CN119481912B - Double LD pumping alternate working temperature control-free pulse solid laser - Google Patents
Double LD pumping alternate working temperature control-free pulse solid laser Download PDFInfo
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- 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
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- H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
- H01S3/06—Construction or shape of active medium
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- 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
- H01S3/094096—Multi-wavelength pumping
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- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
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- 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
- H01S3/131—Stabilisation of laser output parameters, e.g. frequency or amplitude by controlling the active medium, e.g. by controlling the processes or apparatus for excitation
- H01S3/1312—Stabilisation of laser output parameters, e.g. frequency or amplitude by controlling the active medium, e.g. by controlling the processes or apparatus for excitation by controlling the optical pumping
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- H01S5/04—Processes or apparatus for excitation, e.g. pumping, e.g. by electron beams
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Abstract
The invention discloses a dual-LD pumping alternate working temperature control-free pulse solid laser, which comprises a total reflecting mirror, a first wave plate, a first pumping laser module, a first wedge lens group, a second pumping laser module, a pyramid prism, a polaroid, an electro-optic Q-switching component, a second wedge lens group and an output mirror which are sequentially arranged, wherein the output mirror and the total reflecting mirror jointly form a resonant cavity, the first pumping laser module comprises a multi-wavelength LD bar array I and an Nd-YAG bar crystal I which are arranged in parallel, the second pumping laser module comprises a multi-wavelength LD bar array II and an Nd-YAG bar crystal II which are arranged in parallel, and the electro-optic Q-switching component comprises a second wave plate and a Q-switching crystal which are sequentially arranged on an output light path of a polaroid. According to the invention, through the alternation of double multi-wavelength LD bar arrays and the optimization of the optical path, the problems of laser energy reduction and unstable continuous irradiation at high temperature are solved, and the stability and the output continuity of the laser are improved.
Description
Technical Field
The invention relates to the technical field of laser diode pumping all-solid-state laser, in particular to a double-LD pumping alternating working temperature control-free pulse solid-state laser.
Background
The laser tester is used as core laser equipment for laser guidance and plays a vital role in the modern military and scientific research fields. Along with the continuous progress of technology, various photoelectric pods carrying platforms are also continuously upgraded and reformed so as to adapt to wider and more complex application scenes. Under the background, there is an increasing domestic demand for laser light measuring devices having the performances of miniaturization, light weight, low power consumption, instant use and the like. However, the design of the laser light measuring device is not easy, and the core design difficulty is the design of the light source, namely the pulse solid-state laser. In order to meet the requirements of low power consumption and instant use, the laser needs to adopt a temperature control-free design scheme.
The temperature-control-free laser is a pulse laser which can normally work and output certain energy without adopting a conventional semiconductor refrigeration chip (TEC) to refrigerate or heat to a specific temperature control point. The design method has the advantages that the main power of the laser only comprises the power consumption of the LD pumping source and the power consumption of part of the circuit board by omitting the TEC device with larger power consumption, so the design method has the characteristic of low power consumption. Meanwhile, as the waste heat of the laser is reduced, the heat dissipation requirement is correspondingly reduced, and the area of the heat dissipation fins of the laser can be reduced, so that the whole machine tends to be miniaturized and light.
The temperature control-free low power consumption is realized, but a series of technical difficulties are brought.
First, since lasers do not have strict temperature control measures, laser energy fluctuations are much larger relative to lasers with temperature control. The domestic laser light meter product usually has strict requirements on laser energy, and the energy fluctuation calculated according to the PV value calculation method (namely, the difference between the maximum value and the minimum value of the laser energy is divided by 2 and then divided by the average value) is not more than 10 percent. This requirement is far higher than the case of calculating the energy fluctuation by using the standard deviation algorithm, so that the control of the laser energy fluctuation becomes a primary difficulty of the temperature-control-free pulse solid-state laser.
Secondly, the temperature-control-free laser needs to meet the requirement of instant-on and instant-off. Particularly, under the extremely low temperature environment, such as-40 ℃ and even-45 ℃, the laser can output pulse laser with specific energy requirement in a short time, such as 3-5 seconds, after the conventional communication self-test is completed by the whole machine power-on under the condition of not adopting temperature control heating. This requirement presents new challenges to conventional LD pump source designs.
