Compound pulsed laser device

Abstract

The application relates to the technical field of laser pulse, in particular to a composite pulse laser device which comprises an output mirror, a polarizer, a laser gain module, a first reflector, a first Q switch, a second reflector, a second Q switch and a controller, the first reflector, the first Q switch, the polarizer and the output mirror form a first pulse laser resonant arm cavity, the second reflector, the second Q switch, the polarizer and the output mirror form a second pulse laser resonant arm cavity, the polarizer transmits first direction polarized laser and reflects second direction polarized laser, tens of nanoseconds and hundreds of nanoseconds laser are output from the laser gain module and the output mirror, the output of pulse laser of the first pulse laser resonant arm cavity and the second pulse laser resonant arm cavity is controlled by the controller, the pulse interval is flexibly adjustable, the application has compact structure and flexible design, tens of nanoseconds and hundreds of nanoseconds laser output can be simultaneously realized under the control of the same electric signal, and the application has strong practicability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of laser pulse, in particular to a composite pulse laser device. BACKGROUND

[0002] The nanosecond pulse width large energy Q-switched solid-state laser has the advantages of compact structure and low cost, and has wide application in the fields of laser processing, nonlinear optics, material preparation, laser ranging, laser three-dimensional scanning, etc. For example, in the field of nonlinear optics, nanosecond laser can realize high-intensity laser pulse output, and since the damage threshold of the material is proportional to the laser pulse width, short pulse laser needs to be used. In the field of laser ranging, short pulse makes the measurement error smaller, thereby bringing higher measurement accuracy. In the field of laser processing, nanosecond laser has high power, and the longer pulse width can realize sufficient dissolution of the processed material, thereby bringing higher processing efficiency.

[0003] The commonly used nanosecond Q-switched laser is generally a single continuous pulse laser, and the output pulse laser is fixed. For example, the acoustic-optic Q-switching technology generally can obtain hundreds of nanosecond laser pulse output, and the electro-optic Q-switching technology generally can obtain tens of nanosecond laser pulse output. In actual production and life, a single continuous pulse laser is difficult to meet the actual production and life needs in different target application scenarios, and it is urgent to output composite nanosecond pulses with different pulse widths to cope with different target application scenarios. SUMMARY

[0004] The present application provides a composite pulse laser device to solve the defect of single pulse width output of the nanosecond Q-switched laser in the prior art, and realize laser pulses with different pulse widths.

[0005] The present application provides a composite pulse laser device, comprising an output mirror, a polarizer, a laser gain module, a first mirror, a first Q-switch, a second mirror, a second Q-switch and a controller, wherein the output mirror is used for outputting a laser beam; the polarizer is used for transmitting first direction polarized laser and reflecting second direction polarized laser; the laser gain module is located between the output mirror and the polarizer and is used for radiating laser; the first mirror and the first Q-switch are located at the first direction input side of the polarizer, and the first mirror, the first Q-switch, the polarizer and the output mirror are sequentially and spacedly arranged to form a first pulse laser resonant arm cavity; the second mirror and the second Q-switch are located at the second direction input side of the polarizer, and the second mirror, the second Q-switch, the polarizer and the output mirror are sequentially and spacedly arranged to form a second pulse laser resonant arm cavity; and the controller controls the first Q-switch and the second Q-switch respectively to adjust the laser pulse time sequence interval in the first pulse laser resonant arm cavity and the second pulse laser resonant arm cavity.

[0006] According to the composite pulse laser device, the first Q switch is an electro-optic Q switch, and the first pulse laser resonant arm cavity generates a laser pulse of 10 nanoseconds.

[0007] According to the composite pulse laser device, the first Q switch adopts a pressure release type Q switching mode, the electro-optic crystal in the first Q switch includes a high pressure state and a low pressure state, in the high pressure state, the polarization direction of the laser beam passing through the electro-optic crystal is rotated by 90°, and the laser beam is blocked in the first pulse laser resonant arm cavity; in the low pressure state, the polarization direction of the laser beam passing through the electro-optic crystal remains unchanged, and the laser beam forms effective laser oscillation in the first pulse laser resonant arm cavity.

[0008] According to the composite pulse laser device, the first Q switch adopts a pressure release type Q switching mode, the electro-optic crystal in the first Q switch includes a high pressure state and a low pressure state, in the high pressure state, the polarization direction of the laser beam passing through the electro-optic crystal is rotated by 90°, and the laser beam is blocked in the first pulse laser resonant arm cavity; in the low pressure state, the polarization direction of the laser beam passing through the electro-optic crystal remains unchanged, and the laser beam forms effective laser oscillation in the first pulse laser resonant arm cavity.

[0009] According to the composite pulse laser device, the first direction polarized laser is horizontal linear polarized light, the second direction polarized laser is vertical linear polarized light, and the polarizing plate is at an angle of 45° with the horizontal direction.

