Solid laser with adjustable pulse width

Abstract

The embodiment of the invention discloses a solid laser with adjustable pulse width. According to one specific implementation mode, the solid laser comprises a shell, a pumping source, a gain medium, a controller, a pulse width regulation and control assembly, a first cavity mirror, a second cavity mirror, a Q-switching unit and a monitoring feedback device are arranged in the shell, and the pumping source is installed in front of the first cavity mirror; the gain medium is mounted behind the first cavity mirror, and the pumping source is configured to emit pumping light to the gain medium; the gain medium, the Q-switching unit and the second cavity mirror are sequentially arranged from front to back; the pulse width regulation and control assembly is installed in a resonant cavity of the laser. The monitoring feedback device is installed at the output end of the solid laser and used for detecting the actual pulse width and feeding back the actual pulse width to the controller. The controller is in communication connection with the monitoring feedback device and the pulse width regulation and control assembly. According to the embodiment, the actual pulse width of the output laser can be detected in real time, and the pulse width of the output laser can be adjusted. Therefore, the working accuracy of the laser can be improved.

Description

Technical Field

[0001] Embodiments of this disclosure relate to the field of laser technology, and more specifically to pulse-width-adjustable solid-state lasers. Background Technology

[0002] With the development of laser technology, lasers are being used more and more widely in daily life. The requirements for laser pulse width vary depending on the application scenario. Currently used lasers typically do not have a feedback adjustment mechanism.

[0003] However, when using commonly used lasers, there is often a technical problem that the laser's operating accuracy is poor because there is no feedback adjustment mechanism and the pulse width cannot be detected and adjusted in real time.

[0004] The information disclosed in this background section is only intended to enhance the understanding of the background of the present disclosure concept, and therefore may contain information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0005] The summary portion of this disclosure is intended to provide a brief overview of the concepts, which will be described in detail in the detailed description portion. This summary portion is not intended to identify key or essential features of the claimed technical solutions, nor is it intended to limit the scope of the claimed technical solutions.

[0006] Some embodiments of this disclosure propose pulse-width-tunable solid-state lasers to address one or more of the technical problems mentioned in the background section above.

[0007] Some embodiments of this disclosure provide a pulse-width-adjustable solid-state laser, which includes a housing and, inside the housing, a pump source, a gain medium, a controller, a pulse width modulation component, a first cavity mirror, a second cavity mirror, a Q-switching unit, and a monitoring feedback unit. The pump source is mounted in front of the first cavity mirror; the gain medium is mounted behind the first cavity mirror, and the pump source is configured to emit pump light into the gain medium; the gain medium, the Q-switching unit, and the second cavity mirror are arranged sequentially from front to back; the pulse width modulation component is mounted within the resonant cavity of the laser; the monitoring feedback unit is mounted at the output of the solid-state laser and is used to detect the actual pulse width of the laser output and feed it back to the controller; the controller is communicatively connected to the monitoring feedback unit and the pulse width modulation component.

[0008] Optionally, the pulse width modulation component is a etalon; the etalon is located between the gain medium and the Q-switching unit; the etalon is made of quartz or pure yttrium aluminum garnet crystal; and a dielectric film with a preset reflectivity is provided on both sides of the etalon.

[0009] Optionally, the first cavity mirror is located between the pump source and the gain medium; the second cavity mirror is located between the Q-switching unit and the monitoring feedback unit, wherein the Q-switching unit is an acousto-optic Q-switch or an electro-optic Q-switch.

[0010] Optionally, the gain medium can be one of the following: neodymium-doped yttrium aluminum garnet crystal, neodymium-doped lithium fluoride yttrium crystal, ytterbium-doped yttrium aluminum garnet crystal, neodymium-doped yttrium vanadate crystal, holmium-doped yttrium aluminum garnet crystal, thulium-doped yttrium aluminum garnet crystal, or erbium-doped yttrium aluminum garnet crystal.

[0011] Optionally, the aforementioned housing is provided with an interactive device; the interactive device is communicatively connected to the aforementioned controller.

[0012] Optionally, the aforementioned monitoring feedback device incorporates a photodiode.

[0013] Optionally, the pulse width modulation component is a transmissive grating.

[0014] Optionally, the resonant cavity of the pulse-width adjustable solid-state laser is a non-linear cavity; there is a preset angle between the end face of the first cavity mirror and the laser emitted by the gain medium; the first cavity mirror has a reflectivity greater than 95% for the laser emitted by the gain medium and a transmittance greater than 95% for the laser emitted by the pump source; the transmissive grating is located in the optical path of the laser reflected by the first cavity mirror; a third cavity mirror is provided in the optical path of the laser diffracted by the transmissive grating, and the third cavity mirror has a reflectivity greater than 95% for the laser diffracted by the transmissive grating; the second cavity mirror is located behind the gain medium, and the Q-switching unit is located between the second cavity mirror and the gain medium.

[0015] Optionally, the controller is configured to perform the following steps: in response to determining that the actual pulse width of the laser output by the laser is inconsistent with the preset pulse width, detecting the deflection angle of the pulse width control component and obtaining the actual deflection angle value; generating an angle deviation amount based on the actual deflection angle value; and adjusting the deflection angle of the pulse width control component according to the angle deviation amount.