For the two difficulties mentioned above, patent documents CN201610165642.6, CN201911249367.6, CN202223089416.4 and CN202123165108.0, by adopting means of multi-wavelength LD pumping, optimizing crystal absorption characteristics and heat dissipation design, although stability and energy output of the laser are improved to some extent, these methods still expose significant drawbacks when working continuously in the face of conditions of long time, high frequency (e.g. 20 Hz) and extreme temperature (e.g. 70 ℃).
In particular, these patents rely primarily on the multi-wavelength characteristics of the LD bar array to ensure efficient absorption of pump light at different temperatures to maintain stability of laser output. However, as the ambient temperature increases, the wavelength of the LD bar array may drift. Although YAG lath crystals have effective absorption in a wide wavelength range (780 nm to 820 nm), beyond this range the absorption coefficient drops drastically, resulting in a significant loss of laser energy. In addition, due to the size and weight requirements of an airborne platform, the design space of the radiator is extremely limited, and the problems of laser energy reduction, energy fluctuation increase, damage to an LD bar array component and the like caused by the increase of the temperature of the LD bar array caused by long-time operation are difficult to effectively solve.
Particularly, the temperature of the LD bar array rapidly rises under the conditions of high temperature and long-period irradiation. Without an effective temperature control mechanism (such as TEC active refrigeration), the power of LD bar arrays would drop drastically and may even be damaged by overheating, severely limiting the continuous operation capability and lifetime of the laser. Therefore, the conventional strategy of hard-mounting energy requirements by sacrificing the temperature stability of the LD bar array is not feasible in practical applications, and it is difficult to meet the strict requirements of the on-board laser detector under high temperature, high frequency and long period irradiation.
Disclosure of Invention
In view of the above, the present invention aims at overcoming the drawbacks of the prior art, and its main objective is to provide a dual LD pump alternately operated temperature control-free pulse solid laser, which solves the technical problems of laser energy drop and difficulty in realizing continuous stable irradiation for multiple periods in a high temperature environment.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
the invention relates to a double LD pump alternately working temperature control-free pulse solid laser, wherein a resonant cavity is arranged in the solid laser, and the solid laser comprises:
the total reflection mirror is arranged at the reflecting end of the resonant cavity and is used as a reflecting mirror of the resonant cavity;
the first wave plate is arranged at the light path reflecting end of the total reflecting mirror and is used for compensating the depolarization effect caused by the total reflecting mirror;
The first pumping laser module is arranged on the output optical path of the first wave plate and used as a pumping source and a pumping working substance required by generating laser;
The first wedge lens group is arranged on an output light path of the first pumping laser module and used for finely adjusting a laser light path emitted from the first pumping laser module;
the second pumping laser module is arranged on the output light path of the first wedge lens group and used as a pumping source and a pumping working substance for alternately working with the first pumping laser module to generate laser;
the pyramid prism is arranged on the output light path of the second pumping laser module and is used for folding the laser light path to enable the resonant cavity to be U-shaped;
The polarizing plate is arranged on the output light path of the pyramid prism and is used for generating linearly polarized light;
The electro-optic Q-switching component is arranged on an output light path of the polaroid and used for adjusting the polarization state of a light beam and outputting high-energy short-pulse laser;
The second wedge lens group is arranged on the output light path of the electro-optic Q-switching component and used for finely adjusting the laser light path of the high-energy short pulse output by the electro-optic Q-switching component;
The output mirror is arranged on the output light path of the second wedge mirror group and is positioned at the output end of the resonant cavity and used for outputting laser and forming the resonant cavity together with the total reflection mirror.
As a preferable scheme, the first pump laser module comprises a multi-wavelength LD bar array I and an Nd-YAG bar array I which are arranged in parallel, wherein the multi-wavelength LD bar array I is arranged on one side of a long side of the Nd-YAG bar crystal I and is used for providing pump light, and the Nd-YAG bar array I is arranged on an output light path of the first wave plate and is used for serving as a pump working substance of the multi-wavelength LD bar array I and generating laser;
The second pumping laser module comprises a multi-wavelength LD bar array II and an Nd-YAG bar array II which are arranged in parallel, wherein the multi-wavelength LD bar array II is arranged on one side of a long side of the Nd-YAG bar array II and used for alternately working with the multi-wavelength LD bar array I, and the Nd-YAG bar array II is arranged on an output light path of the first wedge lens group and used as a pumping working substance of the multi-wavelength LD bar array II and used for alternately working with the Nd-YAG bar array I to generate laser;
the electro-optical Q-switching assembly comprises a second wave plate and a Q-switching crystal, wherein the second wave plate and the Q-switching crystal are sequentially arranged on an output optical path of the polaroid, the second wave plate is used for adjusting the polarization state of a light beam, and the Q-switching crystal is used for generating high-energy short-pulse laser.