[0010] The first mirror, the first Q switch, the polarizing plate, the laser gain module and the output mirror are arranged in sequence in the horizontal direction, so that the polarizing plate transmits the horizontal linear polarized light.

[0011] The second mirror and the second Q switch generate the vertical linear polarized light, and the vertical linear polarized light is reflected by the polarizing plate into the laser gain module.

[0012] According to the composite pulse laser device, a half wave plate is arranged between the laser gain module and the polarizing plate, and the half wave plate is used to change the energy distribution ratio of the first direction polarized laser and the second direction polarized laser, so as to adjust the intensity of the two pulse lasers.

[0013] The composite pulse laser device provided by the present application comprises a laser gain module and a pump source, the pump source emits pump light into the laser gain medium, and laser is generated in the laser gain medium.

[0014] The laser gain medium of the laser gain module comprises an isotropic crystal and / or an anisotropic crystal, the isotropic crystal is used to form single-wavelength laser output of the first direction polarized laser and the second direction polarized laser, and the anisotropic crystal is used to form different-wavelength laser output of the first direction polarized laser and the second direction polarized laser.

[0015] The pump mode of the pump source adopts side pumping or end pumping.

[0016] The polarizer is a thin film polarizer or a polarization beam splitter prism.

[0017] The composite pulse laser device provided by the present application comprises a laser gain module and a pump source, the pump source emits pump light into the laser gain medium, and laser is generated in the laser gain medium. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort on the basis of these drawings.

[0019] Figure 1 is one of the structural schematic diagrams of the composite pulse laser device provided by the present application.

[0020] Figure 2 is the second structural schematic diagram of the composite pulse laser device provided by the present application.

[0021] Figure 3is a schematic diagram of a composite pulse output by the embodiment one of the present application.

[0022] Figure 4 is a schematic diagram of a composite pulse output by the embodiment two of the present application.

[0023] Figure 5 is a schematic diagram of a composite pulse output by the embodiment three of the present application.

[0024] Fig. 1 is an output mirror; 2 is a polarizer; 3 is a laser gain module; 4 is a first mirror; 5 is a first Q switch; 6 is a second mirror; 7 is a second Q switch; 8 is a controller; 9 is a 1 / 4 lambda wave plate; 10 is a half wave plate. DETAILED DESCRIPTION

[0025] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions in the present application will be described clearly and completely below with reference to the drawings in the present application. Obviously, the described embodiments are some embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0026] In the description of the embodiments of the present application, it should be noted that the orientations or positional relationships indicated by the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the embodiments of the present application and simplifying the description, and are not intended to indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the embodiments of the present application. In addition, the terms "first", "second", "third" are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0027] In the description of the embodiments of the present application, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected", "connected" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium. For those skilled in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0028] In embodiments of the present invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0029] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0030] The following is combined Figures 1 to 5 The specific structure and operation of the composite pulsed laser device of the present invention are described.

[0031] One embodiment of the present invention provides a composite pulsed laser device, see [link to previous document]. Figure 1 As shown, the system includes an output mirror 1, a polarizer 2, a laser gain module 3, a first reflector 4, a first Q-switch 5, a second reflector 6, a second Q-switch 7, and a controller 8. The output mirror 1 outputs a laser beam; the polarizer 2 transmits laser light polarized in a first direction and reflects laser light polarized in a second direction; the laser gain module 3 is located between the output mirror 1 and the polarizer 2 and radiates the laser; the first reflector 4 and the first Q-switch 5 are located on the first direction input side of the polarizer 2, and the first reflector 4, the first Q-switch 5, the polarizer 2, and the output mirror 1 are arranged sequentially at intervals to form a first pulsed laser resonant cavity; the second reflector 6 and the second Q-switch 7 are located on the second direction input side of the polarizer 2, and the second reflector 6, the second Q-switch 7, the polarizer 2, and the output mirror 1 are arranged sequentially at intervals to form a second pulsed laser resonant cavity; the controller 8 is connected to and controls the first Q-switch 5 and the second Q-switch 7 to adjust the timing interval of the laser pulses within the first and second pulsed laser resonant cavities.

[0032] It can be understood that the composite pulse laser device of the embodiment comprises a first pulse laser resonant arm cavity composed of the first reflector 4, the first Q switch 5, the polarizer 2 and the output mirror 1, a second pulse laser resonant arm cavity composed of the second reflector 6, the second Q switch 7, the polarizer 2 and the output mirror 1, the polarizer 2 transmits the first direction polarized laser and reflects the second direction polarized laser, and tens of nanosecond and hundreds of nanosecond pulse lasers can be output from the laser gain module 3 and the output mirror 1, the output of the pulse lasers of the first pulse laser resonant arm cavity and the second pulse laser resonant arm cavity is controlled by the controller 8, so that the pulse interval is flexibly adjustable. The structure is compact and the design is flexible, and tens of nanosecond and hundreds of nanosecond pulse lasers can be simultaneously output under the control of the same electrical signal, which has strong practicability.

