Method and device for realizing directional high-yield crystallization in glass

Abstract

The invention belongs to the related technical field of laser processing, and discloses a method and a device for realizing directional high-yield devitrification in glass, and the method comprises the following steps: applying femtosecond laser pulse to the interior of the glass, modifying agent ions and forming agent ions in the glass are directionally migrated, and an ion component gradient distribution area is formed due to different migration speeds; controlling the femtosecond laser pulse to enable the path of the ion component gradient distribution area in the preset direction to be shortest or enable the ion concentration difference of the boundary of the ion component gradient distribution area in the preset direction to be maximum; and carrying out heat treatment on the glass, so that the ions in gradient distribution are further diffused, the ion diffusion flux in the preset direction is maximum, and in a laser irradiation area, the ions in the glass tend to nucleate and grow in the preset direction to form a nanocrystal structure with consistent orientation. According to the treatment, the precipitation position and the growth direction of the nanocrystals can be accurately controlled while the precipitation yield of the crystals is ensured.

Description

Technical Field

[0001] This invention belongs to the field of laser processing technology, and more specifically, relates to a method and apparatus for achieving high-yield directional crystallization inside glass. Background Technology

[0002] Precisely controlling the orientation and position of nanostructures in homogeneous materials is one of the core challenges in overcoming the performance bottleneck of high-performance photonic devices. Taking glass as an example, by achieving the precipitation of oriented nanocrystals within the matrix through a controlled crystallization process, it is possible to endow it with anisotropic optical functions while maintaining high light transmittance.

[0003] However, while traditional heat treatment processes can achieve large-scale crystal growth and obtain high yields, it is difficult to precisely control the precipitation position and growth orientation of crystals, resulting in crystals that are usually randomly arranged and macroscopically exhibit isotropic properties.

[0004] In recent years, femtosecond laser direct writing technology has become a common method for achieving glass microcrystallization due to its high flexibility, three-dimensional spatial selectivity, and precise controllability of thermal accumulation effects, enabling the manipulation of crystal precipitation sites. However, while femtosecond laser direct writing can control crystal precipitation sites, controlling crystal growth orientation remains challenging for most materials. Furthermore, the inherent micron-scale working volume and relatively narrow crystal growth temperature window of femtosecond lasers severely limit the yield of precipitable nanocrystals and the overall processing efficiency in a single processing run.

[0005] Therefore, how to ensure the yield of crystal precipitation while precisely controlling the precipitation location and growth direction of nanocrystals is a technical problem that urgently needs to be solved. Summary of the Invention

[0006] In view of the above-mentioned defects or improvement needs of the prior art, the present invention provides a method and apparatus for achieving high-yield directional crystallization inside glass. Its purpose is to ensure the crystal precipitation yield while precisely controlling the precipitation position and growth direction of nanocrystals.

[0007] According to a first aspect of the present invention, a method for achieving high-yield directional crystallization within a glass is provided, comprising: Step S1: Apply a femtosecond laser pulse to the inside of the glass, so that the modifier ions and forming agent ions inside the glass undergo directional migration in the laser irradiation area, and form an ion composition gradient distribution area due to the different migration speeds. By controlling the femtosecond laser pulse, the path of the ion composition gradient distribution area in the preset direction is minimized or the ion concentration difference at the boundary of the ion composition gradient distribution area in the preset direction is maximized. Step S2: Heat-treat the glass to allow the gradient-distributed ions to diffuse further and maximize the ion diffusion flux along a preset direction. In the laser irradiation area, ions inside the glass tend to nucleate and grow along the preset direction, forming a nanocrystal structure with a consistent orientation.

[0008] According to a second aspect of the present invention, an apparatus for achieving high-yield directional crystallization within a glass is provided, comprising: A femtosecond laser component is used to apply femtosecond laser pulses to the interior of glass, causing modifier ions and forming agent ions inside the glass to migrate in a directional manner in the laser irradiation area, and forming an ion composition gradient distribution region due to different migration speeds. By controlling the femtosecond laser pulse, the path of the ion composition gradient distribution region in a preset direction is minimized or the ion concentration difference at the boundary of the ion composition gradient distribution region in a preset direction is maximized. The heating component is used to heat-treat the glass, so that the ions forming a gradient distribution diffuse further and the ion diffusion flux along the preset direction is maximized. In the laser irradiation area, the ions inside the glass tend to nucleate and grow along the preset direction to form a nanocrystal structure with consistent orientation.

[0009] In summary, compared with the prior art, the technical solutions conceived in this invention have the following main advantages: The method for achieving high-yield directional crystallization inside glass disclosed in this invention involves applying a femtosecond laser pulse to the glass in step S1. The forming agent ions and modifying agent ions in the glass network undergo directional migration. Since the migration speeds of the forming agent ions and modifying agent ions are different, the migration motion will cause significant composition rearrangement in the laser-irradiated area, thereby forming a significant ion composition gradient distribution region in the laser-irradiated area. In addition to forming a gradient distribution, the state of the gradient distribution region in different directions is controlled by controlling the femtosecond laser pulse, so that the path of the ion composition gradient distribution region in the preset direction is the shortest or the ion concentration difference at the boundary of the ion composition gradient distribution region in the preset direction is the largest. The gradient distribution formed in the first stage and its state in different directions provide favorable conditions for subsequent heat treatment to induce crystal orientation growth. In step S2, the glass is heat-treated. Under thermal drive, the pre-formed chemical gradient is conducive to guiding ions to diffuse in the gradient direction. Since the path of the ion composition gradient distribution region in the preset direction is the shortest or the ion concentration difference at the boundary of the ion composition gradient distribution region in the preset direction is the largest, ions are more inclined to selectively enrich along the preset direction. With the synergistic effect of the orientation distribution of the chemical gradient and thermal drive, the crystal grows preferentially in a specific direction to form a nanocrystalline structure with consistent orientation. Through the above processing method, on the one hand, since the crystal grows in the laser irradiation area, the growth position of the crystal can be controlled by controlling the position of the laser irradiation area; on the other hand, the growth orientation of the crystal can be controlled through the synergistic effect of the orientation distribution of the chemical gradient and thermal driving; furthermore, the large-volume uniform heating characteristics of heat treatment enable efficient precipitation of nanocrystals within the glass, ensuring the yield of crystal precipitation. Overall, the crystallization method disclosed in this invention can ensure the yield of crystal precipitation while precisely controlling the precipitation position and growth direction of nanocrystals. Attached Figure Description

[0010] Figure 1 This is a flowchart of a method for achieving high-yield directional crystallization inside glass according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the crystal formation process using low-frequency linearly polarized laser in one embodiment of the present invention; Figure 3 This is a schematic diagram of the crystal formation process using a high-frequency laser in one embodiment of the present invention; Figure 4 It is the DSC curve of lithium disilicate glass; Figure 5 This is a SEM image of an elliptical phase-separated nanostructure block formed in one embodiment of the present invention; Figure 6 This is an example of XRD patterns of glass obtained under various different processing methods in one embodiment; Figure 7 This is a pole figure analysis result of the (200) and (211) crystal planes of the laser-modified oriented β-spodumene crystal in one embodiment of the present invention. Detailed Implementation

[0011] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0012] This invention discloses a method for achieving high-yield, directional crystallization inside glass.

[0013] like Figure 1 The diagram shows a flowchart of a method for achieving high-yield directional crystallization inside glass according to an embodiment of the present invention. The method mainly includes the following core steps: Step S1: Apply a femtosecond laser pulse to the inside of the glass, so that the modifier ions and forming agent ions inside the glass undergo directional migration in the laser irradiation area and form an ion composition gradient distribution area due to different migration speeds. By controlling the femtosecond laser pulse, the path of the ion composition gradient distribution area in the preset direction is minimized or the ion concentration difference at the boundary of the ion composition gradient distribution area in the preset direction is maximized. Step S2: Heat-treat the glass to allow the ions that form a gradient distribution to diffuse further and maximize the ion diffusion flux along a preset direction. In the laser irradiation area, the ions inside the glass tend to nucleate and grow along the preset direction, forming a nanocrystal structure with a consistent orientation.

[0014] Specifically, in step S1, a femtosecond laser pulse is applied to the glass. When the femtosecond laser pulse is focused inside the glass matrix, local plasma is excited through nonlinear multiphoton absorption and avalanche ionization mechanisms, achieving ultrafast energy deposition and forming transient extreme thermodynamic conditions (high temperature and high pressure conditions). Under these conditions, the forming agent ions and modifier ions in the glass network undergo directional migration. Due to the difference in migration speed between the forming agent ions and modifier ions, the migration movement leads to significant compositional rearrangement in the laser-irradiated area. For example, when the migration speed of the forming agent ions is less than that of the modifier ions, the forming agent ions will be in the center after migration, while the modifier ions will move to the periphery, thus forming a significant ion composition gradient distribution region in the laser-irradiated area. In addition to forming the gradient distribution, it is also necessary to control the state of the gradient distribution region in different directions by controlling the femtosecond laser pulse, so that the path of the ion composition gradient distribution region in the preset direction is the shortest or the ion concentration difference at the boundary of the ion composition gradient distribution region in the preset direction is the largest. The gradient distribution formed in the first stage and its states in different directions provide favorable conditions for subsequent heat treatment to induce crystal orientation growth.

[0015] In step S2, the glass is heat-treated. Under thermal drive, the pre-formed chemical gradient is conducive to guiding the diffusion of ions in the gradient direction. Since the path of the ion composition gradient distribution area in the preset direction is the shortest or the ion concentration difference at the boundary of the ion composition gradient distribution area in the preset direction is the largest, the ions are more inclined to selectively enrich along the preset direction, that is, the ion flux is the largest in the preset direction. With the synergistic effect of the orientation distribution of the chemical gradient and thermal drive, the crystal preferentially grows along a specific direction to form a nanocrystalline structure with consistent orientation.

[0016] Through the above processing method, on the one hand, since the crystal grows in the laser irradiation area, the growth position of the crystal can be controlled by controlling the position of the laser irradiation area; on the other hand, the growth orientation of the crystal can be controlled through the synergistic effect of the orientation distribution of the chemical gradient and thermal driving; furthermore, the large-volume uniform heating characteristics of heat treatment enable efficient precipitation of nanocrystals within the glass, ensuring the yield of crystal precipitation. Overall, the crystallization method disclosed in this invention can ensure the yield of crystal precipitation while precisely controlling the precipitation position and growth direction of nanocrystals.

[0017] The following introduces two processing methods for femtosecond laser pulses. Both methods can form an ion composition gradient distribution region after laser processing. However, by adjusting the parameters of the femtosecond laser pulse, the state of the ion composition gradient distribution region in different directions can be adjusted.

[0018] The first method uses low-frequency linearly polarized lasers. Specifically, the femtosecond laser pulse is a linearly polarized laser with a preset polarization direction. The linearly polarized laser can generate multiple independent elliptical phase-separated nanostructure blocks with their short axes pointing in the preset direction in the laser irradiation area. The elliptical phase-separated nanostructure blocks are ion composition gradient distribution regions. After heat treatment, crystals growing along the short axis direction are precipitated inside each elliptical phase-separated nanostructure block.

[0019] This approach emphasizes that femtosecond laser pulses must satisfy two conditions: Condition 1: Linearly polarized light; The polarization direction of the linearly polarized light is a preset direction, which is the crystal growth orientation; Condition 2: Low frequency; different glass materials require different low frequencies. In principle, the frequency of a femtosecond laser pulse can generate multiple independent elliptical phase-separated nanostructures in the laser irradiation area. The specific value of this frequency can be determined experimentally before operation.

[0020] like Figure 2 The diagram illustrates the crystal formation process using a low-frequency linearly polarized laser in one embodiment of the present invention. Before applying the low-frequency linearly polarized laser, the glass composition is uniformly distributed. After applying the laser, the instantaneous energy deposition causes a sharp increase in local temperature and pressure, leading to directional migration and separation of different components within the glass, forming nanoscale regions of compositional difference. Because the writing effect of the linearly polarized laser is accompanied by a near-field enhancement effect, the local electromagnetic field is significantly enhanced on both sides of the nanostructure perpendicular to the laser polarization direction. This enhancement further strengthens multiphoton ionization and local energy deposition, causing the nanostructure generated by liquid-phase separation to stretch along the direction perpendicular to the polarization direction. This process ultimately leads to the formation of an elliptical phase-separated structure with a chemical gradient within the modified region, i.e., an elliptical phase-separated nanostructure block. The minor axis of this ellipse is parallel to the polarization direction, and the polarization direction, minor axis direction, and preset direction are all in the same direction. Subsequently, heat treatment is performed to achieve the precipitation of a large number of crystals. Since the elliptical phase-separated nanostructure block has the shortest path in the minor axis direction, the thermally driven gradient-distributed ions have the highest flux in the minor axis direction and are more inclined to selectively enrich and nucleate along the minor axis direction, so that the growth direction of most of the precipitated crystals is in the minor axis direction.

[0021] Optionally, the repetition frequency of the linearly polarized laser should not exceed 250 kHz. Too high a frequency will exacerbate the inter-pulse thermal accumulation effect, and the local temperature rise induced by the preceding pulse will not have fully relaxed before subsequent pulses superimpose their effects, leading to an expansion of the thermal diffusion range and disrupting the spatial locality of the phase separation process. Controlling the frequency below 250 kHz ensures sufficient thermal relaxation time between adjacent pulses, allowing the local thermal field to attenuate effectively. This ensures that phase separation proceeds orderly within a limited spatial scale, successfully forming elliptical phase-separated nanostructures with clear boundaries and controllable dimensions.

[0022] Optionally, the scanning speed of the laser should not exceed 0.5 mm / s. If the scanning speed of the low-frequency laser is too fast, the thermal accumulation effect will be too small, resulting in a low yield of elliptical nanostructures and a low yield of oriented crystals. Controlling the scanning speed to not exceed 0.5 mm / s can further ensure the crystal precipitation yield.

[0023] Optionally, the major axis of the elliptical phase-separated nanostructure block ranges from 50 nm to 400 nm, and the minor axis ranges from 20 nm to 250 nm. This size range of the elliptical phase-separated nanostructure block can provide an effective ion concentration difference along a preset direction while ensuring the spatial distribution density of the nanostructure, thereby promoting high-density nucleation and directional growth of oriented nanocrystals during heat treatment.

[0024] The second method uses a high-frequency laser with a scanning direction perpendicular to the laser as a preset direction (crystal growth direction). Specifically, a femtosecond laser pulse scans the glass along a scanning direction perpendicular to the preset direction, and during the scanning, a gradient distribution along the preset direction is generated at the boundary of the modified region formed by laser irradiation. After heat treatment, a nanocrystal structure growing along the scanning direction is generated at the boundary of the modified region formed by laser irradiation.

[0025] This method emphasizes that the femtosecond laser pulse must be high-frequency and scanned along a preset direction. Different glass materials require different high frequencies. In principle, the frequency of the femtosecond laser pulse can be adjusted so that during the scanning process, a gradient distribution is generated along the preset direction at the boundary of the modified region formed by laser irradiation, resulting in the highest ion concentration difference along the preset direction during subsequent heat treatment. The specific value of this frequency can be determined experimentally before operation.

[0026] like Figure 3The diagram shown is a schematic diagram of the crystal formation process using a high-frequency laser in one embodiment of the present invention. Before applying a high-frequency laser, the glass composition is uniformly distributed. After applying the high-frequency laser, the laser scans along a direction perpendicular to a preset direction. Unlike the low-frequency case, with the high-frequency pulse, the thermal accumulation effect becomes the dominant mechanism. The continuous pulse arrives before the heat from the previous pulse has completely dissipated, causing continuous heat accumulation in the focal region and maintaining a high temperature, making it difficult to form multiple independently distributed elliptical structural blocks. However, the thermal accumulation effect still causes local changes in the elemental concentration in the glass, forming an elemental gradient. To maximize the flux of ions along the preset direction during heating, the femtosecond laser pulse is controlled to scan along a direction perpendicular to the preset direction. This generates a gradient distribution with the maximum ion concentration difference at the boundary of the modified region formed by laser irradiation. This gradient direction is perpendicular to the scanning direction. Subsequently, heat treatment is performed to achieve a large-scale crystal precipitation. Because there is a gradient distribution with the maximum ion concentration difference at the boundary of the modified region formed by laser irradiation, the thermally driven gradient-distributed ions have the highest flux in the preset direction and are more inclined to selectively enrich and nucleate along the preset direction, resulting in the majority of the precipitated crystals growing in the preset direction.

[0027] Therefore, unlike in the case of low frequency, where crystal orientation depends on polarization, crystal orientation under high frequency laser irradiation is independent of polarization.

[0028] Optionally, the repetition frequency of the high-frequency femtosecond laser pulse is not less than 300 kHz. When the repetition frequency is too low, nanoscale elliptical phase separation structures are easily formed within the laser focusing region, and their morphology is modulated by the laser polarization direction. Controlling the frequency above 300 kHz enhances the inter-pulse thermal accumulation effect and maintains the temperature of the modified region above the critical phase separation temperature, thereby suppressing the elliptical nanophase separation process and forming a uniform modified region on the micrometer scale. Within this modified region, modifying ions are enriched at the edges, while network-forming ions are aggregated at the center. During subsequent heat treatment, this ion distribution characteristic leads to a difference in the diffusion behavior of modifying ions and network-forming ions along a predetermined direction, thereby establishing an effective ion concentration difference in this direction and driving the nanocrystals to achieve directional growth independent of the laser polarization direction.

[0029] Optionally, the scanning speed of the high-frequency femtosecond laser pulse is not less than 0.05 mm / s. Since the high frequency itself has a strong thermal accumulation effect, if the scanning speed is too slow, the thermal accumulation effect will be stronger, which will lead to the destruction of the laser-modified structure (such as microcracks).

[0030] Optionally, the heat treatment temperature of the glass is within the range of ±50°C of the glass crystallization peak temperature, so as to maximize the precipitation of oriented crystals.

[0031] The following explanation will take the application of low-frequency linearly polarized laser to lithium disilicate glass as an example.

[0032] like Figure 4 The image shows the DSC curve of lithium disilicate glass. Differential scanning calorimetry (DSC) is an important method for analyzing the thermodynamic properties of glass-ceramics, playing a crucial role in determining the annealing temperature and heat treatment regime. Figure 4 As shown, the glass transition temperature (Tg) of lithium disilicate glass is approximately 480℃. The two exothermic peaks appearing in the curve correspond to the crystal precipitation process, and analysis reveals that they are the exothermic peaks of crystallization of lithium metasilicate (Li2SiO3) and lithium disilicate (Li2Si2O5) phases, respectively.

[0033] After applying low-frequency linearly polarized laser light, the diffusion rates of the forming agent ions Si, Al, and O in the lithium disilicate glass are lower than those of the modifying agent ions Li, P, and K. This diffusion results in the formation of multiple elliptical phase-separated nanostructures with the modifying agent ions on the periphery and the forming agent ions at the center. Figure 5 The image shown is an SEM image of an elliptical phase-separated nanostructure block formed in one embodiment of the present invention. When written with a linearly polarized laser, elliptical nanostructures are distributed in the sample before heat treatment, with their major axis direction perpendicular to the laser polarization direction. After heat treatment at 640 °C for 30 min, a large number of oriented nanocrystals precipitate out, and adjacent grains form a three-dimensional interconnection network through the crystallization process, which causes the elliptical boundary of the initial nanostructure to gradually weaken. The formation of this interconnection network makes the micromorphological features of the inner region of the ellipse and its outer region tend to be consistent, and finally difficult to distinguish in the SEM image.

[0034] The experiment also compared the crystal precipitation of glass under various different treatment methods. For example... Figure 6 The image shows the XRD patterns of glass obtained under various processing methods in one embodiment.

[0035] Laser-modified only, without heat treatment, only generates trace amounts of LiAlSi3O8 crystals in the laser-modified region.

[0036] Only heat treatment without laser treatment was performed, resulting in the formation of Li2SiO3 crystals.

[0037] Laser-modified and heat-treated processes were performed, resulting in the precipitation of a large amount of β-LiAlSi2O6 crystals (β-spodumene) in the laser-modified region, accompanied by the formation of a small amount of Li2SiO3 crystals.

[0038] Previous studies have shown that if the precipitated crystal has a preferred orientation, its specific crystal plane will exhibit significant diffraction peak enhancement in the XRD pattern. The (211) crystal plane diffraction peak intensity of the LiAlSi2O6 crystal obtained after laser treatment and heat treatment is significantly higher than other peak positions, indicating that the LiAlSi2O6 crystal may have obvious orientation characteristics. However, the Li2SiO3 crystal precipitated by heat treatment alone does not exhibit this characteristic, indicating that the Li2SiO3 crystal does not possess specific orientation characteristics.

[0039] To further verify this, XRD texture analysis was used to determine the (200) and (211) crystal plane pole figure distributions of the LiAlSi2O6 crystal in the modified region after laser treatment and heat treatment. Figure 7 The figure shown is a pole figure analysis result of the (200) and (211) crystal planes of the laser-modified oriented β-spodumene crystal in one embodiment of the present invention. The measurement results show that the central intensity of the (200) crystal plane pole figure is low, and the outer ring is diffusely distributed, indicating that... <200> The crystal orientation of the (211) plane is relatively weak (left figure). In contrast, the intensity of the (211) crystal plane pole figure is highly concentrated in the central region and the intensity of the outer ring is negligible (right figure). The intensity is mainly concentrated in the center of the pole figure, and the closer to the center of the pole figure, the greater the corresponding diffraction intensity, indicating that... <211> The large number of oriented crystals confirms that β-LiAlSi2O6 crystals exhibit a relatively high degree of orientation. <211> The orientation is more ordered. Therefore, the nanocrystals precipitated by the present invention are oriented.

[0040] The present invention also discloses an apparatus for achieving high-yield directional crystallization inside glass, comprising: The femtosecond laser component is used to apply femtosecond laser pulses to the interior of glass, causing modifier ions and forming agent ions inside the glass to migrate in a directional manner in the laser irradiation area. Due to the different migration speeds, an ion composition gradient distribution region is formed. By controlling the femtosecond laser pulse, the path of the ion composition gradient distribution region in a preset direction is minimized or the ion concentration difference at the boundary of the ion composition gradient distribution region in a preset direction is maximized. The heating component is used to heat-treat the glass, so that the ions that form a gradient distribution diffuse further and the ion diffusion flux along the preset direction is maximized. In the laser irradiation area, the ions inside the glass tend to nucleate and grow along the preset direction to form a nanocrystal structure with consistent orientation.

[0041] The femtosecond laser component can perform step S1 of the crystallization method described above, and the heating component can perform step S2 of the crystallization method described above. The specific functions of each component can be found in the above description and will not be repeated here.

[0042] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as the combination of these technical features does not contradict each other, it should be considered within the scope of this specification. It should be noted that the terms "in one embodiment," "for example," and "again" are intended to illustrate the present invention and are not intended to limit the present invention.

[0043] The above embodiments merely illustrate several implementation methods of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention.

Claims

1. A method for achieving high-yield directional crystallization inside glass, characterized in that, include: Step S1: Apply a femtosecond laser pulse to the inside of the glass, so that the modifier ions and forming agent ions inside the glass undergo directional migration in the laser irradiation area, and form an ion composition gradient distribution area due to the different migration speeds. By controlling the femtosecond laser pulse, the path of the ion composition gradient distribution area in the preset direction is minimized or the ion concentration difference at the boundary of the ion composition gradient distribution area in the preset direction is maximized. Step S2: Heat-treat the glass to allow the ions that form a gradient distribution to diffuse further and maximize the ion diffusion flux along a preset direction. In the laser irradiation area, the ions inside the glass tend to nucleate and grow along the preset direction, forming a nanocrystal structure with a consistent orientation.

2. The method for achieving high-yield directional crystallization inside glass as described in claim 1, characterized in that, The femtosecond laser pulse is a linearly polarized laser with a preset polarization direction. The linearly polarized laser can generate multiple independent elliptical phase-separated nanostructure blocks with the preset short axis direction in the laser irradiation area. The elliptical phase-separated nanostructure blocks are the ion composition gradient distribution regions. After the heat treatment, crystals growing along the short axis direction are precipitated inside each elliptical phase-separated nanostructure block.

3. The method for achieving high-yield directional crystallization inside glass as described in claim 2, characterized in that, The major axis of the elliptical phase-separated nanostructure block ranges from 50 nm to 400 nm, and the minor axis ranges from 20 nm to 250 nm.

4. The method for achieving high-yield directional crystallization inside glass as described in claim 2, characterized in that, The repetition frequency of the linearly polarized laser does not exceed 250 kHz, and the scanning speed of the laser does not exceed 0.5 mm / s.

5. The method for achieving high-yield directional crystallization inside glass as described in claim 1, characterized in that, The femtosecond laser pulse scans the glass along a scanning direction perpendicular to the preset direction, and during the scanning, a gradient distribution along the preset direction is generated at the boundary of the modified region formed by laser irradiation. After the heat treatment, a nanocrystal structure growing along the scanning direction is generated at the boundary of the modified region formed by laser irradiation.

6. The method for achieving high-yield directional crystallization inside glass as described in claim 5, characterized in that, The repetition frequency of the femtosecond laser pulse is not less than 300 kHz.

7. The method for achieving high-yield directional crystallization inside glass as described in claim 5, characterized in that, The single-pulse energy of the femtosecond laser pulse is not higher than 2000 nJ, and the scanning speed of the laser is not lower than 0.05 mm / s.

8. The method for achieving high-yield directional crystallization inside glass as described in any one of claims 1 to 7, characterized in that, The heat treatment temperature for the glass is within the range of ±50°C of the glass crystallization peak temperature.

9. The method for achieving high-yield directional crystallization inside glass as described in any one of claims 1 to 7, characterized in that, The glass is lithium disilicate glass, and the orientation of the nanocrystal structure formed inside the lithium disilicate glass is c-axis.

10. An apparatus for achieving high-yield directional crystallization inside glass, characterized in that, include: A femtosecond laser component is used to apply femtosecond laser pulses to the interior of glass, causing modifier ions and forming agent ions inside the glass to migrate in a directional manner in the laser irradiation area, and forming an ion composition gradient distribution region due to different migration speeds. By controlling the femtosecond laser pulse, the path of the ion composition gradient distribution region in a preset direction is minimized or the ion concentration difference at the boundary of the ion composition gradient distribution region in a preset direction is maximized. The heating component is used to heat-treat the glass, so that the ions forming a gradient distribution diffuse further and the ion diffusion flux along the preset direction is maximized. In the laser irradiation area, the ions inside the glass tend to nucleate and grow along the preset direction to form a nanocrystal structure with consistent orientation.

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