As a preferable scheme, the first multi-wavelength LD bar array and the second multi-wavelength LD bar array both adopt 3-6 wavelengths within the range of 790nm-816nm, the loading power of the first multi-wavelength LD bar array and the second multi-wavelength LD bar array is 3 kW-6 kW, and the second wave plate is a lambda/4 wave plate.
As a preferable scheme, the first Nd-YAG strip crystal and the second Nd-YAG strip crystal are in inverted trapezoids, the long sides of the first Nd-YAG strip crystal and the second Nd-YAG strip crystal are both pumping surfaces, antireflection films are plated on the pumping surfaces, the first Nd-YAG strip crystal and the short sides of the second Nd-YAG strip crystal are both fixing surfaces, the fixing surfaces are sequentially coated with a high-reflection layer, an evanescent wave eliminating layer and a welding layer, the high-reflection layer is arranged on one side of the fixing surface close to the pumping surfaces, and the first multi-wavelength LD strip array and the second multi-wavelength LD strip array are both luminous surfaces close to the first Nd-YAG strip crystal and the second Nd-YAG strip crystal.
As a preferable scheme, the thickness of the antireflection film is 760 nm-820 nm, the high-reflection layer is a high-reflection film, the thickness of the high-reflection layer is 760 nm-820 nm, the evanescent wave layer is an evanescent wave film, the welding layer is used for welding and fixing, and the distance from the light emitting surface to the pumping surface is 0.8 mm-1.4 mm.
As a preferred scheme, the multi-wavelength LD bar array also comprises a main control circuit board, wherein the main control circuit board is respectively and electrically connected with the multi-wavelength LD bar array I and the multi-wavelength LD bar array II through an LD driving circuit A and an LD driving circuit B, and the main control circuit board is also electrically connected with the Q-switching crystal through a Q-switching high-voltage circuit.
As a preferred scheme, the first wedge lens group and the second wedge lens group are composed of two wedge lens pieces with high flatness.
As a preferred embodiment, the wedge angle of the wedge mirror is 15'.
As a preferable scheme, the total reflection mirror is a total reflection Porro prism, the output mirror is a concave-convex mirror, and the first wave plate is a 0.57 lambda wave plate.
As a preferred solution, the output mirror is a VRM gaussian mirror.
Compared with the prior art, the invention has obvious advantages and beneficial effects, in particular, the technical proposal can be adopted to realize that the invention mainly comprises the following steps:
1. the double LD pumping alternate working mechanism realizes continuous stable irradiation of a plurality of periods, namely, the two multi-wavelength LD bar arrays are adopted to realize alternate pumping Nd, namely, the YAG bar crystal working mode is realized, when one multi-wavelength LD bar array is in a working state and generates laser, the other multi-wavelength LD bar array is in a non-working state, so that the heat is fully radiated and the temperature is reduced, the alternate working strategy not only effectively avoids the problem that the multi-wavelength LD bar array is overheated due to continuous working, but also enables the laser to realize continuous irradiation of a plurality of periods at the environmental temperature of up to 70 ℃ and the repetition frequency of 20Hz, and remarkably improves the stability and the reliability of the laser;
2. The method effectively solves the problems of light path deflection and depolarization, namely, two Nd-YAG slab crystals are arranged in a laser resonant cavity, after the light path of the Nd-YAG slab crystal I is adjusted, the Nd-YAG slab crystal II and a first wedge lens group are put in, the first wedge lens group is adjusted to ensure that the light path can enter the Nd-YAG slab crystal II in normal incidence so as to maintain the constant output of laser energy, and a first wave plate is arranged in front of a total reflection mirror to compensate the depolarization effect generated by the light path adjustment and the total reflection of a Porro prism, so that the polarization state of the laser in the p direction can be maintained before the laser enters the Nd-YAG slab crystal I, and the problems of light path deflection and depolarization are effectively solved;
the independent design and optimization of the LD driving circuit are realized by respectively designing independent driving circuits for the two multi-wavelength LD bar arrays, so that the complexity of the design of a hardware circuit is reduced, the reliability of a main control circuit board and the multi-wavelength LD bar arrays is remarkably improved, the trigger signals are switched by flexibly setting the trigger delay of the two multi-wavelength LD bar arrays, and the alternate working time sequence of the multi-wavelength LD bar arrays can be accurately controlled, thereby ensuring the efficient and stable operation of the laser, reducing the overall energy consumption and cost of the system, and improving the performance and the reliability of the laser and providing convenience for the subsequent system maintenance and upgrading.