[0033] In some embodiments of the composite pulse laser device, the first Q switch 5 is an electro-optic Q switch, so as to generate tens of nanosecond laser pulses in the first pulse laser resonant arm cavity; and the second Q switch 7 is an acousto-optic Q switch, so as to generate hundreds of nanosecond laser pulses in the second pulse laser resonant arm cavity.

[0034] It can be understood that the electro-optic Q switch utilizes the electro-optic effect (i.e. the phenomenon that the refractive index of certain crystals changes under the action of an external electric field). When no voltage is applied to the electro-optic crystal, the crystal has high loss to the laser beam passing through it, which prevents laser oscillation. After a suitable voltage is applied, the refractive index of the crystal changes, so that the light beam can pass through, at which time the loss in the laser cavity suddenly decreases, and the energy stored in the laser medium is rapidly released, forming a laser pulse with high peak power. The first Q switch 5 adopts an electro-optic Q switch, which can generate tens of nanosecond laser pulses in the first pulse laser resonant arm cavity.

[0035] The acousto-optic Q switch works based on the acousto-optic effect, i.e. when the ultrasonic wave passes through a specific crystal (such as quartz), a periodic change in refractive index is formed in the crystal, which is equivalent to a dynamic diffraction grating. When there is no ultrasonic wave, the laser beam cannot effectively pass through the crystal because the loss is high at this time. Once the ultrasonic wave is activated, the dynamic grating formed will enable the laser beam of a specific wavelength to pass through, while reducing the loss in the laser cavity, thereby triggering intense laser oscillation. The second Q switch 7 adopts an acousto-optic Q switch, which can generate hundreds of nanosecond laser pulses in the second pulse laser resonant arm cavity.

[0036] Specifically, in some specific examples of the composite pulse laser device of the present application, the first Q-switch 5 adopts a voltage-reduction Q-switching mode, the electro-optic crystal in the first Q-switch 5 includes a high-voltage state and a low-voltage state, in the high-voltage state, the polarization direction of the laser beam passing through the electro-optic crystal is rotated by 90°, and the laser beam is blocked in the first pulse laser resonant arm cavity; in the low-voltage state, the polarization direction of the laser beam passing through the electro-optic crystal remains unchanged, and the laser beam forms effective laser oscillation in the first pulse laser resonant arm cavity.

[0037] It can be understood that the first Q-switch 5 (electro-optic Q-switch) adopts a voltage-reduction Q-switching mode to generate a laser pulse with high energy and short pulse width. In the initial state, the electro-optic Q-switch (EOQ) is in a high-voltage state. At this time, the refractive index of the electro-optic crystal changes under the action of the applied electric field, causing the polarization direction of the laser beam passing through the electro-optic crystal to rotate by 90°. This rotation of the polarization direction makes the laser beam unable to pass through the polarizer 2 or other polarization selection elements in the first pulse laser resonant arm cavity, so the laser beam is blocked in the first pulse laser resonant arm cavity and cannot form effective laser oscillation. In the high-voltage state, the energy of the laser gain medium in the laser gain module 3 is continuously accumulated, but due to the rotation of the polarization direction, the laser beam cannot pass through the first pulse laser resonant arm cavity, and the energy is mainly stored in the laser medium. When a laser pulse needs to be generated, the controller 8 quickly reduces the voltage of the electro-optic Q-switch to a low-voltage state, at this time, the refractive index of the electro-optic crystal returns to the initial state and no longer causes the rotation of the polarization direction, the polarization direction of the laser beam remains unchanged and can smoothly pass through the polarizer 2 or other polarization selection elements in the first pulse laser resonant arm cavity, thereby forming effective laser oscillation in the first pulse laser resonant arm cavity. With the establishment of laser oscillation, the energy stored in the laser gain medium of the laser gain module 3 is rapidly released, forming a laser pulse with high energy and short pulse width, and output through the output mirror 1.

[0038] In other specific examples of the composite pulse laser device of the present application, the first Q-switch 5 adopts a voltage-increasing Q-switching mode, a 1 / 4λ wave plate 9 is arranged between the first Q-switch 5 and the polarizer 2, and the electro-optic crystal in the first Q-switch 5 includes a high-voltage state and a low-voltage state. In the low-voltage state, the polarization direction of the laser beam passing through the electro-optic crystal remains unchanged, and the polarization direction is rotated by 90° after passing through the 1 / 4λ wave plate 9, so that the laser beam is blocked in the first pulse laser resonant arm cavity; in the high-voltage state, the polarization direction of the laser beam passing through the electro-optic crystal is rotated by 90°, and the polarization direction is rotated by another 90° after passing through the 1 / 4λ wave plate 9, so that the laser beam forms effective laser oscillation in the first pulse laser resonant arm cavity.

