Second harmonic laser direct writing system

Abstract

According to the technical scheme, the second harmonic laser direct writing system comprises a control system and a sensor module, the control system comprises an embedded controller and a closed-loop control system, the embedded controller is responsible for receiving sensor data and sending a control instruction, the closed-loop control system is used for adjusting the temperature and the angle in real time through the sensor data, and the temperature and the angle are adjusted in real time. And control software based on machine learning or an optimization algorithm, a temperature sensor is used on the sensor module to monitor the temperature of the nonlinear optical crystal in real time, an optical sensor monitors the intensity and phase of fundamental frequency light and second harmonic light, and an angle sensor monitors and feeds back the cutting angle of the crystal. An optimized nonlinear optical crystal phase matching technology is adopted, phase matching of fundamental frequency light and second harmonic light is ensured by accurately adjusting the cutting angle and temperature of the crystal, in addition, the stability of a laser light source is improved through improved design, the conversion efficiency of the second harmonic light is improved, and the laser output power is enhanced.

Description

Technical Field

[0001] The invention relates to the technical field of laser direct writing, in particular to a laser direct writing system via second harmonic. Background Art

[0002] Laser direct writing technology uses a focused laser beam to perform precise processing or structural writing on the surface or inside of a material. It is a high-precision optical processing method. Laser direct writing is widely used in micro-nano processing, lithography, microelectronics manufacturing, biomedicine and other fields. Second harmonic generation (SHG) is a type of nonlinear optical effect, in which two photons of the same frequency interact through a nonlinear medium to produce a new photon with twice the frequency of the original one.

[0003] However, the second harmonic laser direct writing system currently has some objective disadvantages in use:

[0004] 1. The unsatisfactory phase matching of nonlinear optical crystals and unstable laser light sources lead to low efficiency of second harmonic generation. Low conversion efficiency leads to insufficient laser power, which limits the processing speed and depth.

[0005] 2. High-power lasers produce thermal effects on nonlinear crystals and samples, causing thermal damage to materials and degradation of beam quality, leading to thermal deformation and focus drift during processing, affecting processing accuracy and results. Summary of the invention

[0006] In view of the shortcomings of the prior art, the present invention aims to provide a laser direct writing system via second harmonic.

[0007] In order to achieve the above object, the technical solution of the present invention is as follows:

[0008] A laser direct writing system via second harmonic includes a laser light source, a nonlinear optical crystal, a control system, a sensor module and an actuator. The control system includes an embedded controller responsible for receiving sensor data and sending control instructions, and a closed-loop control system that uses sensor data to adjust temperature and angle in real time, as well as control software based on machine learning or optimization algorithms for predicting and optimizing system parameters. A temperature sensor is used on the sensor module to monitor the temperature of the nonlinear optical crystal in real time, an optical sensor monitors the intensity and phase of fundamental frequency light and second harmonic light, an angle sensor monitors and feeds back the cutting angle of the crystal, the actuator uses a semiconductor refrigeration or heating device to perform dynamic adjustments based on the fed-back temperature data, and uses a rotating table driven by a servo motor to adjust the cutting angle of the crystal at nanometer-level precision, after which the user sets the initial parameters through an interface.

[0009] Preferably, the sensor module continuously monitors the temperature, angle and optical signal of the crystal, and the controller receives the sensor data and adjusts the temperature control device and the angle adjustment device through a feedback loop.

[0010] Preferably, the control system dynamically adjusts the temperature and angle of the crystal and optimizes the phase matching conditions based on real-time data and algorithm prediction results. The feedback loop ensures that the adjustment accuracy is within the nanometer range. The system status is monitored in real time through a graphical interface to view data such as temperature, angle, and optical signals. By remotely adjusting parameters, the system automatically adapts to new settings.

[0011] Preferably, an adaptive optical system capable of dynamically adjusting the position and shape of the laser focus is introduced. The adaptive optical system uses a wavefront sensor to monitor the wavefront distortion of the incident light and the output light in real time, and is equipped with a deformable mirror or a spatial light modulator to dynamically adjust the phase and intensity distribution of the light beam. The embedded processor is used to calculate the wavefront distortion in real time, generate a compensation signal and drive the deformable mirror or the spatial light modulator to make adjustments.

[0012] Preferably, a machine learning algorithm is used to optimize system parameters, or a genetic algorithm is used for global optimization, and the algorithm execution is accelerated by a computing platform to achieve real-time optimization control, and the system continuously collects data during operation.

[0013] Preferably, the integrated thermal management system adopts a semiconductor refrigeration or liquid cooling system, and the temperature controller is combined with a temperature sensor to monitor and adjust the working status of the cooling system in real time.

[0014] Preferably, the control software is developed based on PC, embedded system or mobile device, and a graphical user interface is designed to provide real-time monitoring, parameter setting and data analysis functions, realize remote monitoring and control through a network interface, and support multi-user collaborative operation.