In order to more clearly illustrate the structural features and efficacy of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and examples.
Drawings
FIG. 1 is a schematic diagram of a dual LD pump alternate operation temperature control free pulse solid state laser according to an embodiment of the present application;
FIG. 2 is a schematic diagram of a resonant cavity of a dual LD pump alternate operation temperature control free pulse solid state laser in accordance with an embodiment of the present application;
FIG. 3 is a schematic diagram of a MOPA laser cavity with LD-side pump in combination with side pump in accordance with an embodiment of the present application;
FIG. 4 is a timing diagram of the periodic laser emission according to an embodiment of the present application;
FIG. 5 is a timing diagram of the laser emission of 10 cycles according to an embodiment of the present application.
Reference numerals illustrate:
1. a total reflection mirror;
2. a first wave plate;
3. A first pump laser module; 301, a multi-wavelength LD bar array I, 302, nd, a YAG bar crystal I;
4. A first wedge lens group;
5. A second pump laser module; 501, a second multi-wavelength LD bar array, 502, nd, a second YAG bar crystal;
6. A pyramid prism;
7. A polarizing plate;
8. the device comprises an electro-optic Q-switching component, 801, a second wave plate, 802, a Q-switching crystal;
9. A second wedge lens group;
10. An output mirror.
Detailed Description
For the purpose of making the technical solution and advantages of the present invention more apparent, the present invention will be further described in detail below with reference to the accompanying drawings and examples of implementation. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
It will be understood that when an element is referred to as being "fixed to" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "left," "right," and the like are used herein for illustrative purposes only.
The laser tester is used as core laser equipment of laser guidance technology, and the performance requirements of the laser tester are increasingly improved along with the upgrading and innovation of various photoelectric pod systems of carrying platforms in recent years. At present, domestic scientific research institutions and units are focusing on developing laser measuring devices with characteristics of miniaturization, light weight, low power consumption and instant starting. In the core design of such devices, the most critical technical challenge is the design of the light source, the pulsed solid state laser. In view of the dual requirements of low power consumption and instant start, the laser must employ a temperature control-free design strategy to ensure stable and efficient performance.
The temperature-control-free laser device is laser equipment which can stably work under different environments and output a certain energy pulse without depending on a traditional semiconductor refrigeration chip (TEC) to perform accurate temperature control. The laser mainly concentrates the total power consumption of the laser on the LD pumping source and part of circuit loss by omitting a high-power-consumption TEC component, thereby realizing the characteristic of low power consumption. Meanwhile, due to the fact that waste heat generation is reduced, heat dissipation requirements of the laser are reduced, the area of the heat dissipation fins is reduced, and miniaturization of equipment is further promoted. However, temperature control-free designs, while offering low power consumption advantages, also present significant design challenges, particularly when it is desired to implement a ready-to-use function.
First, the lack of tight temperature control results in a significant increase in laser energy fluctuation compared to temperature controlled lasers. Domestic laser testers typically evaluate energy stability in terms of PV values, requiring no more than 10%, this standard be strict with being based on the standard deviation calculated energy fluctuation requirement. Therefore, how to effectively control the laser energy fluctuation becomes the first technical problem of the temperature control-free pulse solid-state laser.
Secondly, the on-the-fly function requires that the laser can output pulse laser meeting specific energy requirements in a short time, such as 3-5 s, after the complete machine is electrified and communication self-test is completed without preheating under an extremely low temperature environment, such as-40 ℃ to-45 ℃. This presents a new challenge to the design of LD pump sources, requiring them to start quickly at low temperatures and reach steady state operation.