[0039] It can be understood that the first Q-switch 5 adopts a voltage-boosting Q-switching mode, and the 1 / 4λ wave plate 9 inserted in the first pulsed laser resonant arm cavity is used to realize the precise control of the laser pulse. In the initial state, the electro-optic Q-switch (EOQ) is in a low-voltage state. At this time, the refractive index of the electro-optic crystal is not affected by the external electric field, and the polarization direction of the laser beam passing through the electro-optic crystal remains unchanged. The 1 / 4λ wave plate 9 inserted in the first pulsed laser resonant arm cavity will make the polarization direction of the passing laser beam rotate by 90°. Specifically, the linearly polarized light becomes circularly polarized light after passing through the 1 / 4λ wave plate 9, and then becomes linearly polarized light again after passing through the electro-optic crystal and passing through the 1 / 4λ wave plate 9 again, but the polarization direction is rotated by 90°. In the low-voltage state, the polarization direction of the laser beam passing through the electro-optic crystal remains unchanged, but the polarization direction is rotated by 90° after passing through the 1 / 4λ wave plate 9. This makes the laser beam unable to pass through the polarizer 2 or other polarization selection elements in the first pulsed laser resonant arm cavity, so the laser beam is blocked in the first pulsed laser resonant arm cavity and cannot form effective laser oscillation. Therefore, the energy of the laser gain medium in the laser gain module 3 is continuously accumulated, but due to the rotation of the polarization direction, the first pulsed laser resonant arm cavity cannot generate laser, and at this time the energy is mainly stored in the laser gain medium. When a laser pulse is needed, the controller 8 quickly raises the voltage of the electro-optic Q-switch to a high-voltage state. At this time, the refractive index of the electro-optic crystal changes under the action of the external electric field, so that the polarization direction of the laser beam passing through the electro-optic crystal no longer rotates. As a result, the polarization direction of the laser beam remains unchanged and can smoothly pass through the polarizer 2 or other polarization selection elements in the first pulsed laser resonant arm cavity, thereby forming effective laser oscillation in the first pulsed laser resonant arm cavity. With the establishment of laser oscillation, the energy stored in the laser gain medium is rapidly released, forming a high-energy, short-pulse-width laser pulse, and outputting through the output mirror 1.

[0040] In some embodiments of the composite pulsed laser device of the present application, the first mirror 4 and the first Q-switch 5 are in the first pulsed laser resonant arm cavity, the second mirror 6 and the second Q-switch are in the second pulsed laser resonant arm cavity, the first direction polarized laser is generated in the first pulsed laser resonant arm cavity, and the second direction polarized laser is generated in the second pulsed laser resonant arm cavity. The first direction polarized laser is horizontal linearly polarized light, and the second direction polarized laser is vertical linearly polarized light. The polarizer 2 is at an angle of 45° with the horizontal direction, and the polarizer 2 transmits horizontal linearly polarized light and reflects vertical linearly polarized light. Thus, after the gain medium 3 is excited by the pump light, laser output of tens of nanoseconds and hundreds of nanoseconds can be generated, respectively.

[0041] Further, in some embodiments, a half-wave plate 10 is arranged between the laser gain module 3 and the polarizer 2, and the half-wave plate 10 is used to change the energy distribution ratio of the first direction polarized laser and the second direction polarized laser, so as to adjust the intensity of the two-way pulsed laser. It can be understood that the half-wave plate 10 and the polarizer 2 can be combined to simultaneously realize the intensity adjustment of the two-way pulsed laser, wherein the half-wave plate 10 can rotate the polarization direction of the light, and the polarizer 2 can select the polarization direction to be transmitted, and the combination of the half-wave plate 10 and the polarizer 2 can realize the continuous adjustment of the light energy.

[0042] In some embodiments of the composite pulsed laser device of the present application, the laser gain module 3 includes a laser gain medium and a pump source, and the pump mode of the pump source can adopt side pumping or end pumping. The pump light emitted by the pump source enters the laser gain medium to generate laser in the laser gain medium. The laser gain medium of the laser gain module 3 includes an isotropic crystal and / or an anisotropic crystal. The isotropic crystal is used to form single-wavelength laser output of the first direction polarized laser and the second direction polarized laser, and the anisotropic crystal is used to form different-wavelength laser output of the first direction polarized laser and the second direction polarized laser. Specifically, after passing through the polarizer 2, the first direction polarized laser and the second direction polarized laser output are formed. When the laser gain module 3 adopts the isotropic crystal, the isotropic crystal does not preferentially select a certain polarization direction after being excited by laser pumping or other forms of light, and single-wavelength laser output is formed. When the laser gain module 3 adopts the anisotropic crystal, the anisotropic crystal has different optical properties in different directions due to the asymmetric structure inside the anisotropic crystal after being excited by laser pumping or other forms of light, and different-wavelength and different-polarization-state laser output is formed.

