Laser device and laser amplifier

Abstract

The invention discloses a laser device and a laser amplifier, the laser device comprises a pumping source, a laser gain medium, a condition controller and a resonant cavity, the pumping source is used for providing pumping light for the laser gain medium; the laser gain medium is used for absorbing the pump light to generate laser; the condition controller is used for controlling at least one of the temperature of the laser gain medium, the stress on the laser gain medium and the electric excitation on the laser gain medium so as to reduce the optical path difference in the laser propagation process; and the resonant cavity is used for reflecting, oscillating and amplifying the laser and outputting the amplified laser. According to the invention, the condition controller is used for precisely regulating and controlling the external conditions required by the laser gain medium, so as to control the value or relation of the thermal expansion coefficient and / or thermo-optical coefficient of the laser gain medium, reduce the optical path difference in the laser propagation process, and achieve the effect of reducing wavefront distortion.

Description

Technical Field

[0001] The present invention relates to the field of solid-state lasers. More specifically, it relates to a laser device and a laser amplifier. Background Art

[0002] In the field of modern optical technology, laser devices play an indispensable role and are widely used in key fields such as material processing, communication, medical treatment, and scientific research. However, during the actual operation of laser devices, due to the internal electro-optical conversion process and various loss mechanisms, a large amount of heat is generated, resulting in an increase in the temperature of the laser gain medium, and then a series of thermal problems are caused, affecting the output quality of the laser.

[0003] The thermal expansion coefficient and thermo-optic coefficient of the laser gain medium are usually positive. When the laser device operates and generates heat, the temperature rises, causing the size of the laser gain medium to change, resulting in the deformation of the structure of the laser cavity, and then changing the optical path length in the laser cavity, causing a change in the optical path. When the optical paths of different light paths change, the optical path difference between them changes, affecting the wavefront aberration degree of the light beam. On the other hand, the refractive index of the laser gain medium changes with temperature, which also affects the propagation characteristics of light in the laser gain medium, causing different degrees of change in the optical paths of two light beams, and the optical path difference also changes accordingly, affecting the wavefront aberration degree of the light beam, thus limiting the further application of laser devices in application scenarios with high requirements for beam quality. Summary of the Invention

[0004] The present invention provides a laser device and a laser amplifier to solve at least one of the problems existing in the prior art.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] In a first aspect of the present invention, a laser device is provided. The laser device includes a pump source, a laser gain medium, a condition controller, and a resonant cavity, wherein,

[0007] The pump source is used to provide pump light for the laser gain medium;

[0008] The laser gain medium is used to absorb the pump light to generate laser;

[0009] The condition controller is used to control at least one of the temperature of the laser gain medium, the stress applied to the laser gain medium, and the electrical excitation of the laser gain medium to reduce the optical path difference during laser propagation;

[0010] The resonant cavity is used to reflect, oscillate, amplify the laser, and output the amplified laser.

[0011] Optionally, the condition controller is configured to control the value of the thermal expansion coefficient and / or the value of the thermo-optic coefficient of the laser gain medium, so that the value of the thermal expansion coefficient and / or the value of the thermo-optic coefficient approaches zero, or to control the value of the thermo-optic coefficient to be close to the opposite value of a first value, where the first value is (n - 1)(1 + ν)α T , n is the refractive index of the laser gain medium material, and α T is the value of the thermal expansion coefficient, and ν is the Poisson's ratio of the laser gain medium material.

[0012] Optionally, the condition controller is selected from one or more of a stress controller, a temperature controller, and an electrical excitation controller.

[0013] Optionally, the pumping method of the pump source is end pumping or side pumping.

[0014] Optionally, the laser gain medium is a crystal, ceramic, or glass laser gain material including an active ion, and the active ion is selected from at least one of neodymium, ytterbium, erbium, titanium, praseodymium, chromium, thulium, and holmium.

[0015] Optionally, the shape of the laser gain medium is rod-shaped, sheet-shaped, plate-shaped, or block-shaped.

