X-cut lithium niobate crystal growth method and temperature field structure

Abstract

The invention discloses an X-cut lithium niobate crystal growth method and a temperature field structure, the X-axis is defined to extend upwards, the temperature field structure used in the method comprises a heat preservation structure and a crucible, the heat preservation structure and the crucible are both elliptical cylinders with open upper ends and closed lower ends, during use, the crucible is placed in the heat preservation structure, the central axes of the crucible and the heat preservation structure coincide, and the crucible is placed in the heat preservation structure. The thermal insulation structure is provided with a long axis a1 and a short axis b1, the crucible is provided with a long axis a2 and a short axis b2, the long axis of the thermal insulation structure and the long axis of the crucible both extend in the Y-axis direction, the short axis of the thermal insulation structure and the short axis of the crucible both extend in the Z-axis direction, and the lithium niobate crystal grown by the X-cut lithium niobate crystal growth method is an elliptic cylinder. According to the invention, the problem that the crystal is easy to crack in the prior art is solved, and the success rate of growth of the X-axis lithium niobate crystal is improved.

Description

Technical Field

[0001] The invention relates to the technical field of crystal growth, and in particular to an X-cut lithium niobate crystal growth method and a temperature field structure. Background Art

[0002] Lithium niobate crystals have excellent electro-optical effects, almost unlimited intrinsic modulation bandwidth, low optical insertion loss, low transmission power consumption and good device stability, and therefore have attracted widespread attention from researchers. Integrated optical circuits based on lithium niobate single crystal thin films have broken through key performance parameters such as transmission loss and optical confinement of traditional titanium diffusion and proton exchange waveguides. Scientists have achieved various active and passive integrated optoelectronic devices with ultra-low transmission loss, ultra-low half-wave voltage and ultra-small size in the laboratory.

[0003] Lithium niobate single crystal film is peeled off from lithium niobate wafer. Lithium niobate crystal belongs to the trigonal system. The largest component γ in the electro-optic coefficient matrix 33 ~30.9 pm / V@632 nm, to achieve on-chip integration of lithium niobate, an X-axis wafer is required, waveguide coplanar electrodes are used, and an electric field is applied along the Z axis of the crystal to utilize the electro-optical effectγ 33 weight; on the other hand, the preparation of integrated chips requires semiconductor micro-machining technology. The current mainstream semiconductor production line is 8 inches, so the 8-inch X-axis lithium niobate crystal is the cornerstone of the integrated optoelectronic chip industry chain.

[0004] However, the X-axis is a non-rotationally symmetrical axis, and the growth rates of each crystal plane on the growth interface are different, making it the most difficult direction to grow. For a long time, China has only been able to provide a small amount of 3-inch and 4-inch X-axis lithium niobate crystals, and some of them still use the technical route of horizontally digging out small-sized X-axis crystal rods from large-sized Z-axis crystals. Especially as the size of the crystal increases, the horizontal digging technology route becomes increasingly unfeasible. Therefore, breaking through the key technology for the industrialization of large-sized X-axis lithium niobate crystals is the key foundation for building an integrated optoelectronic chip industry chain.

[0005] The growth of X-axis lithium niobate crystals is carried out in a temperature field structure, which includes a crucible and a heat preservation structure. The heat preservation structure and crucible of the existing temperature field structure are cylindrical, and a small hole is opened on one side of the heat preservation structure to observe the growth situation. At the same time, crystal rotation or crucible rotation and pulling are applied to increase forced convection and ensure the uniformity of the entire temperature gradient distribution. The obtained lithium niobate crystal is cylindrical.

[0006] Since the existing temperature field structure is most commonly used to grow Z-axis lithium niobate crystals, and the lithium niobate crystals grown along the Z-axis are isotropic, that is, the various properties and growth rates in the X-axis and Y-axis directions are not much different, the completely symmetrical insulation structure provides an isotropic temperature distribution, which is very consistent with the characteristics of the Z-axis crystal, so it greatly improves the crystal quality. However, when using the existing temperature field structure to grow X-axis lithium niobate crystals, due to the different growth rates of X-axis lithium niobate crystals in different directions, the traditional cylindrical symmetrical insulation structure and crucible are no longer suitable for X-axis crystal growth. When pulling lithium niobate crystals along the X-axis, due to the large difference in growth rates between the Z-axis and Y-axis directions, anisotropic nucleation and twinning are very likely to occur during the growth process; at the same time, it is accompanied by large thermal stress and crystal cracking, resulting in an extremely low success rate of crystal growth and difficulty in industrial production. Summary of the invention

[0007] The embodiment of the present invention provides an X-cut lithium niobate crystal growth method and a temperature field structure to solve the technical problem that the X-axis lithium niobate crystals grown in the prior art are prone to anisotropic nucleation, twinning, and crystal cracking, resulting in a low crystal growth success rate.

[0008] The embodiment of the present invention provides an X-cut lithium niobate crystal growth method and a temperature field structure: An X-cut lithium niobate crystal growth method is used to grow an X-axis lithium niobate crystal, wherein the X-axis is defined to extend upward, and the temperature field structure used in the method comprises a heat preservation structure and a crucible, wherein the heat preservation structure and the crucible are both elliptical cylinders with an upper end opening and a lower end closing. When in use, the crucible is placed in the heat preservation structure, and the central axes of the crucible and the heat preservation structure coincide with each other. The heat preservation structure has a major axis a1 and a minor axis b1, and the crucible has a major axis a2 and a minor axis b2. The major axis of the heat preservation structure and the major axis of the crucible both extend in the Y-axis direction, and the minor axis of the heat preservation structure and the minor axis of the crucible both extend in the Z-axis direction. The lithium niobate crystal grown by the X-cut lithium niobate crystal growth method is an elliptical cylinder.

[0009] Furthermore, the ratio of the major axis a1 to the minor axis b1 of the heat-insulating structure is equal to the ratio of the major axis a2 to the minor axis b2 of the crucible.

[0010] Furthermore, the ratio of the major axis a1 to the minor axis b1 of the thermal insulation structure is d, and 1.1≤d≤1.5.

[0011] Furthermore, the growth rate of the X-axis lithium niobate crystal along the Y-axis is V Y , the growth rate along the Z axis is V z ,d=V Y :V Z .

[0012] Furthermore, the difference between the long axis of the heat-insulating structure and the long axis of the crucible is a=a1-a2, 2cm≤a≤5cm.

[0013] Furthermore, during the growth process, the lithium niobate crystal is pulled along the X-axis at a pulling speed of V t ,0.2mm / h≤V t ≤1mm / h.

[0014] Furthermore, during the growth of the lithium niobate crystal, the crucible and the crystal do not rotate, and the crystal is observed from directly above the temperature field structure.

[0015] Furthermore, the thermal insulation structure includes an elliptical cylinder and a cylinder bottom connected to the lower end of the cylinder, the cylinder includes a quartz layer, a thermal insulation cotton layer and a corundum layer, and the cylinder bottom includes a thermal insulation cotton layer and a zircon sand layer.

[0016] Furthermore, the quartz layer, thermal insulation cotton layer and corundum layer of the cylinder are arranged in sequence from the outside of the cylinder to the inside of the cylinder, and the bottom of the cylinder includes two layers of thermal insulation cotton layers and two layers of zircon sand layers. The bottom layer of the cylinder bottom is the thermal insulation cotton layer, and the top layer is the zircon sand layer. The thermal insulation cotton layer and the zircon sand layer of the cylinder bottom are alternately arranged.

[0017] A temperature field structure for growing an X-cut lithium niobate crystal. The temperature field structure is such as the temperature field structure in the above-mentioned X-cut lithium niobate crystal growth method. The temperature field structure is used to grow an X-axis lithium niobate crystal, and the X-axis is defined to extend upward. The temperature field structure includes a heat preservation structure and a crucible. The heat preservation structure and the crucible are both elliptical cylinders with an open upper end and a closed lower end. When in use, the crucible is placed in the heat preservation structure, and the central axes of the crucible and the heat preservation structure coincide. The heat preservation structure has a major axis a1 and a minor axis b1, and the crucible has a major axis a2 and a minor axis b2. The major axis of the heat preservation structure and the major axis of the crucible both extend in the Y-axis direction, and the minor axis of the heat preservation structure and the minor axis of the crucible both extend in the Z-axis direction. The lithium niobate crystal grown by the X-cut lithium niobate crystal growth method is an elliptical cylinder.

[0018] Furthermore, the ratio of the major axis a1 to the minor axis b1 of the heat-insulating structure is equal to the ratio of the major axis a2 to the minor axis b2 of the crucible.

[0019] Furthermore, the ratio of the major axis a1 to the minor axis b1 of the thermal insulation structure is d, and 1.1≤d≤1.5.

[0020] Furthermore, the growth rate of the X-axis lithium niobate crystal along the Y-axis is V Y , the growth rate along the Z axis is V z , d = V Y :V Z .

[0021] Furthermore, the difference between the long axis of the heat-insulating structure and the long axis of the crucible is a=a1-a2, 2cm≤a≤5cm.

[0022] Furthermore, the thermal insulation structure includes an elliptical cylinder and a cylinder bottom connected to the lower end of the cylinder, the cylinder includes a quartz layer, a thermal insulation cotton layer and a corundum layer, and the cylinder bottom includes a thermal insulation cotton layer and a zircon sand layer.

[0023] Furthermore, the quartz layer, thermal insulation cotton layer and corundum layer of the cylinder are arranged in sequence from the outside of the cylinder to the inside of the cylinder, and the bottom of the cylinder includes two layers of thermal insulation cotton layers and two layers of zircon sand layers. The bottom layer of the cylinder bottom is the thermal insulation cotton layer, and the top layer is the zircon sand layer. The thermal insulation cotton layer and the zircon sand layer of the cylinder bottom are alternately arranged.

[0024] The beneficial effects of the present invention are as follows: the X-cut lithium niobate crystal growth method of the present invention takes into account the growth habits of the X-axis lithium niobate crystal, designs a temperature field structure suitable for the growth of the X-axis crystal, and sets the heat preservation structure and the crucible in the temperature field structure as an elliptical cylindrical structure, and allows the long axis of the heat preservation structure and the crucible to extend along the Y-axis growth direction of the lithium niobate crystal, and the short axis to extend along the Z-axis growth direction of the lithium niobate crystal, so that the long axis with a larger size and the short axis with a smaller size can respectively match the faster growth speed of the lithium niobate crystal on the Y-axis and the slower growth speed on the Z-axis, so that the grown X-axis lithium niobate crystal grows naturally without being squeezed, and the grown lithium niobate crystal is in the shape of an elliptical cylinder. The lithium niobate crystal in the shape of an elliptical cylinder has a uniform internal density distribution, is not prone to anisotropic nucleation and twinning, and is not prone to cracking, thereby improving the success rate of crystal growth.

[0025] In addition, the present invention formulates the major and minor axis ratio parameters of the elliptical insulation structure and the crucible structure according to the growth characteristics of lithium niobate crystals, thereby ensuring the stable growth of X-axis crystals under controllable conditions as much as possible, reducing the possibility of anisotropic nucleation of X-axis crystals, reducing the risks of polycrystal and cracking, and improving the yield rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative labor.

[0027] Figure 1 is a top view of a temperature field structure for growing an X-cut lithium niobate crystal in one embodiment of the present invention; Figure 2 AA cross-sectional schematic diagram of a temperature field structure for growth of an X-cut lithium niobate crystal in one embodiment of the present invention; In the figure: 1. thermal insulation structure; 11. quartz layer; 12. thermal insulation cotton layer; 13. corundum layer; 14. zircon sand layer; 2. crucible; 3. lithium niobate crystal. DETAILED DESCRIPTION

[0028] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0029] In the description of the present invention, it should be understood that the terms "longitudinal", "radial", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0030] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0031] Embodiment 1 of the temperature field structure for growing an X-cut lithium niobate crystal according to the present invention, Figure 1 to Figure 2 As shown, the temperature field structure is used to grow X-axis lithium niobate crystals, and the X-axis is defined to extend upward. The lithium niobate crystal 3 grown by the temperature field structure is an elliptical cylinder. The temperature field structure includes a heat preservation structure 1 and a crucible 2. The heat preservation structure 1 and the crucible 2 are both elliptical cylinders with an upper end opening and a lower end closing. When in use, the crucible 2 is placed in the heat preservation structure 1. The central axes of the crucible 2 and the heat preservation structure 1 coincide. The heat preservation structure 1 has a major axis a1 and a minor axis b1, and the crucible 2 has a major axis a2 and a minor axis b2. The major axis of the heat preservation structure 1 and the major axis of the crucible 2 both extend along the Y-axis direction, and the minor axis of the heat preservation structure 1 and the minor axis of the crucible 2 both extend along the Z-axis direction.

[0032] like Figure 1 and Figure 2As shown, the thermal insulation structure 1 includes an elliptical cylinder and a cylinder bottom connected to the lower end of the cylinder, and the cylinder bottom is an ellipse with the same cross-sectional size as the cylinder. The cylinder includes a quartz layer 11, a thermal insulation cotton layer 12 and a corundum layer 13, and the cylinder bottom includes a thermal insulation cotton layer 12 and a zircon sand layer 14. Specifically, the quartz layer 11, the thermal insulation cotton layer 12 and the corundum layer 13 of the cylinder are sequentially arranged from the outside of the cylinder to the inside of the cylinder, and the cylinder bottom includes two layers of thermal insulation cotton layers 12 and two layers of zircon sand layers 14, the bottom layer of the cylinder bottom is the thermal insulation cotton layer 12, and the top layer is the zircon sand layer 14, and the thermal insulation cotton layer 12 and the zircon sand layer 14 of the cylinder bottom are alternately arranged. In other embodiments of the present invention, the thermal insulation structure 1 can be set with the number of layers, as well as the material and thickness of each layer of the structure according to actual needs.

[0033] The crucible 2 is a platinum crucible 2. The structure of the crucible 2 is different from that of the platinum crucible 2 in the prior art only in the shape of the cross section, that is, the prior art is a cylindrical crucible 2, while the present invention is an elliptical crucible 2. The crucible 2 includes an annular crucible body and a crucible bottom connected to the lower end of the annular crucible body. In the present invention, the cross section of the annular crucible body is an ellipse.

[0034] In this embodiment, the ratio of the long axis a1 to the short axis b1 of the heat preservation structure 1 is equal to the ratio of the long axis a2 to the short axis b2 of the crucible 2. The ratio of the long axis a1 to the short axis b1 of the heat preservation structure 1 is d, and 1.1≤d≤1.5. For the X-axis lithium niobate crystal growth method, d=1.2 is preferred. Of course, in other embodiments, a reasonable value of d can be set according to the growth conditions of lithium niobate crystals under different growth environments. The growth rate of the X-axis lithium niobate crystal along the Y axis is V Y , the growth rate along the Z axis is V z ,d=V Y :V Z .

[0035] In this embodiment, the difference a between the long axis of the heat preservation structure 1 and the long axis of the crucible 2 is a=a1-a2, 2cm≤a≤5cm. In other embodiments, the required difference a can be set according to the growth conditions of the lithium niobate crystal.

[0036] The present invention discloses an X-cut lithium niobate crystal growth method, which adopts the temperature field structure for growing the X-cut lithium niobate crystal. The X-axis lithium niobate crystal grown by the growth method is an elliptical cylinder, the central axis of the elliptical cylinder extends along the X-axis direction, and the cross-sectional shape of the elliptical cylinder lithium niobate crystal perpendicular to the X-axis is an ellipse, and the major axis of the ellipse is a, and the minor axis is b, that is, the major axis of the elliptical cylinder lithium niobate crystal is a, and the minor axis is b. Here, the X-axis is defined as extending upward.

[0037] The temperature field structure used in the method includes a heat preservation structure 1 and a crucible 2, both of which are elliptical cylinders with an open upper end and a closed lower end. When in use, the crucible 2 is placed in the heat preservation structure 1, and the central axes of the crucible 2 and the heat preservation structure 1 coincide with each other. The heat preservation structure 1 has a major axis a1 and a minor axis b1, and the crucible 2 has a major axis a2 and a minor axis b2. The major axis of the heat preservation structure 1 and the major axis of the crucible 2 both extend in the Y-axis direction, and the minor axis of the heat preservation structure 1 and the minor axis of the crucible 2 both extend in the Z-axis direction. The lithium niobate crystal grown by the X-cut lithium niobate crystal growth method is an elliptical cylinder.

[0038] In this method, the ratio of the long axis a1 to the short axis b1 of the heat preservation structure 1 is equal to the ratio of the long axis a2 to the short axis b2 of the crucible 2. The ratio of the long axis a1 to the short axis b1 of the heat preservation structure 1 is d, and 1.1≤d≤1.5. For the X-axis lithium niobate crystal growth method, d=1.2 is preferred. Of course, in other embodiments, a reasonable value of d can be set according to the growth conditions of the lithium niobate crystal under different growth environments. The growth rate of the X-axis lithium niobate crystal along the Y axis is V Y , the growth rate along the Z axis is V z ,d=V Y :V Z .

[0039] In this method, the heat-insulating structure 1 includes an elliptical cylinder and a cylinder bottom connected to the lower end of the cylinder, and the cylinder bottom is an elliptical shape with the same cross-sectional size as the cylinder. Figure 1 to Figure 2 As shown, the cylinder includes a quartz layer 11, a thermal insulation cotton layer 12 and a corundum layer 13, and the cylinder bottom includes a thermal insulation cotton layer 12 and a zircon sand layer 14. Specifically, the quartz layer 11, the thermal insulation cotton layer 12 and the corundum layer 13 of the cylinder are sequentially arranged from the outside of the cylinder to the inside of the cylinder, and the cylinder bottom includes two layers of thermal insulation cotton layers 12 and two layers of zircon sand layers 14. The bottom layer of the cylinder bottom is the thermal insulation cotton layer 12, and the top layer is the zircon sand layer 14. The thermal insulation cotton layer 12 and the zircon sand layer 14 of the cylinder bottom are alternately arranged. In other embodiments of the present invention, the thermal insulation structure 1 can be set according to actual needs to set the number of layers, as well as the material and thickness of each layer of the structure.

[0040] The crucible 2 is a platinum crucible 2. The structure of the crucible 2 is different from that of the platinum crucible 2 in the prior art only in the shape of the cross section, that is, the prior art is a cylindrical crucible 2, while the present invention is an elliptical crucible 2. The crucible 2 includes an annular crucible body and a crucible bottom connected to the lower end of the annular crucible body. In the present invention, the cross section of the annular crucible body is an ellipse.

[0041] The present invention adopts the pulling method to grow the X-axis lithium niobate crystal, that is, the lithium niobate crystal is pulled along the X-axis direction. During the crystal growth process, the pulling speed of the crystal along the X-axis is V t,0.2mm / h≤Vt≤1mm / h. In the growth process of lithium niobate crystal, the crucible 2 and the lithium niobate crystal do not rotate, and the crystal is observed from directly above the temperature field structure. The temperature field structure of the present invention is highly consistent around, ensuring the stability of the internal temperature distribution, providing a stable and good condition for crystal growth.

[0042] In this embodiment, the X-cut lithium niobate crystal growth method of the present invention further includes an equal diameter stage automatic control program, which is a prior art. In the prior art, the diameter of the lithium niobate crystal to be grown can be set in the control program. In the present invention, the diameter R of the lithium niobate crystal is set, R= , a represents the major axis of the elliptical cylinder of lithium niobate crystal, and b represents the minor axis of the elliptical cylinder of lithium niobate crystal.

[0043] The X-cut lithium niobate crystal growth method of the present invention takes into account the growth habits of X-axis lithium niobate crystals and designs a temperature field structure suitable for X-axis crystal growth, that is, by setting the heat preservation structure 1 and the crucible 2 in the temperature field structure to be elliptical cylindrical structures, and allowing the long axes of the heat preservation structure 1 and the crucible 2 to extend along the Y-axis growth direction of the lithium niobate crystal, and the short axes to extend along the Z-axis growth direction of the lithium niobate crystal, so that the larger long axis and the smaller short axis can respectively match the faster growth speed of the lithium niobate crystal on the Y-axis and the slower growth speed on the Z-axis, so that the grown X-axis lithium niobate crystal grows naturally without being squeezed, and the grown lithium niobate crystal is in the shape of an elliptical cylinder, and the internal density distribution of the lithium niobate crystal in the shape of an elliptical cylinder is uniform.

[0044] In addition, the present invention formulates the major axis and minor axis ratio parameters of the elliptical insulation structure 1 and the crucible 2 structure according to the growth characteristics of lithium niobate crystals, thereby ensuring the stable growth of the X-axis crystals under controllable conditions as much as possible, reducing the possibility of anisotropic nucleation of the X-axis crystals, reducing the risks of polycrystal and cracking, and improving the yield rate.

[0045] The embodiments described above are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included in the protection scope of the present invention.

Claims

1. A method for growing an X-cut lithium niobate crystal, characterized in that: The invention is used for growing an X-axis lithium niobate crystal, wherein the X-axis is defined to extend upward. The temperature field structure used in the method comprises a heat preservation structure (1) and a crucible (2). The heat preservation structure (1) and the crucible (2) are both elliptical cylinders with an upper end opening and a lower end closing. When in use, the crucible (2) is placed in the heat preservation structure (1). The central axes of the crucible (2) and the heat preservation structure (1) coincide with each other. The heat preservation structure (1) has a major axis a1 and a minor axis b1. The crucible (2) has a major axis a2 and a minor axis b2. The major axis of the heat preservation structure (1) and the major axis of the crucible (2) both extend in the Y-axis direction. The minor axis of the heat preservation structure (1) and the minor axis of the crucible (2) both extend in the Z-axis direction. The lithium niobate crystal grown by the X-cut lithium niobate crystal growth method is an elliptical cylinder.

2. The X-cut lithium niobate crystal growth method according to claim 1, characterized in that: The ratio of the major axis a1 to the minor axis b1 of the heat-insulating structure (1) is equal to the ratio of the major axis a2 to the minor axis b2 of the crucible (2).

3. The X-cut lithium niobate crystal growth method according to claim 2, characterized in that: The ratio of the major axis a1 to the minor axis b1 of the thermal insulation structure (1) is d, and 1.1≤d≤1.

5.

4. The X-cut lithium niobate crystal growth method according to claim 3, characterized in that: When the X-axis lithium niobate crystal grows, the growth rate along the Y-axis is V Y , the growth rate along the Z axis is Vz,d=V Y :V Z .

5. The X-cut lithium niobate crystal growth method according to any one of claims 1 to 4, characterized in that: The difference between the long axis of the heat-insulating structure (1) and the long axis of the crucible (2) is a=a1-a2, 2cm≤a≤5cm.

6. The X-cut lithium niobate crystal growth method according to any one of claims 1 to 4, characterized in that: During the growth process, the lithium niobate crystal is pulled along the X-axis at a pulling speed of V. t ,0.2mm / h≤V t ≤1mm / h.

7. The X-cut lithium niobate crystal growth method according to any one of claims 1 to 4, characterized in that: During the growth of the lithium niobate crystal, the crucible (2) and the crystal do not rotate, and the crystal is observed from directly above the temperature field structure.

8. The X-cut lithium niobate crystal growth method according to any one of claims 1 to 4, characterized in that: The thermal insulation structure (1) comprises an elliptical cylinder and a cylinder bottom connected to the lower end of the cylinder, the cylinder comprising a quartz layer (11), a thermal insulation cotton layer (12) and a corundum layer (13), and the cylinder bottom comprising a thermal insulation cotton layer (12) and a zircon sand layer (14).

9. The X-cut lithium niobate crystal growth method according to claim 8, characterized in that: The quartz layer (11), the thermal insulation cotton layer (12) and the corundum layer (13) of the cylinder are arranged in sequence from the outside of the cylinder to the inside of the cylinder, and the cylinder bottom comprises two layers of thermal insulation cotton layers (12) and two layers of zircon sand layers (14), the bottom layer of the cylinder bottom is the thermal insulation cotton layer (12), and the top layer is the zircon sand layer (14), and the thermal insulation cotton layers (12) and the zircon sand layers (14) of the cylinder bottom are arranged alternately.

10. A temperature field structure for growing X-cut lithium niobate crystals, characterized in that: The temperature field structure is the temperature field structure in the X-cut lithium niobate crystal growth method as claimed in any one of claims 1 to 9.

Images