[0043] It can be understood that the laser gain module 3 can realize laser output of different polarization directions and wavelengths by selecting appropriate laser gain medium and pumping mode. Isotropic crystal is suitable for single-wavelength laser output, and common isotropic crystals include Nd:YAG (neodymium-doped yttrium aluminum garnet) and Nd:glass (neodymium-doped glass); and anisotropic crystal is suitable for different-wavelength laser output, and common anisotropic crystals include Nd:YVO4 (neodymium-doped yttrium vanadate) and Ti:Sapphire (titanium sapphire). The selection of pumping mode (side pumping or end pumping) depends on the specific application requirements and performance requirements of the laser, the pumping light enters from the side of the laser gain medium, and is usually pumped by an LD bar and a lamp, which is commonly used for isotropic crystal laser gain medium, suitable for high-power lasers, and can provide uniform pumping distribution; the pumping light enters from one end of the laser gain medium, and is usually pumped by a single fiber-coupled crystal rod or chip, which is commonly used for isotropic crystal laser gain medium, suitable for miniaturization and high-efficiency lasers, and can realize higher pumping efficiency and better beam quality.

[0044] In some embodiments of the composite pulse laser device of the present application, the polarizer 2 can be a thin film polarizer or a polarizing beam splitter prism. The polarizer 2 plays a key role in polarization control in the composite pulse laser device, and a thin film polarizer or a polarizing beam splitter prism can be selected according to specific requirements. These two polarizers have advantages and disadvantages and are suitable for different application scenarios.

[0045] Among them, the thin film polarizer is usually composed of multiple layers of transparent materials (such as plastic or glass), which have different refractive indices, and is coated with one or more layers of thin film, which has the property of selectively transmitting or reflecting light of a specific polarization direction. When linearly polarized light is incident on the thin film polarizer, light of a specific polarization direction (first direction polarized laser) is transmitted, and light of a perpendicular polarization direction (second direction polarized laser) is reflected, in this way, the thin film polarizer can selectively transmit light of the desired polarization direction, thereby realizing polarization control. The thin film polarizer has relatively low cost and is easy to integrate into a laser system, and can be designed to have a wide operating wavelength range.

[0046] The polarization beam splitter prism (PBS) is usually made by gluing two right-angle prisms with a polarization beam splitter film in between. The polarization beam splitter film has the property of selectively transmitting or reflecting light of a specific polarization direction. When linearly polarized light is incident on the polarization beam splitter prism, light of a specific polarization direction (first direction polarized laser) is transmitted, while light of a perpendicular polarization direction (second direction polarized laser) is reflected. In this way, the polarization beam splitter prism can selectively transmit light of a desired polarization direction, thereby achieving polarization control. The polarization beam splitter prism is not very sensitive to changes in the incident angle, is suitable for a wide range of angle changes, has high transmittance and reflectance, is suitable for high-power laser applications, and can achieve a high extinction ratio, i.e., the contrast between the transmitted light and the reflected light.

[0047] The composite pulse laser device of the present application is further described below in conjunction with specific examples.

[0048] Example 1 Figure 1 An embodiment structure of the composite pulse laser device of the present application is shown, which is a pulse laser device combining electro-optic de-Q switching and acousto-optic Q switching, and includes an output mirror 1, a polarizer 2, a laser gain module 3, a first mirror 4, a first Q switch 5, a second mirror 6, a second Q switch 7, a controller 8, a half-wave plate 10, and a water cooling device (not shown in the figure).

[0049] The first mirror 4, the first Q-switch 5, the polarizer 2 and the output mirror 1 form a first pulsed laser resonant arm cavity, and the second mirror 6, the second Q-switch 7, the polarizer 2 and the output mirror 1 form a second pulsed laser resonant arm cavity, wherein the polarizer 2 is used for transmitting first direction polarized laser and reflecting second direction polarized laser, the first direction polarized laser is horizontal linear polarized light, and the second direction polarized laser is vertical linear polarized light. The laser gain module 3 is arranged in the resonant cavity to generate oscillation laser; the half-wave plate 10 is combined with the polarizer 2 to adjust the intensity of the output laser pulse; the first Q-switch 5 (electro-optical Q-switch) is arranged in the first pulsed laser resonant arm cavity to generate tens of nanosecond laser pulses, and the second Q-switch 7 (acousto-optical Q-switch) is arranged in the second pulsed laser resonant arm cavity to generate hundreds of nanosecond laser pulses. The controller 8 outputs an electrical signal to control the first Q-switch 5 and the second Q-switch 7, the first Q-switch 5 is a voltage-released electro-optical Q-switch, when the voltage is high, the polarization direction of the laser passing back and forth through the electro-optical Q-switch is rotated by 90°, when the voltage is low, the polarization direction remains unchanged, that is, the output laser pulse, and the output laser is 1064 nm tens of nanosecond pulse laser; the second Q-switch 7 is an acousto-optical Q-switch, and the output laser is 1064 nm hundreds of nanosecond pulse laser. The half-wave plate 10 is arranged between the laser gain module 3 and the polarizer 2, and is combined with the polarizer 2 to change the energy distribution ratio of the first direction polarized laser and the second direction polarized laser by rotating the half-wave plate 10, so as to realize the adjustment of the intensity of the two-way laser pulses. The water cooling device acts on the laser gain medium of the laser gain module 3, and is mainly water-cooled by cooling water, so as to avoid the temperature in the laser gain medium being too high, and causing the power and beam quality of the laser output to decrease.