[0016] Optionally, the resonator includes a reflector disposed on one side of the first end face of the laser gain medium and an output mirror disposed on one side of the second end face of the laser gain medium.

[0017] A second aspect of the present invention provides a laser amplifier, which includes a pump source, a seed laser source, a laser gain medium, and a condition controller, where

[0018] the pump source is configured to provide pump light for the laser gain medium;

[0019] the seed laser source is configured to provide seed laser for the laser gain medium;

[0020] the condition controller is configured to control at least one of the temperature of the laser gain medium, the stress applied to the laser gain medium, and the electrical excitation of the laser gain medium to reduce the optical path difference during laser propagation;

[0021] the laser gain medium is configured to absorb the pump light to amplify the energy of the seed laser and is further configured to output the amplified seed laser.

[0022] Optionally, the condition controller is configured to control the value of the thermal expansion coefficient and / or the value of the thermo-optic coefficient of the laser gain medium, so that the value of the thermal expansion coefficient and / or the value of the thermo-optic coefficient approaches zero, or to control the value of the thermo-optic coefficient to be close to the opposite value of a first value, where the first value is (n - 1)(1 + ν)α T , where n is the refractive index of the laser gain medium material, and α T is the value of the thermal expansion coefficient, and ν is the Poisson's ratio of the laser gain medium material.

[0023] Optionally, the condition controller is selected from one or more of a stress controller, a temperature controller, and / or an electrical excitation controller.

[0024] The beneficial effects of the present invention are as follows:

[0025] The present invention uses a condition controller to precisely regulate the external conditions required by the laser gain medium. By controlling at least one of the temperature of the laser gain medium, the stress applied to the laser gain medium, and the electrical excitation of the laser gain medium, the value or relationship of the thermal expansion coefficient and / or the thermo-optic coefficient of the laser gain medium is controlled, reducing the optical path difference during laser propagation, thereby achieving the effect of reducing wavefront distortion. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The following further describes in detail the specific embodiments of the present invention with reference to the accompanying drawings.

[0027] Figure 1 Schematic diagram of the structure of a laser device for reducing the degree of laser distortion in the first embodiment of the present invention;

[0028] Figure 2 Schematic diagram showing the variation of the thermal expansion coefficient and the thermo-optic coefficient of the Yb:YLF crystal with temperature in the first embodiment of the present invention;

[0029] Figure 3 Schematic diagram showing the variation of the thermal expansion coefficient of the Yb:YAP crystal with temperature in the second embodiment of the present invention;

[0030] Figure 4 Schematic diagram of the structure of a laser amplifier for reducing the degree of laser distortion in the second embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0031] To more clearly illustrate the present invention, the following further describes the present invention with reference to preferred embodiments and the accompanying drawings. Similar components in the drawings are denoted by the same reference numerals. Those skilled in the art should understand that the content specifically described below is illustrative rather than restrictive, and should not be used to limit the protection scope of the present invention.

[0032] During the operation of the laser device, the inventor found that the external conditions of the laser device would affect the degree of wavefront distortion of the laser. Furthermore, it was found that by influencing the values of the thermal expansion coefficient and / or the thermo-optic coefficient of the laser gain medium through external conditions, after analysis and verification, both the value of the thermal expansion coefficient and the value of the thermo-optic coefficient of the laser gain medium were factors affecting wavefront distortion. That is, to reduce wavefront distortion, the values of the thermal expansion coefficient and / or the thermo-optic coefficient of the laser gain medium can be controlled. Therefore, the present invention proposes to control at least one of the temperature of the laser gain medium, the stress applied to the laser gain medium, and the electrical excitation of the laser gain medium through a condition controller, thereby controlling the value and / or the relationship of the thermal expansion coefficient and the thermo-optic coefficient, reducing the optical path difference during laser propagation, and achieving the effect of reducing wavefront distortion. This laser device is simple to control and applicable to various materials.

