A debye temperature operating laser device

Abstract

The application provides a Debye temperature operating laser device, which comprises a vacuum cavity, a laser gain medium and a heat sink sample table located in the vacuum cavity, the heat sink sample table is used to fix the laser gain medium, a pumping module is used to provide pumping light for the laser gain medium, and a temperature adjusting module is correspondingly matched with the heat sink sample table, the temperature adjusting module is configured to adjust the temperature of the heat sink sample table so that the working temperature of the laser gain medium is stably kept at the Debye temperature. The Debye temperature operating laser device is used to realize the operation of the laser gain medium at the Debye temperature, which can theoretically improve the thermal and optical performance, obtain laser output with high power, high beam quality and high efficiency, and provide support and impetus for the application and development of laser technology.

Description

Technical Field

[0001] This invention relates to the field of laser technology. More specifically, it relates to a Debye temperature-operated laser device. Background Technology

[0002] Laser technology, as an advanced technology characterized by high precision, high efficiency, and high energy density, has been widely applied in fields such as industry, medicine, communications, and materials science. Its role and importance in modern science and technology are increasingly significant, holding profound background implications.

[0003] Lasers are the core equipment of laser technology, and high-power, high-beam-quality laser output is an important development direction for solid-state laser technology. All-solid-state lasers are widely used due to their advantages such as high efficiency, compact structure, and high reliability. However, as output power increases, the internal thermal stress of the laser gain medium increases dramatically, severely limiting the laser's output power and beam quality, and in severe cases, even causing crystal fragmentation. Therefore, achieving higher power while maintaining high beam quality and high efficiency has become a bottleneck in the development of high-power lasers.

[0004] Low-temperature operating solid-state lasers can improve the thermo-optical properties (high thermal conductivity, low thermo-optical coefficient, low thermal expansion coefficient) and spectral characteristics (increased cross-section) of the gain medium, effectively alleviating the severe thermal effects associated with high-power output of solid-state lasers, thereby directly improving the overall performance of the laser system.

[0005] By testing the relationship between the temperature and thermal conductivity of laser gain media, it was found that the thermal conductivity of many laser gain media has a maximum value as the temperature changes. The temperature point where this maximum value is located is called the Debye temperature. Lasers operating at the Debye temperature have the best heat dissipation capacity, thus having a smaller thermal effect. The thermal effect of the laser determines the upper limit of the average power obtained from the laser gain medium and the beam quality of the laser. Therefore, it can be expected that lasers operating at the Debye temperature will have a great advantage in obtaining high-power, high-beam-quality lasers. Summary of the Invention

[0006] To address the aforementioned problems, this invention provides a Debye temperature-operated laser device for enabling the laser gain medium to operate at the Debye temperature. This can fundamentally improve thermal and optical performance, resulting in high-power, high-beam-quality, and high-efficiency laser output, thus providing support and impetus for the application and development of laser technology.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] This invention provides a Debye temperature-operated laser device, comprising:

[0009] Vacuum cavity;

[0010] A laser gain medium and a heat sink sample stage are located inside a vacuum cavity, wherein the heat sink sample stage is used to fix the laser gain medium.

[0011] A pump module for providing pump light to the laser gain medium; and

[0012] A temperature control module that works in conjunction with the heat sink sample stage;

[0013] The temperature control module is configured to regulate the temperature of the heat sink sample stage so that the operating temperature of the laser gain medium is kept stable at the Debye temperature.

[0014] In a preferred embodiment, the heat sink sample stage includes a first heat sink assembly and a second heat sink assembly fixed to the first heat sink assembly; the laser gain medium is snapped between the first heat sink assembly and the second heat sink assembly.

[0015] The preferred embodiment is that the thermal expansion coefficients of the heat sink sample stage and the laser gain medium are matched over a wide temperature range.

[0016] A preferred embodiment is that the Debye temperature-operated laser device further includes a window mirror for injecting pump light into the vacuum cavity or for emitting laser light out of the vacuum cavity.

[0017] A preferred embodiment is that the Debye temperature-operated laser device further includes two cavity mirrors located on both sides of the laser gain medium for laser reflection and output.