[0050] The laser gain module 3 includes a quasi-continuous semiconductor 808 nm laser pump source, the laser gain medium is a Nd:YAG crystal, and the quasi-continuous 1064 nm laser is output in a side-pumping mode; the laser gain medium Nd:YAG crystal rod has a doping concentration of 1%, a size of D3 mm x 80 mm, and the crystal surface is coated with 808 nm and 1064 nm high-transmission film (transmittance greater than 99%); the output mirror 1 is coated with 1064 nm high-reflection film (reflectivity greater than 90%); the first mirror 4 and the second mirror 6 are coated with 1064 nm high-reflection film (reflectivity greater than 99%).

[0051] Specifically, the laser gain module 3 radiates 1064 nm laser by side pumping, oscillates to form laser in the resonant cavity, the polarizer 2 transmits horizontal linearly polarized light and reflects vertical linearly polarized light, and the first mirror 4 and the second mirror 6 form a first pulsed laser resonant arm cavity and a second pulsed laser resonant arm cavity to realize two-way 1064 nm fundamental frequency light operation of horizontal linearly polarized light and vertical linearly polarized light; the first Q switch 5 and the second Q switch 7 are respectively arranged in the first pulsed laser resonant arm cavity and the second pulsed laser resonant arm cavity and are controlled by an output electric signal of the controller 8; the first Q switch 5 (electro-optical Q switch) outputs 1064 nm laser with a pulse width of 10 ns and a frequency of 500 Hz, the second Q switch 7 (acousto-optical Q switch) outputs 1064 nm laser with a pulse width of 100 ns and a frequency of 500 Hz, the controller 8 adjusts the relative delay of the first Q switch 5 and the second Q switch 7 to 1 ms, and the output composite pulse frequency is 500 Hz asymmetric pulse, wherein the frequency between different pulse width pulses is 1 kHz, and the half-wave plate is rotated to change the angle to control the intensity of two-way polarized laser to be equal; finally, nanosecond pulsed laser with different pulse widths, the same intensity and the same pulse interval is output through the output mirror 1, as shown in Figure 3

[0052] In the embodiment, the resonant cavity is composed of the input mirror 1, the polarizer 2, the first mirror 4 and the second mirror 6; the nanosecond pulse with two pulse widths is output through the electro-optical Q switch and the acousto-optical Q switch; the delay time of the output electric signal of the controller 8 is adjusted to realize adjustable nanosecond pulse interval with the same pulse width; the half-wave plate 10 and the polarizer 2 are combined to realize pulse intensity adjustment of two pulse widths, so that the composite pulse laser device of the embodiment has the advantages of compact structure and high Q-switched laser conversion efficiency.

[0053] Embodiment two: Figure 2 Another embodiment structure of the composite pulse laser device of the application is shown, which is a pulsed laser device combined with voltage boosting Q switching and acousto-optical Q switching, comprising an output mirror 1, a polarizer 2, a laser gain module 3, a first mirror 4, a first Q switch 5, a second mirror 6, a second Q switch 7, a controller 8, a half-wave plate 10 and a water cooling device (not marked in the figure).

[0054] The composite pulse laser device in the embodiment and the structure of the embodiment one are mostly the same, and the difference lies in that, in the embodiment, the first Q switch 5 is in the voltage boosting electro-optical Q switching mode, at this time, the first pulsed laser resonant arm cavity is additionally provided with a 1 / 4λ wave plate 9, the polarization direction of laser back and forth between the first Q switch 5 and the 1 / 4λ wave plate 9 is rotated by 90° at low voltage, the polarization direction remains unchanged at high voltage, that is, the output laser pulse, and the output laser is 1064 nm tens of nanosecond laser.

[0055] ​Specifically, the laser gain device 3 radiates 1064 nm laser by side pumping, oscillates to form laser in the resonant cavity, the polarizer 2 transmits horizontal linearly polarized light and reflects vertical linearly polarized light, and the first mirror 4 and the second mirror 6 form a first pulsed laser resonant arm cavity and a second pulsed laser resonant arm cavity to realize two-way 1064 nm fundamental frequency light operation of horizontal linearly polarized light and vertical linearly polarized light; the first Q switch 5 and the second Q switch 7 are respectively arranged in the first pulsed laser resonant arm cavity and the second pulsed laser resonant arm cavity and are controlled by an output electrical signal of the controller 8; the first Q switch 5 (electro-optical Q switch) outputs 1064 nm laser with a pulse width of 10 ns and a frequency of 500 Hz, and the second Q switch 7 (acousto-optical Q switch) outputs 1064 nm laser with a pulse width of 100 ns and a frequency of 500 Hz. The controller 8 adjusts a relative delay to be 0.5 ms, and outputs a composite pulse with a frequency of 500 Hz asymmetric pulse, wherein the frequency between different pulse width pulses is 2 kHz, and the angle of the half-wave plate 10 is changed at the same time to control the intensity of two-way polarized laser to be equal; finally, nanosecond pulsed laser with different pulse widths, the same intensity and different pulse intervals is output through the output mirror 1, as shown in Figure 4