[0033] In a first aspect of the present invention, a laser device is provided. The laser device includes a pump source, a laser gain medium, a condition controller, and a resonator. Among them,

[0034] The pump source is used to provide pump light for the laser gain medium; the pump source can be a pump bar, a flash lamp, a semiconductor laser, or a fiber laser, and the pumping method of the pump source can be end pumping or side pumping.

[0035] The laser gain medium is used to absorb the pump light to generate laser; the laser gain medium is a crystal, ceramic, or glass laser gain material including active ions, and the active ions are selected from at least one of neodymium Nd, ytterbium Yb, erbium Er, titanium Ti, praseodymium Pr, chromium Cr, thulium Tm, and holmium Ho. The active ions play a key role in the generation and amplification of the laser. The shape of the laser gain medium can be rod-shaped, sheet-shaped, slab-shaped, or block-shaped. A laser gain medium with a suitable shape is selected according to different laser application scenarios to meet diverse actual needs.

[0036] The condition controller is used to control at least one of the temperature of the laser gain medium, the stress applied to the laser gain medium, and the electrical excitation of the laser gain medium, so as to reduce the optical path difference during laser propagation; thereby reducing wavefront distortion; by controlling the value of the thermal expansion coefficient and / or the thermo-optic coefficient of the laser gain medium through the condition controller, making the value of the thermal expansion coefficient and / or the thermo-optic coefficient close to zero, or controlling the value of the thermo-optic coefficient to be close to the opposite value of the first value, where the first value is (n - 1)(1 + ν)α T , n is the refractive index of the laser gain medium material, α T is the value of the thermal expansion coefficient, and ν is the Poisson's ratio of the laser gain medium material. When the absolute value of the thermal expansion coefficient is less than 1×10 -6 K -1 it can be regarded as close to zero, and the value of the thermo-optic coefficient is in the range of -1×10 -6 K-1 ~1×10 -6 K -1 When in the range, it can be regarded as approaching zero; the absolute value of the coefficient of thermal expansion includes the cases where the coefficient of thermal expansion is positive and the coefficient of thermal expansion is negative, and the absolute value of the thermo-optic coefficient includes the cases where the thermo-optic coefficient is positive and the thermo-optic coefficient is negative. The condition controller is selected from one or more of a stress controller, a temperature controller, and an electrical excitation controller. By precisely controlling the operating conditions of the laser device through the condition controller, the controllable external conditions can be one or more of stress, temperature, and electrical excitation to meet the requirements of the external conditions required by the laser device.

[0037] The resonant cavity is used to reflect, oscillate, amplify the laser, and output the amplified laser; the resonant cavity includes a reflector disposed on one side of the first end face of the laser gain medium and an output mirror disposed on one side of the second end face of the laser gain medium. The reflector can continuously reflect the laser in the resonant cavity, enabling the laser to be continuously amplified during the round-trip process to form a stable oscillation; while ensuring the continuous oscillation of the laser in the resonant cavity, the output mirror can output part of the laser to provide the required laser beam for practical applications. The two cooperate with each other to precisely control the oscillation mode and output characteristics of the laser, ensuring that the entire laser device can work stably and efficiently.

[0038] During the propagation of the laser, the optical path is determined by the product of the geometric path length of the light propagation and the refractive index of the material. Whether it is the change in the geometric path length caused by the coefficient of thermal expansion or the change in the refractive index of the material caused by the thermo-optic coefficient, any change in one of these factors will cause a change in the optical path, thereby triggering an optical path difference. The change in the optical path difference will cause wavefront distortion, which has many adverse effects on the performance of the laser.

[0039] Under normal circumstances, the value of the coefficient of thermal expansion of the laser gain medium is positive. When the laser device operates and generates heat, the temperature rises, and the laser gain medium will change in size due to thermal expansion, directly acting on the laser cavity, causing the structure of the laser cavity to deform, and changing the path length of the light propagation in the laser cavity. The change in the geometric path length directly leads to a change in the optical path, and the optical path difference between different optical paths also changes accordingly.

