CN118417685A

CN118417685A - Laser processing system and processing method

Info

Publication number: CN118417685A
Application number: CN202410575849.5A
Authority: CN
Inventors: 罗先刚; 李雄; 王青松; 沈李; 方瑶
Original assignee: Tianfu Xinglong Lake Laboratory
Current assignee: Tianfu Xinglong Lake Laboratory
Priority date: 2024-05-10
Filing date: 2024-05-10
Publication date: 2024-08-02

Abstract

The application provides a laser processing system and a processing method, which are provided with an energy control module and a polarization control module, wherein the energy control module comprises a first polarization device, a first phase regulation device, a first quarter wave plate and a second polarization device which are sequentially arranged along the emergent direction of a first laser light path, and the energy of laser is changed to obtain second laser after the first laser passes through the energy control module; the polarization control module comprises a third polarization device, a second phase regulating device and a second quarter wave plate which are sequentially arranged along the emergent direction of the second laser light path, the polarization direction of the second laser light is changed to obtain third laser light after passing through the polarization control module, and the two modules jointly act to achieve the technical effect of jointly controlling the laser energy and the polarization state.

Description

Laser processing system and processing method

Technical Field

The application relates to the technical field of laser manufacturing, in particular to a laser processing system and a processing method.

Background

Since the advent of optics, light field modulation has become an especially important issue in optics. Researchers have at the earliest achieved modulation of beam transmission, such as lenses, by designing the profile of the natural material to vary the optical path difference. The geometrical optical device has simple design and stable function, but is difficult to realize the function of regulating and controlling the phase distribution. In recent years, a geometric phase device and a polarization conversion device realize continuous modulation through the direction of a nano unit without changing the thickness and the refractive index of the device, so that the device and the polarization conversion device become a new choice for light field regulation. The device has the advantages of small volume, high diffraction efficiency and the like, and is a very ideal integrated optical element.

The femtosecond laser processing relies on the interaction of light and materials to process different kinds of materials based on different mechanisms such as photopolymerization, ablation, melting and the like, has the advantages of high processing precision, small heat affected zone, no contact with the materials, green and environment protection and the like, and is widely applied to the fields such as laser marking, three-dimensional printing, metal cutting, welding, surface treatment and the like.

During femtosecond laser processing, researchers reported different types of modifications due to the complexity of the nonlinear effects during the interaction of the femtosecond laser with transparent substances, where the femtosecond laser induced self-assembled nanograting and nanopores are of particular interest due to their polarization-dependent birefringence properties. By regulating and controlling the parameters of the laser light field, birefringent nano periodic structures with different patterns, such as self-assembled nano gratings and self-assembled nano holes, can be carved on the substrate. At present, a self-assembled nanopore structure inscribed with double refraction characteristics on quartz by femtosecond laser is a processing mode for manufacturing optical field regulation with high thermochemical stability and high damage threshold, and the fast axis angle of the nanopore is changed mainly by adjusting the polarization direction of the laser, so that the adjustment of geometric phase is realized, and the optical field regulation is realized.

However, in the preparation process, the phase retardation of the prepared nano holes under the femtosecond pulses with different polarization states and the same energy is different, so that if only the polarization states are changed in the preparation process and the laser energy is not changed, the phase retardation of the prepared optical field regulation device in the fast axis direction is easily inconsistent, the performance of the final device is affected, and besides the polarization direction needs to be changed in real time in the preparation process, the performance of the device is ensured by adjusting the laser pulse energy in real time, so that the development of a laser processing system with the dual regulation effect of the laser energy and the laser polarization state is a technical problem focused in the field.

Disclosure of Invention

In order to at least solve the above technical problems, the present application provides a laser processing system and a processing method, which achieve the technical effect of jointly controlling the laser energy and the polarization state by designing an energy control module and a polarization control module.

To achieve the above technical effects, an aspect of the present application provides a laser processing system, including:

The laser generation module is used for emitting first laser;

The energy control module comprises a first polarization device, a first phase regulation device, a first quarter wave plate and a second polarization device which are sequentially arranged along the emergent direction of a first laser light path, and after the first laser passes through the energy control module, the laser energy is changed to obtain second laser;

The polarization control module comprises a third polarization device, a second phase regulating device and a second quarter wave plate which are sequentially arranged along the emergent direction of the second laser light path, and the polarization direction of the second laser light is changed to obtain third laser light after passing through the polarization control module;

the output third laser is incident to the sample stage after azimuth adjustment, and then laser processing can be performed.

In one embodiment of the present application, the first phase adjustment device is a first electro-optic modulator.

In one embodiment of the present application, the first electro-optical modulator is selected from one of an interferometric electro-optical modulator, a mach-zehnder electro-optical modulator, a PN junction electro-optical modulator, and a micro-ring resonant electro-optical modulator.

In one embodiment of the application, the first electro-optic modulator is a pockels cell.

In one embodiment of the application, it is characterized in that: the first polarizing device and the second polarizing device are selected from one or more of an absorption polarizer, a reflection polarizer and a light splitting polarizer.

In one embodiment of the present application, the first polarizing device is a half wave plate.

In one embodiment of the present application, the second polarizing device is a polarizer.