[0056] Example three: the same structure as example two is adopted in this example, and the difference lies in that, in this example, the laser gain module 3 contains a quasi-continuous semiconductor 980 nm laser pumping source, the laser gain medium is a Yb:KGW crystal, and quasi-continuous 1028 nm laser and 1037 nm laser are output in a side pumping mode; the laser gain medium Yb:KGW crystal rod is D3 mm × 10 mm in size and 3% in doping concentration, and the crystal surface is coated with 980 nm, 1028 nm and 1037 nm high-transmission film (transmittance greater than 99%); the output mirror 1 is coated with 1028 nm and 1037 nm high-reflection film (reflectivity greater than 90%); the first mirror 4 and the second mirror 6 are coated with 1028 nm and 1037 nm high-reflection film (reflectivity greater than 99%).

[0057] The first Q switch 5 adopts a boost electro-optical Q-switching mode, at this time, the first pulsed laser resonant arm cavity is further provided with the 1 / 4λ wave plate 9, the polarization direction of laser back and forth between the first Q switch 5 and the 1 / 4λ wave plate 9 is rotated by 90° at low voltage, and the polarization direction remains unchanged at high voltage, that is, the output laser pulse, and the output laser is 1028 nm tens of nanosecond pulsed laser.

[0058] ​Specifically, the laser gain device 3 radiates 1064 nm laser by side pumping, oscillates to form laser in the resonant cavity, the polarizer 2 transmits horizontal linearly polarized light and reflects vertical linearly polarized light, and the first mirror 4 and the second mirror 6 form a first pulsed laser resonant arm cavity and a second pulsed laser resonant arm cavity to realize two-way 1064 nm fundamental frequency light operation of horizontal linearly polarized light and vertical linearly polarized light; the first Q switch 5 and the second Q switch 7 are respectively arranged in the first pulsed laser resonant arm cavity and the second pulsed laser resonant arm cavity and are controlled by an electric signal output by the controller 8; the first Q switch 5 (electro-optical Q switch) outputs 1028 nm laser with a pulse width of 10 ns and a frequency of 500 Hz, the second Q switch 7 (acousto-optical Q switch) outputs 1037 nm laser with a pulse width of 100 ns and a frequency of 500 Hz, the controller 8 adjusts a relative delay of 0.5 ms, and the output composite pulse frequency is 500 Hz asymmetric pulse, wherein the frequency between different pulse widths is 2 kHz, the angle of the half-wave plate 10 is changed at the same time, and the intensities of the two-way polarized lasers are controlled to be different; finally, nanosecond pulsed laser with different pulse widths, different intensities and different pulse intervals is output through the output mirror 1, as shown in Figure 5 .

[0059] Through the specific description of the above embodiment one to embodiment three, and in combination with Figure 3 , Figure 4 and Figure 5 , it can be known that the composite pulsed laser device provided by the application is a composite pulsed laser device capable of outputting different pulse widths and adjustable pulse intervals and intensities, the laser gain module 3, the Q switch (the first Q switch 5 and the second Q switch 7), the half-wave plate 10 and the polarizer 2 form two-way pulsed laser resonant arm cavities of the same resonant cavity, and the structure is compact; the polarizer 2 transmits horizontal linearly polarized light and reflects vertical linearly polarized light, and the cavity mirrors (the output mirror 1, the first mirror 4 and the second mirror 6) form cavity arms respectively; the Q switch is an electro-optical Q switch and an acousto-optical Q switch controlled by the same controller 8, the electro-optical Q switch is arranged in the first pulsed laser resonant arm cavity, and the acousto-optical Q switch is arranged in the second pulsed laser resonant arm cavity, and the Q switch can realize pulsed laser output of tens of nanoseconds and hundreds of nanoseconds respectively; the output of the pulsed laser is controlled by the electric signal of the controller 8 to realize flexible adjustment of the pulse interval; the half-wave plate 10 and the polarizer 2 can realize adjustment of the intensity of the two-way pulsed laser at the same time. The structure is compact and flexible in design, can realize pulsed laser output of tens of nanoseconds and hundreds of nanoseconds at the same time under the control of the same electric signal, and the pulse interval and intensity of different pulse widths can be flexibly adjusted, and has strong practicability.