[0018] A preferred embodiment is to deposit a high-reflectivity laser film or a high-transmittance laser film at both ends of the laser gain medium to achieve laser oscillation and output.

[0019] A preferred embodiment is that the temperature regulation module includes a cooling module for cooling the heat sink sample stage, a heating module for heating the heat sink sample stage, and a temperature control module for controlling the working status of the cooling module and the heating module.

[0020] The heat sink sample stage is fixed to the cooling module; the heating module is disposed on the heat sink sample stage; the temperature control module is configured to adjust the temperature of the heat sink sample stage by controlling the cooling module and the heating module and make it reach the corresponding Debye temperature.

[0021] In a preferred embodiment, the pump module includes a pump source and a coupling mirror coupled to a window mirror; the pump light can enter the vacuum cavity through the coupling mirror and the window mirror.

[0022] A preferred embodiment is that the Debye temperature-operated laser device further includes an adjustment base for regulating the spatial degree of freedom of the laser gain medium;

[0023] The adjustment base includes a base plate and an adjustment plate mounted on the base plate by anchor screws; the adjustment plate is used to support the laser gain medium; the height and level of the adjustment plate can be finely adjusted by rotating the anchor screws.

[0024] The preferred embodiment is that the heat sink sample stage is made of copper or aluminum; and the laser gain medium is made of crystal or ceramic.

[0025] The beneficial effects of this invention are as follows:

[0026] The Debye temperature-operated laser device designed in this invention has a wide adjustable temperature range, capable of adjustment within a broad temperature range of 4K-300K. Utilizing low-temperature operation improves the thermo-optical performance and spectral characteristics of the laser gain medium, mitigating the severe thermal effects associated with high-power output. Testing is conducted at the Debye temperature, the point of maximum thermal conductivity of the laser gain medium. This device ensures that the operating temperature of the laser gain medium remains stably at the Debye temperature, stabilizing heat dissipation and directly improving the overall performance of the laser system. Secondly, under the low-temperature conditions provided by this device, most Boltzmann thermal distribution particles are deposited at the ground state energy level, reducing the laser threshold and improving laser efficiency. This enables high-power laser output while reducing laser size, achieving high-power, high-beam-quality, and high-efficiency laser beam emission from different laser gain media at their Debye temperatures. Furthermore, this device features a compact structure, a wide cooling range, high temperature control and optical adjustment accuracy, simple operation, and low overall cost. Attached Figure Description

[0027] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0028] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0029] Figure 2 This is a structural block diagram of the present invention.

[0030] Figure 3 This is a schematic diagram of the combination of the laser gain medium and the heat sink sample stage of the present invention.

[0031] Figure 4 This is a schematic diagram of the structure of the three-axis adjustment base of the present invention.

[0032] Figure 5A This is a schematic diagram showing the effect of temperature on the thermal conductivity of Yb:YAG crystals.

[0033] Figure 5B This is a schematic diagram of the Debye inflection point of a Yb:YAG crystal.

[0034] Figure 6A This is the energy level diagram of a Yb:YAG crystal.

[0035] Figure 6B This is a schematic diagram of the Boltzmann partition ratio of the two transition energy levels from Debye temperature to room temperature. Detailed Implementation

[0036] Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention.

[0037] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the invention or its application or use.

[0038] Technologies and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such technologies and equipment should be considered part of the specification.

[0039] In all the examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0040] It should be noted that similar labels and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures.