In one embodiment of the present application, the fast axis direction of the first quarter wave plate is the same as the polarization direction of the first laser light incident on the first phase adjustment device, and the included angle between the polarization direction of the first laser light incident on the first phase adjustment device and the fast axis angle of the first phase adjustment device is 45 °.

In one embodiment of the present application, the second phase adjustment device is a second electro-optic modulator.

In one embodiment of the present application, the second electro-optical modulator is selected from one of an interferometric electro-optical modulator, a mach-zehnder type electro-optical modulator, a PN junction electro-optical modulator, and a micro-ring resonance type electro-optical modulator.

Further, the second electro-optic modulator is a pockels cell.

In one embodiment of the present application, the third polarizing device is selected from one or more of an absorption polarizer, a reflection polarizer, and a spectroscopic polarizer.

Further, it is characterized in that: the third polarization device is a half wave plate.

In one embodiment of the application, the third polarizing device modulates the polarization direction of the second laser light to an angle of 45 ° to the fast axis of the second electro-optic modulator.

In one embodiment of the present application, the fast axis angle of the second quarter wave plate coincides with the polarization angle of the second laser light incident on the second phase adjustment device.

In one embodiment of the present application, the laser processing system further includes a mirror group, and the mirror group is used for lifting the optical path, and the first laser emitted from the laser generating module is incident to the mirror group, and the first laser is incident to the energy control module after being lifted by the optical path.

In one embodiment of the present application, the mirror group includes at least two mirrors, and the first laser light is reflected to the second mirror after entering the first mirror, and is emitted to the energy control module again.

In one embodiment of the application, the laser processing system further comprises an illumination module.

In one embodiment of the present application, the illumination module is an LED light source, and can emit illumination light.

Further, the laser processing system further comprises a signal acquisition module for acquiring the shape of the sample stage in real time.

In one embodiment of the application, the signal acquisition module comprises a camera.

In an embodiment of the application, the signal acquisition module further includes a beam splitter group, the beam splitter group and the camera are coaxially disposed, the beam splitter group includes at least a first beam splitter and a second beam splitter, the first beam splitter is disposed below the camera, and the second beam splitter is disposed below the first beam splitter.

Further, the illumination light emitted by the illumination module can be incident to the first beam splitter and forms an included angle of 45 degrees with the central axis of the first beam splitter; the third laser can be incident to the second beam splitter and forms an included angle of 45 degrees with the central axis of the second beam splitter.

In one embodiment of the present application, the laser processing system further includes an objective lens, the objective lens is located below the second beam splitter and is disposed with the same optical axis as the second beam splitter, and the illumination light and the third laser light can be focused into the sample piece through the objective lens.

In one embodiment of the present application, the laser illumination processing system further includes a control system, where the control system is connected to the laser module, the energy control module, the polarization control module, and the displacement table, and is capable of controlling the laser module, the energy control module, the polarization control module, and the displacement table.

In a second aspect, the present application also provides a laser processing method of a laser processing system, including the steps of:

Step S01: adjusting parameters of the laser module 1, emitting femtosecond lasers with different parameters, adjusting a control console, preparing different self-assembled nanopores, testing phase delay amounts of the self-assembled nanopores prepared by the different laser parameters and the scanning parameters according to the corresponding laser parameters and the scanning parameters, and simultaneously verifying fast axis directions of the self-assembled nanopores prepared by the lasers with different polarization directions to obtain a processing diagram of the delay amounts of the self-assembled nanopores corresponding to the laser parameters and the scanning parameters;

Step S02: drawing a phase distribution diagram of a required laser processing device according to the range of a region to be processed and the required fast axis angle distribution, calculating and generating an energy distribution diagram according to the phase distribution diagram, so that the phase delay amounts of the nanopores prepared under polarized lasers in different directions are kept consistent, and selecting processing parameters from a processing diagram in the step S01 according to the designed wavelength of the device, wherein the processing parameters comprise laser parameters, scanning speed, scanning interval, scanning layer number and the like;

Step S03: and (3) inputting the phase distribution diagram and the energy distribution diagram obtained in the step S02 into a control system, controlling the displacement table to move according to the processing parameters provided in the step S02 by the control system, controlling the laser module to emit first laser according to the preset parameters in the step S02, modulating the first laser in real time by the energy control module and the polarization control module, and then, inputting the first laser to a sample sheet of the displacement table for laser processing.

The application has the technical advantages that:

1. the application adopts the femtosecond laser to prepare the light field regulation and control device in the quartz-induced self-assembly nano-pore, utilizes the characteristic of the femtosecond laser to induce the sub-wavelength self-assembly nano-pore with the birefringence characteristic under specific parameters, can realize the control of geometric phase, can prepare various light field regulation and control devices, and simultaneously, as the structure of the self-assembly nano-pore is smaller than 100nm, the pixel point of the preparation device can be smaller than 1 mu m, so the fineness is higher and the miniaturization can be realized;

2. The device prepared by the technical scheme has good thermal stability, long service life, high transmittance and damage threshold close to a quartz substrate, and is a light field regulating device capable of being used for high-energy laser application;

3. The energy control module and the polarization control module are arranged, so that the polarization angle can be changed at high speed to prepare a complex geometric phase device, and meanwhile, the phase offset in the processing process can be compensated, so that the processed device meets the processing requirement more.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following description will briefly explain the drawings required for the embodiments, it being understood that the following drawings illustrate only some embodiments of the present application and are therefore not to be considered limiting of the scope, and that other related drawings may be obtained according to these drawings without the inventive effort of a person skilled in the art.

