Method for explaining damage threshold improvement in fused quartz femtosecond laser processing / welding process

Abstract

The invention discloses an explanation method for damage threshold improvement of a fused quartz material in a femtosecond laser processing / welding process. By establishing a fused quartz electron-lattice heat transfer model under femtosecond laser irradiation, a dissociation model of environment molecules and interstitial molecules under the action of femtosecond laser and a defect-containing fused quartz molecule dynamic reaction model based on a ReaxFF reaction force field, atomic structure changes in a system before and after a reaction are analyzed; and finally, obtaining a chemical reaction mechanism of the fused quartz containing the defects under the action of the femtosecond laser, and explaining the phenomenon that the damage threshold of the fused quartz is increased after the fused quartz is irradiated by the low-flux femtosecond laser. According to the method, the research in the current fused quartz femtosecond laser processing / welding process is perfected, and meanwhile, the theoretical blank that the damage threshold lifting mechanism is not clear in the fused quartz glass femtosecond laser processing / welding process is filled up.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of strengthening the laser damage resistance of fused quartz, and particularly relates to a method for obtaining the chemical reaction process of point defect healing of fused quartz under femtosecond laser irradiation based on a two-temperature equation, a molecular dynamics model and a time-dependent density functional theory model. BACKGROUND

[0002] In recent years, with the development of high-power laser devices, the application of optical window materials under extreme laser loading service conditions has been promoted, and in this context, it is crucial to improve the laser damage resistance of optical window materials.

[0003] Fused quartz glass has good optical properties and chemical stability, and has high transmittance in the ultraviolet, visible and near-infrared wavelength bands. At the same time, the low thermal conductivity and low thermal expansion coefficient of the material make it have very high thermal stability in high-temperature environments, so it is widely used in high-power laser devices to prepare optical elements such as lenses, wave plates and vacuum windows. In order to further improve the laser damage threshold of fused quartz materials, its processing method is being actively researched to meet the needs of laser loading.

[0004] The femtosecond laser processing / welding method is a clean, precise and efficient post-processing method that is very suitable for the surface treatment of fused quartz. Femtosecond lasers directly excite electrons and cause non-thermal structural changes in dielectric materials. It can avoid as much as possible the rupture and crack propagation of fused quartz glass caused by thermal stress. However, the current femtosecond laser processing / welding of fused quartz glass to improve the damage threshold is still in the exploratory stage, so it is necessary to further explore its mechanism.

[0005] For the characterization of fused quartz before and after femtosecond laser processing / welding, a large amount of experimental cost needs to be invested, and it is very difficult to characterize the changes in point defects on the surface of fused quartz glass under macroscopic conditions. Therefore, thanks to the development of computer technology and numerical simulation methods in recent years, the changes in point defects on the surface of fused quartz glass before and after femtosecond laser processing / welding can be explored at the microscale. SUMMARY

[0006] In view of the lack of mechanism-based explanation of the damage threshold improvement during the above-mentioned femtosecond laser processing / welding of fused quartz glass, and the difficulty in characterizing the changes in point defects of fused quartz glass before and after femtosecond laser processing / welding at the macroscopic scale, the present application provides a method for obtaining the chemical reaction process of point defect healing of fused quartz under femtosecond laser irradiation based on a two-temperature equation, a molecular dynamics model and a time-dependent density functional theory model.

[0007] The technical solution of the present application is as follows:

[0008] An explanation method of damage threshold enhancement in a fused quartz femtosecond laser processing / welding process, comprising the following steps:

[0009] Step 1, determining the laser parameters used in the femtosecond laser processing / welding process;

[0010] Step 2, determining the macroscopic size of the fused quartz glass research area used;

[0011] Step 3, establishing an electron-lattice heat transfer model based on the free electron generation theory, the Drude equation and the two-temperature equation to simulate the process of energy transfer from electrons to materials under the action of electroacoustic coupling;

[0012] Step 4, constructing a fused quartz amorphous structure in a molecular dynamics simulation software;

[0013] Step 5, simulating the reaction process of molecules existing in the environment and interstitial molecules in the fused quartz glass under the action of femtosecond laser in a time-dependent density functional simulation software.

[0014] Step 6, in the molecular dynamics simulation software, selecting a reaction potential function, constructing point defects in the fused quartz amorphous structure constructed in step 4 and adding the molecular / atomic structure calculated in step 5. The model is fully relaxed and energy minimization is performed.