In view of the above technical difficulties, various technical solutions have been proposed and put into practice in China, and these solutions are described in journal literature and patents in the related laser optical field. For example, the multi-wavelength pumping temperature control-free solid laser and the multi-wavelength selection method with the patent application number of CN201610165642.6 adopt a multi-wavelength pumping technology and combine with the design of an LD end pump crystal rod to ensure that the crystal can keep certain absorption coefficient under pumping light with different wavelengths, thereby maintaining stable output of laser energy and realizing temperature control-free design. Similarly, a high-repetition-frequency temperature-control-free semiconductor pump 1064nm disc laser with a patent application number of CN201911249367.6, a temperature-control-free debugging-free solid laser with a patent application number of CN202223089416.4, a resonant cavity of an all-solid-state laser with a patent application number of CN202123165108.0 and the all-solid-state laser also adopt a multi-wavelength LD pumping strategy, have good heat dissipation characteristics through disc crystals, and have sufficient absorption through LD angle pumping lath crystals, so that the design target of the temperature-control-free laser is realized.
Although the domestic papers and patent documents disclose designs of temperature control-free lasers, and solve part of the design difficulties, the prior art schemes still have significant shortcomings in coping with specific application scenarios, especially the pulsed solid state lasers required by laser light meters. Particularly, under the strict requirements of an airborne platform on laser energy (reaching the order of 130 mJ) and continuous multi-period light emitting time (comprising 10 short periods and 4 long periods), the conventional temperature-control-free laser scheme is difficult to be qualified.
Particularly in the high temperature 70 ℃ environment, the design of the temperature control-free laser faces great challenges. The aforementioned published patent inventions are based mainly on LD multi-wavelength pumping technology, ensuring that LD can fully absorb and maintain a certain energy output at different temperatures. However, these schemes are mainly applicable to application scenarios with shorter laser light emission times and within a certain temperature range. When the light is emitted for a longer time, particularly in a high-temperature environment, the wavelength of the LD can be greatly shifted, for example, the LD at 808nm can be raised to more than 820nm at 70 ℃ according to the temperature shift coefficient of 0.28 nm/DEG C, and the effective absorption wavelength range of the Nd-YAG crystal near 800nm is limited, generally 780 nm-820 nm, and the absorption coefficient is greatly reduced beyond the range.
To solve this problem, designers often choose LD bars of lower wavelengths at ambient temperature to combine. However, this approach requires compromise in low temperature performance, so long wavelength LD bars also need to maintain a certain power, resulting in a significant increase in power requirements for a single multi-wavelength LD bar array. The heat dissipation pressure is increased, and the load voltage is increased due to the increase of the number of the serially connected LD bars, so that the design difficulty of the LD circuit is increased.
More seriously, under the high-temperature environment of 70 ℃, the temperature of the LD bar array gradually rises along with the light emitting time due to the lack of TEC active refrigeration. Under the condition that the whole machine is strictly limited in volume and weight, the radiator is limited in size, so that the temperature of the LD bar array is quickly increased to about 80 ℃. At this time, the laser energy rapidly decreases, the average energy decreases, and the laser energy fluctuates beyond a prescribed 10% range. In addition, long-time high-temperature operation can reduce the power of the LD bar, even burn out part of the LD bar chips, and seriously affect the service life of the whole machine.
Therefore, with the technical solution of maintaining laser energy by leaving the LD bar temperature rising, it is not feasible under the continuous long period irradiation requirement of 20 Hz. Once the LD bar temperature rises to around 80 ℃, power-off protection is required, otherwise the LD bar will be damaged or power reduced.
In order to solve the above problems, referring to fig. 1 to 5, an embodiment of the present invention provides a dual LD pump alternately operating temperature control-free pulse solid laser, in which a resonant cavity is disposed, the solid laser includes:
The total reflection mirror 1 is arranged at the reflecting end of the resonant cavity and is used as a reflecting mirror of the resonant cavity.
The first wave plate 2 is arranged at the light path reflecting end of the total reflecting mirror 1 and is used for compensating the depolarization effect caused by the total reflecting mirror 1 and ensuring the stability of the polarization state of laser.
The first pump laser module 3 is disposed on the output optical path of the first wave plate 2, and is used as a pump source and a pump working substance required for generating laser.
The first wedge lens group 4 is arranged on the output optical path of the first pump laser module 3 and used for finely adjusting the laser optical path emitted from the first pump laser module 3.
The second pump laser module 5 is arranged on the output light path of the first wedge lens group 4 and used as a pump source and a pump working substance to alternately work with the first pump laser module 3 to generate laser, so that continuous and stable laser output is realized, and meanwhile, the heat accumulation of a single pump source is reduced. The design of the first wedge lens group 4 ensures that the laser emitted by the first pump laser module 3 can accurately enter the second pump laser module 5.