FIG. 1 is a schematic diagram of an energy control module according to an embodiment of the present application;

FIG. 2 is a schematic diagram of a polarization control module according to an embodiment of the present application;

FIG. 3 is a schematic diagram of a laser processing system according to an embodiment of the present application;

fig. 4 is a flow chart of a laser processing method provided in one embodiment of the application.

In the figure: 1-a laser module; 2-a mirror group; 3-an energy control module; 301-a first polarizing device; 302-a first phase modulating device; 303-a first quarter wave plate; 304-a second polarizing device; 4-polarization control module; 401-a third polarizing device; 402-a second phase modulating device; 403-a second quarter wave plate; 5-beam splitting lens group; 6-an illumination module; 7-a signal acquisition module; 8-an objective lens; 9-a displacement table; 10-control system.

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the embodiments of the present application more apparent, the technical solutions of the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application, and it is apparent that the described embodiments are some embodiments of the present application, but not all embodiments of the present application. The components of the embodiments of the present application generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.

Thus, the following detailed description of the embodiments of the application, as presented in the figures, is not intended to limit the scope of the application, as claimed, but is merely representative of selected embodiments of the application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.

It should be noted that: like reference numerals and letters denote like items in the following figures, and thus once an item is defined in one figure, no further definition or explanation thereof is necessary in the following figures.

In the description of the present application, it should be noted that, the azimuth or positional relationship indicated by the terms "upper", "lower", etc. are based on the azimuth or positional relationship shown in the drawings, or the azimuth or positional relationship that is commonly put in use of the product of the application, are merely for convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element to be referred to must have a specific azimuth, be configured and operated in a specific azimuth, and therefore should not be construed as limiting the present application. Furthermore, the terms "first," "second," and the like, are used merely to distinguish between descriptions and should not be construed as indicating or implying relative importance.

In the description of the present application, it should also be noted that, unless explicitly specified and limited otherwise, the terms "disposed," "connected," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art in specific cases.

It should be noted that, in the case of no conflict, different features in the embodiments of the present application may be combined with each other.

With the increasingly stringent requirements of micro-nano structure devices, laser processing is an advanced micro-nano processing means, and has been vigorously developed in recent years. Among them, the femtosecond laser micro-nano processing technology has unique characteristics and advantages, and is attracting more attention.

With the advent of mode locking technology, laser technology has been developed to ultra-short pulse, and femtosecond laser micro-nano processing technology has been developed. The femtosecond laser micro-nano processing is to obtain a focus with ultra-high energy density by tightly focusing ultra-short pulse laser, and the focus and the material have nonlinear action under the microscale condition, thereby inducing the modification and the molding of the material. Compared with the traditional long pulse laser or continuous laser, the pulse width of the femtosecond laser is very narrow, from a few femtoseconds to hundreds of femtoseconds, and the peak power is extremely high.

When the light beam output by the femtosecond laser oscillator is focused, the magnitude of the power density at the focus can reach 1011-1012W/cm ², the peak power can reach 1020-1021W/cm ², the corresponding electric field is far stronger than the coulomb field in atoms, various nonlinear optical effects can be generated when the femtosecond laser interacts with substances, the energy can be rapidly and accurately acted in a specific area, and extremely high processing precision and resolution can be obtained. Due to the advantages, the femtosecond laser has great research value and application prospect in the micro-nano processing field.

In the study of femtosecond laser processing, it was found that the femtosecond laser can generate a uniaxial birefringent structure by direct writing in quartz, and the direction of the birefringent fast axis of the modified region is related to the polarization direction, and the periodic grating structure region with nanometer size can be seen under an electron microscope. This phenomenon is commonly explained by interference between the incident optical field and the plasma wave electric field, resulting in permanent structural changes of the quartz. However, the self-assembled nano-grating has lower transmittance and lower damage threshold, so that the application of the device in high-energy laser is limited, and the subsequent research shows that under the specific femtosecond laser parameters, the self-assembled nano-pore structure with the characteristic similar to the nano-grating can be prepared, and the self-assembled nano-pore structure has extremely high transmittance and damage threshold, and the performance of the light field regulation device is greatly improved.

Based on the above laser processing principle, an embodiment of the present application provides a laser processing system, including:

a laser module 1 for emitting a first laser;

The main components of the laser module 1 include a laser, for example, one or more of a gas laser, a solid state laser, a semiconductor laser, a fiber laser, and a dye laser may be used to generate laser light, and different lasers may be selected according to practical situations.

When the laser processing device is used for laser processing, parameters of a laser can be adjusted according to actual working conditions, and the adjustable parameters include laser pulse width, laser repetition frequency, laser energy and the like, so that the laser processing device is used for better adapting to the processing requirements of micro-nano devices under different conditions.