[0016] Some embodiments of this disclosure provide a pulse-width-adjustable solid-state laser that can improve the operating accuracy of the laser. Specifically, the reason for the poor operating accuracy of most lasers is that currently used lasers do not have a feedback adjustment mechanism. Because there is no feedback adjustment mechanism, it is impossible to detect in real time whether the actual output pulse width meets the preset standard, and therefore the pulse width cannot be adjusted in real time, resulting in poor laser operating accuracy. Based on this, some embodiments of this disclosure provide a pulse-width adjustable solid-state laser. The pulse-width adjustable solid-state laser includes a housing, and inside the housing are a pump source, a gain medium, a controller, a pulse width modulation component, a first cavity mirror, a second cavity mirror, a Q-switching unit, and a monitoring feedback unit. The pump source is mounted in front of the first cavity mirror; the gain medium is mounted behind the first cavity mirror, and the pump source is configured to emit pump light into the gain medium; the gain medium, the Q-switching unit, and the second cavity mirror are arranged sequentially from front to back; the pulse width modulation component is mounted within the laser's resonant cavity; the monitoring feedback unit is mounted at the output end of the solid-state laser, used to detect the actual pulse width of the laser output and feed it back to the controller; the controller is communicatively connected to the monitoring feedback unit and the pulse width modulation component. Through the communicative connection between the controller and the monitoring feedback unit and the pulse width modulation component, the actual pulse width of the output laser can be detected, and the pulse width of the output laser can be adjusted in real time. This improves the operating accuracy of the laser. Attached Figure Description

[0017] The above and other features, advantages, and aspects of the embodiments of this disclosure will become more apparent from the accompanying drawings and the following detailed description. Throughout the drawings, the same or similar reference numerals denote the same or similar elements. It should be understood that the drawings are schematic, and elements are not necessarily drawn to scale.

[0018] Figure 1 This is a schematic diagram of the structure of a pulse-width adjustable solid-state laser according to some embodiments of the present disclosure when the pulse width control component is a standard etalon;

[0019] Figure 2 This is a schematic diagram of the structure of a pulse-width adjustable solid-state laser according to some embodiments of the present disclosure when the pulse width modulation component is a transmission grating;

[0020] Figure 3 This is an emission spectrum of a neodymium-doped yttrium aluminum garnet crystal used in the gain medium of a pulse-width-adjustable solid-state laser according to some embodiments of this disclosure. Detailed Implementation

[0021] Embodiments of this disclosure will now be described in more detail with reference to the accompanying drawings. While some embodiments of this disclosure are shown in the drawings, it should be understood that this disclosure can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of this disclosure. It should be understood that the accompanying drawings and embodiments of this disclosure are for illustrative purposes only and are not intended to limit the scope of protection of this disclosure.

[0022] It should also be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings. Unless otherwise specified, the embodiments and features described in this disclosure can be combined with each other.

[0023] It should be noted that the concepts of "first" and "second" mentioned in this disclosure are used only to distinguish different devices, modules or units, and are not used to limit the order of functions performed by these devices, modules or units or their interdependencies.

[0024] It should be noted that the terms "a" and "a plurality of" used in this disclosure are illustrative rather than restrictive, and those skilled in the art should understand that, unless otherwise expressly indicated in the context, they should be understood as "one or more".

[0025] The names of messages or information exchanged between multiple devices in the embodiments of this disclosure are for illustrative purposes only and are not intended to limit the scope of such messages or information.

[0026] This disclosure will now be described in detail with reference to the accompanying drawings and embodiments.

[0027] Figure 1 This is a schematic diagram of the structure of a pulse-width adjustable solid-state laser according to some embodiments of the present disclosure, where the pulse width control component is a standard etalon. Figure 1 It includes a pump source 1, a first cavity mirror 2, a gain medium 3, a pulse width modulation component 4, a Q-switching unit 5, a second cavity mirror 6, a monitoring feedback device 7, and a controller 8.

[0028] Figure 2 This is a schematic diagram of the structure of a pulse-width adjustable solid-state laser according to some embodiments of the present disclosure, where the pulse width control component is a transmission grating. Figure 2 include Figure 1 It includes a pump source 1, a first cavity mirror 2, a gain medium 3, a pulse width modulation component 4, a Q-switching unit 5, a second cavity mirror 6, a monitoring feedback device 7, a controller 8, and a third cavity mirror 9.

[0029] In some embodiments, the pulse-width adjustable solid-state laser may include a housing, and inside the housing may be a pump source 1, a gain medium 3, a controller 8, a pulse width modulation component 4, a first cavity mirror 2, a second cavity mirror 6, a Q-switching unit 5, and a monitoring feedback unit 7. The housing may be made of aluminum alloy or stainless steel, and may have an internal shock-absorbing layer (such as a sponge pad) to protect the internal components. The shape of the housing may be square, and no specific limitation is made here. The pump source 1 may be a laser energy input component. For example, the pump source 1 may be a laser diode. The gain medium 3 may be a core component for generating laser light (such as a neodymium-doped yttrium aluminum garnet crystal, Nd:YAG crystal). The controller 8 may be an integrated circuit board based on a microcontroller or field-programmable gate array (FPGA) capable of implementing control functions. The pulse width modulation component 4 may be a key execution component for pulse width adjustment. The pulse width modulation component 4 may be a component capable of changing the pulse width of the laser. The principle by which the pulse width modulation component 4 can adjust the pulse width is explained here. For a Q-switched laser, its pulse width can be determined by the following formula:

[0030]

[0031] Among them, t p The values ​​represent: pulse width (L), resonant cavity length (c), speed of light (R), reflectivity of the output mirror (R), loss (c), and internal cavity loss (n). i This represents the numerical value of the upper-level particle density in the gain medium after pumping and before the generation of the Q-pulse, n. f The value representing the remaining upper-level particle density after the Q-pulse is generated, n t The numerical value of the threshold-inverted particle density is represented by `ln`, which represents the logarithmic operator with the base being the natural constant and has no symbolic meaning in this formula. The numerical value of the threshold-inverted particle density is `n`. t It can be determined by the following formula:

[0032] n t = [ln(1 / R)+L] / (2σl)

[0033] Where, n t R represents the threshold inversion particle density, L represents the reflectivity of the output mirror, L represents the resonant cavity length, σ represents the emission cross-section of the gain medium, l represents the length of the gain medium, and ln represents the logarithmic operator with a base of a natural constant, which has no symbolic meaning in this formula. i n f n t The order of the three values ​​is n i >n t >n f >0. With other parameters remaining constant, t p It's about nt A monotonically increasing function. The numerical value n of the threshold-reversed particle mentioned above. t This refers to the minimum number of inverted particles required to achieve laser oscillation in a laser.