The pyramid prism 6 is arranged on the output light path of the second pump laser module 5 and is used for folding the laser light path to enable the resonant cavity to be U-shaped, namely devices in the resonant cavity are divided into two support arms to be placed, so that the mechanical length of the solid laser is effectively shortened, the compactness of the structure is improved, the anti-detuning effect is facilitated, the light path stability of the solid laser under the high-temperature and vibration impact environment is enhanced, and the constancy of laser output energy is ensured.
And a polarizing plate 7 provided on the output light path of the corner cube 6 for generating linearly polarized light and improving coherence and directivity of laser light.
The electro-optic Q-switching component 8 is arranged on an output light path of the polaroid 7 and used for adjusting the polarization state of a light beam and outputting high-energy short-pulse laser so as to realize accurate control and optimization of the laser pulse.
The second wedge lens group 9 is arranged on the output light path of the electro-optic Q-switching component 8 and is used for finely adjusting the laser light path of the high-energy short pulse output by the electro-optic Q-switching component 8 so as to ensure that the laser is accurately focused on the output lens 10.
The output mirror 10 is arranged on the output light path of the second wedge mirror group 9 and is positioned at the output end of the resonant cavity, and is used for outputting laser, and forms the resonant cavity together with the total reflection mirror 1, so that stable oscillation and amplification of the laser in the resonant cavity are ensured.
In this embodiment, the first pump laser module 3 includes a multi-wavelength LD bar array 301 and a nd:yag slab crystal 302 disposed in parallel, and the multi-wavelength LD bar array 301 is disposed on a long side of the nd:yag slab crystal 302 for providing pump light to achieve efficient energy conversion. YAG slab crystal one 302 is arranged on the output optical path of the first wave plate 2 and is used as a pumping working substance of the multi-wavelength LD slab array one 301 and generates laser light as an initial laser source of the solid laser.
The second pump laser module 5 comprises a second multi-wavelength LD bar array 501 and a second Nd-YAG bar array 502 which are arranged in parallel, wherein the second multi-wavelength LD bar array 501 is arranged on one side of the long side of the second Nd-YAG bar array 502 and is used for alternately working with the first multi-wavelength LD bar array 301, and the second Nd-YAG bar array 502 is arranged on the output light path of the first wedge lens group 4 and is used as a pump working substance of the second multi-wavelength LD bar array 501 and is used for alternately working with the first Nd-YAG bar array 302 to generate laser so as to ensure the continuity and stability of laser output.
The electro-optic Q-switching component 8 comprises a second wave plate 801 and a Q-switching crystal 802 which are sequentially arranged on an output optical path of the polaroid 7, the second wave plate 801 is used for adjusting the polarization state of a light beam, ensuring the accurate control of the polarization direction of laser, and the Q-switching crystal 802 is used for generating high-energy short-pulse laser, and compressing the laser pulse and intensively outputting energy through a rapid switching effect.
Here, the pumping substance, i.e., the gain medium, is a pumping crystal, essentially nd—yag lath crystal itself.
Further, 3-6 wavelengths in the range of 790nm-816nm are adopted for the first multi-wavelength LD bar array 301 and the second multi-wavelength LD bar array 501, so that absorption peaks of Nd: YAG plate bar crystals are efficiently matched, pumping efficiency is improved, loading power of the first multi-wavelength LD bar array 301 and the second multi-wavelength LD bar array 501 is 3 kW-6 kW, sufficient pumping energy is ensured, high-power laser output is achieved, the second wave plate 801 is a lambda/4 wave plate, and the second wave plate 801 is used for accurately adjusting the polarization state of laser, and polarization control in the electro-optic Q-switching process is achieved.
The first Nd-YAG plate bar crystal 302 and the second Nd-YAG plate bar crystal 502 are in inverted trapezoids, so that the thermal lens effect in the inside of the Nd-YAG plate bar crystal is reduced, and the quality of laser beams is improved. The incident surfaces of the first YAG plate bar crystal 302 and the second YAG plate bar crystal 502 are cut according to the Brewster angle, so that reflection loss of laser during incidence is reduced, and the transmission efficiency of the laser is improved. The long sides of the trapezium of the first and second Nd-YAG strip crystals 302 and 502 are both pumping surfaces, and the pumping surfaces are coated with antireflection films, so that the reflection of pumping light is further reduced, and the pumping efficiency is improved. The first and second Nd-YAG strip crystals 302 and 502 are both fixed surfaces coated with a high-reflection layer, an evanescent wave eliminating layer and a welding layer in sequence, the high-reflection layer is arranged on one side of the fixed surface close to the pumping surface and used for reflecting unabsorbed pumping light so as to improve the utilization rate of the pumping light, and one side of the first and second multi-wavelength LD strip arrays 301 and 501 close to the first and second Nd-YAG strip crystals 302 and 502 is respectively a luminous surface and used for providing uniform and efficient pumping light for the second and third Nd-YAG strip crystals.