[0041] To achieve high-power, high-beam-quality, and high-efficiency laser output, this invention provides a Debye temperature-operated laser device, combined with... Figures 1 to 6BAs shown, the Debye temperature-operated laser device specifically includes: a vacuum cavity; a laser gain medium 1 and a heat sink sample stage 3 located within the vacuum cavity, the heat sink sample stage 3 being used to fix the laser gain medium 1, the laser gain medium 1 being a gain material capable of generating laser light; a pump module for providing pump light to the laser gain medium 1; and a temperature regulation module corresponding to and cooperating with the heat sink sample stage 3; the temperature regulation module is configured to regulate the temperature of the heat sink sample stage 3 so that the operating temperature of the laser gain medium 1 is stably maintained at the Debye temperature. The Debye temperature-operated laser device provided by this invention, combined with its various modules, provides a wide temperature range of 4k-300K. It utilizes low-temperature operation to improve the thermo-optical performance and spectral characteristics of the laser gain medium 1, alleviating the severe thermal effects associated with high-power output. Testing is conducted at the temperature point of maximum thermal conductivity of the laser gain medium, i.e., the Debye temperature, and the temperature is continuously maintained at the corresponding Debye temperature to improve heat dissipation, thereby directly improving the overall performance of the laser system and reducing the limitation on laser output power caused by laser thermal effects. Secondly, under low-temperature conditions, most Boltzmann thermal distribution particles are deposited at the ground state energy level, reducing the laser threshold and improving laser efficiency, achieving high-power laser output while reducing the space occupied by the laser. This enables high-power, high-beam-quality, and high-efficiency laser beam emission from different laser gain media at their Debye temperatures.

[0042] In the above embodiments, the laser gain medium 1 can be any laser-generating gain material such as crystal or ceramic, and can be of various shapes such as round bars, slabs, or disks, with the specific shape set according to the specific working conditions. The heat sink sample stage 3 is designed according to experimental requirements and the conditions of the laser gain medium 1. The heat sink sample stage 3 is made of heat sink material, which refers to a material with high thermal conductivity and high heat capacity, which can effectively absorb and disperse heat, prevent overheating of devices or equipment, and extend their lifespan. The laser gain medium 1 and the heat sink sample stage 3 can be designed according to requirements in terms of material, size, and shape. Commonly used heat sink materials include aluminum, copper, cermets, and graphite, which are widely used in electronics, communications, aerospace, and military fields. The heat sink sample stage 3 must be made of a heat sink material with a coefficient of thermal expansion that matches that of the laser gain medium 1. The coefficients of thermal expansion of the heat sink sample stage 3 and the laser gain medium 1 must match within a wide temperature range. The design of the heat sink sample stage 3 is optimized to reduce the impact of mechanical stress on the system. If the coefficients of thermal expansion of the heat sink material and the gain medium material do not match, both will expand thermally when the ambient temperature changes, but to different degrees, leading to relative displacement and thermal stress. This stress may damage the laser structure or affect laser performance. In the long term, it may also damage the structural performance of the heat sink, reducing its lifespan and stability. Selecting materials with matching coefficients of thermal expansion can reduce structural deformation caused by temperature changes, improve the bonding strength between the heat sink and the gain medium, and enhance the stability of the laser system. In one specific embodiment, the heat sink sample stage 3 includes a first heat sink assembly 31 and a second heat sink assembly 32 fixed to the first heat sink assembly 31; the laser gain medium 1 is snapped between the first heat sink assembly 31 and the second heat sink assembly 32. The laser gain medium 1 is placed in the slot between the two heat sink components of the heat sink sample stage 3. The two heat sink components are tightly fitted together and fixed with screws. Then, the fixed heat sink sample stage 3 containing the laser gain medium is placed under the adapter base 4, and the heat sink sample stage 3 is fixed to the adapter base 4 with screws to achieve a cooling effect. Figure 3 As shown.

[0043] In one specific embodiment, the Debye temperature-operated laser device further includes two window mirrors 5 for pump light to be incident into the vacuum cavity or for laser light to be emitted from the vacuum cavity. The two window mirrors 5 can be divided into an incident window mirror and an exit window mirror. The pump module includes a pump source and a coupling mirror coupled to the window mirrors 5. The pump light can enter the vacuum cavity through the coupling mirror and the window mirrors 5. The pump module is used to provide pump light to the laser gain medium 1. The pump source can be an LD laser or a fiber laser. The emission wavelength is determined according to the spectral characterization results of the specific laser gain medium 1. The incident pump light is coupled by the coupling mirror and passes through the window mirrors 5 to be incident on the laser gain medium 1 in the middle of the heat sink sample stage 3. The laser gain medium 1 achieves population inversion and emits laser light, which then exits from the exit window mirror.

[0044] In one specific embodiment, the temperature regulation module is used to ensure that the laser can operate precisely at the Debye temperature. The temperature regulation module includes a cooling module for cooling the heat sink sample stage 3, a heating module for heating the heat sink sample stage 3, and a temperature control module for controlling the operating states of the cooling module and the heating module. The heat sink sample stage 3 is fixed to the cooling module. The heating module is disposed on the heat sink sample stage 3. The temperature control module is configured to adjust the temperature of the heat sink sample stage 3 by controlling the cooling module and the heating module to make its temperature reach the corresponding Debye temperature.

[0045] The cooling module is used to cool the working environment. The cooling module is a refrigerator 2, specifically comprising a cold head, a compressor, and a water chiller. The compressor increases the refrigerant pressure to achieve cyclic cooling. The adapter chassis 4 at the bottom of the refrigerator 2 is the cold head, which directly contacts the heat sink sample stage 3 for cooling. To maximize the cooling range, direct cooling is abandoned; instead, a compressor pressurizes the refrigerant, and helium is used as the circulating refrigerant, ultimately achieving a minimum temperature of 4K. The cooling module can be set to a lower temperature range, using helium as the circulating refrigerant. The compressor piston movement increases the refrigerant pressure, creating a circulating helium environment for cooling. The adapter chassis 4 of the cooling module is connected to the heat sink sample stage 3, where the laser gain medium 1 is placed, using screws. The cooling module, heating module, and laser gain medium 1 are all used in a vacuum environment below 10 Pa.

[0046] The heating module can be a semiconductor heating element or a resistance wire installed on the heat sink sample stage 3, and the heat sink sample stage 3 can be heated and regulated by the temperature control module.

[0047] The temperature control module is a common commercial device, serving as a temperature controller for measuring and maintaining a set temperature experimental environment. This temperature controller is a commonly used commercial device in the industry and responds to experimental conditions. The temperature control module is used to maintain the ambient temperature at the set temperature. It includes a customized high-precision wide-temperature-range thermometer (measuring range 10K-300K) and a PID controller. Through PID tuning, heating or cooling is controlled, achieving stable and high-precision temperature control to ensure the laser gain medium 1 operates at the Debye temperature. The thermal conductivity of the laser gain medium 1 initially increases and then decreases as the temperature decreases. Figure 5A and Figure 5B As shown, the maximum thermal conductivity is the Debye inflection point, where the laser gain medium 1 has the highest thermal conductivity, theoretically offering the best heat dissipation capacity and minimal thermal effect. The thermal effect directly affects laser beam characteristics such as output power and beam quality. Therefore, the experiment was conducted at the Debye temperature of the laser gain medium 1. The Debye temperature-operated laser device utilizes a cooling module for cooling, while corresponding temperature parameters are set in the temperature controller. A high-precision thermometer capable of measuring a wide temperature range and a heating module are installed on the heat sink sample stage 3. Stable and high-precision temperature control is achieved through PID tuning, enabling the Debye temperature-operated laser experiment.

[0048] In one specific embodiment, the Debye temperature-operated laser device further includes two cavity mirrors 6 located on both sides of the laser gain medium 1 for laser reflection and output; either of the two cavity mirrors 6 located on both sides of the laser gain medium 1 for laser reflection and output can be placed outside or inside the vacuum cavity, and the position of the cavity mirror 6 can be considered according to the actual experimental space conditions; or laser high reflectivity film or laser high transmittance film can be directly deposited at both ends of the laser gain medium 1 to achieve laser oscillation and output.

[0049] In one specific embodiment, the Debye temperature-controlled laser device further includes an adjustment base 7 for adjusting the spatial degrees of freedom of the laser gain medium 1; the adjustment base 7 includes a base plate 71 and an adjustment plate 73 disposed on the base plate by anchor screws 72, the adjustment plate 73 is used to support the laser gain medium 1, and the height and level of the adjustment plate 73 can be finely adjusted by rotating the anchor screws 72, as shown in the specific structure. Figure 4 As shown, the height and level of the adjustment plate 73 are adjusted by rotating the three anchor screws 72 respectively, thereby driving the vacuum cavity to rise and fall, and controlling the swaying and pitching of the laser gain medium 1, so as to facilitate the adjustment of the optical path.

[0050] Reference Figure 5A and Figure 5BAs shown, the Debye temperature of the laser gain medium Yb:YAG crystal is known to be 23K. Yb:YAG crystal at the Debye temperature exhibits the highest thermal conductivity, best heat dissipation, and least thermal effect, resulting in the best beam characteristics, including the upper limit of laser output power and beam quality. This ensures high-power, high-beam-quality laser output. A heat sink material matching the thermal expansion coefficient of the Yb:YAG crystal is used, and the heat sink structure is optimized to reduce the impact of mechanical stress. Simultaneously, a GM refrigerator is used as the cold source, relying on the compressor to increase the refrigerant pressure to achieve recyclable helium cooling, realizing a wide temperature range of 4-300K. This meets the requirements of Debye temperature lasers based on different laser gain media 1 operating at different Debye temperatures, precisely controlling the laser gain medium 1 to achieve high-power, high-beam-quality laser beam output at the Debye temperature.

[0051] The energy level structure and Boltzmann partition ratio of Yb:YAG crystal at room temperature are as follows: Figure 6A and Figure 6B As shown in the figure, f i s and f i p These are the Boltzmann decimals representing the thermal partitioning of particles in each Stark level in the upper and lower energy levels, respectively:

[0052]

[0053] Where E represents the energy level, k represents the Boltzmann constant, and T represents the temperature.

[0054] At low temperatures, because most of the Boltzmann thermal distribution particles are concentrated in the ground state, the number of particles excited to higher energy levels is relatively small. This reduces the energy or current required to reach the excitation level in the laser, thus lowering the laser threshold. This makes it easier for the laser to excite particles to transition to higher energy levels and generate laser output.

[0055] Furthermore, in lasers, when the occupancy rate of the ground state energy level is relatively high, particles are more likely to transition to the excited state under the stimulation of photons, thereby increasing the efficiency of the laser. The deposition of particles on the ground state energy level increases the particle number density in the laser, thereby increasing the intensity of laser radiation, and the output power of the laser will also increase accordingly.

[0056] Place the laser gain medium Yb:YAG crystal 1 into the central slot of the two heat sink components of the heat sink sample stage 3 and tighten it with screws. Then place the heat sink sample stage 3 containing the Yb:YAG crystal under the adapter plate 4 of the cold head at the bottom of the GM chiller. After the adapter plate 4 is in contact with the heat sink sample stage 3, tighten it with screws. At this time, the GM chiller 2 and the laser gain medium Yb:YAG crystal are both placed in the vacuum chamber. Turn on the equipment to evacuate until the vacuum degree reaches below 10Pa. Turn on the water chiller and at the same time check whether the parameters in the compressor display panel are normal. Set the Debye temperature parameter of 23K on the temperature controller. Check the pump source LD laser on the side of the incident window mirror and the laser power meter, spectrometer and M on the side of the exit window mirror. 2 Before starting the device to conduct laser experiments on Yb:YAG crystals at the Debye temperature, ensure that all measuring equipment, including the measuring instruments, is functioning correctly. Simultaneously, the spatial degrees of freedom (swing and pitch, etc.) of the Yb:YAG laser gain medium can be controlled by adjusting the base, allowing as much pump light as possible to enter the Yb:YAG crystal. Utilizing a low-temperature environment improves the thermo-optical performance of the laser gain medium 1, mitigating the severe thermal effects associated with high-power output. Testing is conducted at the temperature point of maximum thermal conductivity of the laser gain medium 1, i.e., the Debye temperature of 23K, to improve heat dissipation and directly enhance the overall performance of the laser system. Secondly, under low-temperature conditions, most Boltzmann thermal distribution particles are deposited at the ground state energy level, reducing the laser threshold and improving laser efficiency, achieving high-power laser output while reducing laser size. Ultimately, this results in high-power, high-beam-quality, and high-efficiency laser beam emission from the Yb:YAG laser gain medium at its Debye temperature of 23K.