[0060] It should be pointed out finally that the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit the same; and although the present application has been described in detail with reference to the foregoing embodiments, it should be appreciated by those skilled in the art that the technical solutions recorded in the foregoing embodiments can be modified, or some technical features thereof can be replaced equivalently; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A composite pulsed laser device, characterized in that, include: Output mirror (1) is used to output a laser beam; Polarizer (2) is used to transmit laser light polarized in the first direction and reflect laser light polarized in the second direction; A laser gain module (3) is located between the output mirror (1) and the polarizer (2) and is used to radiate laser light. The first reflector (4) and the first Q switch (5) are located on the first direction input side of the polarizer (2). The first reflector (4), the first Q switch (5), the polarizer (2) and the output mirror (1) are arranged in sequence at intervals to form the first pulse laser resonant arm cavity. The first Q switch (5) is an electro-optic Q switch to generate a laser pulse on the order of ten nanoseconds in the cavity of the first pulsed laser resonator arm; The second reflector (6) and the second Q switch (7) are located on the second direction input side of the polarizer (2). The second reflector (6), the second Q switch (7), the polarizer (2) and the output mirror (1) are arranged in sequence at intervals to form the second pulsed laser resonant arm cavity. The second Q switch (7) is an acousto-optic Q switch to generate a laser pulse at the level of hundreds of nanoseconds in the second pulsed laser resonant arm cavity. The controller (8) controls the first Q switch (5) and the second Q switch (7) respectively to adjust the timing interval of the laser pulses in the first pulse laser resonator cavity and the second pulse laser resonator cavity; the controller (8) is configured to control the output of the pulse laser in the first pulse laser resonator cavity and the second pulse laser resonator cavity by adjusting the relative delay of the first Q switch (5) and the second Q switch (7), and simultaneously realize the pulse laser output at the tens of nanosecond level and the hundreds of nanosecond level under the control of the same electrical signal.

2. The composite pulsed laser device according to claim 1, characterized in that, The first Q switch (5) adopts a de-voltage type Q-switching method. The electro-optic crystal in the first Q switch (5) includes a high voltage state and a low voltage state. In the high voltage state, the polarization direction of the laser beam passing through the electro-optic crystal is rotated by 90°, and the laser beam is blocked in the cavity of the first pulse laser resonator. In the low voltage state, the polarization direction of the laser beam passing through the electro-optic crystal remains unchanged, and the laser beam forms an effective laser oscillation in the cavity of the first pulse laser resonator.

3. The composite pulsed laser device according to claim 1, characterized in that, The first Q switch (5) adopts a boost-type Q-switching method. A 1 / 4λ waveplate (9) is arranged between the first Q switch (5) and the polarizer (2). The electro-optic crystal in the first Q switch (5) includes a high-voltage state and a low-voltage state. In the low-voltage state, the polarization direction of the laser beam passing through the electro-optic crystal remains unchanged. After passing through the 1 / 4λ waveplate (9), the polarization direction is rotated by 90°, and the laser beam is blocked in the cavity of the first pulse laser resonator. In the high-voltage state, the polarization direction of the laser beam passing through the electro-optic crystal is rotated by 90°. After passing through the 1 / 4λ waveplate (9), the polarization direction is rotated by another 90°, and the laser beam forms an effective laser oscillation in the cavity of the first pulse laser resonator.

4. The composite pulsed laser device according to claim 1, characterized in that, The first directional polarized laser is horizontally linearly polarized light, the second directional polarized laser is vertically linearly polarized light, and the polarizer (2) is at a 45° angle to the horizontal direction; The first reflector (4), the first Q switch (5), the polarizer (2), the laser gain module (3) and the output mirror (1) are arranged sequentially at intervals in the horizontal direction so that the polarizer (2) transmits the horizontally polarized light; The second reflector (6) and the second Q switch (7) generate the vertically polarized light, which is reflected by the polarizer (2) into the laser gain module (3).

5. The composite pulsed laser device according to claim 4, characterized in that, A half-wave plate (10) is arranged between the laser gain module (3) and the polarizer (2). The half-wave plate (10) is used to change the energy distribution ratio of the first directional polarized laser and the second directional polarized laser to adjust the intensity of the two pulsed lasers.

6. The composite pulsed laser device according to any one of claims 1 to 5, characterized in that, The laser gain module (3) includes a laser gain medium and a pump source. The pump light emitted by the pump source enters the laser gain medium and generates laser light in the laser gain medium.

7. The composite pulsed laser device according to claim 6, characterized in that, The laser gain medium of the laser gain module (3) includes an isotropic crystal and / or anisotropic crystal. The isotropic crystal is used to form a single wavelength laser output of the first directional polarized laser and the second directional polarized laser, and the anisotropic crystal is used to form a different wavelength laser output of the first directional polarized laser and the second directional polarized laser.

8. The composite pulsed laser device according to claim 6, characterized in that, The pump source uses either side pumping or end-face pumping.

9. The composite pulsed laser device according to any one of claims 1 to 5, characterized in that, The polarizer (2) is a thin-film polarizer or a polarizing beam splitter.

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