[0015] Preferably, use optical design software to optimize the optical path to ensure minimal light loss and optimal phase matching, select nonlinear optical crystals, accurately calculate and process the cutting angles and sizes of the crystals, apply anti-reflection coatings on the surface of optical components to reduce reflection losses and improve system efficiency.

[0016] Preferably, the nonlinear optical crystal is made of potassium titanium phosphate or barium borate or lithium niobate or periodically poled lithium niobate or potassium sodium niobate, and the nonlinear optical crystal adopts a multilayer structure or periodic poling technology.

[0017] Preferably, the laser light source is a nanosecond pulse laser, a femtosecond pulse laser, a picosecond pulse laser, or a fiber laser.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. The present invention adopts optimized nonlinear optical crystal phase matching technology, and ensures the phase matching of fundamental frequency light and second harmonic light by accurately adjusting the cutting angle and temperature of the crystal. In addition, the stability of the laser light source is also improved through improved design, which improves the conversion efficiency of second harmonic light and enhances the laser output power. At the same time, higher laser power allows faster processing speed and deeper processing depth, thereby improving production efficiency and processing effect;

[0020] 2. The present invention introduces adaptive optical technology and high-precision control algorithms, which can dynamically adjust the laser focus position. At the same time, the sample moving platform is optimized to improve its stability and precision, significantly improve the precision and consistency of the processed pattern, and ensure the processing quality, which is suitable for application scenarios with higher requirements;

[0021] 3. The present invention adopts efficient thermal management technology, including cooling system and heat sink design, to reduce the heat accumulation of nonlinear crystals and samples. At the same time, the pulsed laser mode is adopted to reduce the average heat load, effectively reducing the problems of thermal damage to materials and degradation of beam quality. The processing process is more stable, and the accuracy and effect are guaranteed.

[0022] 4. The present invention optimizes the optical system design, reduces the complexity of optical path adjustment, and develops intelligent control software to realize the automation and intelligent operation of the system, reducing the difficulty of operation and maintenance, so that non-professionals can also operate it conveniently. The system is more stable and reliable and suitable for a wider range of application scenarios. DETAILED DESCRIPTION

[0023] It is easy to understand that according to the technical solution of the present invention, without changing the essential spirit of the present invention, a person skilled in the art can propose a variety of interchangeable structural modes and implementation modes. Therefore, the following specific implementation modes are only exemplary descriptions of the technical solution of the present invention, and should not be regarded as the whole of the present invention or as a limitation or restriction to the technical solution of the present invention.

[0024] The laser direct writing system via second harmonic of the present invention comprises a laser light source, a nonlinear optical crystal, an optical element, a precision lens system, a mobile platform, a scanning system and a post-processing system. The laser light source adopts a nanosecond pulse laser or a femtosecond pulse laser or a picosecond pulse laser or an optical fiber laser. The nanosecond pulse laser generates high-power and high-stability fundamental frequency light. The high peak power of the ultrafast laser is utilized by the femtosecond pulse laser or the picosecond pulse laser to effectively stimulate nonlinear effects such as multiphoton absorption and second harmonic generation. The short pulse width of the ultrafast laser can achieve higher processing accuracy and a smaller heat-affected zone. At the same time, the ultrafast laser can more efficiently stimulate nonlinear effects and improve the second harmonic generation efficiency. The high power and Laser output with high beam quality realizes efficient generation of second harmonic by integrating nonlinear optical fiber. High-stability laser light source is used to reduce power fluctuation and ensure stable output. Nonlinear optical crystals use potassium titanium phosphate or barium borate or lithium niobate or periodically poled lithium niobate or potassium sodium niobate. KTP (potassium titanium phosphate), BBO (barium borate), LiNbO3 (lithium niobate) crystals have high nonlinear coefficient and damage threshold, and high stability. Periodically poled lithium niobate (PPLN) and potassium sodium niobate (KNN) are new high-efficiency nonlinear optical materials that can significantly improve the conversion efficiency of second harmonics. In addition, materials and structures can be customized according to specific needs to adapt to different application scenarios. Nonlinear optical crystals use multilayer structures or periodic poling technology to improve phase matching conditions and nonlinear conversion efficiency.

[0025] It also includes a control system, a sensor module and an actuator. The control system is started and the sensors and actuators are initialized. The control system includes an embedded controller, such as ARM or FPGA, which is responsible for receiving sensor data and sending control instructions, and a closed-loop control system. The sensor data is used to adjust the temperature and angle in real time to ensure stable phase matching, as well as control software based on machine learning or optimization algorithms for predicting and optimizing system parameters. A high-precision temperature sensor is used on the sensor module to monitor the temperature of the nonlinear optical crystal in real time. The optical sensor monitors the intensity and phase of the fundamental light and the second harmonic light. The high-precision angle sensor monitors and feeds back the cutting angle of the crystal. The actuator adopts a semiconductor refrigeration or heating device to dynamically adjust according to the feedback temperature data, and uses a high-precision servo motor-driven rotating table to adjust the cutting angle of the crystal with nanometer-level precision. After that, the user sets the initial parameters through the interface, such as the target temperature, cutting angle range, etc. The sensor module continuously monitors the temperature and angle of the crystal The controller receives the sensor data and adjusts the temperature control device and the angle adjustment device through the feedback loop to ensure the phase matching of the fundamental frequency light and the second harmonic light. The control system dynamically adjusts the temperature and angle of the crystal according to the real-time data and algorithm prediction results to optimize the phase matching conditions. The feedback loop ensures that the adjustment accuracy is within the nanometer range to achieve efficient second harmonic generation. The user monitors the system status in real time through the graphical interface to view data such as temperature, angle and optical signals. If necessary, the user can adjust the parameters remotely, and the system automatically adapts to the new settings. It adopts a fully automated and intelligent control system. Through real-time monitoring and feedback mechanism, combined with high-precision servo motors and nanometer-level adjustment devices, it automatically adjusts the cutting angle and temperature of the nonlinear optical crystal. The system uses advanced optimization algorithms to achieve adaptive optimization and maintain the best phase matching state under different environmental conditions, thereby significantly improving the second harmonic generation efficiency. The system has higher environmental stability and durability and is suitable for a wide range of application scenarios.

[0026] Use a wavefront sensor (such as a Shack-Hartmann sensor) to monitor the wavefront distortion of the incident light and the output light in real time. Equipped with a deformable mirror or spatial light modulator (SLM), it can dynamically adjust the phase and intensity distribution of the light beam. ARM or FPGA is used to calculate the wavefront distortion in real time, generate compensation signals and drive the deformable mirror or SLM to adjust. The embedded processor or FPGA is used to calculate the wavefront distortion in real time, generate compensation signals and drive the deformable mirror or SLM to adjust. By introducing an adaptive optical system, the position and shape of the laser focus can be dynamically adjusted to cope with changes in the processing process, ensuring that the focus is always in the best position.

[0027] Use machine learning algorithms (such as neural networks or deep learning) to optimize system parameters, or genetic algorithms for global optimization. Accelerate algorithm execution through high-performance computing platforms (such as GPUs or FPGAs) to achieve real-time optimization control. The system continuously collects data during operation, optimizes the control algorithm through self-learning functions, improves long-term performance, and uses advanced control algorithms to achieve precise control of laser focus and sample movement, improving processing accuracy and consistency.

[0028] Use semiconductor refrigeration, such as Peltier cooling or liquid cooling system, and combine high-precision temperature controller with temperature sensor to monitor and adjust the working status of the cooling system in real time. Design optimized heat dissipation structure, such as heat pipe or heat sink, to improve cooling efficiency. By integrating efficient cooling system, reduce heat accumulation of nonlinear crystals and samples, prevent thermal damage, use pulsed laser mode, reduce average heat load, and reduce the impact of thermal effects on materials and beam quality.

[0029] Develop control software based on PC, embedded system or mobile device. Design graphical user interface (GUI), provide real-time monitoring, parameter setting and data analysis functions, realize remote monitoring and control through network interface, support multi-user collaborative operation, realize system automation and intelligent operation through the development of intelligent control software, and simplify user operation process.

[0030] Use optical design software (such as Zemax or Code V) to optimize the optical path to ensure minimal light loss and optimal phase matching. Select high-quality nonlinear optical crystals, accurately calculate and process the cutting angles and sizes of the crystals, apply efficient anti-reflection coatings on the surface of optical components to reduce reflection losses and improve system efficiency. Through the optimized design of the optical system, reduce the complexity of optical path adjustment and enhance the stability and reliability of the system.

[0031] Generate high-power, high-stability fundamental frequency light through the laser, optimize the output of the fundamental frequency light by adjusting the operating parameters of the laser (such as pump power, pulse width, etc.), select appropriate nonlinear optical crystals, introduce the fundamental frequency light into the nonlinear optical crystals, convert the fundamental frequency light into the second harmonic light with twice the frequency through the second harmonic generation (SHG) process, optimize the phase matching conditions, ensure the phase matching of the fundamental frequency light and the second harmonic light by adjusting the cutting angle and temperature of the crystal to improve the conversion efficiency, use optical elements (such as lenses, spatial light modulators) to shape the second harmonic beam to obtain the desired spot shape and size, focus the beam onto the surface or inside of the sample through a precision lens system to form a focus with high power density, prepare the sample to be processed, ensure the surface smoothness and uniformity of the sample to obtain the best processing effect, and focus the sample The sample is fixed on a high-precision mobile platform to ensure the stability and controllability of the sample during the processing. The processing parameters (such as laser power, scanning speed, focus position, etc.) are set and adjusted according to the required processing pattern and depth. A high-precision scanning system (such as a scanning mirror or an XY mobile platform) is used to guide the laser beam to scan the surface or inside of the sample according to a preset path to complete the direct writing processing. During the processing, the laser power, beam position and processing effect are monitored in real time, and dynamic adjustments are made to ensure the processing quality and consistency. After the laser direct writing processing is completed, the sample is subjected to necessary post-processing (such as cleaning, polishing, etc.) through the post-processing system to remove the residues generated during the processing process. Microscopes, scanning electron microscopes (SEM) and other instruments are used to conduct quality inspections on the processed samples to evaluate the processing accuracy and effect to ensure that they meet the design requirements.

[0032] The technical scope of the present invention is not limited to the contents in the above description. Those skilled in the art can make various deformations and modifications to the above embodiments without departing from the technical idea of ​​the present invention, and these deformations and modifications should all fall within the protection scope of the present invention.

Claims

1. Laser direct writing system via second harmonic, characterized by: It includes a laser light source, a nonlinear optical crystal, a control system, a sensor module and an actuator, wherein the control system includes an embedded controller, which is responsible for receiving sensor data and sending control instructions, and a closed-loop control system, which uses sensor data to adjust temperature and angle in real time, and control software based on machine learning or optimization algorithms, which is used to predict and optimize system parameters; A temperature sensor is used on the sensor module to monitor the temperature of the nonlinear optical crystal in real time, an optical sensor monitors the intensity and phase of the fundamental frequency light and the second harmonic light, and an angle sensor monitors and feeds back the cutting angle of the crystal; The actuator uses a semiconductor cooling or heating device to perform dynamic adjustments based on feedback temperature data, and uses a servo motor-driven rotating table to adjust the cutting angle of the crystal with nanometer-level precision, after which the user sets initial parameters through the interface.

2. The laser direct writing system via second harmonic generation according to claim 1, characterized in that: The sensor module continuously monitors the temperature, angle and optical signal of the crystal, and the controller receives the sensor data and adjusts the temperature control device and the angle adjustment device through a feedback loop.

3. The second harmonic laser direct writing system according to claim 2, characterized in that: The control system dynamically adjusts the temperature and angle of the crystal and optimizes the phase matching conditions based on real-time data and algorithm prediction results. The feedback loop ensures that the adjustment accuracy is within the nanometer range. The system status is monitored in real time through a graphical interface to view data such as temperature, angle, and optical signals. By remotely adjusting parameters, the system automatically adapts to new settings.

4. The second harmonic laser direct writing system according to claim 3, characterized in that: An adaptive optical system is introduced that can dynamically adjust the position and shape of the laser focus. The adaptive optical system uses a wavefront sensor to monitor the wavefront distortion of the incident light and the output light in real time. It is equipped with a deformable mirror or a spatial light modulator to dynamically adjust the phase and intensity distribution of the light beam. The embedded processor is used to calculate the wavefront distortion in real time, generate a compensation signal and drive the deformable mirror or spatial light modulator to make adjustments.

5. The laser direct writing system via second harmonic generation according to claim 4, characterized in that: Use machine learning algorithms to optimize system parameters, or genetic algorithms for global optimization, accelerate algorithm execution through the computing platform, achieve real-time optimization control, and continuously collect data during system operation.

6. The laser direct writing system via second harmonic generation according to claim 5, characterized in that: The integrated thermal management system uses a semiconductor refrigeration or liquid cooling system, and the thermostat is combined with a temperature sensor to monitor and adjust the working status of the cooling system in real time.

7. The second harmonic laser direct writing system according to claim 6, characterized in that: Develop control software based on PC, embedded system or mobile device, design graphical user interface, provide real-time monitoring, parameter setting and data analysis functions, realize remote monitoring and control through network interface, and support multi-user collaborative operation.

8. The second harmonic laser direct writing system according to claim 7, characterized in that: Use optical design software to optimize the optical path to ensure minimal light loss and optimal phase matching, select nonlinear optical crystals, accurately calculate and process the cutting angles and sizes of the crystals, apply anti-reflection coatings on the surface of optical components to reduce reflection losses and improve system efficiency.

9. The laser direct writing system via second harmonic generation according to claim 8, characterized in that: The nonlinear optical crystal adopts potassium titanium phosphate or barium borate or lithium niobate or periodically poled lithium niobate or potassium sodium niobate, and the nonlinear optical crystal adopts a multilayer structure or periodically poled technology.

10. The second harmonic laser direct writing system according to claim 1, characterized in that: The laser light source is a nanosecond pulse laser, a femtosecond pulse laser, a picosecond pulse laser or a fiber laser.