A pulse-width-tunable ultraviolet laser

Abstract

This utility model relates to the field of laser technology, specifically providing a continuously adjustable pulse width ultraviolet laser, comprising: an infrared laser, a green light generation module, a delay module, and an ultraviolet light generation module; the infrared laser generates infrared light; the green light generation module converts a portion of the input infrared light into green light; the delay module includes a transmission mirror, an optical path adjustment module, and a first mirror; the transmission mirror reflects the input first light beam, transmits the second light beam, and transmits the second light beam along the target optical path to the optical path adjustment module; the optical path adjustment module increases the optical path of the input second light beam before it is emitted; the first mirror reflects the output light from the optical path adjustment module; and the ultraviolet light generation module generates ultraviolet light based on the first and second light beams. This solves the problems in related technologies where the output pulse width of ultraviolet lasers is fixed, adjusting the pulse width of ultraviolet light requires hardware replacement, and pulse width adjustment can only cover a limited discrete range.

Description

Technical Field

[0001] This utility model relates to the field of laser technology, and in particular to an ultraviolet laser with continuously adjustable pulse width. Background Technology

[0002] In the field of ultraviolet laser applications, the ultraviolet pulse width is a key parameter that determines its suitability for different scenarios. For example, short pulse widths are used for high-precision processing, while long pulse widths are used to improve material removal rates. Therefore, flexible adjustment of the pulse width is crucial for expanding the application scenarios of ultraviolet lasers.

[0003] In related technologies, the pulse width of ultraviolet lasers is usually fixed. If the pulse width of ultraviolet light needs to be adjusted, the corresponding laser needs to be disassembled and replaced or a complex optical cavity needs to be replaced to change the pulse width of the ultraviolet laser. This is not only cumbersome to operate, increasing equipment maintenance costs and downtime, but also prone to damaging the optical path alignment accuracy due to hardware disassembly and assembly, resulting in a decrease in system output stability. Moreover, replacing hardware has low conversion efficiency and insufficient optical path control accuracy, which can easily lead to problems such as nonlinear pulse width adjustment and large fluctuations in output power. It is difficult to meet the requirements of wide range and high linearity pulse width adjustment in high-precision lithography, femtosecond transient carrier research and other scenarios.

[0004] There is currently no effective solution to the problem that the output pulse width of ultraviolet lasers is fixed, adjusting the pulse width of ultraviolet light requires replacing hardware, and the pulse width adjustment can only cover a limited discrete range. Summary of the Invention

[0005] This invention provides a continuously adjustable pulse width ultraviolet laser, which at least solves the problems in related technologies where the output pulse width of ultraviolet lasers is fixed, adjusting the pulse width of ultraviolet light requires hardware replacement, and the pulse width adjustment can only cover a limited discrete range.

[0006] This invention provides a continuously adjustable pulse width ultraviolet laser, comprising: an infrared laser 1, a green light generation module 2, a delay module 3, and an ultraviolet light generation module 4; the infrared laser 1 generates infrared light and transmits the infrared light to the green light generation module 2; the green light generation module 2 converts a portion of the input infrared light into green light and outputs the remaining infrared light and the green light to the delay module 3; the delay module 3 includes a transmission and reflection mirror 31, an optical path adjustment module 32, and a first reflection mirror 33; the transmission and reflection mirror 31 reflects the input first light beam, transmits the second light beam, and directs the second light beam along the target optical path. The light is transmitted to the optical path adjustment module 32; wherein, the first light is green light or infrared light, and the second light is infrared light or green light; the optical path adjustment module 32 is used to increase the optical path of the input second light before it is emitted; the first reflector 33 is disposed on the output optical path of the optical path adjustment module 32, and the first reflector 33 is used to reflect the output light of the optical path adjustment module 32 so that the output light returns from the target optical path to the transmission reflector 31, and passes through the transmission reflector 31 and is input to the ultraviolet light generating module 4 with the first light; the ultraviolet light generating module 4 is used to generate ultraviolet light according to the first light and the second light.

[0007] In one embodiment of this utility model, the optical path adjustment module 32 is an acousto-optic modulator; the acousto-optic modulator is disposed on the transmission optical path of the transmission mirror 31.

[0008] In one embodiment of the present invention, the output optical path side and the input optical path side of the acousto-optic modulator are respectively provided with a first waste light processing device 34 and a second waste light processing device 35; the first waste light processing device 34 and the second waste light processing device 35 are used to absorb stray light reflected by the acousto-optic modulator.

[0009] In one embodiment of the present invention, the delay module 3 further includes a control component; the control component is connected to the optical path adjustment module 32, and the control component is used to control the optical path adjustment module 32 to adjust the optical path of the input second light.

[0010] In one embodiment of this utility model, the delay module 3 further includes a detection component; the detection component is connected to the control component; the detection component is disposed at the output port of the ultraviolet light generation module 4; the detection component is used to detect the pulse width and / or energy of the ultraviolet light.

[0011] In one embodiment of the present invention, a motor is further provided on the first reflector 33; the motor is used to control the deflection angle of the first reflector 33.

[0012] In one embodiment of the present invention, the delay module 3 further includes a lens 36 and / or an integrated pump laser module 37; the lens 36 is disposed between the transmission optical path of the transmission mirror 31 and the optical path adjustment module 32; the integrated pump laser module 37 is disposed between the lens 36 and the optical path adjustment module 32.

[0013] In one embodiment of this utility model, a third waste light processing device 5 and an isolator 6 are further included between the infrared laser 1 and the green light generating module 2; the isolator 6 is disposed on the output optical path of the infrared laser 1; and the third waste light processing device 5 is disposed on the waste light reflection optical path of the isolator 6.

[0014] In one embodiment of the present invention, a reflective component 7 is further provided between the infrared laser 1 and the green light generating module 2; the reflective component 7 includes a second reflector, which is located at the intersection of the output optical path of the infrared laser 1 and the input optical path of the green light generating module 2.

[0015] In one embodiment of this utility model, the ultraviolet light generating module 4 is disposed on the input optical path of the green light generating module 2; the input optical path of the ultraviolet light generating module 4 is collinear with the input optical path of the green light generating module 2; wherein, the ultraviolet light generating module 4 is used to convert the light emitted from the green light generating module 2 into ultraviolet light and emit it.