[0034] From the above formula, it can be seen that the larger the emission cross-section σ of the gain medium, the higher the value of the threshold inversion particle density n. t The smaller the value, the greater the pulse width t. p The shorter the length. Taking neodymium-doped yttrium aluminum garnet crystal as an example, Figure 3 This is the emission spectrum of a neodymium-doped yttrium aluminum garnet crystal. Figure 3 It is evident that in the 1064nm band, the maximum emission cross-section corresponds to the peak value of the emission spectrum. If the wavelength deviates from the peak value, the emission cross-section will decrease. The emission cross-section is a microscopic parameter that quantifies the stimulated emission efficiency of the gain medium. When the emission cross-section decreases, the pulse width will increase according to the above formula. Therefore, the pulse width of the output laser can be changed by altering the incident laser wavelength of the gain medium. Thus, the pulse width control component 4 can be composed of elements capable of changing the incident laser wavelength of the gain medium. These elements may include, but are not limited to, etalons and transmission gratings, without specific limitations. Taking an etalon as an example, in practical use, the controller 8 can adjust the placement angle of the etalon via a motor, changing the angle at which the laser in the resonant cavity enters the etalon, thereby changing the wavelength of the laser allowed to pass through the etalon. Since the angle control of the etalon is continuous, continuous control of the laser output pulse width can also be achieved, making it more versatile than lasers that can only adjust the pulse width at specific levels. The first cavity mirror 2 can be a quartz dichroic mirror, exhibiting greater than 95% transmittance for the laser emitted from the pump source 1 and greater than 99% reflectivity for the laser emitted from the gain medium 3. The second cavity mirror 6 can also be a quartz dichroic mirror, serving as the laser's output coupler to extract the output beam from the laser resonant cavity. The Q-switching unit 5 can be an acousto-optic crystal; no specific limitation is made, as long as it can adjust the laser's Q-value (quality factor). The monitoring feedback unit 7 can be an assembly of multiple components, including a detection component. This detection component can be used to detect output laser parameters such as pulse width, and signal conditioning circuits. It receives electrical signals transmitted from the detection component, performs preset processing, and feeds back the pre-processed electrical signal to the data transmission interface of the controller 8. The detection component can be a photoelectric sensor. The preset processing can include, but is not limited to, amplifying and filtering the electrical signal.

[0035] In some embodiments, the pump source 1 can be installed in front of the first cavity mirror 2. "In front" refers to a forward position in the optical path, meaning the optical signal emitted by the pump source 1 can first pass through the first cavity mirror 2 before being transmitted to subsequent components. The gain medium 3 can be installed behind the first cavity mirror 2, and the pump source 1 can be configured to emit pump light into the gain medium 3. The gain medium 3 can receive the pump light emitted by the pump source 1 and achieve population inversion, providing the energy basis for laser generation. The gain medium 3, the Q-switching unit 5, and the second cavity mirror 6 can be arranged sequentially from front to back, and adjacent components can be spaced by a preset distance. This preset distance may vary in different types of lasers and is not specifically limited here, as long as it allows the laser to operate normally. The Q-switching unit 5 can pulse-modulate the continuous laser generated by the gain medium 3 to adjust the quality factor of the laser output by the laser. The second cavity mirror 6 can serve as an output reflector of the resonant cavity, transmitting a portion of the laser according to a preset transmittance to achieve output. The pulse width modulation component 4 can be installed inside the resonant cavity of the laser, directly acting on the reciprocating laser beam, and changing the pulse width by adjusting the emission cross-section of the gain medium. The resonant cavity is the core area for pulse width modulation. The monitoring feedback unit 7 can be installed at the output end of the solid-state laser to detect the actual pulse width of the laser output and feed it back to the controller. The output end can be the laser emission side of the second cavity mirror 6. The controller 8 can communicate with the monitoring feedback unit 7 and the pulse width modulation component 4. The communication connection can be wired (e.g., USB, serial port) or wireless (e.g., Bluetooth). The controller 8 can receive the detection data from the monitoring feedback unit 7, calculate the pulse width deviation in real time, and send adjustment commands to the modulation component to form a closed-loop control to improve the accuracy of pulse width modulation.

[0036] Optionally, such as Figure 1As shown, the pulse width modulation component 4 can be an etalon. The etalon can be a parallel planar plate-shaped optical element that filters out laser light of a specific wavelength through multi-beam interference, allowing this specific wavelength of laser light to enter the gain medium 3. When lasers of different wavelengths enter the gain medium 3, the laser emission cross-section will be different, thus the pulse width of the laser can be controlled by adjusting the laser emission cross-section. The etalon can be located between the gain medium 3 and the Q-switching unit 5, so that the laser light generated by the gain medium 3 first has its emission cross-section controlled by the etalon, and then the pulse is modulated by the Q-switching unit 5, so that pulse width adjustment and pulse generation work synergistically. The etalon can be made of quartz or pure yttrium aluminum garnet (YAG) crystal, without specific limitations. Quartz has good light transmittance (ultraviolet to infrared band), low dispersion, and high temperature stability, making it suitable as a high-precision optical modulation element. Pure yttrium aluminum garnet crystal has excellent thermomechanical properties, with a thermal conductivity of approximately 13 W / (m·K), much higher than some optical glasses, and a low coefficient of thermal expansion. When the laser operates at high power, even with fluctuations in the temperature of the gain medium and the surrounding environment, the physical dimensions and optical parallelism of the pure yttrium aluminum garnet crystal etalon are not easily shifted due to thermal deformation, thus improving the stability of wavelength selection. A dielectric film with a preset reflectivity can be applied to both sides of the etalon. This dielectric film can be a dielectric film, and there can be at least one layer. The preset reflectivity can be adjusted by controlling the film thickness and material. When the etalon thickness and reflectivity are constant, the tilt angle of the etalon can be adjusted (i.e., changing the angle at which the laser is incident on the etalon). Through the selection effect of the etalon, lasers of specific wavelengths are selected and output from the etalon, thereby changing the laser emission cross-section and achieving the purpose of adjusting the pulse width.