[0015] Step 7, in the molecular dynamics simulation software, obtaining an atomic trajectory file at the temperature calculated in step 3.

[0016] Step 8, analyzing the atomic trajectory file calculated in step 7.

[0017] Further, the femtosecond laser parameters of step 1 include femtosecond laser pulse width, wavelength, power, repetition frequency and spot radius.

[0018] Further, the free electron generation theory, the Drude equation and the two-temperature equation in step 3 are shown as formulas (1)-(24):

[0019]

[0020]

[0021] The above formulas (1)-(9) are the free electron generation theory, wherein n e is the free electron concentration; T e is the electron temperature; G e is the electron generation rate; R eJ is the carrier current due to carrier diffusion; D is the bipolar diffusion coefficient; w is the rate of electron concentration due to multi-photon absorption; ω is the angular frequency of the incident laser; Φ(x) is the probability integral function; U0 is the band gap width of fused quartz; U eff is the corrected band gap width; m e is the number of photons of multi-photon absorption; e is the elementary charge; F is the laser electric field strength; β is the multi-photon absorption coefficient; I is the laser intensity; δ is the impact ionization coefficient; K B is the Boltzmann constant; τ AR is the minimum Auger recombination time; C AR is the Auger recombination rate; h is the reduced Planck constant.

[0022] After femtosecond laser irradiation on the surface of fused quartz, the original optical properties of the target material change. Under the action of nonlinear ionization, a large number of valence band electrons transition to the conduction band, and the free electron concentration on the surface of the material rapidly increases to 10 21 ~ 10 22 cm -3 The optical properties of the surface of the fused quartz change and exhibit metallic properties. The transient optical properties of the surface of the material can be represented by the complex dielectric function using the Sipe-Drude model, as shown in equations (10)-(16).

[0023]

[0024] In the above equations (10)-(16), ε is the dielectric constant of fused quartz; ε' is the complex dielectric constant of the plasma; ω p (n e ) is the frequency of the plasma; N0 is the initial carrier concentration of the valence band; v is the carrier collision rate; ε0 is the vacuum dielectric constant; c is the speed of light in vacuum; f is the negative refractive index; f1 is the refractive index, f2 is the extinction coefficient, ε1 is the real part of the plasma complex dielectric constant, and ε2 is the imaginary part of the plasma complex dielectric constant ε'. R is the surface reflectivity of the ionized material, and α b is the heating coefficient of the Fresnel carrier.

[0025] When femtosecond laser irradiation is performed on the surface of fused quartz, the carriers in the material interior are rapidly excited under the action of ionization, and then transfer energy to the lattice under the action of electro-acoustic coupling. The relaxation process of the lattice temperature is described by a set of coupled differential equations through the two-dimensional two-temperature model (TTM), as shown in equations (17)-(24).

[0026]

[0027] C e = 3n eK B (20)

[0028]

[0029] K e = -0.556 + 7.13 x 10 -3 T e (22)

[0030] K l = 0.1585 T l -1.23 (23)

[0031] C l = 1.978 + 3.54 x 10 -4 T l - 3.68 x T l -2 (24)

[0032] In the above equations (17)-(24), C e is the electronic specific heat; C l is the lattice specific heat; g is the electron-lattice coupling coefficient; T l is the lattice temperature; K e is the electronic thermal conductivity; K l is the lattice thermal conductivity; S is the heat source term of the femtosecond laser; f is the femtosecond laser repetition frequency; P is the average power of the femtosecond laser; R0 is the spot radius; τ p is the laser pulse width; K B is the Spitzler constant.

[0033] Further, step 4 constructs the construction of fused quartz amorphous structure using the LAMMPS program based on the molecular dynamics method to simulate the heating and annealing process in the manufacture of fused quartz, so that the quartz crystal is converted into a molten amorphous state. The unit cell of the quartz crystal initial structure is selected as β-cristobalite, and the classical potential function tersoff three-body potential is used for the interaction between atoms. The pressure P used in the simulation process is 1 atm, and the ensemble used is divided into NPT and NVT ensembles. The heating process first uses the NPT ensemble, and the constructed SiO2 crystal system is heated from 300K to 6000K within 0.2ns, and then annealed under the NVT ensemble after being kept at 0.1ns. The annealing process uses the NVT ensemble, and is cooled from 6000K to 300K within 1ns, and is kept at 300K for 50ps.