Considering that the laser works in the temperature range of-40 ℃ to 70 ℃, the wavelength of the multi-wavelength LD bar array can change along with the ambient temperature, and the change range is in the range of 760nm to 820nm, so that the thickness of the anti-reflection film is designed to be 760nm to 820nm, and the transmittance of pump light in the whole temperature range is ensured. In addition, the high-reflection layer is a high-reflection film, and the thickness of the high-reflection layer is 760 nm-820 nm, so that the reflectivity of pump light passing through the bottom of the Nd-YAG strip crystal in the full temperature range is ensured. The evanescent wave layer is an evanescent wave film, and has the effects of effectively inhibiting reflection loss of evanescent waves on an interface of the Nd-YAG slab crystal and improving coupling efficiency of pump light in the Nd-YAG slab crystal. The welding layer is used for welding and fixing, and ensures the stable operation of the Nd-YAG lath crystal under high-power pumping. The distance from the light emitting surface to the pumping surface is 0.8 mm-1.4 mm, so that pumping light of the multi-wavelength LD bar array can enter the Nd-YAG bar crystal, the absorption efficiency of the Nd-YAG bar crystal on the pumping light is improved, and the pumping light can be pumped relatively uniformly in the Nd-YAG bar crystal.
Referring to fig. 3, the dual LD pump alternately-operated temperature control-free pulse solid laser further includes a main control circuit board electrically connected to the first and second multi-wavelength LD bar arrays 301 and 501 through the LD driving circuits a and B, respectively, to ensure independent and accurate control and driving of the two multi-wavelength LD bar arrays. The main control circuit board is also electrically connected with the Q-switching crystal 802 through a Q-switching high-voltage circuit, and the connection ensures the quick response and accurate regulation of the Q-switching process, so that the flexible regulation of parameters such as laser pulse width, repetition frequency and the like is realized.
Specifically, in the operation mechanism of the solid-state laser, the first multi-wavelength LD bar array 301 and the second multi-wavelength LD bar array 501 are independently powered and are independently driven by the LD driving circuit a and the LD driving circuit B, respectively. The two driving circuits are integrated with 485 communication interfaces so as to realize effective communication with the main control circuit board. In order to generate pulse light output, the Q-switched high-voltage circuit is responsible for applying high voltage with lambda/4 wavelength to a Q-switched crystal 802 built in the solid laser, so as to realize an electro-optic Q-switched function.
Under the control of the main control circuit board, the two paths of driving circuits can synchronously trigger the Q-switched high-voltage circuit according to a preset sequence, so that the switching of power supply is realized. The specific flow is that firstly, according to the instruction of the upper computer, the main control circuit board activates the LD driving circuit A through the trigger signal A, and starts the power supply of the multi-wavelength LD bar array one 301. In one pumping cycle, the LD current is pumped at a pulse width of 230 μm. Next, the main control circuit board synchronously triggers the Q-switched high voltage circuit after 230 μm delay based on the trigger signal a, and the Q-switched high voltage circuit immediately applies high voltage to the Q-switched crystal 802, thereby completing one cycle of pulse light output. During this period, the LD driving circuit B remains in a standby state, and the multi-wavelength LD bar array two 501 is also in a non-operating state. After the first multi-wavelength LD bar array 301 completes the laser output and enters the rest interval, the second multi-wavelength LD bar array 501 starts to enter the working state. The main control circuit board activates the LD driving circuit B through the trigger signal B, and then synchronously triggers the Q-switched high-voltage circuit according to the set delay time, so that the pulse light output of the multi-wavelength LD bar array II 501 is realized. The process is alternately carried out between the two multi-wavelength LD bar arrays, so that each multi-wavelength LD bar array can obtain more sufficient rest time, and the overall working efficiency and stability are improved.