Referring to fig. 1, the energy control module 3 includes a first polarization device 301, a first phase adjusting device 302, a first quarter wave plate 303, and a second polarization device 304 sequentially arranged along an outgoing direction of a first laser light path, where after the first laser light passes through the energy control module 3, the laser light energy is changed to obtain a second laser light;

The first polarization device 301 is used to change the polarization direction of the first laser light, and any device that can change the polarization direction of light may be used as the first polarization device 301. The first phase adjustment device 302 may adjust the first laser phase delay amount in the fixed axis direction by adjusting an input parameter, such as adjusting a voltage, and the first phase adjustment device 302 may select an optoelectronic modulator.

In the prior art, a phase regulation scheme is generally adopted as a technical scheme of mounting a 1/2 wave plate on an electric control rotary table, but the technical effect of high-speed polarization modulation cannot be achieved.

The first laser light incident on the first quarter wave plate 303 has completed the conversion of the polarization state, the first quarter wave plate 303 is used for changing the polarization direction of the first laser light, the laser light passing through the first quarter wave plate 303 is linearly polarized light (first laser light) after the direction change, and the second polarization device 304 is used for adjusting the linearly polarized light (first laser light) after the direction change to a specific direction and changing the energy of the laser light.

The quarter wave plate uses the anisotropic characteristics of the material, has different refractive indexes and propagation speeds for light in different polarization directions, so that two component phase differences are caused, linear polarized light is converted into elliptical polarized light, or elliptical polarized light is converted into linear polarized light, when the optical axis direction of the linear polarized light is 45 degrees with the quarter wave plate, the linear polarized light can be converted into circular polarized light, and therefore, the quarter wave plate can be used for changing the polarization state of laser light; the linearly polarized light is modulated into elliptically polarized light by the electro-optical modulator, and the elliptically polarized light is converted into linearly polarized light rotated by a certain angle after passing through the first quarter wave plate 303.

In the present application, the linearly polarized light is modulated into elliptically polarized light by the first phase adjusting device 302, and the elliptically polarized light is converted into linearly polarized light rotated by a certain angle after passing through the first quarter wave plate 303.

In the application, the energy control module 3 is arranged for changing the laser energy in real time, and the purpose of changing the laser energy is as follows: in practical processing, the retardation of the nanopores prepared in different polarization states is slightly different under the same energy, and most geometrical phase light field regulation devices need to keep consistent phase retardation under all fast axis angles, such as lambda/2, for example, vortex wave plates, flat cone lenses, perfect vortex light generators and the like. Therefore, in order to ensure the performance of the device, the laser energy needs to be adjusted under different polarization states, so as to ensure that the phase retardation of the prepared nano-holes under all polarization states is consistent.

The polarization control module 4, please refer to fig. 2, includes a third polarization device 401, a second phase adjusting device 402, and a second quarter wave plate 403 sequentially arranged along the outgoing direction of the second laser light path, and the polarization direction of the second laser light is changed after passing through the polarization control module 4, so as to obtain a third laser light;

The third polarization device 401 is used to change the polarization direction of the second laser light, and any device that can change the polarization direction of light may be used as the third polarization device 401. The second phase adjustment device 402 may adjust the second laser phase retardation in the fixed axis direction by adjusting an input parameter, such as an adjustment voltage.

The second quarter waveplate 403 functions in the same way as the first quarter waveplate 303 to change the polarization state of the second laser light.

In the prior art, a plurality of phase type light field regulating devices designed according to the requirements are extremely complex in phase distribution, the polarization state needs to be changed in real time in the preparation process, and the preparation of the nano-holes with the required fast axis angles is completed. The speed of changing polarization in real time determines the preparation efficiency and precision of the optical field regulating device. Therefore, in the application, the polarization control module 4 is arranged to change the polarization state of the laser in real time, thereby achieving the technical effect of controlling the fast axis angle of the prepared nano-hole in real time and realizing the preparation of the light field regulating device with complex phase.

The output third laser beam is subjected to azimuth adjustment and then enters the sample piece loaded on the displacement table 9, so that laser processing is performed.

The output third laser light is required to be subjected to azimuth adjustment, for example, the third laser light is reflected by a plurality of mirrors, and is focused in the sample piece loaded on the displacement stage 9, thereby realizing laser processing.

In one possible implementation, the first phase adjustment device 302 is a first electro-optical modulator, the electro-optical modulator is an optical modulator that works by using an electro-optical effect, a process of loading information on the laser is called modulation, and a device that performs this process is called a modulator. The physical basis of the electro-optic modulation is the electro-optic effect, namely that the refractive index of certain crystals changes under the action of an external electric field, when light waves pass through the medium, the transmission characteristics of the crystals are affected and changed, and the electro-optic modulation can be divided into amplitude modulation, frequency modulation, phase modulation, intensity modulation and the like according to the modulation property of the crystals.

In the present application, the first electro-optical modulator is illustratively a phase modulation electro-optical modulator, and in a typical example, the change of the phase retardation amount on the fixed axis can be achieved by applying different voltages to the first electro-optical modulator, so that the polarization state of the incident laser light is changed, and the laser light with the changed polarization state passes through the first quarter wave plate 303 to achieve the change of the rotation direction of the linearly polarized light, so that the electro-optical modulator and the first quarter wave plate 303 form a whole body, that is, the linearly polarized light is rotated by a specific angle. Finally, the effect of adding the polarization device is that the energy irradiated on the sample in real time is changed, so that the phase retardation of the nano holes generated in real time in processing is kept consistent.