[0037] Optionally, such as Figure 1 As shown, the first cavity mirror 2 can be located between the pump source 1 and the gain medium 3. The first cavity mirror 2 is permeable to light emitted from the pump source 1 and reflective of laser light generated by the gain medium 3, thus neither obstructing the pump light from entering the gain medium 3 nor hindering the reflection of laser light generated by the gain medium 3 back to the resonant cavity, thereby enhancing the resonance effect. The second cavity mirror 6 can be located between the Q-switching unit 5 and the monitoring feedback unit 7. The Q-switching unit 5 can be an acousto-optic Q-switch or an electro-optic Q-switch, without specific limitations.

[0038] Optionally, the gain medium 3 can be one of the following: neodymium-doped yttrium aluminum garnet crystal, neodymium-doped lithium fluoride yttrium crystal, ytterbium-doped yttrium aluminum garnet crystal, neodymium-doped yttrium vanadate crystal, holmium-doped yttrium aluminum garnet crystal, thulium-doped yttrium aluminum garnet crystal, or erbium-doped yttrium aluminum garnet crystal.

[0039] Optionally, the aforementioned housing may be equipped with an interactive device. This interactive device allows the user to set the target pulse width and view the laser's operating status. The interactive device may include an OLED display screen and buttons. The display screen may be preset to be touch-sensitive. The user can interact with the laser through virtual buttons. The interactive device can communicate with the controller 8, enabling it to receive user-input parameters and transmit them to the controller 8, while also receiving operating data from the controller 8, such as the current pulse width and power, and displaying this operating data to achieve human-machine interaction.

[0040] Optionally, the monitoring feedback unit 7 described above can have a built-in photodiode. This photodiode can convert the optical signal of the incident laser into an electrical signal, enabling the detection of the laser's pulse width and power information.

[0041] Optionally, the pulse width modulation component 4 can be a transmissive grating. The transmissive grating can be an optical device composed of a predetermined number of parallel grooves of equal width and spacing. For example, the transmissive grating can be a flat piece of glass, and the surface of this flat glass is engraved with a predetermined number of grooves of equal width and spacing. The principle of controlling the laser pulse width using a transmissive grating is explained here. A transmissive grating can separate light of different wavelengths through the diffraction phenomenon. The operation of the transmissive grating follows the grating diffraction equation:

[0042] mλ=d(sinα+sinβ)

[0043] Where m represents the diffraction order, λ is the wavelength of the laser light in the resonant cavity, d represents the grating period, α represents the incident angle, and β represents the diffraction angle. In practical applications, the first-order diffracted light of the grating can be preset as the working beam, so the diffraction order can be set to "1". The above-mentioned transmission grating can adopt a Littrow structure, that is, the incident angle and the diffraction angle of the grating are equal. In this case, the above grating diffraction equation can be simplified to:

[0044] λ=2dsinα

[0045] Where λ is the wavelength of the laser within the resonant cavity, d represents the grating period, and α represents the incident angle. Therefore, by adjusting the angle of the laser incident on the grating, the wavelength of the laser within the resonant cavity can be changed, thereby controlling the pulse width. Specifically, in a laser, the gain medium generates spontaneous emission after being pumped, and the wavelength range of the emitted light is determined by the emission spectrum of the gain medium. As this light propagates back and forth within the resonant cavity, only specific wavelengths that satisfy the aforementioned grating diffraction equation and resonant cavity resonance conditions can form stable oscillations and ultimately be output as laser light. The role of the grating is to "select" this specific wavelength that satisfies the aforementioned grating diffraction equation and resonant cavity resonance conditions through the diffraction equation: when the grating angle is adjusted, only specific wavelengths can satisfy the equation, thus continuously oscillating within the cavity and being output.

[0046] Optionally, such as Figure 2 As shown, the resonant cavity of the pulse-width adjustable solid-state laser can be a non-linear cavity (such as a V-type). A non-linear cavity refers to a cavity where the laser propagation path is not linear. The optical path is altered by reflecting components (such as the first and second cavity mirrors), increasing the intracavity optical path and improving laser mode stability compared to a linear cavity. The end face of the first cavity mirror 2 can have a preset angle with the laser emitted from the gain medium 3 to adapt the optical path to the non-linear cavity structure. The first cavity mirror 2 can have a reflectivity greater than 95% for the laser emitted from the gain medium 3 and a transmittance greater than 95% for the laser emitted from the pump source 1. This characteristic allows the first cavity mirror 2 to reflect the laser to form a resonance, while allowing the pump light to pass through and be incident on the gain medium 3. The transmission grating can be located on the optical path of the laser reflected by the first cavity mirror 2. This allows the laser reflected by the first cavity mirror 2 to be directly incident on the transmission grating. The transmission grating filters lasers of specific wavelengths through diffraction, thereby controlling the emission cross-section. A third cavity mirror 9 can be provided in the optical path of the laser diffracted by the aforementioned transmissive grating, and the third cavity mirror 9 can have a reflectivity greater than 95% for the laser diffracted by the transmissive grating. The third cavity mirror 9 can be a dielectric film reflector. The third cavity mirror 9 can reflect the diffracted laser back to the transmissive grating, forming a non-linear resonant path together with the first cavity mirror 2 and the second cavity mirror 6, thereby enhancing laser oscillation. It should be noted that when the transmissive grating is used as the pulse width modulation component, whenever the placement angle of the transmissive grating is changed, the third cavity mirror 9 needs to be adjusted synchronously to ensure that the third cavity mirror 9 can successfully reflect back the laser filtered by the transmissive grating. For example, it can be preset that for every 0.1° rotation of the transmissive grating angle, the third cavity mirror rotates synchronously by 0.05°. The second cavity mirror 6 can be located behind the gain medium 3, and the Q-switching unit 5 can be located between the second cavity mirror 6 and the gain medium 3. This positional relationship allows the laser generated by the gain medium 3 to be first modulated into a pulse by the Q-switching unit 5, and then transmitted and output by the second cavity mirror 6, thereby improving the stability and controllability of the output pulse.