Referring to fig. 4, let the light emitting time of a single laser cycle of the laser light measuring device be T, and the interval time between adjacent cycles be Δt. The specific process is that the main control circuit board firstly triggers the multi-wavelength LD bar array one 301 to make it continuously emit light for T time at 20 Hz. Subsequently, the system enters an intermittent period of Δt. Next, the main control circuit board triggers the second multi-wavelength LD bar array 501 to emit light at the same frequency of 20Hz for a period of T, and then goes through an intermittent period of Δt. Thereafter, the flow returns to the multi-wavelength LD bar array one 301, and so on.
In this mode, each multi-wavelength LD bar array actually enjoys a rest period of t+2Δt after completing one light emitting period T, and the light emitting-intermittent mode of the whole laser system still maintains the rule of the interval of T light emitting and Δt.
Taking the parameters in fig. 5 as an example, if the light emitting time of a single period is set to 60 seconds, i.e., t=60 s, and the interval time is set to 10 seconds, i.e., Δt=10s, according to the present invention, the actual working time of each multi-wavelength LD bar array is set to 60 seconds, and the rest interval is extended to 80 seconds, i.e., t+2Δt=80s. This extended rest period, i.e., 80 seconds, is sufficient to ensure that the LD assembly dissipates heat effectively, maintaining its operation at a lower temperature level.
Further, in combination with a laser energy control method and related apparatus of patent application number CN202211309935.9, stable control of laser energy in each cycle can be achieved by precisely fitting a control curve between the pulse width of LD current and the LD temperature, keeping the fluctuation range within about 5%, and supporting stable irradiation for more than 10 consecutive cycles.
Furthermore, the first wedge lens group 4 and the second wedge lens group 9 are composed of two wedge lens pieces with high flatness, so that the laser enters the second Nd-YAG plate bar crystal 502 after exiting through the first Nd-YAG plate bar crystal 302, the laser is ensured to enter according to the Brewster angle, and the conversion efficiency of the pump light is improved.
The wedge angle of the wedge mirror piece is 15', and the material of the wedge mirror piece is quartz.
The total reflection mirror 1 is a total reflection Porro prism, the output mirror 10 is a concave-convex mirror, the first wave plate 2 is a 0.57 lambda wave plate, and it is ensured that laser light does not have p-direction polarized light when entering the Nd-YAG lath crystal I302 after being totally reflected by the total reflection Porro prism, wherein the p-direction is vertical direction according to the placement direction of the Nd-YAG lath crystal I302 in fig. 2.
The output mirror 10 is a VRM gaussian mirror, i.e. a graded index mirror, whose radius of curvature is designed according to the cavity length of the resonant cavity and the slab lens.
The above description is only of the preferred embodiments of the present invention and is not intended to limit the invention, but any modifications, equivalents, improvements, etc. within the principles of the present invention should be included in the scope of the present invention.
Claims (10)
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| CN109301684A (en) * | 2018-11-14 | 2019-02-01 | 西南技术物理研究所 | The solid state laser that diode is pumped in advance-normally pumped |
| CN113451870A (en) * | 2021-05-13 | 2021-09-28 | 中国科学院西安光学精密机械研究所 | High-power laser suitable for extreme environment and laser generation method thereof |
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| CN203911216U (en) * | 2014-06-25 | 2014-10-29 | 北京国科欣翼科技有限公司 | Laser |
| CN113659419A (en) * | 2021-08-04 | 2021-11-16 | 江苏亮点光电研究有限公司 | A temperature-free high beam quality electro-optical Q-switched pulsed laser |
| CN114300922B (en) * | 2021-12-31 | 2022-07-15 | 湖南大科激光有限公司 | Method for improving working stability of fiber laser |
| CN219371669U (en) * | 2023-03-30 | 2023-07-18 | 中国电子科技集团公司第二十七研究所 | A 100Hz high repetition rate and high energy DPL laser |
| CN116742457A (en) * | 2023-06-20 | 2023-09-12 | 北京中星时代科技有限公司 | LD symmetric side pump module and laser |
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| CN109301684A (en) * | 2018-11-14 | 2019-02-01 | 西南技术物理研究所 | The solid state laser that diode is pumped in advance-normally pumped |
| CN113451870A (en) * | 2021-05-13 | 2021-09-28 | 中国科学院西安光学精密机械研究所 | High-power laser suitable for extreme environment and laser generation method thereof |
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