In one possible implementation manner, the first electro-optical modulator is selected from one of an interference type electro-optical modulator, a mach-zehnder type electro-optical modulator, a PN junction electro-optical modulator and a micro-ring resonance type electro-optical modulator, and different types of electro-optical modulators can be selected according to different working conditions.

Illustratively, the first electro-optic modulator is a pockels cell. Pockels cell, also called a pockels cell, is a device consisting of an electro-optic crystal (with electrodes attached) through which a light beam can propagate. The phase delay in the crystal (pockels effect) can be modulated by applying a variable voltage. Thus, the pockels cell acts as a voltage controlled wave plate. Pockels cells are an essential component of electro-optic modulators, for example for Q-switched lasers.

The principle is that the kerr electro-optic effect, i.e. the orientation (deflection) of a crystal placed in an electric field, occurs due to its molecules being subjected to an electric force, which exhibits anisotropy, as a result of which birefringence, i.e. the refractive power of a substance for light in two different directions, is different.

The pockels cell is generally used as an electro-optical modulator, the electro-optical modulator is a set of system, the pockels cell is added with a driving power supply, and different modulation types and modulation frequencies can be selected according to different parameter requirements. There are typically 3 modulations of light: intensity modulation, polarization modulation, and phase modulation.

In one possible implementation manner, the first polarizing device 301 and the second polarizing device 304 are illustratively one or more selected from an absorption polarizer, a reflection polarizer, and a spectroscopic polarizer, and each of the polarizing devices may change the polarization direction of the first laser light.

In one possible implementation, in one embodiment of the present application, the fast axis direction of the first quarter wave plate 303 is the same as the polarization direction of the first laser light incident on the first phase adjustment device 302, and the angle between the polarization direction of the first laser light incident on the first phase adjustment device 302 and the fast axis angle of the first phase adjustment device 302 is 45 °.

In one possible implementation, the first polarization device 301 is a half-wave plate.

In one possible implementation, the second polarizer device 304 is a polarizer. Here, the second polarization device 304 is not a half wave plate. The second polarizer 304 is illustratively one selected from a linear polarizer, a circular polarizer, and a birefringent polarizer, and the choice of the polarizer is adjusted according to practical situations.

The principle by which the energy control module 3 can regulate the first laser energy is as follows:

The polarization state of the first laser incidence is only consistent with the relative angles of the other devices, and the following deduction process is exemplified by deduction according to the fact that the first laser is horizontally polarized incidence, and the expression of the first laser at the moment is as follows according to the Jones vector after the first laser passes through the lambda/2 wave plate:

if the phase delay amount of the first electro-optic modulator on the adjustment fixed shaft is a (deflection angle delta=180° x 2a/λ), and the included angle between the polarization direction of the first laser light and the fast axis angle of the first electro-optic modulator is 45 °, the jones matrix expression of the first electro-optic modulator is:

the lambda/4 wave plate fast axis angle is consistent with the incident first laser direction, so the lambda/4 wave plate jones matrix expression is:

The jones vector of the outgoing laser after the first laser passes through the first electro-optical modulator is:

After the outgoing laser passes through the lambda/4 wave plate, the Jones vector of the outgoing laser again is as follows:

The Jones vector expresses that the included angle between the polarization direction and the vertical direction is Therefore, the linearly polarized light angle of the first laser light is rotatedMeanwhile, since the polarizer 304 angle is horizontally polarized light in accordance with the incident first electro-optic modulator linear polarization angle, the energy of the second laser light passing through the polarizer 304 is:

In another possible implementation of the present application, the angle of the polarizer 304 may be different from the linear polarization angle of the incident first electro-optic modulator, and when the angles are not identical, the energy of the second laser light passing through the polarizer 304 is:

where phi is the angle between the polarizer 304 and the incident first electro-optic modulator linear polarization.

Thus, in this way, high speed real time variation of laser energy can be achieved.

In one possible implementation, the second phase modulation device 402 is a second electro-optic modulator. Illustratively, the second phase adjustment device 402 is selected to be the same as the first phase adjustment device 302, and the selected electro-optic modulator is a phase-modulated electro-optic modulator, and in a typical example, the change in the amount of phase retardation on the fixed axis may be achieved by applying different voltages, where the change in the amount of phase retardation may change the polarization state of the incident second laser light, and the second laser light with the changed polarization state may then achieve a change in the rotation direction of the linearly polarized light through the second quarter wave plate 403.

The second electro-optic modulator and the second quarter wave plate 403 form a whole, i.e. the linearly polarized light (second laser) can be rotated by a specific angle. Finally, the technical effect is that the femtosecond laser with the preset polarization state is irradiated at the specific position of the sample, so that the nano hole with the required fast axis angle is processed in real time.

In one possible implementation manner, the second electro-optical modulator is selected from one of an interference type electro-optical modulator, a mach-zehnder type electro-optical modulator, a PN junction electro-optical modulator and a micro-ring resonance type electro-optical modulator, and different types of electro-optical modulators can be selected according to different working conditions. Illustratively, the second electro-optic modulator is a pockels cell.