[0016] Compared with the prior art, the above-mentioned technical solution of this utility model has the following beneficial effects: By controlling the relative time delay of infrared light and green light pulses through a precision optical delay line, the pulse width of the ultraviolet laser can be continuously adjusted. Specifically, after the green light generation module 2 converts part of the infrared light into green light, the delay module 3, through the coordinated action of the transmission and reflection mirror 31, the optical path adjustment module 32, and the first reflection mirror 33, can achieve continuous and gradual adjustment of the infrared optical path to realize the phase difference between infrared light and green light in the time domain, without the need to replace hardware equipment, so that the overlap of infrared light and green light smoothly transitions from the maximum range to the minimum range. The ultraviolet light pulse width generated by the ultraviolet light generation module 4 is equal to the overlap time of infrared light and green light. Therefore, the continuous adjustment of the overlap time by the delay module 3 can realize the continuous adjustment of the ultraviolet light pulse width. This effectively solves the technical problems in related technologies where the output pulse width of the ultraviolet laser is fixed, adjusting the pulse width of the ultraviolet light requires hardware replacement, and the pulse width adjustment can only cover a limited discrete range. Attached Figure Description

[0017] To more clearly illustrate the embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other embodiments can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the optical path structure of a pulse-tunable ultraviolet laser device according to an embodiment of the present invention.

[0019] Figure 2 This is a schematic diagram showing the superposition and comparison of the time-domain waveforms of the first ray, the second ray, and the ultraviolet light in an embodiment of this utility model.

[0020] Figure 3 This is a schematic diagram of the structure of a pulse-tunable ultraviolet laser device according to an embodiment of the present invention.

[0021] The above-mentioned figures include the following reference numerals: 1. Infrared laser; 2. Green light generation module; 3. Delay module; 31. Transmission mirror; 32. Optical path adjustment module; 33. First mirror; 34. First waste light treatment device; 35. Second waste light treatment device; 36. Lens; 37. Integrated pump laser module; 4. Ultraviolet light generation module; 5. Third waste light treatment device; 6. Isolator; 7. Reflection component; 8. Fourth waste light treatment device. Detailed Implementation

[0022] Embodiments of the present invention will now be described in more detail with reference to the accompanying drawings. While some embodiments of the present invention are shown in the drawings, it should be understood that the present invention 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 the present invention. It should be understood that the accompanying drawings and embodiments of the present invention are for illustrative purposes only and are not intended to limit the scope of protection of the present invention.

[0023] In related technologies, fixed-pulse-width ultraviolet lasers rely on nonlinear frequency conversion modules with fixed parameters, such as green light generating components and ultraviolet light generating components with specific phase matching, resulting in a fixed output pulse width. If the ultraviolet light pulse width needs to be adjusted, the laser needs to be replaced or the corresponding optical cavity needs to be disassembled and replaced, such as different models of green light generating components, ultraviolet light generating components, pump light adjustment components, etc. This is not only cumbersome to operate, increasing equipment maintenance costs and downtime, but also prone to damaging the optical path alignment accuracy due to hardware disassembly and assembly, leading to a decrease in system output stability.

[0024] To address the aforementioned problems, this utility model provides a continuously adjustable pulse width ultraviolet laser, which solves the problems in the above-mentioned related technologies where the output pulse width of the ultraviolet laser is fixed, adjusting the pulse width of the ultraviolet light requires hardware replacement, and the pulse width adjustment can only cover a limited discrete range.

[0025] like Figures 1 to 3 As shown, this utility model provides a continuously adjustable pulse width ultraviolet laser, including: an infrared laser 1, a green light generating module 2, a delay module 3, and an ultraviolet light generating module 4. The output optical paths of the delay module 3, the green light generating module 2, and the ultraviolet light generating module 4 are collinear, and the delay module 3 is connected to the green light generating module 2. It is used to receive the green light generated by the green light generating module 2, perform delay processing, and then send it back to the ultraviolet light generating module 4.

[0026] Specifically, infrared laser 1 is used to generate infrared light, which is then transmitted to green light generation module 2. Infrared laser 1 provides the basic laser source for ultraviolet laser. The subsequent generation of green and ultraviolet light, as well as the delay control, are all based on the basic laser source. Therefore, a stable infrared laser is the key to the continuously adjustable pulse width of the laser.

[0027] The wavelength of the infrared light emitted by the infrared laser 1 needs to be matched with the nonlinear crystals of the subsequent ultraviolet light generation module 4 and green light generation module 2 to ensure efficient harmonic generation. For example, if it is necessary to generate 532nm green light through the green light generation module 2 and 355nm ultraviolet light through the ultraviolet light generation module 4, an infrared laser 1 with a wavelength of 1064nm is preferred.

[0028] The pulse width emitted by infrared laser 1 is preferably in the nanosecond range, which can balance energy density and conversion efficiency between ultraviolet and green light. That is, picosecond or femtosecond lasers with pulse widths shorter than nanoseconds require special crystal adaptation, which is costly; microsecond lasers with pulse widths longer than nanoseconds have insufficient energy density.

[0029] Infrared laser 1 may include solid-state infrared laser, fiber infrared laser, gas infrared laser and semiconductor infrared laser, etc. The type of infrared nanosecond laser can be flexibly selected according to specific application requirements (such as processing accuracy, cost budget, wavelength conversion requirements, etc.).

[0030] The green light generation module 2 converts a portion of the input infrared light into green light and outputs the remaining infrared and green light to the delay module 3. The green light generation module 2 primarily uses a nonlinear crystal to generate a second harmonic to convert a portion of the infrared light into green light.

[0031] The conversion of some infrared light into green light is affected by factors such as the nonlinear coefficient of the nonlinear crystal, light intensity, and phase matching accuracy. Furthermore, some infrared light suffers energy loss due to crystal absorption and lens reflection, preventing it from participating in the conversion. Therefore, even with optimal crystal and optical path parameters, the conversion efficiency of the second harmonic generation effect cannot reach 100%, typically ranging from 50% to 70%. Thus, the green light generation module 2 only converts a portion of the infrared light into green light, outputting the remaining infrared and green light to the delay module 3.

[0032] The aforementioned nonlinear crystals can be KTP (Potassium Titanium Oxide Phosphate) or LBO (Lithium Triborate). The nonlinear crystal needs to be adapted to the infrared wavelength. For example, for 1064nm infrared light, KTP crystals are chosen because they have advantages such as high conversion efficiency and suitability for room temperature operation. LBO crystals are chosen because they have advantages such as high resistance to light damage threshold and suitability for high-power scenarios.

[0033] The second harmonic generation effect is a nonlinear optical effect. Under high-intensity light excitation, the atomic polarization response within a nonlinear crystal generates a second harmonic, which consists of two lower-energy infrared photons that merge into a higher-energy green photon. According to the law of conservation of energy, photon energy is inversely proportional to wavelength; therefore, the wavelength of green light is half that of infrared light. For example, if the input is 1064nm infrared light, the output will be 532nm green light.

[0034] The delay module 3 includes a transmission reflector 31, an optical path adjustment module 32, and a first reflector 33. The transmission reflector 31 is used to reflect the input first light and transmit the second light, and transmit the second light along the target optical path to the optical path adjustment module 32. The first light is green light or infrared light, and the second light is infrared light or green light.

[0035] The transmission-reflection mirror 31 needs to separate the infrared light and green light emitted from the green light generation module 2, passing them through different paths to create an optical path difference between the infrared and green light, thus achieving a phase difference in the time domain. The optical path difference between the first and second light rays results in a relative delay. Assuming the relative delay time ∆t = 0, where ∆t represents the relative delay time between the first and second light rays (i.e., the pulses completely overlap), the pulse width of the output ultraviolet light is determined by the harmonic average of the input pulse widths. The formula for the output ultraviolet light pulse width is as follows:

[0036]

[0037] in, This indicates the pulse width of the output ultraviolet light. The pulse width represents the full width at half maximum (FWHM) of infrared light. This indicates the pulse width at half maximum width of the green light.

[0038] For example ,but T is a hypothetical pulse width.

[0039] When Δt≠0, in this embodiment, the first ray is green light, and the second ray is infrared light. Figure 2 As shown, the horizontal axis represents the time t of the time-domain waveform, and the vertical axis represents the light intensity amplitude A of the time-domain waveform. The green waveform is the time-domain waveform of the first ray, the red waveform is the time-domain waveform of the second ray, and the purple waveform is the time-domain waveform of the ultraviolet light. The delay generated by the delay module 3 on the second ray causes an overlap region between the time-domain waveforms of the first and second rays. The pulse width of the ultraviolet light is determined by the overlap region of the time-domain waveforms of the first and second rays. The actual pulse width of the ultraviolet light is further narrowed, approximated as:

[0040]

[0041] When Δt≫ , When the phase difference between the first and second rays is greater than the pulse width of the infrared and green light, the phases of the first and second rays do not overlap, the ultraviolet pulse disappears, so the relative delay has a maximum value. The maximum optical path difference can be calculated and adjusted based on the maximum relative delay.

[0042] The transmission and reflection mirror 31 can achieve differentiated processing of light of different wavelengths through special optical coating. For example, it can have high transmission for a certain wavelength of light, such as infrared light at 1064nm, i.e., transmittance ≥90%; and high reflection for another wavelength of light, such as green light at 532nm, i.e., reflectance ≥90%.

[0043] The transmission and reflection mirror 31 can transmit infrared light and reflect green light, that is, allow the infrared light to be combined with the green light after passing through the optical path adjustment module 32; it can also transmit green light and reflect infrared light, that is, allow the green light to be combined with the infrared light after passing through the optical path adjustment module 32.

[0044] The optical path adjustment module 32 is used to increase the optical path length of the input second light beam before it exits. The optical path adjustment module 32 achieves precise adjustment of the optical path difference by controlling the geometric distance of the beam transmission path or the refractive index of the medium. The optical path difference can be adjusted by changing the refractive index by adjusting the gas pressure in the gas chamber, or by stretching the optical fiber using an electrically controlled fiber delay line. In this embodiment, an acousto-optic modulator is preferred to change the deflection angle of the diffracted light; combined with the adjustment of the reflector position, dynamic adjustment of the optical path can be achieved.

[0045] The first reflector 33 is disposed on the output optical path of the optical path adjustment module 32. The first reflector 33 is used to reflect the output second light of the optical path adjustment module 32 so that the output light returns from the target optical path to the transmission reflector 31 and passes through the transmission reflector 31 to input the first light into the ultraviolet light generation module 4.

[0046] The first reflector 33 is a reflector that can achieve precise control of angle deflection, tilting or position translation. By adjusting the angle and position, the first reflector 33 compensates for the different deflection angles and positions of the second light rays after adjustment by different optical path adjustment modules 32, ensuring that the light path returned through the first reflector 33 is the same as the original light path.

[0047] The first reflecting mirror 33 can be a motor-driven reflecting mirror for angle compensation, or it can be a piezoelectric ceramic reflecting mirror. In this embodiment, the motor-driven reflecting mirror for angle compensation is preferred, as it has high-speed dynamic response, high-precision angle adjustment, and wide-range compensation capabilities. The wide angle adjustment range can adapt to different amplitude angle fluctuations and meet the needs of fine-tuning correction, while the millisecond-level response speed matches the timeliness of dynamic optical path adjustment.

[0048] The ultraviolet light generation module 4 is used to generate ultraviolet light based on the first and second light rays. The ultraviolet light generation module 4 mainly uses a nonlinear crystal to perform a third harmonic generation effect to cut the first light ray (such as 532nm green light) and the second light ray (such as 1064nm infrared light) at a 355nm phase matching angle to generate and output 355nm ultraviolet light.

[0049] Phase-matched cutting refers to the process of cutting the nonlinear crystal at a specific angle during the sum-frequency effect to ensure that the first and second rays (532nm+1064nm) and the generated 355nm ultraviolet light satisfy momentum conservation (phase synchronization) within the crystal, thus avoiding photon cancellation.

