical axis.
Further, the optical polarization element performs light splitting processing on the laser light secondarily amplified by the gain cell, forms high-power S polarized light and low-power P polarized light,
wherein the low-power P-polarized light is transmitted through the optical polarization element and processed by the Q-switching element, and the high-power S-polarized light is reflected out of the resonant cavity of the Q-switching laser.
Further, the low-power P-polarized light is processed by the Q-switching element to form high-repetition-frequency narrow-pulse P-polarized light;
the P polarized light of the high-repetition-frequency narrow pulse is converted into elliptically polarized light after being amplified for the first time and changing the polarization direction for the first time, and the elliptically polarized light is converted into linearly polarized light after changing the polarization direction for the second time.
Further, the Q-switched laser further comprises a beam size adjusting device disposed between the optical polarization element and the Q-switched element.
Further, the beam size adjusting device is a Galilean telescope system.
Further, an included angle between the optical polarization element and an optical axis of the resonant cavity of the Q-switched laser is a brute's angle.
Compared with the prior art, the invention has one of the following advantages:
(1) the Q-switched laser disclosed by the invention has a simple and compact structure, does not need a synchronous trigger device and a laser isolation device, and can realize laser output with high average power, high repetition frequency and narrow pulse under the condition of ensuring that a Q-switched element works in a safe state by utilizing the ingenious combination of the optical polarization element and the optical phase delay element.
(2) According to the Q-switched laser provided by the invention, the conventional Q-switched element sensitive to power can be utilized to realize high average power, high repetition frequency and narrow pulse laser output, the problem of low output power of the Q-switched laser with high repetition frequency and narrow pulse is hopefully solved, and the Q-switched laser has good application prospect in the fields of laser superfinishing, laser radar, photoelectric countermeasure and the like.
Drawings
Other objects and advantages of the present invention will become apparent from the following description of the invention which refers to the accompanying drawings, and will assist in a comprehensive understanding of the invention.
Fig. 1 is a schematic structural diagram of a Q-tuning device according to an embodiment of the present invention;
fig. 2 is a schematic diagram of a process of forming a single laser pulse.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings of the embodiments of the present invention. It should be apparent that the described embodiment is one embodiment of the invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the described embodiments of the invention without any inventive step, are within the scope of protection of the invention.
Unless defined otherwise, technical or scientific terms used herein shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention belongs.
As shown in fig. 1, the present invention provides a Q-switched laser 100 that achieves high average power, high repetition rate, and narrow pulse laser output. The Q-switched laser 100 may include a gain cell 12, a Q-switched element 31, an optical polarization element 20, an optical phase retardation element 11, and an optical reflection element 32.
The optical polarization element 20 plays a role in light splitting, and can divide the resonant cavity of the whole Q-switched laser 100 into two laser branches, wherein the high-power laser branch 10 is formed by the gain cell 12 and the optical phase delay element 11 and is used for amplifying laser and changing the polarization direction; the low power laser branch 30 is formed by the Q-switching element 31 and the optical reflection element 32 for providing feedback laser light and ensuring that the Q-switching element 31 operates at safe laser power.
Specifically, the optical polarization element 20 may be disposed between the gain cell 12 and the Q-switching element 31, and is configured to divide the laser light amplified by the gain cell 12 into two parts, one part is high-power laser light, and the other part is low-power laser light. The high-power laser is reflected out of the resonant cavity by the optical polarization element 20, and the low-power laser passes through the optical polarization element 20 and enters the low-power laser branch 30. The low-power laser entering the low-power laser branch 30 forms feedback laser under the action of the Q-switching element 31 and the optical reflection element 32, and enters the high-power laser branch 10 to be amplified and change the polarization direction, and then is divided into two parts by the optical polarization element 20, wherein one part is high-power laser and the other part is low-power laser, and the part of the low-power laser forms feedback laser under the action of the low-power laser branch 30, so that the feedback laser enters the high-power laser branch 10 to be amplified and change the polarization direction.
Thus, as the number of round-trip amplification times increases, the laser intensity of the low-power laser and the high-power laser increases, the number of inversion particles in the gain cell 12 decreases rapidly, the gain decreases accordingly, when the number of inversion particles is depleted, the Q-switching element 31 is turned off, the resonant cavity is in a high-loss low-Q state, and at this time, a complete laser pulse with high average power, high repetition frequency and narrow pulse is reflected out of the resonant cavity by the optical polarization element 20, so that the Q-switching laser 100 outputs the laser pulse with high average power, high repetition frequency and narrow pulse. It should be noted that, although the laser intensities of the low-power laser and the high-power laser are increasing, the laser intensity of the high-power laser is much larger than that of the low-power laser, and the intensity of the low-power laser is always within the safety threshold range of the Q-switching element 31.
In this embodiment, the optical polarization element 20 may be a polarizer and its angle to the optical axis of the resonator may be a brute's angle.
In the high power laser branch 10, an optical phase delay element 11 may be used to change the polarization direction of the feedback laser light and adjust the laser power ratio of the two branches. The gain cell 12 may be used to amplify the laser light.
Specifically, after entering the high-power laser branch 10, the feedback laser is first amplified under the action of the gain cell 12, and the feedback laser after the first amplification enters the gain cell 12 again for the second amplification under the action of the optical phase delay element 11. Moreover, the feedback laser after the first amplification changes the original polarization direction under the action of the optical phase delay element 11. After the second amplification by the gain cell 12, the light enters the optical polarization element 20 for light splitting.
In this embodiment, in order to enable the feedback laser to enter the gain cell 12 again for secondary amplification, the optical phase retardation element 11 may include a total reflection mirror 112 and a quarter-wave plate 111 disposed between the total reflection mirror 112 and the gain cell 12.
Thus, the feedback laser light amplified by the gain cell 12 for the first time is changed in polarization direction by the quarter-wave plate 111 for the first time, and then is reflected to the quarter-wave plate 111 by the total reflection mirror 112 for the second time; the feedback laser after the first amplification and the second polarization direction change enters the gain cell 12 for the second amplification.
In this embodiment, the quarter-wave plate 111 may be placed perpendicular to the optical axis of the resonator and may be capable of rotating around a rotation axis perpendicular to the optical axis, i.e., rotating in a plane perpendicular to the optical axis of the resonator, so that the angle between the optical axis of the quarter-wave plate 111 and the vibration plane of the feedback laser light once amplified by the gain cell 12 may be freely changed. Note that the angle needs to deviate from 45 °. If the included angle is 45 °, the feedback laser beam whose polarization direction is changed twice by the quarter-wave plate 111 is totally reflected out of the resonant cavity by the optical polarization element 20, and no low-power laser beam enters the right low-power laser branch 30 through the polarizer, and thus the feedback laser beam cannot be formed.
In the low power laser branch 30, the Q-switching element 31 is used to form the low power laser light transmitted through the optical polarization element 20 into feedback laser light, and the optical reflection element 32 is used to transmit the feedback laser light into the high power laser branch 10.
In a further preferred embodiment, since the clear aperture of the Q-switching element 31 is smaller than the lateral aperture of the gain cell 12, a beam size adjusting device 40 is required in the low power laser branch 30 and may be arranged between the optical polarization element 20 and the Q-switching element 31.
The beam size adjusting means 40 may be a galilean telescope system and the parameters of the telescope system determine how well the modes of the two laser branches match and how high the laser efficiency is.
The gain cell 12 in the embodiment of the present invention may be a gas gain medium or a solid gain medium. The Q-switching element 31 may be a mechanical chopper plate, an electro-optical Q-switching element 31, or an acousto-optical Q-switching element 31. The quarter wave plate 111 may be transmissive or reflective.
The following describes how the Q-switch provided by the embodiment of the present invention can output laser light with high average power, high repetition frequency and narrow pulse in detail with reference to fig. 1 and fig. 2.
As shown in fig. 1, the laser light amplified by the gain cell 12 is divided into low-power P-polarized light and high-power S-polarized light by the optical polarization element 20, wherein the low-power P-polarized light enters the low-power laser branch 30 to form high-repetition-frequency narrow-pulse P-polarized laser light, i.e., feedback laser light, and the high-power S-polarized light is reflected out of the resonant cavity by the optical polarization element 20.
Specifically, the low-power P-polarized light is formed into high-repetition-frequency narrow-pulse P-polarized laser light by the Q-switching element 31, and the Q-switching element 31 causes the Q value in the resonant cavity to be changed alternately at the corresponding frequency by the high-repetition-frequency modulation signal. The high repetition frequency narrow pulse P-polarized laser light enters the gain cell 12 through the optical reflection element 32, such as a mode matching element and a thin film polarizer, for primary amplification. The high repetition frequency narrow pulse P-polarized laser after primary amplification enters the gain cell 12 again for secondary amplification after passing through the optical phase delay element 11. In this process, the quarter-wave plate 111 of the optical phase delay element 11 converts the once-amplified high repetition frequency narrow pulse P-polarized laser light into elliptically polarized laser light, i.e., once changes the polarization direction. Then, the elliptically polarized laser beam is returned to the quarter-wave plate 111 again through the half-mirror 112 to change the secondary polarization direction, at this time, the elliptically polarized laser beam is converted into linearly polarized laser beam (non-S-polarized laser beam, non-P-polarized laser beam), the linearly polarized laser beam is secondarily amplified by the gain cell 12, and then enters the optical polarization element 20, and is divided into high-power S-polarized laser beam and low-power P-polarized laser beam, and the amplitude of the low-power P-polarized laser beam is much smaller than that of the high-power S-polarized laser beam. The high-power S-polarized laser light is reflected out of the resonant cavity by the optical polarization element 20, the low-power P-polarized laser light penetrates through the optical polarization element 20 and enters the low-power laser branch 30, forms feedback laser light under the action of the Q-switching element 31, and enters the high-power laser branch 10 under the action of the optical reflection element 32. Thus, as the number of round-trip amplification times increases, the intensities of the low-power P-polarized laser and the high-power S-polarized laser divided by the optical polarization element 20 become larger and larger, the number of inversion particles in the gain cell 12 decreases rapidly, the gain becomes lower, when the number of inversion particles is depleted, the Q-switching element 31 is turned off, the resonant cavity is in a high-loss low-Q state, and at this time, a complete S-polarized laser pulse with high average power, high repetition frequency and narrow pulse is reflected out of the resonant cavity by the optical polarization element 20, so that the Q-switching laser 100 outputs laser pulses with high average power, high repetition frequency and narrow pulse.