[0040] The value of the thermo-optic coefficient of the laser gain medium is usually also positive. When the laser device operates and generates heat, the temperature rises, and the refractive index of the laser gain medium will increase accordingly. As the laser device operates and generates heat, the temperature continues to rise. Based on the characteristic that the thermo-optic coefficient is positive, the refractive index of the laser gain medium increases, and the optical path will also become longer due to the increase in the refractive index. The change degrees of the optical paths in different optical paths are different, thereby triggering a change in the optical path difference, which affects the wavefront distortion.

[0041] The values of the coefficient of thermal expansion and the coefficient of thermo-optic generally increase with the increase of temperature. Adjust the condition controller so that the value of the coefficient of thermo-optic is close to the opposite value of the first value, that is, the values of the coefficient of thermo-optic and the first value are one positive and one negative, and there will be no extreme cases where the positive value is extremely large and the negative value is extremely small, nor will there be extreme cases where the positive value is extremely small and the negative value is extremely large.

[0042] The optical path difference formula during laser propagation is

[0043] OPD(r) ∝ dn / dT + (n - 1)(1 + ν)α T +2n 3 α T C r,θ ,

[0044] where OPD is the optical path difference during laser propagation, dn / dT is the value of the coefficient of thermo-optic of the laser gain medium, n is the refractive index of the laser gain medium material, T is the temperature, α T is the value of the coefficient of thermal expansion of the laser gain medium, ν is the Poisson's ratio of the laser gain medium material, C r,θ is the photoelastic coefficient, the photoelastic coefficient can be ignored, r is the radial distance, and θ is the tangential distance.

[0045] According to the above optical path difference formula, control the value of the coefficient of thermal expansion and / or the value of the coefficient of thermo-optic of the laser gain medium through the condition controller, so that the value of the coefficient of thermal expansion and / or the value of the coefficient of thermo-optic is close to zero, greatly reducing the optical path difference, thereby reducing the wavefront aberration;

[0046] Control the value of the coefficient of thermo-optic through the condition controller to be close to the opposite value of the first value (n - 1)(1 + ν)α T to greatly reduce the optical path difference during laser propagation, thereby reducing the wavefront aberration.

[0047] In a specific embodiment, Figure 1 is a schematic structural diagram of a laser device for reducing the degree of laser aberration. The laser device includes a pump source 1, a laser gain medium 2, a condition controller 3, and a resonant cavity. The resonant cavity includes a reflector 4 provided on one side of the first end face of the laser gain medium 2 and an output mirror 5 provided on one side of the second end face of the laser gain medium 2.

[0048] In this laser device, a pump source 1 provides pump light to a laser gain medium 2. After the pump light enters the laser gain medium 2, it is absorbed by the laser gain medium 2, providing energy for the active ions in the laser gain medium 2. The active ions undergo energy level transitions under the energy of the pump light. Ions in the ground state absorb the energy of the pump light and are excited to higher energy levels, thereby forming a population inversion distribution state and generating laser light. The laser gain medium 2 in the particle number inversion state is in a resonant cavity. Photons generated by spontaneous emission trigger stimulated emission. The photons continuously reflect back and forth and are amplified by the reflecting mirror 4 and the output mirror 5 in the resonant cavity. During the laser oscillation process, the reflecting mirror 4 reflects the light back into the laser material to enhance the laser intensity. The light travels back and forth in the laser material multiple times and is amplified. During the oscillation process, by adjusting the condition controller 3, at least one of the temperature of the laser gain medium 2, the stress on the laser gain medium 2, and the electrical excitation of the laser gain medium 2 is controlled, so that the value of the thermal expansion coefficient and / or the value of the thermo-optic coefficient is close to zero, or the value of the thermo-optic coefficient is controlled to be close to the opposite value of the first value (n - 1)(1 + ν)α T and reduce the optical path difference during propagation, achieving the effect of reducing wavefront distortion, and finally forming laser light with sufficient intensity to be emitted through the output mirror 5.

[0049] During the oscillation process of the laser device, by controlling the value and / or relationship of the thermal expansion coefficient and the thermo-optic coefficient of the laser gain medium through a condition controller, the optical path difference during laser propagation is minimized to the greatest extent, the wavefront distortion degree of the laser is reduced, and low-distortion laser light is output.

[0050] In this embodiment, the condition controller is a temperature controller, which controls the temperature of the laser gain medium. By adjusting the test temperature of the temperature controller, the value of the thermo-optic coefficient is controlled to be close to the opposite value of the first value, reducing the optical path difference during laser propagation, thereby reducing wavefront distortion. The laser gain medium is a Yb:YLF crystal, and the thermal expansion coefficient and thermo-optic coefficient of the Yb:YLF crystal in a wide temperature range are further tested. As Figure 2 shown, it is a schematic diagram of the thermal expansion coefficient and thermo-optic coefficient of the Yb:YLF crystal varying with temperature in a wide temperature range. The abscissa represents the test temperature range from 10 to 300 K, the ordinate represents the values of the thermal expansion coefficient and thermo-optic coefficient of the Yb:YLF crystal, and c represents the test in the c-axis direction of the Yb:YLF crystal.

[0051] According to the variation of the thermal expansion coefficient and thermo-optic coefficient with temperature, the test temperature of the condition controller is adjusted.

[0052] According to the optical path difference formula during laser propagation

[0053] OPD(r) ∝ dn / dT + (n - 1)(1 + ν)α T + 2n3 α T C r,θ ,

[0054] It has been experimentally proven that by substituting the values of the thermal expansion coefficient and the thermo-optic coefficient corresponding to the Yb:YLF crystal at 75K into the optical path difference formula, the value of the thermo-optic coefficient is close to the opposite value of the first value. Compared with substituting the values of the thermal expansion coefficient and the thermo-optic coefficient corresponding to 300K into the above optical path difference formula, the optical path difference during laser propagation is effectively reduced, thereby reducing the wavefront distortion.

[0055] In another embodiment, the condition controller is adjusted so that the value of the thermal expansion coefficient of the laser gain medium is close to zero, reducing the optical path difference during laser propagation, thereby reducing the wavefront distortion. The laser gain medium is a Yb:YAP crystal, and the thermal expansion coefficient of the Yb:YAP crystal is further tested in a wide temperature range. As Figure 3 shown, it is the variation of the thermal expansion coefficient of the Yb:YAP crystal at different temperatures in a wide temperature range. The abscissa represents the test temperature range of 10 - 300K, the ordinate represents the thermal expansion coefficient of the Yb:YAP crystal, b indicates that the test is carried out in the b-axis direction of the Yb:YAP crystal, and the temperature control of the thermal expansion coefficient of the laser gain medium is performed through the condition controller; according to the variation of the thermal expansion coefficient with temperature, when the test temperature is about 25K, the value of the thermal expansion coefficient of the Yb:YAP crystal can reach a state where the absolute value is nearly zero, that is, |α T | < 1×10 -6 K -1 , and at this time, the size of the Yb:YAP crystal almost remains unchanged.

[0056] According to the optical path difference formula during laser propagation

[0057] OPD(r) ∝ dn / dT + (n - 1)(1 + ν)α T +2n 3 α T C r,θ ,

[0058] Under normal circumstances, the thermal expansion coefficient of the laser gain medium is positive. Substituting the absolute value of the thermal expansion coefficient corresponding to 25K into the optical path difference formula effectively reduces the optical path difference during propagation, thereby reducing the wavefront distortion.

[0059] The second aspect of the present invention provides a laser amplifier, which includes a pump source, a seed laser source, a laser gain medium, and a condition controller. Among them,

[0060] The pump source is used to provide pump light for the laser gain medium; the pump source can be a pump bar, a flash lamp, a semiconductor laser, or a fiber laser, and the pumping method of the pump source can be end pumping or side pumping.

[0061] The seed laser source is used to provide seed laser for the laser gain medium.