[0034] Finally, the NPT ensemble is used to relax at 300K for 0.2ns to reach equilibrium. The time step is 1fs.

[0035] Further, the environment molecules that will react with the fused quartz system and the gap molecules in the fused quartz in step 5 are mainly O2. In the time-dependent density functional simulation software Octopus, first, the gs ground state of O2 is calculated, in the subsequent td calculation, femtosecond laser is set through the Gaussian function tdf_gaussian in TDFunctions, in the TDExternalFields module, the femtosecond laser is set in the form of Gaussian wave packet, and the total calculation time is set to the end of the single pulse laser. The position information file and the energy file calculated are extracted, the interatomic distance and the potential energy change are calculated to judge whether the O2 molecule is dissociated.

[0036] Further, in step 6, the point defects are constructed in the amorphous structure of the fused quartz constructed in step 1, and O2 molecules and O atoms are randomly added, respectively, and the model is fully relaxed and energy minimization is performed.

[0037] Further, in step 7, the molecular dynamics reaction temperature is set to the equilibrium point of the electronic temperature and the lattice temperature calculated in step 3, the ReaxFF reaction force field is set, the NVT ensemble is adopted, the step is 0.1 fs, and the time is 20 ps.

[0038] Further, in step 8, the xyz file generated by the molecular dynamics reaction is analyzed by using the visual simulation software, the movement of atoms and the bonding process in the whole reaction process are observed, and whether the defect position in the fused quartz reacts with the introduced O2 molecules and O atoms to form a defect healing reaction is judged.

[0039] Compared with the prior art, the beneficial effects of the present application are:

[0040] The present application is an explanation method for damage threshold value improvement of fused quartz material in femtosecond laser processing / welding process, by establishing the electron-lattice heat transfer model of fused quartz under femtosecond laser irradiation, the dissociation model of environment molecules and gap molecules under the action of femtosecond laser and the molecular dynamics reaction model of fused quartz containing defects based on the ReaxFF reaction force field, the atomic structure change in the system before and after the reaction is analyzed, and finally the chemical reaction mechanism of fused quartz containing defects under the action of femtosecond laser is obtained, which explains the phenomenon of damage threshold value improvement of fused quartz after low-flux femtosecond laser irradiation. The present application perfects the current research on the process of femtosecond laser processing / welding of fused quartz, and fills the theoretical gap that the mechanism of damage threshold value improvement in the process of femtosecond laser processing / welding of fused quartz is not clear.

[0041] The present application uses simulation methods of various scales to simulate the chemical reaction process of fused quartz containing defects under the action of femtosecond laser. Compared with the experimental method, on the one hand, time and cost are greatly saved, and on the other hand, the problem that the current characterization means cannot accurately measure the change of defects with lower concentration is avoided.

[0042] The method of the present application helps to reveal the mechanism of the damage threshold improvement of fused quartz material under femtosecond laser, and provides an effective means for further improving the laser damage resistance of fused quartz material. BRIEF DESCRIPTION OF DRAWINGS

[0043] Figure 1 The lattice temperature evolution curve with time calculated by the electron-lattice heat transfer model based on the free electron generation theory, Drude equation and two-temperature equation in the embodiment of the present application.

[0044] Figure 2 The fused quartz model obtained after simulating the heating and annealing process in the manufacturing of fused quartz using the LAMMPS program based on the molecular dynamics method in the embodiment of the present application.

[0045] Figure 3 The evolution curve of the distance between the two oxygen atoms in the oxygen molecule under the action of femtosecond laser calculated based on the time-dependent density functional theory in the embodiment of the present application.

[0046] Figure 4 The evolution curve of the potential energy between the two oxygen atoms in the oxygen molecule under the action of femtosecond laser calculated based on the time-dependent density functional theory in the embodiment of the present application.

[0047] Figure 5 The model of constructing point defects in the amorphous structure of fused quartz constructed in step 1 and then adding O atoms in the embodiment of the present application.

[0048] Figure 6 The model of constructing point defects in the amorphous structure of fused quartz constructed in step 1 and then adding O2 molecules in the embodiment of the present application.

[0049] Figure 7 The model observed by using visual simulation software after randomly adding O atoms in the defect-containing fused quartz system and molecular dynamics reaction in the embodiment of the present application.

[0050] Figure 8 The model observed by using visual simulation software after randomly adding O2 molecules in the defect-containing fused quartz system and molecular dynamics reaction in the embodiment of the present application. DETAILED DESCRIPTION

[0051] The present application will be further described below in combination with the drawings and specific embodiments.

[0052] An explanation method of damage threshold improvement in the process of femtosecond laser machining / welding of fused quartz, comprising the following steps:

[0053] Step 1, determining the laser parameters used in the process of femtosecond laser machining / welding;

[0054] The femtosecond laser pulse width, wavelength, and repetition frequency of the femtosecond laser processing / welding system used are basically fixed values. In actual femtosecond laser processing / welding, the average power and spot radius are mainly adjusted.

[0055] Step 2, determining the macroscopic size of the fused quartz glass research area used;

[0056] Because the spot and heat-affected zone of the femtosecond laser are small, the length is set to 40 μm and the width is set to 20 μm in the determination of the macroscopic size. The calculation amount is reduced while accurately simulating the surface temperature change of the fused quartz under the action of the femtosecond laser.

[0057] Step 3, establishing an electron-lattice heat transfer model based on the free electron generation theory, Drude equation, and two-temperature equation to simulate the process of energy transfer from electrons to materials under the action of electroacoustic coupling;

[0058] Because the band gap of the fused quartz material is about 9 eV, it belongs to a dielectric material and does not have free electrons itself. Based on the electron transition theory, the free electron loss caused by multiphoton ionization, collision ionization, and Auger recombination, the Drude equation, and the two-temperature equation, an electron-lattice heat transfer model based on the free electron generation theory, the Drude equation, and the two-temperature equation is established as shown in formulas (1)-(24).

[0059]

[0060] The above formulas (1)-(9) are the free electron generation theory, wherein n e is the free electron concentration; T e is the electron temperature; G e is the electron generation rate; R e is the electron loss rate in the conduction band due to Auger recombination; J is the carrier current due to carrier diffusion; D is the bipolar diffusion coefficient; w is the electron concentration rate caused by multiphoton absorption; ω is the angular frequency of the incident laser; Φ(x) is the probability integral function; U0 is the band gap width of the fused quartz; U eff is the corrected band gap width; m e is the electron mass; m is the number of photons of multiphoton absorption; e is the elementary charge; F is the laser electric field strength; β is the multiphoton absorption coefficient; I is the laser intensity; δ is the collision ionization coefficient; K B is the Boltzmann constant; τ AR is the minimum Auger recombination time; C AR is the Auger recombination rate; is the reduced Planck constant.

[0061] After femtosecond laser irradiation on the surface of fused quartz, the original optical properties of the target material are changed. Under the action of nonlinear ionization, a large number of valence band electrons jump to the conduction band, and the free electron concentration on the surface of the material rapidly increases to 10 21 ~10 22 cm -3 The optical properties of the surface of the fused quartz change accordingly and exhibit metallic properties. The transient optical properties of the material surface can be represented by the complex dielectric function using the Sipe-Drude model, as shown in equations (10)-(16).

[0062]

[0063] In the above equations (10)-(16), ε is the dielectric constant of fused quartz; ε' is the complex dielectric constant of the plasma; ω p (n e )

[0064] is the frequency of the plasma; N0 is the initial carrier concentration of the valence band; ν is the collision rate of the carriers; ε0 is the vacuum dielectric constant; c is the speed of light in vacuum; f is the negative refractive index; f1 is the refractive index, f2 is the extinction coefficient, ε1 is the real part of the plasma complex dielectric constant, and ε2 is the imaginary part of the plasma complex dielectric constant ε'. R is the surface reflectivity of the ionized material, and α b is the heating coefficient of the Fresnel carrier.

[0065] When femtosecond laser irradiation is applied to the surface of fused quartz, the carriers inside the material are rapidly excited under the action of ionization, and then the energy is transferred to the lattice under the action of electro-acoustic coupling. The relaxation process of the lattice temperature is described by a set of coupled differential equations using the two-dimensional two-temperature model (TTM), as shown in equations (17)-(24).

[0066]

[0067] C e = 3n e K B (20)

[0068]

[0069] K e = -0.556 + 7.13 x 10 -3 T e (22)

[0070] K l = 0.1585 T l -1.23 (23)

[0071] C l= 1.978 + 3.54 x 10 -4 x T l - 3.68 x T l -2 (24) In the above formulae (17)-(24), C e is the electronic specific heat; C l is the lattice specific heat; g is the electron-lattice coupling coefficient; T l is the lattice temperature; K e is the electronic thermal conductivity; K l is the lattice thermal conductivity; S is the heat source term of the femtosecond laser; f is the femtosecond laser repetition frequency; P is the average power of the femtosecond laser; R0 is the spot radius; τ p is the laser pulse width; K B is the Spitzler constant.

[0072] The lattice temperature evolution curve calculated by the electron-lattice heat transfer model based on the free electron generation theory, the Drude equation and the two-temperature equation is shown in Figure 1 . The lattice temperature reached a peak at 12.2 ps, and then began to slowly decrease due to the low thermal conductivity of fused quartz. Since the time used in the molecular dynamics simulation is short, the equilibrium temperature can be directly taken as the reaction temperature under this power. In addition, the femtosecond laser action time is extremely short, and the lattice temperature can be reduced to room temperature at the end of a cycle, so the temperature effect cannot be superimposed, and therefore only the thermodynamic response of fused quartz under single-pulse laser action needs to be considered.

[0073] Step 4, constructing the amorphous structure of fused quartz in the molecular dynamics simulation software;

[0074] As shown in Figure 2 , the LAMMPS program based on the molecular dynamics method is used to simulate the heating and annealing process in the manufacture of fused quartz to convert the quartz crystal into a molten amorphous state. The unit cell of the quartz crystal initial structure is selected as β-cristobalite, and the classical potential function tersoff three-body potential is used for the interaction between atoms. The pressure P used in the simulation process is 1 atm, and the ensemble used is NPT and NVT ensemble. The heating process first uses the NPT ensemble, and the SiO2 crystal system constructed is heated from 300 K to 6000 K within 0.2 ns, and then annealed under the NVT ensemble after 0.1 ns of heat preservation. The annealing process uses the NVT ensemble, and is cooled from 6000 K to 300 K within 1 ns, and is heat preserved at 300 K for 50 ps. Finally, the NPT ensemble is used to relax at 300 K for 0.2 ns to reach equilibrium. The time step is 1 fs.

[0075] Step 5, simulate the reaction process of the molecules existing in the environment and the interstitial molecules inside the fused quartz glass under the action of femtosecond laser in the time-dependent density functional simulation software.

[0076] In the time-dependent density functional simulation software Octopus, the gs ground state calculation of O2 is first performed, in the subsequent td calculation, the femtosecond laser is set through the Gaussian function tdf_gaussian in TDFunctions, the parameters are the laser parameters confirmed in step 1, the femtosecond laser is set in the form of Gaussian wave packet in the TDExternalFields module, and the total calculation time is set to the end of single pulse laser. Extract the position information and interatomic potential information output by the calculation as shown in Figure 3 and Figure 4 The potential energy gradually tends to 0 while the bond length increases greatly. It can be judged that the oxygen molecules have neutral dissociation and produce neutral oxygen atoms.

[0077] Step 6, in the molecular dynamics simulation software, select the reaction potential function, add the molecular / atomic structure calculated in step 5 to the fused quartz amorphous structure constructed in step 4. The model is fully relaxed and energy minimized.

[0078] As shown in Figure 5 and Figure 6 , the point defects are constructed in the fused quartz amorphous structure constructed in step 1, and O2 molecules and O atoms are randomly added, respectively. The model is fully relaxed and energy minimized.

[0079] Step 7, in the molecular dynamics simulation software, obtain the atomic trajectory file at the temperature calculated in step 3.

[0080] Set the molecular dynamics reaction temperature to the equilibrium temperature of the electronic temperature and lattice temperature calculated in step 3, set the ReaxFF reaction force field corresponding to Si-O elements, use NVT ensemble, step size is 0.1 fs, and time is 20 ps.

[0081] Step 8, analyze the atomic trajectory file calculated in step 7.

[0082] As shown in Figure 7 and Figure 8 , analyze the xyz file generated by the molecular dynamics reaction using the visualization simulation software to observe the movement of atoms and the bonding process during the entire reaction process. The results show that oxygen atoms can fill the point defects in the fused quartz model, which is a chemical mechanism-based explanation method for the damage threshold improvement in the process of femtosecond laser processing / welding of fused quartz.

[0083] Further, in order to verify the accuracy of the interpretation method, a flight mass spectrometer, a photoluminescence spectrum, and an electron paramagnetic resonance can be used to verify the accuracy and feasibility.

[0084] Although the present application has been disclosed with reference to the above preferred embodiments, the above description is only preferred embodiments of the present application and is not intended to limit the present application, and various changes and modifications can be made by those skilled in the art without departing from the spirit and scope of the present application, and these changes and modifications will fall within the scope of the present application.

Claims

1. A method of explaining the damage threshold enhancement in a fused silica femtosecond laser machining / welding process, characterized by, The method comprises the following steps: Step 1, determining laser parameters used in femtosecond laser processing / welding process; Step 2, determining macroscopic size of fused quartz glass research area used; Step 3, establishing electron-lattice heat transfer model based on free electron generation theory, Drude equation and two-temperature equation to simulate the process that energy is transferred to material by electrons under the action of electroacoustic coupling; Step 4, constructing fused quartz amorphous structure in molecular dynamics simulation software; Step 5, simulating reaction process of molecules existing in environment and interstitial molecules in fused quartz glass under the action of femtosecond laser in time-dependent density functional simulation software; Step 6, in the molecular dynamics simulation software, selecting a reaction potential function, constructing point defects in the fused quartz amorphous structure constructed in step 4 and adding the molecular / atomic structure calculated in step 5; and performing energy minimization processing on the model after full relaxation; Step 7, in the molecular dynamics simulation software, obtaining an atomic trajectory file at the temperature calculated in step 3; Step 8, analyzing the atomic trajectory file calculated in step 7.

2. The method of claim 1, wherein, Step 1 determines laser parameters used in femtosecond laser processing / welding process; the laser parameters include femtosecond laser pulse width, wavelength, power, repetition frequency and spot radius.

3. The method of claim 1, wherein, Step 3 establishes an electron-lattice heat transfer model based on free electron generation theory, Drude equation and two-temperature equation to calculate the equilibrium point of electron temperature and lattice temperature.

4. The method of claim 1, wherein, Step 4 constructs a fused quartz amorphous structure; a LAMMPS program based on a molecular dynamics method is used to simulate the heating and annealing process in fused quartz manufacturing, so that the quartz crystal is converted into a molten amorphous state; a beta-cristobalite is selected as the unit cell of the initial structure of the quartz crystal, and a tersoff three-body potential is used as the classical potential function between atoms; an atmospheric pressure P of 1 atm is used in the simulation process, and the ensemble used is divided into NPT and NVT ensembles; in the heating process, the NPT ensemble is used first, the SiO2 crystal system constructed is heated from 300K to 6000K within 0.2ns, and annealing is performed after 0.1ns of heat preservation in the NVT ensemble; in the annealing process, the NVT ensemble is used, the temperature is lowered from 6000K to 300K within 1ns, and the temperature is maintained at 300K for 50ps; finally, the NPT ensemble is used, and the system is relaxed at 300K for 0.2ns to reach equilibrium; the time step is 1fs.

5. The method of claim 1, wherein, The environment molecules and interstitial molecules in the fused quartz that will react with the fused quartz system mainly include O2. In the time-dependent density functional simulation software Octopus, the gs ground state of O2 is calculated first, in the subsequent td calculation, the femtosecond laser is set through the Gaussian function tdf_gaussian in TDFunctions, the femtosecond laser is set in the form of Gaussian wave packet in the TDExternalFields module, and the total calculation time is set to the end of the single-pulse laser; the position information file and the energy file calculated are extracted, the atomic distance and the potential energy change are calculated to determine whether the O2 molecule is dissociated.

6. The method of claim 1, wherein, In step 6, point defects are constructed in the fused quartz amorphous structure constructed in step 1, and O2 molecules and O atoms are randomly added, respectively, and energy minimization processing is performed on the model after full relaxation.

7. The method of claim 1, wherein, In step 7, the molecular dynamics reaction temperature is set to the equilibrium point of the electron temperature and the lattice temperature calculated in step 3, the ReaxFF reaction force field is set, the NVT ensemble is used, the step is 0.1 fs, and the time is 20 ps.

8. The method of claim 1, wherein, In step 8, the xyz file generated by the molecular dynamics reaction in step 7 is analyzed by using a visual simulation software, the movement of atoms and the bonding process in the entire reaction process are observed, and it is judged whether the defect position in the fused quartz reacts with the introduced O2 molecules and O atoms to heal the defects.

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