Fig. 2 shows the formation of a single laser pulse, and it can be seen that the laser intensity of the high power laser is much greater than that of the low power laser, and the gain of the gain cell 12 becomes lower with time, with the resulting decrease in resonance. Although the laser intensity of the low power laser and the high power laser is larger, the intensity of the low power laser is always within the safety threshold range of the Q-switching element 31.
Compared with the prior art, the embodiment of the invention has the following advantages:
(1) the Q-switched laser disclosed by the invention has a simple and compact structure, does not need a synchronous trigger device and a laser isolation device, and can realize laser output with high average power, high repetition frequency and narrow pulse under the condition of ensuring that a Q-switched element works in a safe state by utilizing the ingenious combination of the optical polarization element and the optical phase delay element.
(2) According to the Q-switched laser provided by the invention, the conventional power sensitive Q-switched element can be utilized to realize high average power, high repetition frequency and narrow pulse laser output, the problem of low output power of the Q-switched laser with high repetition frequency and narrow pulse is hopefully solved, and the Q-switched laser has good application prospect in the fields of laser superfinishing, laser radar, photoelectric countermeasure and the like.
It should also be noted that, in the case of the embodiments of the present invention, features of the embodiments and examples may be combined with each other to obtain a new embodiment without conflict.
Finally, it should be noted that the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting, and although the present invention is described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions may be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.
Claims (9)
1. A Q-switched laser comprising a gain cell and a Q-switched element, wherein the Q-switched laser further comprises:
an optical polarizing element located between the gain cell and the Q-switching element;
an optical phase retarding element, the gain cell being located between the optical phase retarding element and the optical polarizing element; and
and the optical reflection element is used for reflecting the laser processed by the Q-switching element so that the laser enters the gain cell to be amplified for the first time.
2. The Q-switched laser of claim 1, wherein the laser light once amplified by the gain cell enters the gain cell again for secondary amplification after the polarization direction of the laser light is changed by the optical phase delay element.
3. The Q-switched laser of claim 1 or 2, wherein the optical phase delay element comprises:
a total reflection mirror;
the quarter wave plate is arranged between the total reflection mirror and the gain cell;
after the polarization direction of the laser light which is amplified by the gain cell for the first time is changed by the quarter-wave plate for the first time, the laser light is reflected to the quarter-wave plate by the full-reflection mirror, and the polarization direction of the laser light is changed for the second time; and the laser after primary amplification and secondary polarization direction change enters the gain cell for secondary amplification.
4. A Q-switched laser as claimed in claim 3, wherein the quarter-wave plate is arranged perpendicular to the optical axis of the resonant cavity of the Q-switched laser and is rotatable about a rotation axis perpendicular to the optical axis.
5. The Q-switched laser according to claim 3, wherein the optical polarization element performs a light splitting process on the laser light secondarily amplified by the gain cell and forms high-power S-polarized light and low-power P-polarized light,
wherein the low-power P-polarized light is transmitted through the optical polarization element and processed by the Q-switching element, and the high-power S-polarized light is reflected out of the resonant cavity of the Q-switching laser.
6. The Q-switched laser of claim 5, wherein the low power P-polarized light is processed by the Q-switching element to form high repetition frequency narrow pulse P-polarized light;
the P polarized light of the high-repetition-frequency narrow pulse is converted into elliptically polarized light after being amplified for the first time and changing the polarization direction for the first time, and the elliptically polarized light is converted into linearly polarized light after changing the polarization direction for the second time.
7. A Q-switched laser as claimed in claim 1, 2, 4, 5 or 6, further comprising beam size adjusting means disposed between the optical polarising element and the Q-switched element.
8. The Q-switched laser of claim 7, wherein the beam size adjusting means is a Galilean telescope system.
9. The Q-switched laser of claim 7, wherein the optical polarization element is at a Brute angle with respect to an optical axis of the resonant cavity of the Q-switched laser.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201810977528.2A CN110858699A (en) | 2018-08-24 | 2018-08-24 | Q-switched laser |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201810977528.2A CN110858699A (en) | 2018-08-24 | 2018-08-24 | Q-switched laser |
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| CN110858699A true CN110858699A (en) | 2020-03-03 |
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Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN204290029U (en) * | 2014-09-30 | 2015-04-22 | 中国工程物理研究院应用电子学研究所 | A kind of ring-shaped light spot thin slice amplifier |
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2018
- 2018-08-24 CN CN201810977528.2A patent/CN110858699A/en active Pending
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN204290029U (en) * | 2014-09-30 | 2015-04-22 | 中国工程物理研究院应用电子学研究所 | A kind of ring-shaped light spot thin slice amplifier |
Non-Patent Citations (1)
| Title |
|---|
| 柯常军等: "调Q CO2激光功率放大器的输出特性", 《光学学报》 * |
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