[0047] The above-described optional embodiments, as an inventive point of this disclosure, solve the technical problem of "poor laser stability in solid-state lasers." The specific factors leading to poor laser stability in solid-state lasers are as follows: Currently, most commonly used solid-state laser resonator cavities are linear cavities, with short optical paths that easily lead to poor laser stability. Solving these factors can improve the output laser stability of solid-state lasers. To achieve this goal, this disclosure also provides a non-linear resonator solution. Using a non-linear cavity increases the intracavity optical path, improving laser mode stability; furthermore, through the design of the non-linear resonator, while increasing the intracavity optical path, the length of the laser is not directly increased. Therefore, the stability of the output laser from the solid-state laser is improved.

[0048] Optionally, the controller described above is configured to perform the following steps:

[0049] The first step involves detecting the deflection angle of the pulse width control component in response to the discrepancy between the actual pulse width output by the laser and the preset pulse width. The controller compares the actual pulse width measured by the monitoring feedback device with the preset pulse width. If the deviation exceeds a preset range, it is determined that the actual pulse width of the laser output is inconsistent with the preset pulse width. The specific value of the preset pulse width is not limited and can be adjusted according to actual needs. For example, if the actual pulse width is 10 nanoseconds, the preset pulse width is 6 nanoseconds, and the preset range is 3 nanoseconds, then |10-6|>3, indicating an inconsistency between the actual and preset pulse widths. In practice, the controller can utilize a preset photoelectric encoder for detecting the deflection angle of the control component to obtain the deflection angle of the pulse width control component, thereby obtaining the actual deflection angle value.

[0050] The second step is to generate an angle deviation based on the actual deflection angle value. This angle deviation can be the difference between the actual deflection angle and a preset deflection angle. The preset deflection angle can be the deflection angle value corresponding to the pulse width control component at the target pulse width. In practice, the controller can obtain the angle deviation by subtracting the preset deflection angle from the actual deflection angle. The specific value of the target pulse width is not limited here and can be adjusted according to actual needs.

[0051] The third step is to adjust the deflection angle of the pulse width modulation component based on the angle deviation. In practice, the controller can adjust the deflection angle of the pulse width modulation component to the angle value represented by the angle deviation. Specifically, if the angle deviation is positive (the actual angle is too small), the deflection angle needs to be increased by the angle value represented by the angle deviation; if the angle deviation is negative (the actual angle is too large), the deflection angle needs to be decreased by the angle value represented by the angle deviation. For example, if the angle deviation is 0.02°, the deflection angle will be increased by 0.02°.

[0052] In the process of adopting technical solutions to address the aforementioned technical problems, the following technical problem often arises: solid-state lasers experience crystal heating during prolonged operation, leading to poor processing accuracy. A conventional solution to this problem is to pre-set the laser's operating time and shut it down after the preset time to alleviate crystal heating. However, considering that stopping the laser to alleviate crystal heating would reduce laser processing efficiency, and leveraging the laser research and development advantages of our organization, we decided to adopt the following solution:

[0053] Optionally, the aforementioned pulse-width adjustable solid-state laser may further include a temperature sensor, a temperature control component, and an angle encoder. The temperature sensor can be a thermocouple, without specific limitations, as long as it can capture real-time temperature changes in the gain medium. The temperature control component can be a thermoelectric cooler (TEC), without specific limitations, as long as it has rapid cooling or heating capabilities. The angle encoder can be a photoelectric encoder with a resolution of 0.0001°, suitable for detecting minute angular changes in the pulse-width modulation component. Both the temperature sensor and the temperature control component can be mounted on the clamping structure of the gain medium, enabling measurement and control of the gain medium's temperature. The clamping structure can be a protruding structure inside the laser housing for fixing the gain medium. The clamping structure can be in close contact with the gain medium. The temperature sensor can be positioned close to the gain medium to improve the accuracy of the gain medium temperature acquired by the temperature sensor. The temperature control component can be installed inside the clamping structure and can be spaced at a preset distance from the gain medium. This allows the cooling or heating effect of the temperature control component to be indirectly transferred to the gain medium through the clamping structure, reducing the risk of medium cracking due to thermal expansion and contraction differences. This is particularly suitable for brittle gain media, such as neodymium-doped yttrium aluminum garnet crystals. The preset distance can be 0.5–2 mm, without specific limitation, and can be adjusted according to the size of the gain medium. Simultaneously, the interval setting facilitates the filling of thermally conductive silicone grease between the clamping structure and the gain medium, further optimizing the heat conduction path and improving the temperature control response speed. The angle encoder can be mounted on the drive device of the pulse width modulation component and can be used to detect the rotation angle of the pulse width modulation component. The drive device can be a piezoelectric inertial stage, without specific limitation. The angle encoder can be directly connected to the drive shaft to provide real-time feedback on the actual deflection angle of the pulse width modulation component. The temperature sensor, the temperature control component, and the angle encoder can all communicate with the controller. Communication methods can include, but are not limited to, I2C and SPI, without specific limitation. The controller can also be configured to perform the following steps:

[0054] The first step involves activating the temperature control component at a preset power level in response to a predetermined preset duration of continuous laser operation. This is because, after continuous laser operation, the gain medium gradually accumulates heat due to pump light absorption, altering its emission cross-section and causing the output laser pulse width to deviate from the preset value. Since different lasers have different powers, the rate of heat accumulation in the gain medium also varies. Therefore, the preset duration can be determined based on the laser power. This preset power can be between 50 and 80W, without a specific limitation. In practice, the controller can activate the temperature control component at a preset power level after detecting the preset duration of continuous laser operation, thereby slowing the temperature rise of the gain medium and extending the continuous operating time of the laser.