[0057] In summary, the Debye temperature-operated laser device designed in this invention has a wide adjustable temperature range, capable of adjustment within a broad temperature range of 4K-300K. Utilizing low-temperature operation improves the thermo-optical performance and spectral characteristics of the laser gain medium, alleviating the severe thermal effects associated with high-power output. By selecting the Debye temperature—the temperature point of maximum thermal conductivity of the laser gain medium—for testing, this device ensures that the operating temperature of the laser gain medium is stably maintained at the Debye temperature, stabilizing heat dissipation and directly improving the overall performance of the laser system. Secondly, under the low-temperature conditions provided by this device, most Boltzmann thermal distribution particles are deposited at the ground state energy level, reducing the laser threshold and improving laser efficiency. This enables high-power laser output while reducing the laser's size, achieving high-power, high-beam-quality, and high-efficiency laser beam emission from different laser gain media at their Debye temperatures. Furthermore, this device features a compact overall structure, a wide cooling range, high temperature control and optical adjustment accuracy, simple operation, and low overall cost.

[0058] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. For those skilled in the art, other variations or modifications can be made based on the above description. It is impossible to exhaustively list all the implementation methods here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A Debye temperature-operated laser device, characterized in that, include: Vacuum cavity; A laser gain medium and a heat sink sample stage are located inside a vacuum cavity, wherein the heat sink sample stage is used to fix the laser gain medium. A pump module for providing pump light to the laser gain medium; as well as A temperature control module that works in conjunction with the heat sink sample stage; The temperature control module is configured to regulate the temperature of the heat sink sample stage so that the operating temperature of the laser gain medium is stably maintained at the Debye temperature.

2. The Debye temperature-controlled laser device according to claim 1, characterized in that, The heat sink sample stage includes a first heat sink assembly and a second heat sink assembly fixed to the first heat sink assembly; the laser gain medium is snapped between the first heat sink assembly and the second heat sink assembly.

3. The Debye temperature-controlled laser device according to claim 1, characterized in that, The thermal expansion coefficients of the heat sink sample stage and the laser gain medium are matched over a wide temperature range.

4. The Debye temperature-controlled laser device according to claim 1, characterized in that, The Debye temperature-operated laser device also includes a window mirror for injecting pump light into the vacuum cavity or for emitting laser light out of the vacuum cavity.

5. The Debye temperature-operated laser device according to claim 1, characterized in that, The Debye temperature-operated laser device also includes two cavity mirrors located on both sides of the laser gain medium for laser reflection and output.

6. The Debye temperature-operated laser device according to claim 1, characterized in that, Laser oscillation and output are achieved by depositing high-reflectivity or high-transmittance laser films at both ends of the laser gain medium.

7. The Debye temperature-operated laser device according to claim 1, characterized in that, The temperature regulation module includes a cooling module for cooling the heat sink sample stage, a heating module for heating the heat sink sample stage, and a temperature control module for controlling the working status of the cooling module and the heating module. The heat sink sample stage is fixed to the cooling module; the heating module is disposed on the heat sink sample stage; the temperature control module is configured to adjust the temperature of the heat sink sample stage by controlling the cooling module and the heating module and make it reach the corresponding Debye temperature.

8. The Debye temperature-controlled laser device according to claim 4, characterized in that, The pump module includes a pump source and a coupling mirror coupled to a window mirror; the pump light can enter the vacuum cavity through the coupling mirror and the window mirror.

9. The Debye temperature-controlled laser device according to claim 1, characterized in that, The Debye temperature-operated laser device also includes an adjustment base for regulating the spatial degree of freedom of the laser gain medium. The adjusting base includes a base plate and an adjusting plate mounted on the base plate by anchor screws; the adjusting plate is used to support the vacuum chamber; the height and level of the adjusting plate can be finely adjusted by rotating the anchor screws.

10. The Debye temperature-operated laser device according to claim 1, characterized in that, The heat sink sample stage is made of copper or aluminum; the laser gain medium is made of crystal or ceramic.

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