In one possible implementation manner, the third polarizing device 401 is selected from one or more of an absorption polarizer, a reflection polarizer, and a beam-splitting polarizer, which can achieve the technical effect of changing the polarization state of the laser.

In one possible implementation, the third polarization device 401 modulates the polarization direction of the second laser light to an angle of 45 ° with respect to the fast axis of the second electro-optic modulator.

In one possible implementation, the third polarization device 401 is a half-wave plate. The half wave plate is a mature commercial optical device and has more selectivity.

In one possible implementation, the fast axis angle of the second quarter wave plate 403 coincides with the polarization angle of the second laser light incident on the second phase adjustment device 402.

The principle by which the polarization control module 4 can regulate the polarization state of the second laser energy is as follows:

The second laser is horizontally polarized, and according to the jones vector, the incident light expression is:

If the phase delay of the second electro-optic modulator on the adjustment fixed axis is a (deflection angle δ=180° ×2a/λ), and the polarization direction of the second laser light forms an angle of 45 ° with the fast axis of the second electro-optic modulator, the jones matrix expression of the second electro-optic modulator is:

the fast axis angle of the lambda/4 wave plate is consistent with the direction of the incident laser, so the lambda/4 wave plate Jones matrix expression is:

the emergent light Jones vector of the second laser after passing through the second electro-optic modulator is as follows:

after the emergent light passes through the lambda/4 wave plate, the Jones vector of the third laser which is emergent again is as follows:

The Jones vector expresses that the included angle between the polarization direction and the vertical direction is Therefore, the polarization angle of the second laser light is rotated after passing through the polarization control module 4In this way, a high-speed real-time change of the polarization direction of the laser light can be achieved.

In one possible implementation, the laser module 1 includes a femtosecond pulse laser, and the above technical advantages are that the self-assembled nanopore can only be prepared under the condition of the femtosecond pulse laser, and even if a nanograting is adopted, the pulse width range is narrow, and the machining process cannot be completed, so the self-assembled nanopore structure is a unique machining structure of the femtosecond pulse laser.

The center wavelength of the femtosecond pulse laser is 1030nm, for example.

In the prior art, two femtosecond lasers are commonly used for processing, one is a titanium sapphire solid-state laser, the other is an ytterbium-doped optical fiber femtosecond laser, the fixed output wavelength of the titanium sapphire solid-state laser is 800nm, the repetition frequency is lower and is 1KHz, the titanium sapphire solid-state laser is not suitable for high-repetition frequency rapid processing, the advantages are that the pulse width is narrower, but the narrow pulse width is not needed for writing a nanometer grating/a nanometer hole in quartz of the technology, so the titanium sapphire solid-state laser is not suitable for the scheme of the application, but the solid-state laser can process other materials, such as silicon, tiO ₂, graphene oxide and the like.

Therefore, the application selects the ytterbium-doped fiber femtosecond laser, the output wavelength of the laser is fixed to 1030nm, and the ytterbium-doped fiber femtosecond laser has the technical advantages of high repetition frequency, high power, proper pulse width (usually adjustable at 300fs-5 ps) and the like, so the ytterbium-doped fiber femtosecond laser is the laser which is most suitable for nano grating/nano hole processing at present.

In one possible implementation manner, the laser processing system further includes a mirror group 2, which is used for lifting a light path, the first laser emitted by the laser module 1 enters the mirror group 2, the first laser enters the energy control module 3 after lifting the light path, and due to system setting reasons, the general position of the laser is lower, and the position of the laser emitted by the laser module 1 needs to be adjusted to enter the subsequent module.

In one possible implementation, the mirror group 2 includes at least two mirrors, and the first laser light is reflected to the second mirror after entering the first mirror, and exits to the energy control module 3 again. In other implementations, the mirror group 2 may also include three-sided, four-sided or even multi-sided mirrors, so long as the technical effect of lifting the light path can be achieved through reasonable mirror surface arrangement. The technical purpose can be achieved by changing the reflecting mirror into a device with the function of reflecting light.

In a possible implementation, the laser processing system further comprises an illumination module 6 for providing illumination light to the sample stage. The sample piece on the surface of the sample table needs to be observed in real time to observe the processing condition, so that an external light source needs to be provided to improve the illumination effect.

The illumination module 6 is an LED light source, for example, and emits illumination light. The LED light source may be an LED lamp, an LED light emitting diode, or the like.

In a possible implementation, the laser processing system further comprises a signal acquisition module 7 for acquiring the sample morphology of the sample stage in real time, so as to observe from the sample processing situation.

The signal acquisition module 7 comprises, for example, a camera. The camera can be one of a single-lens reflex camera, a micro-lens reflex camera, a non-lens reflex camera, a double-lens reflex camera and a CCD camera, and the camera capable of collecting images can be used for the technical scheme of the application.

In one possible implementation manner, the signal acquisition module 7 further includes a beam splitter group 5, where the beam splitter group 5 is disposed on the same central axis as the camera, and the beam splitter group 5 includes at least a first beam splitter and a second beam splitter, where the first beam splitter is disposed below the camera, and the second beam splitter is disposed below the first beam splitter. The beam splitter is coated glass. One or more thin films are coated on the surface of the optical glass, and when one beam of light is projected onto the coated glass, the beam of light can be split into two or more beams by reflection and refraction. In the scheme of the application, the adopted beam splitting lens group is a reflector aiming at 1030nm wavelength laser, and has a beam splitting effect on illumination light emitted by the illumination module.