[0055] The second step involves determining the temperature information by acquiring the temperature of the gain medium through a temperature sensor in response to the determination of preset conditions. These preset conditions may include a discrepancy between the actual pulse width of the laser output from the laser and a preset pulse width, and the deflection angle of the pulse width control component being consistent with a preset angle. The temperature information can be the temperature value of the gain medium measured by the temperature sensor. In practice, the controller can acquire the temperature value of the gain medium by collecting the information detected by the temperature sensor and determine the acquired temperature value as the temperature information.

[0056] The third step is to compare the temperature information with the preset standard temperature to obtain the temperature deviation information. The preset standard temperature can be 25℃, and no specific limitation is made here. In practice, the controller can subtract the preset standard temperature from the temperature information and determine the difference as the temperature deviation information.

[0057] The fourth step is to generate angle adjustment information based on the temperature deviation information. This angle adjustment information can be the angle value that the pulse width control component needs to adjust. In practice, the controller can look up the angle adjustment information corresponding to the temperature deviation information in a preset "temperature deviation information - angle adjustment information" mapping table. For example, in the preset "temperature deviation information - angle adjustment information" mapping table, the angle adjustment information corresponding to a temperature deviation of -1℃ is +0.01°. In this case, the deflection angle of the pulse width control component needs to be increased by 0.01°.

[0058] The fifth step is to adjust the deflection angle of the pulse width control component based on the angle control information. In practice, the controller can read the angle control information generated in the fourth step and control the drive device of the pulse width control component according to the value corresponding to the angle control information, thereby adjusting the deflection angle of the pulse width control component. For example, if the angle control information is "+0.01°", the deflection angle of the pulse width control component will be increased by 0.01°.

[0059] The above-described optional embodiments, as an inventive point of this disclosure, solve the technical problem of "poor processing accuracy of solid-state lasers under long-term operation". The specific factors leading to poor processing accuracy of solid-state lasers under long-term operation are as follows: During long-term operation, the gain medium inside the laser gradually accumulates heat due to pump light absorption, causing a change in the emission cross-section of the gain medium, resulting in the output laser pulse width deviating from the preset value. Solving these factors can improve the processing accuracy of solid-state lasers under long-term operation. To achieve this effect, this disclosure further provides a coordinated control scheme integrating temperature sensing and angle detection. A temperature sensor monitors the temperature of the gain medium in real time, and an angle encoder confirms the angle status of the pulse width control component. On one hand, the angle encoder provides real-time feedback on the actual angle of the pulse width control component, enabling detection of whether abnormal pulse width is caused by an abnormal deflection angle of the pulse width control component. On the other hand, adjusting the angle of the pulse width control component compensates for the influence of temperature on the emission cross-section, while the early activation of the temperature control component reduces the rate of temperature rise. Therefore, the processing accuracy of solid-state lasers under long-term operation is improved.

[0060] In the process of adopting technical solutions to address the aforementioned technical problems, the following technical problem two often arises: the pulse width control accuracy of the laser becomes poor during long-term operation. The conventional solution to this second technical problem is to periodically replace aging electronic components. However, considering the complexity of replacing laser electronic components, the lack of experience among ordinary users, and the increased operating costs, and leveraging the laser research and development advantages of our organization, we have decided to adopt the following solution:

[0061] Optionally, the pulse-width adjustable solid-state laser may further include a power sensor, a pump source power control component, and a drive voltage monitor. The power sensor can be installed in the optical path between the pump source and the first cavity mirror, and can be used to monitor the power of the pump light output from the pump source in real time. The power sensor can be a photoelectric sensor, with its sensing end facing the transmission path of the pump light for sampling. Real-time monitoring of the pump light power can provide a basis for subsequent judgment on whether the pump source is operating normally. The pump source power control component can be installed in the drive circuit of the pump source, and can be used to adjust the output power of the pump source. The pump source power control component can be a power MOSFET, and can adjust the output power of the pump source by changing the current in the drive circuit. For example, when the sampling current is lower than a preset standard, the conduction of the power MOSFET can be increased to increase the current intensity and thus increase the power of the pump source. The drive voltage monitor can be installed in the power supply circuit of the Q-switching unit, and can detect the actual drive voltage of the Q-switching unit. The aforementioned drive voltage monitor can consist of a voltage sampling resistor and a signal processing unit. The signal processing unit may include a filter circuit to reduce high-frequency noise in the signal and improve signal purity; an operational amplifier to amplify the signal for subsequent processing; and an AD converter to convert the amplified analog signal into a digital signal and transmit it to the laser controller. The drive voltage monitor can detect the actual drive voltage of the Q-switching unit. The power sensor, pump source power control component, and drive voltage monitor can all be communicatively connected to the controller. This communication connection can be achieved via wired or wireless connection, without specific limitations. The controller can also be configured to perform the following steps:

[0062] The first step involves determining that the actual pulse width of the laser output deviates from the target pulse width range for a predetermined number of consecutive preset number of times, and that the deflection angle of the pulse width control component is within the normal range. This is achieved by acquiring the pump light power using a power sensor to obtain power monitoring information. The predetermined number of times can be a trigger threshold for activating the power sensor. The specific value of this predetermined number of times is not specifically limited. The target pulse width range can be a predetermined target interval for the output pulse width of the laser during normal operation. This predetermined target interval is not specifically limited and can be adjusted according to actual needs. The power monitoring information can be the power value of the pump light detected by the power sensor. In practice, after reading from the monitoring feedback device that the actual pulse width of the laser output deviates from the target pulse width range for a predetermined number of consecutive preset number of times, the controller can invoke a preset photoelectric encoder used to detect the deflection angle of the control component to obtain the deflection angle value of the pulse width control component. When it is determined that the deflection angle value is within a predetermined normal range, the power sensor is invoked to obtain the real-time power value of the pump light, and this real-time power value is determined as the power monitoring information. For example, suppose the target pulse width range is 10–20 ns, and within this target pulse width range, the preset normal range of the deflection angle of the pulse width control component is 3–7°, and the preset number of times is 3. If the actual pulse width of the laser output is 25 ns for 3 consecutive tests, and the photoelectric encoder detects that the deflection angle of the pulse width control component is always stable at 5°, then the controller controls the power sensor to collect the pump light power between the pump source and the first cavity mirror in real time, obtaining an actual power of 90W, and defining "90W" as the power monitoring information.

[0063] The second step involves acquiring the actual drive voltage of the Q-switching unit through a drive voltage monitor, thus obtaining voltage monitoring information. This voltage monitoring information can be the drive voltage value of the Q-switching unit at the current moment. In practice, the controller can read the signal transmitted in real-time from the drive voltage monitor to obtain the drive voltage value of the Q-switching unit, and then use this obtained drive voltage value as the voltage monitoring information.

[0064] The third step is to compare the power monitoring information with the preset standard pump power to obtain the power deviation value. The preset standard pump power can be the pump power corresponding to the target pulse width range. For example, assuming the target pulse width range is 10–20 ns, the corresponding pump power is 100 W, then the preset standard pump power is 100 W. In practice, the controller can subtract the preset standard pump power from the power monitoring information and determine the difference as the power deviation value. For example, if the preset standard pump power is 100 W and the power monitoring information is 90 W, then the power deviation value is 90 W - 100 W = -10 W. The positive and negative signs of the power deviation value represent the two cases: the actual power is greater than the preset standard pump power and the actual power is less than the preset standard pump power, respectively.

[0065] The fourth step is to compare the voltage monitoring information with the preset standard drive voltage to obtain the voltage deviation value. The preset standard drive voltage can be the voltage value when the Q-switching unit is operating normally, and can be preset by the operator based on the rated operating parameters of the Q-switching unit. In practice, the controller can subtract the preset standard drive voltage from the voltage monitoring information and determine the difference as the voltage deviation value. For example, if the preset standard drive voltage is 100V and the voltage monitoring information is 95V, then the voltage deviation value is 95V - 100V = -5V. The positive or negative sign of the voltage deviation value represents the two cases: the actual drive voltage of the Q-switching unit is greater than the preset standard drive voltage, and the actual drive voltage is less than the preset standard drive voltage, respectively.

[0066] The fifth step is to generate power adjustment information based on the power deviation value. This power adjustment information can be a specific instruction for adjusting the pump source power. For example, the power adjustment information could be "increase by 10W". In practice, when the power deviation value is positive, the controller generates power adjustment information indicating a reduction in power; when the power deviation value is negative, it generates power adjustment information indicating an increase in power. The specific adjustment amount can be the numerical part of the power deviation value. For example, if the power deviation value is "-10W", the power adjustment information can be generated as "increase by 10W".

[0067] The sixth step involves controlling the pump source power regulation component to adjust the output power of the pump source based on the power regulation information. In practice, the controller can compare the power regulation information with a preset power regulation information-current change mapping table to obtain the current change that needs to be controlled by the pump source power regulation component. The pump source power regulation component is then adjusted according to the obtained current change to achieve the purpose of adjusting the pump source output power. For example, in the preset power regulation information-current change mapping table, the current change corresponding to "increase by 10W" is "increase the pump source drive current by 2A". When the power regulation information is "increase by 10W", the controller can adjust the current flux of the pump source power regulation component, thereby adjusting the current of the pump source drive circuit.

[0068] Step 7: Generate voltage compensation information based on the voltage deviation value. This voltage compensation information can be a specific instruction for adjusting the drive voltage of the Q-switching unit. For example, the power adjustment information could be "boost by 5V". In practice, when the voltage deviation value is positive, the controller generates voltage compensation information indicating a reduction in voltage; when the voltage deviation value is negative, it generates voltage compensation information indicating a boost in voltage. The specific adjustment amount can be the numerical part of the voltage deviation value. For example, if the voltage deviation value is "-5V", the voltage compensation information can be generated as "boost by 5V".

[0069] Step 8: Adjust the drive voltage of the Q-switching unit according to the voltage compensation information. Specifically, the controller can adjust the power supply output voltage of the Q-switching unit to adjust its drive voltage. In practice, the controller can adjust the power supply output voltage of the Q-switching unit according to the operation corresponding to the voltage compensation information. For example, if the voltage compensation information is "boost by 5V", the controller can boost the power supply output voltage of the Q-switching unit by 5V.

[0070] The above-mentioned optional embodiments, as an inventive point of this disclosure, solve the second technical problem: "poor pulse width modulation accuracy of the laser during long-term operation." The specific factors leading to poor pulse width modulation accuracy during long-term laser operation are as follows: During long-term laser operation, the pump source may experience power drift due to aging, and the Q-switching unit may experience inconsistencies between the actual voltage and the command voltage due to drive line losses. These problems cannot be directly corrected by mechanical adjustment structures similar to pulse width modulation components, thus resulting in poor laser pulse width modulation accuracy. Solving these factors can improve the accuracy of laser pulse width modulation. To achieve this effect, this disclosure further provides a method for coordinated monitoring and control of pump power and Q-switching voltage. On one hand, the pump power is monitored in real time by a power sensor, and the pump source output power is adjusted based on the power deviation to improve the stability of the pump energy supply and reduce pulse width errors caused by power drift. On the other hand, the actual drive voltage of the Q-switching unit is detected in real time by a drive voltage monitor, and the actual drive voltage of the Q-switching unit is adjusted based on the voltage deviation, improving the operating voltage stability of the Q-switching unit and mitigating voltage anomalies caused by line losses. This improves the accuracy of laser pulse width modulation.

[0071] Some embodiments of this disclosure provide a pulse-width-adjustable solid-state laser that can improve the operating accuracy of the laser. Specifically, the reason for the poor operating accuracy of most lasers is that currently used lasers do not have a feedback adjustment mechanism. Because there is no feedback adjustment mechanism, it is impossible to detect in real time whether the actual output pulse width meets the preset standard, and therefore the pulse width cannot be adjusted in real time, resulting in poor laser operating accuracy. Based on this, some embodiments of this disclosure provide a pulse-width adjustable solid-state laser. The pulse-width adjustable solid-state laser includes a housing, and inside the housing are a pump source, a gain medium, a controller, a pulse width modulation component, a first cavity mirror, a second cavity mirror, a Q-switching unit, and a monitoring feedback unit. The pump source is mounted in front of the first cavity mirror; the gain medium is mounted behind the first cavity mirror, and the pump source is configured to emit pump light into the gain medium; the gain medium, the Q-switching unit, and the second cavity mirror are arranged sequentially from front to back; the pulse width modulation component is mounted within the laser's resonant cavity; the monitoring feedback unit is mounted at the output end of the solid-state laser, used to detect the actual pulse width of the laser output and feed it back to the controller; the controller is communicatively connected to the monitoring feedback unit and the pulse width modulation component. Through the communicative connection between the controller and the monitoring feedback unit and the pulse width modulation component, the actual pulse width of the output laser can be detected, and the pulse width of the output laser can be adjusted in real time. This improves the operating accuracy of the laser.

[0072] The above description is merely a selection of preferred embodiments of this disclosure and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in the embodiments of this disclosure is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the above-described inventive concept. For example, technical solutions formed by substituting the above-described features with (but not limited to) technical features with similar functions disclosed in the embodiments of this disclosure.

Claims

1. A pulse width adjustable solid state laser, characterized by, The pulse-width-adjustable solid-state laser comprises a housing, and a pump source, a gain medium, a controller, a pulse-width-adjusting assembly, a first cavity mirror, a second cavity mirror, a Q-switching unit and a monitoring feedback device arranged in the housing, The pump source is arranged in front of the first cavity mirror; The gain medium is arranged behind the first cavity mirror, and the pump source is configured to emit pump light to the gain medium; The gain medium, the Q-switching unit and the second cavity mirror are arranged in sequence from front to back; The pulse-width-adjusting assembly is arranged in the resonant cavity of the laser; The monitoring feedback device is arranged at the output end of the solid-state laser, and is configured to detect the actual pulse width of the laser output and feed back to the controller; The controller is in communication connection with the monitoring feedback device and the pulse-width-adjusting assembly.

2. The pulse width adjustable solid state laser of claim 1, wherein, The pulse-width-adjusting assembly is a etalon; The etalon is located between the gain medium and the Q-switching unit; The etalon is made of quartz or yttrium aluminum garnet crystal; The etalon is provided with a medium film with a preset reflectivity on both sides.

3. The pulse width adjustable solid state laser of claim 2, wherein, The first cavity mirror is located between the pump source and the gain medium; The second cavity mirror is located between the Q-switching unit and the monitoring feedback device, wherein the Q-switching unit is an acousto-optic Q-switch or an electro-optic Q-switch.

4. The pulse-width-adjustable solid-state laser of claim 1, wherein, The gain medium is one of a neodymium-doped yttrium aluminum garnet crystal, a neodymium-doped lithium yttrium fluoride crystal, a ytterbium-doped yttrium aluminum garnet crystal, a neodymium-doped yttrium vanadate crystal, a holmium-doped yttrium aluminum garnet crystal, a thulium-doped yttrium aluminum garnet crystal, and an erbium-doped yttrium aluminum garnet crystal.

5. The pulse-width adjustable solid state laser of claim 1, wherein, The housing is provided with an interactive device; The interactive device is in communication connection with the controller.

6. The pulse-width-adjustable solid-state laser of claim 1, wherein, The monitoring feedback device is provided with a photodiode.

7. The pulse-width-adjustable solid-state laser of claim 1, wherein, The pulse-width-adjusting assembly is a transmission grating.

8. The pulse width adjustable solid state laser of claim 7, wherein, The resonant cavity of the pulse-width-adjustable solid-state laser is a non-linear cavity; The end face of the first cavity mirror has a preset angle with the laser emitted by the gain medium; The first cavity mirror has a reflectivity of greater than 95% for the laser emitted by the gain medium, and a transmittance of greater than 95% for the laser emitted by the pump source; The transmission grating is located on the light path of the laser reflected by the first cavity mirror; A third cavity mirror is arranged on the light path of the laser diffracted by the transmission grating, and the third cavity mirror has a reflectivity of greater than 95% for the laser diffracted by the transmission grating; The second cavity mirror is located behind the gain medium, and the Q-switching unit is located between the second cavity mirror and the gain medium.

9. The pulse-width-adjustable solid-state laser of claim 1, wherein, The controller is configured to perform the following steps: In response to determining that the actual pulse width of the laser output is inconsistent with the preset pulse width, detecting the deflection angle of the pulse-width-adjusting assembly to obtain an actual deflection angle value; Based on the actual deflection angle value, generating an angle deviation amount; Adjusting the deflection angle of the pulse-width-adjusting assembly according to the angle deviation amount.

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