[0062] The condition controller is used to control at least one of the temperature of the laser gain medium, the stress on the laser gain medium, and the electrical excitation of the laser gain medium, so as to reduce the optical path difference during laser propagation; by adjusting the condition controller to control the value of the thermal expansion coefficient and / or the value of the thermo-optic coefficient of the laser gain medium, the value of the thermal expansion coefficient and / or the value of the thermo-optic coefficient is made close to zero, or, the value of the thermo-optic coefficient is controlled to be close to the opposite value of the first value (n - 1)(1 + ν)α T to reduce the optical path difference during laser propagation. The condition controller is selected from one or more of a stress controller, a temperature controller, and an electrical excitation controller. By precisely controlling the operating conditions of the laser device through the condition controller, the controllable external conditions can be one or more of stress, temperature, and electrical excitation to meet the requirements of the external conditions required by the laser device.

[0063] The laser gain medium is used to absorb pump light to amplify the energy of the seed laser, and is also used to output the amplified seed laser; the laser gain medium is a crystal, ceramic, or glass laser gain material including an active ion, and the active ion is selected from at least one of neodymium Nd, ytterbium Yb, erbium Er, titanium Ti, praseodymium Pr, chromium Cr, thulium Tm, and holmium Ho. The shape of the laser gain medium includes rod-shaped, flake-shaped, slab-shaped, or block-shaped. The laser gain medium with a suitable shape is selected according to different laser application scenarios to meet diverse actual needs.

[0064] In the second specific embodiment, as Figure 4 shown, it is a schematic structural diagram of a laser amplifier for reducing the degree of laser distortion. In this embodiment, only the differences from the first embodiment are discussed, and the same parts are not discussed again.

[0065] An initial laser signal is provided by a seed laser source 6, and a seed laser is output. The seed laser is a laser beam having specific frequency, phase, and intensity characteristics, and is incident into a laser gain medium 2 from one side of the first end face of the laser gain medium 2. At the same time, pump light energy is provided to the laser gain medium 2 by a pump source 1. The pump light energy is absorbed by particles in the laser gain medium 2, causing a change in the particle distribution state inside the laser gain medium 2 and forming a population inversion distribution. In this state, the laser gain medium 2 has the ability to amplify light. When the seed laser enters the laser gain medium 2 in the population inversion distribution state, it interacts with the particles in the laser gain medium 2. During this process, the seed laser stimulates the particles in the high energy level to transition to the low energy level, thereby releasing photons having the same frequency, phase, and polarization direction as the seed laser. The newly added photons propagate together with the photons in the seed laser, causing the light intensity to continuously increase. Through the gain effect of the laser gain medium 2, the light intensity of the seed laser is continuously amplified, and the amplified seed laser is output from the second end face of the laser gain medium 2. During the process of amplifying the seed laser, at least one of the temperature of the laser gain medium 2, the stress applied to the laser gain medium 2, and the electrical excitation of the laser gain medium 2 is controlled by adjusting a condition controller 3, so that the value of the thermal expansion coefficient and / or the value of the thermo-optic coefficient of the laser gain medium 2 approaches zero, or the value of the thermo-optic coefficient is controlled to be close to the opposite value of a first value, thereby reducing the optical path difference during propagation and achieving the effect of reducing wavefront distortion.

[0066] During the process of amplifying the seed laser by this laser amplifier, the external conditions required by the laser gain medium 2 are controlled by adjusting a condition control system 3, so that the value of the thermal expansion coefficient and / or the value of the thermo-optic coefficient of the laser gain medium 2 is approximately zero under a certain specific condition. The laser amplifier under this specific external condition can effectively reduce the optical path difference compared with the laser amplifier under normal conditions, thereby reducing wavefront distortion.

[0067] The present invention precisely controls the external conditions required by the laser gain medium by using a condition controller. At least one of the temperature of the laser gain medium, the stress applied to the laser gain medium, and the electrical excitation of the laser gain medium is controlled by the condition controller to reduce the optical path difference during laser propagation. By adjusting the condition controller, the value of the thermal expansion coefficient and / or the value of the thermo-optic coefficient of the laser gain medium is made to approach zero, or the value of the thermo-optic coefficient is controlled to be close to the opposite value of a first value, thereby reducing the optical path difference during laser propagation and achieving the effect of reducing wavefront distortion.