[0050] The aforementioned nonlinear crystals can include CLBO (Cesium Lithium Borate), LBO (Lithium Triborate), and BBO (Beta-Barium Borate). CLBO mixes 1064nm infrared light with 532nm green light to generate 355nm ultraviolet light. BBO converts 532nm green light into 266nm ultraviolet light; LBO has a wide transmission range and is often used for frequency third-harmonic generation of 1064nm lasers to 355nm.

[0051] The third harmonic generation effect refers to the conversion of the first and second light rays into ultraviolet light through the sum-frequency effect. The sum-frequency effect refers to the fact that when two incident photons, a 1064nm infrared photon and a 532nm green photon, meet in a nonlinear crystal and are excited by high light intensity, they merge into a new photon. According to the law of conservation of energy, the frequency of the new photon is equal to the sum of the frequencies of the original photons. Substituting the corresponding wavelengths of 1064nm and 532nm, we get 355nm ultraviolet light.

[0052] This scheme utilizes delay module 3 to control the relative time delay (Δt) between infrared and green light pulses, thereby achieving an effective method for continuously adjustable ultraviolet laser pulse width during the sum-frequency effect generation process. The scheme has a clear structure, with its core lying in high-precision delay control technology and fine-tuning of spatiotemporal overlap. The ultraviolet laser pulse width output by the system can be continuously and precisely adjusted within the design range, providing a powerful technical means for ultraviolet light sources requiring flexible pulse width parameters in scientific research and industrial applications.

[0053] The key to successful implementation lies in the phase matching control of the high-precision delay module 3, the stable infrared laser 1, the high-quality transmission and reflection mirror 31, and the green light generation module 2 and the ultraviolet light generation module 4. By utilizing the optical path difference between infrared and green light, the infrared pulse is delayed, creating a phase difference with the green light in the time domain. This reduces the time overlap between the infrared and green light, and the pulse width of the ultraviolet light generated after summing is approximately equal to the overlap time of the infrared and ultraviolet light. This overlap time is controlled by the adjustable optical path difference.

[0054] In summary, by controlling the relative time delay between infrared and green light pulses using a precision optical delay line, the width of the ultraviolet laser pulse can be continuously adjusted. Specifically, after the green light generation module 2 converts part of the infrared light into green light, the delay module 3, through the coordinated action of the transmission and reflection mirror 31, the optical path adjustment module 32, and the first reflection mirror 33, can achieve continuous and gradual adjustment of the infrared optical path to realize the phase difference between the infrared and green light in the time domain. This eliminates the need to replace hardware and allows the overlap between the infrared and green light to smoothly transition from the maximum range to the minimum range.

[0055] The ultraviolet light pulse width generated by the ultraviolet light generation module 4 is equal to the overlap time of the infrared and green light. Therefore, the ultraviolet light pulse width can be continuously adjusted by continuously controlling the overlap time through the delay module 3. This effectively solves the technical problems in related technologies where the output pulse width of the ultraviolet laser is fixed, adjusting the ultraviolet light pulse width requires hardware replacement, and the pulse width adjustment can only cover a limited discrete range.

[0056] In one embodiment of this utility model, the optical path adjustment module 32 is an acousto-optic modulator; the acousto-optic modulator is disposed on the transmission optical path of the transmission mirror 31.

[0057] An acousto-optic modulator uses a radio frequency (RF) signal to drive a piezoelectric transducer to form an acoustic grating in a crystal. Incident light undergoes Bragg diffraction on the grating. That is, changing the RF signal frequency can adjust the wavelength of the grating, thereby changing the deflection angle of the diffracted light. Combined with precise control of the light propagation path length and the path difference of the diffraction order, rapid, inertia-free tuning of the optical delay can be achieved.

[0058] The second ray passes through the acousto-optic modulator twice. The first time, the 0th-order light directly transmitted through the modulator is unreflected, belonging to the 0th-order diffraction. The second time, the light beam, after diffraction by the modulator, is deflected in one direction, belonging to the 1st-order diffraction. The 1st-order light is the signal light to be used after passing through the modulator; it can exit to the first reflecting mirror 33 and return.

[0059] During the second pass, the beam of light, after being diffracted by the acousto-optic modulator, is deflected in the opposite direction, corresponding to the -1 secondary order in the grating equation. The -1 order light is symmetrical to the +1 order light. The -1 order light diffracted by the acousto-optic modulator is reflected by the first reflecting mirror 33 and returns along the original optical path, so that the -1 order light returns to the transmission reflecting mirror 31.

[0060] When the acousto-optic modulator is driven at different frequencies, the deflection angle of the first-order light will change. This difference can be compensated by controlling the angle through the first reflector 33, ensuring that the reflected light path is consistent with the original light path, and ensuring that the second light ray returns to the original path stably and accurately, and is converted into ultraviolet light by frequency conversion with the first light ray.

[0061] The different angles at which the first-order light reaches the first reflector 33 result in differences in the optical path of the first-order light reaching the first reflector 33. The optical path of the second ray includes the optical path of the first-order light. Therefore, the optical path difference of the second ray can be changed by using an acousto-optic modulator to change the deflection angle of the first-order light.

[0062] The aforementioned acousto-optic modulator can achieve optical path control via electrical signals without the need for hardware replacement or disassembly, and its response time can reach the nanosecond level. This enables rapid and continuous adjustment of the optical path, which in turn allows for rapid and continuous adjustment of the optical path difference between the second and first rays. Continuous adjustment of the optical path difference allows for continuous adjustment of the delay between the second and first rays, and the delay difference can meet the requirement of continuously adjustable pulse width.

[0063] In one embodiment of the present invention, a first waste light processing device 34 and a second waste light processing device 35 are respectively provided on the output optical path side and the input optical path side of the acousto-optic modulator; the first waste light processing device 34 and the second waste light processing device 35 are used to absorb stray light reflected by the acousto-optic modulator.

[0064] When the second light beam passes through the acousto-optic modulator, it generates multi-order diffraction light (such as 0th-order light, 1st-order light, -1st-order light, etc.). Among them, the 1st-order light and -1st-order light are the effective light used in subsequent optical paths. If the unused 0th-order light propagates in the system, it will form stray light, which will interfere with the transmission of effective light and affect the accuracy of laser pulse width modulation and the quality of the output beam.