In one possible implementation manner, the illumination light emitted from the illumination module 6 may be incident on the first beam splitter and form an angle of 45 ° with the central axis of the first beam splitter.

In one possible implementation, the third laser light may be incident on the second beam splitter and form an angle of 45 ° with the central axis of the second beam splitter.

In one embodiment of the application, the angle of the mirror in the illumination module is set to be 45 degrees, on one hand, the incident angle of the device is 45 degrees, on the other hand, the illumination light and the laser are required to be combined, so that the illumination light and the laser can be irradiated at the same place, and meanwhile, the illumination light reflected by the sample and the flash energy generated by the laser irradiating the sample also need to be ensured to enter the camera through the two beam splitters, so that the device is set according to the angles. The reflected light of the laser is generally not directly observed through a camera, and the reflectivity of quartz to 1030nm laser is very low.

In a possible implementation manner, the laser processing system further includes an objective lens 8, where the objective lens 8 is located below the second beam splitter and is disposed on the same optical axis as the second beam splitter, and the illumination light and the third laser may be focused into the sample slice through the objective lens 8.

Inside the objective lens 8 is a lens group composed of a plurality of lenses. The objective lens can be selected from one of 5×,10×,20×, and 50× according to the requirement, and particularly 10×, and the focal length can be selected according to the requirement, and can be selected from 1-400mm.

In the use process, the first beam splitter is used for reflecting the illumination light emitted by the illumination module 6 to the second beam splitter, meanwhile, the illumination light emitted by the reflected illumination module 6 is transmitted into the signal acquisition module 7, an illumination light source is provided for the signal acquisition module 7, the second beam splitter reflects the emitted third laser to the objective lens 8, and meanwhile, the illumination light passes through the second beam splitter to the objective lens 8.

The illumination light sequentially passes through the first beam splitter and the second beam splitter, the object lens 8 passes through the object lens 8 again after being reflected by the sample, the second beam splitter enters the signal acquisition module 7 after passing through the first beam splitter, and the shape of the sample at the focusing position can be observed.

In a possible implementation manner, referring to fig. 3, the laser illumination processing system further includes a control system 10, where the control system 10 is connected to the laser module 1, the energy control module 3, the polarization control module 4, and the displacement table 9, and can control the laser module 1, the energy control module 3, the polarization control module 4, and the displacement table 9. The control system 10 can control the laser module 1 to emit laser with different pulse widths, repetition frequencies and energy through software, can control the voltages of the first phase regulating device and the second phase regulating device in the electro-optical modulator in the energy control module 3 and the polarization control module 4 so as to control the energy and the polarization state of the emitted laser, and can control the moving mode of the displacement table 9, thereby realizing the scanning interval, the scanning speed and the scanning layer number required by the preparation device.

Preferably, the control system 10 comprises a computer.

In a second aspect, referring to fig. 4, the present application provides a laser processing method based on the laser processing system, including the following steps:

the scanning parameters have a very large influence on the phase retardation, so that not only the relation between the laser parameters and the nanopore phase retardation, but also the relation between the scanning parameters and the nanopore phase retardation is required.

Because the phase delay of the self-assembled nano-pore prepared under the same laser parameters and under the same scanning parameters is different under different polarizations of laser, the relationship between the laser parameters and the scanning parameters and the phase delay of the self-assembled nano-pore is also needed under different polarizations.

Step S03: the phase distribution diagram and the energy distribution diagram obtained in the step S02 are input into the control system 10, the control system 10 controls the displacement table 9 to move according to the processing parameters provided in the step S02, and controls the laser module 1 to emit first laser according to the preset parameters in the step S02, and the first laser is incident on the sample piece of the displacement table 9 for laser processing after being modulated in real time by the energy control module 3 and the polarization control module 4.

In a specific processing process, the voltage value of the energy distribution diagram is amplified by using a voltage amplifier according to the laser processing position and is input into an electro-optical modulator, meanwhile, a control circuit triggers an optical switch, so that the laser emits ray polarization femtosecond laser according to a set parameter, namely, the first laser passes through a high-speed energy control module 3, the laser energy is adjusted to be a preset energy value, and meanwhile, polarization direction control is realized through a high-speed polarization control module 4, and at the moment, the control circuit moves a control displacement table 9 according to preset parameters, such as a scanning rate, a scanning interval and the like, so that the laser completely scans a processing area. In the scanning process, according to the voltage value of the voltage diagram corresponding to the scanning position, the laser energy and the polarization direction are changed in real time until the input gray-scale diagram single layer is completely processed.

Because the phase delay amount of the single-layer structure often cannot meet the requirement, after the single-layer scanning is finished, the control system 10 can control the displacement table 9 to move downwards, the laser spot position moves upwards, the specific distance of movement is determined according to the requirement of the actual processing working condition, the next layer of processing is performed, the single-layer scanning is repeated again until the preset layer number is completely scanned, the phase delay amount meets the requirement of a used device, in the embodiment, the displacement table 9 is selected to move downwards, and the laser characteristic can be influenced by the structure processed by the upward movement of the displacement table 9.