[0068] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by terms such as "upper", "lower", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention. Unless otherwise clearly specified and defined, the terms "mounted", "connected", and "coupled" shall be construed broadly. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0069] It should also be noted that in the description of the present invention, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprising", "including" or any other variation thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the phrase "comprising an..." does not exclude the presence of additional identical elements in the process, method, article or device comprising the said element.

[0070] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, rather than limitations on the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is impossible to enumerate all the implementation manners here. Any obvious changes or modifications derived from the technical solutions of the present invention still fall within the protection scope of the present invention.

Claims

1. A laser device, characterized in that: The laser device comprises a pump source, a laser gain medium, a condition controller and a resonant cavity, wherein: The pump source is used to provide pump light for the laser gain medium; The laser gain medium is used to absorb the pump light to generate laser; The condition controller is used to control at least one of the temperature of the laser gain medium, the stress on the laser gain medium and the electrical excitation of the laser gain medium, so as to reduce the optical path difference during the laser propagation process; The resonant cavity is used for reflecting the oscillated amplified laser and outputting the amplified laser.

2. The laser device according to claim 1, characterized in that The condition controller is used to control the value of the thermal expansion coefficient and / or the value of the thermo-optic coefficient of the laser gain medium, so that the value of the thermal expansion coefficient and / or the value of the thermo-optic coefficient is close to zero, or to control the value of the thermo-optic coefficient to be close to the opposite value of the first value, wherein the first value is (n-1)(1+ν)α T , n is the refractive index of the laser gain medium material, α T is the value of the thermal expansion coefficient, and ν is the Poisson's ratio of the laser gain medium material.

3. The laser device according to claim 1, characterized in that The condition controller is selected from one or more of a stress controller, a temperature controller and an electrical excitation controller.

4. The laser device according to claim 1, characterized in that The pumping mode of the pump source is end pumping or side pumping.

5. The laser device according to claim 1, characterized in that The laser gain medium is a crystal, ceramic or glass laser gain material including active ions, wherein the active ions are selected from at least one of neodymium, ytterbium, erbium, titanium, praseodymium, chromium, thulium and holmium.

6. The laser device according to claim 1, characterized in that The laser gain medium is in the shape of a rod, a sheet, a strip or a block.

7. The laser device according to claim 1, characterized in that: The resonant cavity comprises a reflecting mirror arranged on one side of the first end face of the laser gain medium and an output mirror arranged on one side of the second end face of the laser gain medium.

8. A laser amplifier, characterized in that: The laser amplifier comprises a pump source, a seed laser source, a laser gain medium and a condition controller, wherein: The pump source is used to provide pump light for the laser gain medium; The seed laser source is used to provide seed laser for the laser gain medium; The condition controller is used to control at least one of the temperature of the laser gain medium, the stress on the laser gain medium and the electrical excitation of the laser gain medium, so as to reduce the optical path difference during the laser propagation process; The laser gain medium is used to absorb the pump light to amplify the energy of the seed laser, and is also used to output the amplified seed laser.

9. The laser amplifier according to claim 8, characterized in that: The condition controller is used to control the value of the thermal expansion coefficient and / or the value of the thermo-optic coefficient of the laser gain medium, so that the value of the thermal expansion coefficient and / or the value of the thermo-optic coefficient is close to zero, or to control the value of the thermo-optic coefficient to be close to the opposite value of the first value, wherein the first value is (n-1)(1+ν)α T , n is the refractive index of the laser gain medium material, α T is the value of the thermal expansion coefficient, and ν is the Poisson's ratio of the laser gain medium material.

10. The laser amplifier according to claim 8, characterized in that The condition controller is selected from one or more of a stress controller, a temperature controller and an electrical excitation controller.

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