[0065] The first waste light treatment device 34 is used to absorb the 0th-order light that passes through the acousto-optic modulator for the first time but is not deflected. After the 1st-order light returns through the first reflector 33, it will diffract when it passes through the acousto-optic modulator for the second time. At this time, the original 1st-order light will diffract into -1st-order light and return. The residual 1st-order light that is not deflected when it passes through the acousto-optic modulator for the second time is absorbed by the second waste light treatment device 35.

[0066] The first waste light treatment device 34 and the second waste light treatment device 35 are based on the principle of light absorption. They convert the light energy of waste light into heat energy through materials or structures with high absorption rates, thereby completely dissipating the energy of stray light and preventing it from propagating in the system. The first waste light treatment device 34 and the second waste light treatment device 35 can be laser absorbers or extinction devices.

[0067] The first waste light treatment device 34 and the second waste light treatment device 35 need to be precisely positioned on the emission path of the waste light, and the angle of the waste light treatment device should match the emission angle of the waste light to ensure that all the waste light enters the device and can be directly incident into the device, so as to avoid the waste light being scattered or reflected before reaching the treatment device, which would affect the absorption effect.

[0068] At the same time, the first waste light treatment device 34 and the second waste light treatment device 35 must maintain a sufficient spatial distance from the effective light path to avoid interference between the waste light treatment device and the effective light transmission, and also to prevent the effective light from accidentally entering the waste light treatment device and causing energy loss.

[0069] In one embodiment of this utility model, such as Figure 3 As shown, the delay module 3 also includes a control component; the control component is connected to the optical path adjustment module 32, and the control component is used to control the optical path adjustment module 32 to adjust the optical path of the input second light.

[0070] The control component changes the optical path of the second light beam by adjusting the optical path adjustment module 32, thereby controlling the optical path difference and ultimately achieving continuous adjustment of the pulse width. The pulse width of the ultraviolet laser is determined by the optical path difference between the first and second light beams. The larger the optical path difference, the smaller the phase difference between the first and second light beams when superimposed in the ultraviolet light generation module 4, and the shorter the pulse width of the output ultraviolet light; conversely, the smaller the optical path difference, the longer the pulse width.

[0071] Optical path adjustment requires nanometer- or micrometer-level precision, which is difficult to achieve manually. The control component drives the optical path adjustment module 32 through electrical signals, enabling high-precision and repeatable optical path control, avoiding errors and drift caused by mechanical adjustment, and ensuring the stability of the laser pulse width.

[0072] The laser pulse width needs to be adjusted in real time according to the scenario, such as the different pulse width requirements for different materials in material processing. The control component can receive the pulse width of the ultraviolet light or the delay Δt of the first light beam relative to the second light beam set by the user. According to the target set value, the control component precisely controls the optical path adjustment of the second light beam, realizing continuous and precise adjustment of Δt. That is, continuous adjustment of the ultraviolet pulse width does not require hardware replacement; the user only needs to input signals through software to control the optical path of the second light beam to achieve the delay of the first light beam relative to the second light beam.

[0073] When the control component receives an external control signal, it converts it into a target value for optical path adjustment, including the radio frequency frequency of the acousto-optic modulator and the deflection of the first reflector 33. Based on the target value, it outputs a drive signal (such as a radio frequency signal or an electrical signal) to the optical path adjustment module 32, causing the acousto-optic modulator and the first reflector 33 to perform optical path adjustment actions, such as changing the ultrasonic frequency of the acousto-optic crystal through the radio frequency signal or moving the first reflector 33 through the electrical signal.

[0074] If the optical path adjustment module 32 is an acousto-optic modulator, the control component can be an RF signal generator. By changing the frequency or power of the output RF signal, the optical path can be dynamically adjusted. If the optical path adjustment module 32 is a mechanical displacement structure, the control component can be a motor drive controller. In conjunction with the host computer software, the position of the first reflector 33 can be precisely adjusted by controlling the rotation angle of the motor, thereby changing the optical path length. For high-precision composite control scenarios, a combination of a microprocessor and a dedicated driver chip can also be used, integrating signal processing, closed-loop feedback, and drive functions to achieve higher precision optical path control.

[0075] In one embodiment of the present invention, the delay module 3 further includes a detection component; the detection component is connected to the control component; the detection component is disposed at the output port of the ultraviolet light generating module 4; the detection component is used to detect the pulse width and / or energy of the ultraviolet light.

[0076] During operation, the ultraviolet laser may experience deviations in pulse width or energy output from the set values ​​due to environmental changes or module errors, such as frequency shifts in the acousto-optic modulator or displacement deviations in the translation stage. A detection component located at the output port of the ultraviolet light generation module 4 can monitor the output parameters in real time. The detection component is connected to the control component, which receives feedback signals of the actual optical path length, compares them with the target value, and corrects the drive signal to ensure the accuracy of optical path length adjustment.

[0077] In industrial processing or scientific research applications of ultraviolet lasers, the pulse width and energy stability of the ultraviolet light directly affect processing accuracy or experimental results. The detection component can capture parameter fluctuations in real time and dynamically adjust the optical path by controlling the component, ensuring the consistency of laser parameters during long-term operation.

[0078] At the output port of the ultraviolet light generation module 4, a small amount of ultraviolet light can be intercepted by optical elements (such as a beam splitter) without affecting the main optical path output, and used as a detection sample. A dedicated sensor is used to convert the pulse width and energy of the ultraviolet light into electrical signals, respectively. The pulse width corresponds to the duration of the electrical signal, and the energy corresponds to the amplitude of the electrical signal.

[0079] The processed electrical signal is transmitted to the control component and compared with the electrical signal of the preset target pulse width or energy parameter. If there is a deviation between the detected value and the target value, the control component will adjust the parameters of the optical path adjustment module 32, namely the deflection of the first reflector 33 and the radio frequency of the acousto-optic modulator, until the detected value returns to the target range.

[0080] The detection module can integrate a fast photodetector to monitor the ultraviolet pulse energy. Since the energy also varies with Δt, monitoring the ultraviolet pulse energy can also provide insight into the adjustment of the delay module. The detection module can also use an autocorrelation / cross-correlation meter to monitor the pulse width in real time, forming a closed-loop control to improve stability.

[0081] In one embodiment of the present invention, a motor is also provided on the first reflector 33; the motor is used to control the deflection angle of the first reflector 33.

[0082] The diffraction angle of the acousto-optic modulator is directly related to the driving frequency. When the driving frequency of the acousto-optic modulator is changed, the deflection angle of the first-order diffracted light it produces will change. If the angle of the first reflecting mirror 33° is fixed, the returned light will deviate from the original path, causing the beams in subsequent optical paths to not be precisely aligned, affecting the ultraviolet pulse width modulation and output quality.

[0083] The purpose of setting up the motor is to dynamically compensate for changes in the diffraction angle, ensuring that the light returned by the first reflector 33 is completely consistent with the original path, guaranteeing the optical path length and alignment accuracy of the second light beam's outward and return journeys, and ultimately achieving stable adjustment of the laser pulse width. Through the dynamic angle adjustment of the motor, it is ensured that the first-order and -1st-order light beams passing through the acousto-optic modulator twice are completely overlapped in space, providing a stable optical path foundation for subsequent pulse width adjustment and ultraviolet light generation.

[0084] The diffraction angle formula of the acousto-optic modulator satisfies λ is the laser wavelength, f is the driving frequency, and v is the ultrasonic velocity. When f changes, the diffraction angle... As this changes, the deflection angle of the first-order light also changes. The control component sends a command to the motor according to the driving frequency of the acousto-optic modulator to adjust the deflection angle of the first reflector 33, so that the reflected light returns along the original path, that is, while satisfying the condition that the incident angle equals the reflection angle, it compensates for the change in the diffraction angle.

[0085] The motor controlling the first reflector 33 needs to be highly precise, have a fast response, and be highly stable. A servo motor with a high-precision encoder can be used, providing real-time feedback of the angle of the first reflector 33 via a photoelectric encoder. The angle adjustment precision can reach the micro-radian level, enabling rapid response to diffraction angle fluctuations caused by changes in the frequency of the acousto-optic modulator. Alternatively, a piezoelectric motor can be used, achieving nanometer-level precision angle fine-tuning based on the piezoelectric effect. This eliminates mechanical friction, achieves a microsecond-level response speed, and can accurately compensate for small-range diffraction angle changes.

[0086] In one embodiment of the present invention, the delay module 3 further includes a lens 36 and / or an integrated pump laser module 37; the lens 36 is disposed between the transmission optical path of the transmission mirror 31 and the optical path adjustment module 32; the integrated pump laser module 37 is disposed between the lens 36 and the optical path adjustment module 32.

[0087] In the transmission optical path from the transmission mirror 31 to the optical path adjustment module 32, the second ray may diverge due to diffraction and scattering. The lens 36 can focus or collimate the beam, ensuring that the laser beam entering the optical path adjustment module 32 has good parallelism or focusing characteristics, thereby improving the accuracy of optical path adjustment, ensuring the effective function of the acousto-optic modulator, and avoiding energy loss or optical path deviation caused by beam divergence.

[0088] Lens 36 can be a focusing lens, such as a cemented doublet convex lens, to focus the second light ray onto the effective area of ​​the optical path adjustment module 32, thereby improving the interaction efficiency between the second light ray and the module. Alternatively, a collimating lens, such as an achromatic collimating lens, can be selected to convert the diverging second light ray into parallel light, ensuring the stability of the beam propagation direction during optical path adjustment.

[0089] The integrated pump laser module 37 is a module that enhances laser energy by coupling the pump light with the signal light to supplement the energy of the transmitted second light.

[0090] The second light beam experiences energy loss during its round-trip path through the delay module 3, such as via the transmission and reflection mirror 31 and the optical path adjustment module 32. The integrated pump laser module 37 can replenish the laser energy in real time, ensuring that the laser entering the ultraviolet light generation module 4 has sufficient power, thereby guaranteeing the output energy and pulse width adjustment range of the ultraviolet light, while compensating for the energy loss during the optical path adjustment process.

[0091] The integrated pumped laser module 37 can employ a semiconductor pump module, such as an 808nm semiconductor laser, which combines with the second beam through an optical fiber or optical coupling element to replenish energy to the laser gain medium. When the second beam passes through the laser gain medium in a population-inverted state, stimulated emission is induced, thereby amplifying the energy of the second beam through superposition. Alternatively, an all-solid-state pump module can be used, integrating the pump source, coupling lens, and laser gain medium to directly amplify the transmitted laser energy online, suitable for highly integrated laser systems.

[0092] In one embodiment of this utility model, a third waste light processing device 5 and an isolator 6 are further included between the infrared laser 1 and the green light generating module 2; the isolator 6 is disposed on the output optical path of the infrared laser 1; the third waste light processing device 5 is disposed on the waste light reflected optical path of the isolator 6.

[0093] Isolator 6 is a unidirectional optical element that allows laser light to propagate in only one direction, preventing backlight, such as reflected light and stray light, from returning to the light source. In this embodiment, isolator 6 is located at the output end of infrared laser 1, allowing infrared light to propagate only in the output direction of infrared laser 1 and preventing reflected light and stray light from returning to the light source.

[0094] The infrared light generated by infrared laser 1 needs to be stably transmitted to green light generating module 2. If there is backlight in the optical path, such as reflected light from green light generating module 2 or backlight from optical elements, it will interfere with the working stability of infrared laser 1 after returning, causing laser mode switching, power fluctuations, or even damage to the laser medium. Isolator 6 can completely block backlight, ensuring unidirectional transmission of infrared light and guaranteeing the output stability and lifespan of the laser.

[0095] The isolator 6 can be a Faraday optical isolator, a free-space optical isolator, a two-stage optical isolator, or a polarization-independent optical isolator. The preferred Faraday optical isolator in this embodiment is based on the Faraday magneto-optical effect, effectively preventing backlight from returning to the infrared laser 1 and ensuring stable laser operation. It is suitable for various wavelengths, including the infrared band, and offers high isolation, exceeding 30 dB.

[0096] The third waste light treatment device 5 is a component that absorbs the reverse waste light or stray light generated by the isolator 6. When the isolator 6 blocks the reverse light, it may generate a small amount of stray light. If this waste light is not treated, it will propagate in the optical path and interfere with other modules. The third waste light treatment device 5 can directionally absorb this waste light, avoid stray light interference, and ensure the optical purity of the system.

[0097] The third waste light treatment device 5 can employ a laser absorber, which is made of high-absorption materials (such as black anodized aluminum, silicon carbide ceramics, etc.) and designed as a conical or nested structure, so that the waste light is reflected multiple times inside and completely absorbed. It is suitable for treating low-power stray light generated by the isolator 6. Alternatively, an extinction device can be used, which is coated with a high extinction ratio coating with an absorptivity greater than 99% to directly absorb the incident waste light. It has a compact structure and is suitable for waste light treatment scenarios with small angles and low power.

[0098] In summary, isolator 6 ensures stable unidirectional transmission of infrared light and prevents reverse light from damaging the laser; the third waste light treatment device 5 absorbs stray light generated by isolator 6 and eliminates optical interference. Together, they improve the stability and purity of the infrared light transmission path, laying the foundation for subsequent green light generation and ultraviolet light output.

[0099] In one embodiment of the present invention, a reflective component 7 is further provided between the infrared laser 1 and the green light generating module 2; the reflective component 7 includes a second reflector, which is located at the intersection of the output optical path of the infrared laser 1 and the input optical path of the green light generating module 2.

[0100] The core function of the reflective component 7 is to change the direction of the optical path and realize the turning and coupling of the optical path from the output optical path of the infrared laser 1 to the input optical path of the green light generating module 2.

[0101] The output optical path of the infrared laser 1 and the input optical path of the green light generating module 2 may have angular deviations due to the installation location and space limitations of the equipment, such as perpendicular intersection or non-collinearity. The reflective component 7 changes the propagation direction of the infrared light by reflection, so that the infrared light accurately enters the input port of the green light generating module 2, avoiding spatial layout conflicts caused by direct light path and improving the space utilization of the system.

[0102] The reflective component 7 can flexibly change the direction of the light path through one or more reflections (which may include multiple reflectors), so that the infrared light enters the green light generating module 2 with the shortest path and the best angle, thus balancing the spatial layout and optical performance.

[0103] By adjusting the angle, the reflector 7 can precisely control the reflection direction of infrared light, ensuring that it enters the green light generating module 2 at the optimal angle, thereby improving the coupling efficiency between the infrared light and the green light generating module 2 and reducing energy loss.

[0104] The reflective component 7 includes a second reflector, which can be a high-reflectivity lens, such as a metal film reflector or a dielectric film reflector. It is designed for the 1064nm infrared light wavelength and has a reflectivity of more than 99%, which can ensure efficient reflection of infrared light.

[0105] The reflector assembly 7 may also include a filter. If stray light exists in the optical path, a bandpass filter can be integrated to allow only the target infrared wavelength to pass through, further purifying the beam. It may also include a polarizer. If the green light generating module 2 has requirements for the polarization state of the incident light, such as requiring linearly polarized light, a polarizer can be added to ensure that the infrared light reflected by the reflector assembly 7 meets the polarization state requirements. It may also include a fine-tuning bracket, a precision mechanical structure used to fix the second reflector, supporting fine-tuning of the angle, such as pitch and yaw adjustments, for precise alignment of the optical path.

[0106] In one embodiment of this utility model, the ultraviolet light generating module 4 is disposed on the input optical path of the green light generating module 2; the input optical path of the ultraviolet light generating module 4 is collinear with the input optical path of the green light generating module 2; wherein, the ultraviolet light generating module 4 is used to convert the light emitted by the green light generating module 2 into ultraviolet light and emit it.

[0107] The ultraviolet light generating module 4 receives the second beam and the first beam after the optical path difference has been adjusted by the delay module 3. It mixes the second and first beams and integrates their energy through specific optical effects, such as frequency doubling and sum-frequency conversion, to generate ultraviolet light that meets the power and pulse width requirements. Simultaneously, during wavelength conversion, the ultraviolet light generating module 4 maintains the optical path difference characteristic controlled by the delay module 3, ensuring that the pulse width of the output ultraviolet light matches the preset value, thus achieving the ultimate goal of continuously adjustable pulse width.

[0108] The ultraviolet light generating module 4 includes a nonlinear crystal that converts green light into ultraviolet light through nonlinear optical effects. The nonlinear crystal can be selected according to the conversion method, such as an LBO for third harmonics or a BBO for fourth harmonics.

[0109] The ultraviolet light generating module 4 also includes a fourth waste light treatment device 8, which is located at the output end of the ultraviolet light generating module 4. It is used to separate and process stray light such as green light and infrared light left over from the conversion process in the ultraviolet light generating module 4, to ensure the purity of the output ultraviolet light, and at the same time to avoid the waste light from affecting the equipment or personnel.

[0110] The conversion efficiency of nonlinear crystals is extremely sensitive to temperature. For example, a temperature deviation of 0.1℃ may cause a significant drop in efficiency. The ultraviolet light generation module 4 can be equipped with a temperature controller, such as a hermoelectric cooler (TEC), and a temperature sensor to stabilize the crystal temperature at the optimal operating point.

[0111] The ultraviolet light generating module 4 may also include beam focusing or collimating elements, such as focusing lenses or collimating mirrors, to focus the incident first beam and second beam onto the center of the crystal, thereby increasing the light intensity density and ensuring the beam quality of the emitted ultraviolet light.

[0112] The input optical path of the ultraviolet light generating module 4 is collinear with the input optical path of the green light generating module 2, which means that the first and second beams after being reflected and adjusted by the delay module 3 can directly enter the module along the original optical path without additional reflection and deflection, thus avoiding energy loss and beam deviation caused by multiple reflections.

[0113] The optical path difference between the two light sources is formed in the path from the green light generation module 2 to the delay module 3 and then to the ultraviolet light generation module 4. The collinear layout of the input optical path of the ultraviolet light generation module 4 and the input optical path of the green light generation module 2 ensures that the optical path difference does not change during transmission and directly affects the wavelength conversion in the crystal, thus ensuring the accuracy and stability of the ultraviolet light pulse width.

[0114] The infrared light output from the infrared laser to the ultraviolet light generation module 4 does not produce ultraviolet light, while the first and second rays returning from the delay module 3 along the green light generation module 2 are converted into ultraviolet light. The core of the ultraviolet light generation module 4 is a nonlinear crystal (such as LBO, BBO, etc.), and the sum-frequency effect for generating ultraviolet light has strict triggering conditions.

[0115] The aforementioned triggering conditions require the simultaneous action of two different wavelengths of light, and the propagation speeds of the two incident lights within the crystal must be matched to ensure the continuous superposition of sum-frequency light energy. In this embodiment, the sum-frequency condition is only satisfied when green light and infrared light are simultaneously incident on the nonlinear crystal. That is, after the second light enters the delay module 3 for adjustment, it simultaneously enters the ultraviolet light generation module 4 with the first light, at which point the ultraviolet light generation module 4 activates to generate and output ultraviolet light.

[0116] It should be noted that the term "comprising" and its variations used in the embodiments of this utility model are open-ended, meaning "including but not limited to". The term "based on" means "at least partially based on". The term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; and the term "some embodiments" means "at least some embodiments". The modifications of "one" and "multiple" mentioned in the embodiments of this utility model are illustrative and not restrictive. Those skilled in the art should understand that, unless explicitly indicated otherwise in the context, they should be understood as "one or more".

[0117] The steps described in the method embodiments of this utility model can be performed in different orders and / or in parallel. Furthermore, the method embodiments may include additional steps and / or omit the steps shown. The scope of protection of this utility model is not limited in this respect.

[0118] The term "embodiment" in this specification refers to a specific feature, structure, or characteristic described in connection with an embodiment that may be included in at least one embodiment of the present invention. The appearance of this phrase in various places in the specification does not necessarily imply the same embodiment, nor does it imply independence or alternativeity from other embodiments. The various embodiments in this specification are described in a related manner, with reference to each other for similar or identical parts. In particular, for apparatus, device, and system embodiments, since they are substantially similar to method embodiments, the description is relatively simple, and relevant details are referred to in the description of the method embodiments.

[0119] The embodiments described above are merely illustrative of several implementations of this utility model, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of protection. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this utility model, and these all fall within the scope of protection of this utility model. Therefore, the scope of protection of this utility model should be determined by the appended claims.

Claims

1. A pulse width continuously tunable ultraviolet laser, characterized by, include: Infrared laser (1), green light generating module (2), delay module (3), ultraviolet light generating module (4); The infrared laser (1) is used to generate infrared light and transmit the infrared light to the green light generating module (2). The green light generating module (2) is used to convert part of the input infrared light into green light and output the remaining part of the infrared light and the green light to the delay module (3). The delay module (3) includes a transmission reflector (31), an optical path adjustment module (32), and a first reflector (33); the transmission reflector (31) is used to reflect the input first light, transmit the second light, and transmit the second light along the target optical path to the optical path adjustment module (32); wherein, the first light is green light or infrared light, and the second light is infrared light or green light; The optical path adjustment module (32) is used to increase the optical path of the input second light before it is emitted; the first reflector (33) is disposed on the output optical path of the optical path adjustment module (32), and the first reflector (33) is used to reflect the output light of the optical path adjustment module (32) so that the output light returns from the target optical path to the transmission reflector (31) and passes through the transmission reflector (31) and is input to the ultraviolet light generating module (4) with the first light. The ultraviolet light generating module (4) is used to generate ultraviolet light based on the first light and the second light.

2. The continuously adjustable pulse width ultraviolet laser according to claim 1, wherein The optical path adjustment module (32) is an acousto-optic modulator; The acousto-optic modulator is disposed on the transmission light path of the transmission mirror (31).

3. The continuously adjustable pulse width ultraviolet laser according to claim 2, wherein The output optical path side and the input optical path side of the acousto-optic modulator are respectively provided with a first waste light treatment device (34) and a second waste light treatment device (35). The first waste light treatment device (34) and the second waste light treatment device (35) are used to absorb stray light reflected by the acousto-optic modulator.

4. The continuously tunable pulse width ultraviolet laser according to claim 1, wherein The delay module (3) also includes a control component; The control component is connected to the optical path adjustment module (32), and the control component is used to adjust the optical path of the second light ray through the optical path adjustment module (32).

5. The continuously adjustable pulse width ultraviolet laser according to claim 4, wherein The delay module (3) also includes a detection component; The detection component is connected to the control component; the detection component is located at the output port of the ultraviolet light generating module (4); The detection component is used to detect the pulse width and / or energy of ultraviolet light.

6. The continuously adjustable pulse width ultraviolet laser according to claim 1, wherein A motor is also provided on the first reflector (33); The motor is used to control the deflection angle of the first reflector (33).

7. The continuously adjustable pulse width ultraviolet laser according to claim 1, wherein The delay module (3) also includes a lens (36) and / or an integrated pump laser module (37). The lens (36) is disposed between the transmission and reflection mirror (31) and the optical path adjustment module (32); The integrated pump laser module (37) is disposed between the lens (36) and the optical path adjustment module (32).

8. The continuously tunable pulse width ultraviolet laser according to claim 1, wherein The infrared laser (1) and the green light generating module (2) are further separated by a third waste light treatment device (5) and an isolator (6). The isolator (6) is disposed in the output optical path of the infrared laser (1); The third waste light treatment device (5) is installed on the waste light path reflected by the isolator (6).

9. The continuously tunable pulse width ultraviolet laser according to claim 1, wherein A reflective component (7) is also provided between the infrared laser (1) and the green light generating module (2); The reflective component (7) includes a second reflector, which is located at the intersection of the output optical path of the infrared laser (1) and the input optical path of the green light generating module (2).

10. The continuously tunable pulse width ultraviolet laser according to claim 1, wherein, The ultraviolet light generating module (4) is disposed on the input optical path of the green light generating module (2); the input optical path of the ultraviolet light generating module (4) is collinear with the input optical path of the green light generating module (2); The ultraviolet light generating module (4) is used to convert the light emitted by the green light generating module (2) into ultraviolet light and emit it.

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