For example, multiple layers can be processed according to actual requirements, the phase delay of a single layer of the nano-pore is low, the number of layers is relatively high, and more than 5 layers are usually obtained.

In summary, the application provides a system and a method for preparing a light field regulation device by using femtosecond laser to induce self-assembled nanopores, which can realize the control of geometric phases by using the characteristic of the femtosecond laser to induce sub-wavelength self-assembled nanopores with birefringence characteristics under specific parameters, the device can realize the control of geometric phases, various light field regulation devices can be prepared, and the self-assembled structure of the nanopores is smaller than 100nm, so that the fineness is higher and the device can be miniaturized; the device prepared by the technical scheme has good thermal stability, long service life, high transmittance and damage threshold close to a quartz substrate, and is a light field regulating device capable of being used for high-energy laser application; by arranging the energy control module and the polarization control module, the laser energy and the polarization angle in the laser processing process can be adjusted in real time, so that the processed device meets the processing requirement.

The above description is only of the preferred embodiments of the present application and is not intended to limit the present application, but various modifications and variations can be made to the present application by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A laser processing system, comprising:

The laser generation module is used for emitting first laser;

2. The laser processing system of claim 1, wherein: the first phase regulating device is a first electro-optic modulator.

3. The laser processing system of claim 2, wherein: the first electro-optic modulator is selected from one of an interference type electro-optic modulator, a Mach-Zehnder type electro-optic modulator, a PN junction electro-optic modulator and a micro-ring resonance type electro-optic modulator.

4. The laser processing system of claim 2, wherein: the first electro-optic modulator is a pockels cell.

5. The laser processing system of claim 1, wherein: the first polarizing device and the second polarizing device are selected from one or more of an absorption polarizer, a reflection polarizer and a light splitting polarizer.

6. The laser processing system of claim 1, wherein: the first polarization device is a half wave plate.

7. The laser processing system of claim 1, wherein: the fast axis direction of the first quarter wave plate is the same as the polarization direction of the first laser light entering the first phase regulating device, and the included angle between the polarization direction of the first laser light entering the first phase regulating device and the fast axis angle of the first phase regulating device is 45 degrees.

8. The laser processing system of claim 1, wherein: the second phase regulating device is a second electro-optic modulator.

9. The laser processing system of claim 8, wherein: the second electro-optic modulator is selected from one of an interference type electro-optic modulator, a Mach-Zehnder type electro-optic modulator, a PN junction electro-optic modulator and a micro-ring resonance type electro-optic modulator.

10. The laser processing system of claim 8, wherein: the second electro-optic modulator is a pockels cell.

11. The laser processing system of claim 1, wherein: the third polarizing device is selected from one or more of an absorption polarizer, a reflection polarizer and a beam splitting polarizer.

12. The laser processing system of claim 1, wherein: the third polarization device is a half wave plate.

13. The laser processing system of claim 1, wherein: the third polarization device modulates the polarization direction of the second laser light to an included angle of 45 degrees with the fast axis angle of the second electro-optic modulator.

14. The laser processing system of claim 13, wherein: the fast axis angle of the second quarter wave plate is consistent with the polarization angle of the second laser light incident on the second phase adjustment device.

15. The laser processing system of claim 1, wherein: the laser processing system further comprises a reflecting mirror group, wherein the reflecting mirror group is used for lifting the light path, the first laser emitted by the laser generating module enters the reflecting mirror group, and the first laser enters the energy control module after being lifted by the light path.

16. The laser processing system of claim 15, wherein: the reflecting mirror group comprises at least two reflecting mirrors, and the first laser is reflected to the second reflecting mirror after entering the first reflecting mirror and is emitted to the energy control module again.

17. The laser processing system of claim 1, wherein: the laser processing system further includes an illumination module.

18. The laser processing system of claim 17, wherein: the illumination module is an LED light source and can emit illumination light.

19. The laser processing system of claim 17, wherein: the laser processing system also comprises a signal acquisition module for acquiring the shape of the sample stage in real time.

20. The laser processing system of claim 19, wherein: the signal acquisition module includes a camera.

21. The laser processing system of claim 20, wherein: the signal acquisition module further comprises a beam splitter group, the beam splitter group and the camera are arranged on the same central axis, the beam splitter group comprises at least a first beam splitter and a second beam splitter, the first beam splitter is arranged below the camera, and the second beam splitter is arranged below the first beam splitter.

22. The laser processing system of claim 21, wherein: the illumination light emitted by the illumination module can be incident to the first beam splitter and form an included angle of 45 degrees with the central axis of the first beam splitter, and the third laser can be incident to the second beam splitter and form an included angle of 45 degrees with the central axis of the second beam splitter.

23. The laser processing system of claim 22, wherein: the laser processing system further comprises an objective lens, the objective lens is located below the second beam splitter and is arranged on the same optical axis with the second beam splitter, and the illumination light and the third laser can enter the sample piece through focusing of the objective lens.

24. The laser processing system of claim 1, wherein: the laser processing system further comprises a control system, wherein the control system is connected with the laser module, the energy control module, the polarization control module and the displacement table and can control the laser module, the energy control module, the polarization control module and the displacement table.

25. The laser processing method based on the laser processing system according to any one of claims 1 to 24, characterized by comprising the steps of: