Guanyl nitrate nonlinear optical crystal, preparation method and application thereof

Abstract

The disclosure provides a guanidine nitrate nonlinear optical crystal and a preparation method and application thereof, and belongs to the technical field of crystal materials and the field of optical technology. The chemical formula of the guanidine nitrate nonlinear optical crystal is C(NH2)3NO3, belongs to a monoclinic system, a space group is Cm, and cell parameters are as follows: a=12.69+ / -0.02 angstrom, b=7.27+ / -0.02 angstrom, c=3.63+ / -0.02 angstrom, alpha=90 DEG, beta=120.85+ / -0.02 DEG, gamma=90 DEG, and Z=2.

Description

Technical Field

[0001] This disclosure relates to the fields of crystal materials technology and optical technology, and in particular to a guanidine nitrate nonlinear optical crystal, its preparation method and application. Background Technology

[0002] With the rapid development of the modern optoelectronic industry, nonlinear optical materials, as the core material basis of optoelectronic technology, have demonstrated irreplaceable value in fields such as laser frequency doubling, electro-optic modulation, optical storage, optical limiting, and optical switching. Of particular note is the research breakthrough in nonlinear optical materials for the ultraviolet solar blind region (210-280 nm). These materials provide a key solution for overcoming the technical bottlenecks of traditional optical systems by extending the output wavelength of solid-state lasers into the ultraviolet solar blind band.

[0003] Currently, nonlinear optical crystals used in the ultraviolet solar-blind band include β-BaB2O4, LiB3O5, and CsLiB6O. 10 Crystals such as KBe2BO3F2 and KH2PO4 (KDP) are examples. Although the crystal growth technology for these materials has become increasingly mature, there are still obvious shortcomings: such as the crystals being prone to deliquescence, having long growth cycles, and exhibiting severe layered growth habits. Summary of the Invention

[0004] In view of this, the present disclosure provides a guanidine nitrate nonlinear optical crystal, its preparation method and application.

[0005] According to one aspect of the present disclosure, a guanidine nitrate nonlinear optical crystal is provided, wherein the chemical formula of the guanidine nitrate nonlinear optical crystal is C(NH2)3NO3, it belongs to the monoclinic crystal system, the space group is Cm, and the cell parameters are: a=12.69±0.02Å, b=7.27±0.02Å, c=3.63±0.02Å, alpha=90°, beta=120.85±0.02°, gamma=90°, Z=2.

[0006] According to embodiments of the present disclosure, the aforementioned guanidine nitrate nonlinear optical crystal includes one or more diffraction peaks at one of the following locations in the X-ray powder diffraction pattern with a diffraction angle of 2θ: 14.6°±0.2°, 16.3°±0.2°, 24.6°±0.2°, 28.2°±0.2°, 29.5°±0.2°, and 35.9°±0.2°.

[0007] According to embodiments of this disclosure, the guanidine nitrate nonlinear optical crystal has a length dimension of 5 to 30 mm.

[0008] According to embodiments of this disclosure, the phase matching direction of the guanidine nitrate nonlinear optical crystal includes the

[100] direction.

[0009] According to another embodiment of this disclosure, a method for preparing a guanidine nitrate nonlinear optical crystal is also provided, comprising: dissolving a guanidine-containing compound and a nitrate-containing compound in water to obtain a guanidine nitrate aqueous solution; and crystallizing guanidine nitrate by a room temperature solution method or a hydrothermal method to obtain the guanidine nitrate nonlinear optical crystal; wherein the room temperature solution method comprises: placing the guanidine nitrate aqueous solution in a sealed container, allowing the solvent in the solution to evaporate through a small hole at 15~40°C to obtain the guanidine nitrate nonlinear optical crystal; and the hydrothermal method comprises: placing the guanidine nitrate aqueous solution in a sealed container, heating it to 50~180°C at a rate of 20~60°C / h, holding it at that temperature for 3~15 days, and then cooling it to room temperature at a rate of 10~100°C / day to obtain the guanidine nitrate nonlinear optical crystal.

[0010] According to embodiments of this disclosure, the molar ratio of the guanidine-containing compound to the nitrate-containing compound is (0.8~1.2):(0.8~1.2).

[0011] According to embodiments of this disclosure, the above-mentioned guanidine-containing compounds include at least one of guanidine carbonate, guanidine sulfate, guanidine phosphate, and guanidine chloride.

[0012] According to embodiments of this disclosure, the nitrate-containing compounds include at least one of nitric acid, barium nitrate, calcium nitrate, strontium nitrate, and ammonium nitrate.

[0013] According to an embodiment of another aspect of this disclosure, the application of guanidine nitrate nonlinear optical crystal in optical devices is also provided.

[0014] According to embodiments of this disclosure, the optical device includes a frequency multiplier, an up or down frequency converter, or an optical parametric oscillator.

[0015] According to embodiments of this disclosure, the above-described guanidine nitrate nonlinear optical crystal is used for frequency doubling light output in the ultraviolet solar blind band.

[0016] According to embodiments of this disclosure, the guanidine nitrate nonlinear optical crystal described above outputs harmonic light at harmonics of 2nd, 3rd, 4th, 5th, or 6th harmonics from the 1064nm fundamental frequency light output by the Nd:YAG laser.

[0017] According to embodiments of this disclosure, the frequency doubling effect of the guanidine nitrate nonlinear optical crystal can be 5 to 6 times that of KDP, and the absorption cutoff edge is in the ultraviolet solar blind region (200 to 280 nm). The phase matching of the target band can be achieved by controlling the birefringence of the crystal, and combined with its strong frequency doubling response characteristics, the frequency doubling laser output in the ultraviolet solar blind band can be effectively generated.

[0018] According to embodiments of this disclosure, guanidine nitrate nonlinear optical crystals grown using room temperature solution methods and hydrothermal methods exhibit no obvious layered growth habit, and millimeter-sized guanidine nitrate nonlinear optical crystals can be obtained. The preparation method provided by the embodiments of this disclosure has advantages such as simple operation, low cost, and short growth cycle.

[0019] The guanidine nitrate nonlinear optical crystal provided in this disclosure has a wide transmission band, is easy to cut, polish and store, and can be used as an ultraviolet solar-blind nonlinear optical crystal in all-solid-state lasers. Attached Figure Description

[0020] Figure 1 A crystal structure diagram of the guanidine nitrate nonlinear optical crystal provided in an embodiment of this disclosure is shown;

[0021] Figure 2 The X-ray powder diffraction pattern of the guanidine nitrate nonlinear optical crystal provided in the embodiments of this disclosure is shown.

[0022] Figure 3 The diagram shows the working principle of a nonlinear optical device fabricated from a nonlinear optical crystal according to an embodiment of the present disclosure, wherein 1 is a laser, 2 is a convex lens, 3 is a nonlinear optical crystal, 4 is a prism, and 5 is a filter. Detailed Implementation

[0023] The embodiments of the present disclosure will now be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the disclosure. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of the present disclosure for ease of explanation. However, it will be apparent that one or more embodiments may be practiced without these specific details. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concepts of the present disclosure.

[0024] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. The term "comprising" as used herein indicates the presence of features, steps, or operations, but does not exclude the presence or addition of one or more other features.

[0025] When using expressions such as "at least one of A, B, and C," the expression should generally be interpreted in accordance with the meaning commonly understood by a person skilled in the art (e.g., "a system having at least one of A, B, and C" should include, but is not limited to, systems having A alone, having B alone, having C alone, having A and B, having A and C, having B and C, and / or having A, B, and C, etc.). When using expressions such as "at least one of A, B, or C," the expression should generally be interpreted in accordance with the meaning commonly understood by a person skilled in the art (e.g., "a system having at least one of A, B, or C" should include, but is not limited to, systems having A alone, having B alone, having C alone, having A and B, having A and C, having B and C, and / or having A, B, and C, etc.).

[0026] In the field of nonlinear optics, the nonlinear optical properties of different compounds often exhibit significant unpredictability due to their extreme sensitivity to material composition, electronic structure, and microscopic interactions. Although a noncentrosymmetric crystal structure is a necessary condition for second-order nonlinear optical activity, nonlinear optical properties (such as frequency doubling efficiency and nonlinear polarizability) are also subject to complex regulation by intramolecular / intermolecular charge transfer characteristics, hyperconjugation effects, excited-state energy level distribution, and the cooperative nature of dipole orientations in the crystal lattice. There is a lack of universal quantitative correlation between crystal form parameters (such as unit cell parameters and molecular packing mode) and nonlinear optical properties (such as frequency doubling efficiency and nonlinear polarizability).

[0027] Furthermore, microscopic mechanisms such as local field correction factor, phase matching condition, electron-phonon coupling strength, and defect-induced local states can significantly modulate nonlinear optical behavior. These factors often cannot be directly obtained through conventional crystal form analysis, which further exacerbates the difficulty of predicting nonlinear optical performance.

[0028] In the process of realizing this disclosure, it was unexpectedly discovered that guanidine nitrate nonlinear optical crystals with special crystal structures can be used in the ultraviolet solar blind zone.

[0029] Specifically, according to one aspect of this disclosure, a guanidine nitrate nonlinear optical crystal is provided, wherein the guanidine nitrate nonlinear optical crystal has the chemical formula C(NH2)3NO3, belongs to the monoclinic crystal system, has space group Cm, and has the following unit cell parameters: a=12.69±0.02Å, b=7.27±0.02Å, c=3.63±0.02Å, alpha=90°, beta=120.85±0.02°, gamma=90°, Z=2. Exemplarily, the unit cell parameters can be: a=12.686(3)Å, b=7.274(2)Å, c=3.629(1)Å, β=120.85(2), Z=2; the unit cell volume is 287.496Å.3 .

[0030] According to embodiments of this disclosure, the molecular weight of the guanidine nitrate nonlinear optical crystal can be 122.10.

[0031] According to embodiments of this disclosure, the frequency doubling effect of the guanidine nitrate nonlinear optical crystal can reach 5 to 6 times that of KDP, and the absorption cutoff edge is in the ultraviolet solar blind region (200 to 280 nm). The phase matching of the target band can be achieved by controlling the birefringence of the crystal, and combined with its strong frequency doubling response characteristics, frequency doubling laser output in the ultraviolet solar blind band can be effectively generated.

[0032] Figure 1 A crystal structure diagram of the guanidine nitrate nonlinear optical crystal provided in an embodiment of this disclosure is shown.

[0033] According to embodiments of this disclosure, the guanidine nitrate nonlinear optical crystal may include one or more diffraction peaks at 14.6°±0.2°, 16.3°±0.2°, and 28.2°±0.2° in an X-ray powder diffraction pattern with a diffraction angle of 2θ.

[0034] According to embodiments of this disclosure, the guanidine nitrate nonlinear optical crystal may also include one or more diffraction peaks at 24.6°±0.2°, 29.5°±0.2°, and 35.9°±0.2° in the X-ray powder diffraction pattern with a diffraction angle of 2θ.

[0035] For example, the guanidine nitrate nonlinear optical crystal may include diffraction peaks at 14.6°±0.2°, 16.3°±0.2°, 24.6°±0.2°, 28.2°±0.2°, 29.5°±0.2°, and 35.9°±0.2° in the X-ray powder diffraction pattern with a diffraction angle of 2θ.

[0036] According to embodiments of this disclosure, the nonlinear optical crystal can be a functional crystal material that modulates the frequency, phase, intensity, and other characteristics of laser light through nonlinear optical effects. The crystal can be a solid formed by the periodic and ordered arrangement of atoms, ions, or molecules in three-dimensional space. Different crystals can be identified and distinguished from each other using one or more characterization techniques, including, for example, X-ray powder diffraction (XRPD). According to embodiments of this disclosure, the X-ray powder diffraction pattern of the guanidine nitrate nonlinear optical crystal has one or more diffraction peaks at one or more specified 2θ diffraction angles.

[0037] According to embodiments of this disclosure, X-ray powder diffraction is a method for performing diffraction analysis on powdered polycrystalline samples using monochromatic X-rays. An X-ray powder diffraction pattern refers to an experimentally obtained spectrum plotted as signal position (x-axis) versus signal intensity (y-axis). For amorphous materials, an X-ray powder diffraction pattern may include one or more broad, flat diffraction peaks; for crystalline materials, an X-ray powder diffraction pattern may include one or more fine, tall, and sharp diffraction peaks, each identified by its angle value, measured as angle 2θ, plotted on the x-axis of the X-ray powder diffraction pattern.

[0038] According to embodiments of this disclosure, the repeatability of the measured angle value is within ±0.2°, that is, the angle value can be an angle value +0.2°, an angle value -0.2°, or any value between these two endpoints (angle value +0.2° and angle value -0.2°). Optionally, the repeatability of the measured angle value is within ±0.1°.

[0039] According to embodiments of this disclosure, the X-ray powder diffraction pattern of the guanidine nitrate nonlinear optical crystal is essentially as follows: Figure 2 As shown. "Basically" refers to the fact that the positions and intensities of diffraction peaks in an X-ray powder diffraction pattern can vary. For example, the position of the diffraction peak (2θ) can show some inter-equipment variability, typically up to 0.2°. Sometimes, depending on equipment calibration differences, the variability may be greater than 0.2°.

[0040] According to embodiments of this disclosure, the guanidine nitrate nonlinear optical crystal has a length dimension of 5 to 30 mm. Exemplarily, the length dimension of the guanidine nitrate nonlinear optical crystal can be any two values ​​between 5 mm, 8 mm, 10 mm, 12 mm, 15 mm, 18 mm, 20 mm, 25 mm, and 30 mm.

[0041] The phase-matching direction of nonlinear optical crystals is a crucial factor for achieving efficient energy conversion. It is related to various factors such as the crystal's birefringence, wavelength dispersion, temperature sensitivity, and the tensor components of the nonlinear coefficient. For example, crystals of the same crystal form may have their phase-matching direction shifted due to differences in birefringence or defect-induced local field distortion. Therefore, the phase-matching direction of nonlinear optical crystals is unpredictable.

[0042] According to embodiments of this disclosure, the phase matching direction of a guanidine nitrate nonlinear optical crystal may include a

[100] direction. The

[100] direction may represent the positive direction along the a-axis of the unit cell, i.e., the direction from the origin (0,0,0) of the unit cell to the vertex (1,0,0).

[0043] According to another embodiment of this disclosure, a method for preparing a guanidine nitrate nonlinear optical crystal is also provided, comprising steps S1 and S2.

[0044] In step S1, the guanidine-containing compound and the nitrate-containing compound are dissolved in water to obtain an aqueous solution of guanidine nitrate;

[0045] In step S2, guanidine nitrate is crystallized using either a room-temperature solution method or a hydrothermal method to obtain a guanidine nitrate nonlinear optical crystal. The room-temperature solution method involves placing an aqueous solution of guanidine nitrate in a sealed container and allowing the solvent in the solution to evaporate through a small hole at 15–40°C to obtain the guanidine nitrate nonlinear optical crystal. The hydrothermal method involves placing an aqueous solution of guanidine nitrate in a sealed container, heating it to 50–180°C at a rate of 20–60°C / h, holding it at that temperature for 3–15 days, and then cooling it back to room temperature at a rate of 10–100°C / day to obtain the guanidine nitrate nonlinear optical crystal.

[0046] According to embodiments of this disclosure, guanidine nitrate nonlinear optical crystals grown using room-temperature solution methods and hydrothermal methods exhibit no obvious layered growth habit, and millimeter-sized guanidine nitrate nonlinear optical crystals can be obtained. The preparation method provided by embodiments of this disclosure has advantages such as simple operation, low cost, and short growth cycle. The frequency doubling effect of the guanidine nitrate nonlinear optical crystal prepared by embodiments of this disclosure can reach 5 to 6 times that of KDP, and the absorption cutoff edge is in the ultraviolet solar blind region (200-280 nm). Phase matching of the target band can be achieved by controlling the birefringence of the crystal, and combined with its strong frequency doubling response characteristics, frequency-doubled laser output in the ultraviolet solar blind band can be effectively generated.

[0047] According to embodiments of this disclosure, in step S1, the guanidine-containing compound may include at least one of guanidine carbonate, guanidine sulfate, guanidine phosphate, and guanidine chloride. The nitrate-containing compound may include at least one of nitric acid, barium nitrate, calcium nitrate, strontium nitrate, and ammonium nitrate.

[0048] According to embodiments of this disclosure, in step S1, the molar ratio of the guanidine-containing compound to the nitrate-containing compound can be (0.8~1.2):(0.8~1.2). Exemplarily, the molar ratio of the guanidine-containing compound to the nitrate-containing compound can be 0.8:1, 0.9:1, 1:1, 1.1:1, 1.2:1, or any two of these ratios. Optionally, the molar ratio of the guanidine-containing compound to the nitrate-containing compound can be 1:1.

[0049] Optionally, in step S2, in the room temperature solution method, the solvent in the solution can evaporate through the orifice at room temperature. For example, the solvent in the solution can evaporate through the orifice at any two values ​​between 15°C, 18°C, 20°C, 22°C, 25°C, 28°C, 30°C, 32°C, 35°C, 38°C, 40°C or above.

[0050] For example, the room temperature solution method may include: transferring an aqueous solution of guanidine nitrate into a beaker, treating it with ultrasound to ensure thorough mixing and dissolution, adjusting the pH of the solution to 1-11, filtering it with filter paper, sealing it with a polyvinyl chloride film, placing it in a static environment free from shaking, pollution, and air convection, punching several small holes in the seal to adjust the evaporation rate of the solvent in the solution, allowing it to stand at room temperature until growth is complete, thus obtaining a guanidine nitrate nonlinear optical crystal with a size in the millimeter range.

[0051] Optionally, in step S2, in the hydrothermal method, the heating rate can be any two values ​​between 20℃ / h, 25℃ / h, 30℃ / h, 35℃ / h, 40℃ / h, 45℃ / h, 50℃ / h, 55℃ / h, 60℃ / h, or more. The isothermal time can be any two values ​​between 3 days, 4 days, 5 days, 6 days, 7 days, 8 days, 9 days, 10 days, 11 days, 12 days, 13 days, 14 days, 15 days, or more. The cooling rate can be any two values ​​between 10℃ / day, 20℃ / day, 30℃ / day, 40℃ / day, 50℃ / day, 60℃ / day, 70℃ / day, 80℃ / day, 90℃ / day, 100℃ / day, or more.

[0052] For example, the hydrothermal method may include: transferring an aqueous solution of guanidine nitrate into the polytetrafluoroethylene liner of a high-pressure reactor and sealing the reactor opening tightly; placing the high-pressure reactor in a constant temperature chamber, heating it to 50-180°C at a rate of 20-60°C / h, holding it at that temperature for 3-15 days, and then cooling it to room temperature at a rate of 10-100°C / day; opening the high-pressure reactor, and obtaining millimeter-sized guanidine nitrate nonlinear optical crystals in the colorless, clear solution.

[0053] According to an embodiment of another aspect of this disclosure, the application of guanidine nitrate nonlinear optical crystal in optical devices is also provided.

[0054] The guanidine nitrate nonlinear optical crystal provided in this disclosure has a wide transmission band, is easy to cut, polish and store, and can be used as an ultraviolet solar-blind nonlinear optical crystal in all-solid-state lasers.

[0055] The guanidine nitrate nonlinear optical crystal provided in this disclosure can be cut into crystals according to the required angle, thickness and cross-sectional size, and the light-transmitting surface of the crystal can be polished and coated with a dielectric film, so that it can be used as a nonlinear optical device.

[0056] According to embodiments of this disclosure, the optical device includes a frequency multiplier, an up- or down-frequency converter, or an optical parametric oscillator.

[0057] According to embodiments of this disclosure, a guanidine nitrate nonlinear optical crystal is used for frequency doubling light output in the ultraviolet solar blind band.

[0058] According to embodiments of this disclosure, a guanidine nitrate nonlinear optical crystal outputs harmonic light at 2nd, 3rd, 4th, 5th, or 6th harmonics from the 1064nm fundamental frequency light output by an Nd:YAG laser.

[0059] The following detailed description provides several specific embodiments to illustrate the technical solutions of this disclosure. It should be noted that the specific embodiments described below are merely examples and are not intended to limit this disclosure.

[0060] Example 1

[0061] This embodiment provides a guanidine nitrate nonlinear optical crystal and its preparation method.

[0062] The guanidine nitrate nonlinear optical crystal was prepared by room temperature solution growth, including the following steps:

[0063] (1) Mix guanidine carbonate and nitric acid in a molar ratio of 1:1 until homogeneous, and add 100 mL of deionized water to mix and dissolve them thoroughly.

[0064] (2) Transfer the mixed solution from step (1) into a 200 mL beaker, treat it with ultrasound to fully mix and dissolve it, adjust the pH of the solution to 7, filter it with filter paper, seal it with a polyvinyl chloride film, place it in a static environment without shaking, pollution, or air convection, punch several small holes in the seal to adjust the evaporation rate of the solvent in the solution, let it stand at room temperature, and after the growth is completed, a guanidine nitrate nonlinear optical crystal with a size of Φ12 mm × 15 mm × 9 mm is obtained.

[0065] Example 2

[0066] This embodiment provides a guanidine nitrate nonlinear optical crystal and its preparation method.

[0067] The guanidine nitrate nonlinear optical crystal was prepared by room temperature solution growth, including the following steps:

[0068] (1) Mix guanidine sulfate and barium nitrate in a molar ratio of 1:0.8 until homogeneous, and add 10 mL of deionized water to dissolve them thoroughly.

[0069] (2) Transfer the mixed solution from step (1) into a 50 mL beaker, treat it with ultrasound to fully mix and dissolve it, adjust the pH of the solution to 1, filter it with filter paper, seal it with a polyvinyl chloride film, and place it in a static environment without shaking, pollution, or air convection. Make several small holes in the seal to adjust the evaporation rate of the solvent in the solution. Let it stand at room temperature until the growth is complete, and you will get a guanidine nitrate nonlinear optical crystal with a size of Φ9 mm × 7 mm × 7 mm.

[0070] Example 3

[0071] This embodiment provides a guanidine nitrate nonlinear optical crystal and its preparation method.

[0072] The guanidine nitrate nonlinear optical crystal was prepared by room temperature solution growth, including the following steps:

[0073] (1) Mix guanidine sulfate and calcium nitrate at a molar ratio of 1.2:1 until homogeneous, and add 75 mL of deionized water to dissolve them thoroughly.

[0074] (2) Transfer the mixed solution from step (1) into a 150 mL beaker, treat it with ultrasound to fully mix and dissolve it, adjust the pH of the solution to 11, filter it with filter paper, seal it with a polyvinyl chloride film, and place it in a static environment without shaking, pollution, or air convection. Make several small holes in the seal to adjust the evaporation rate of the solvent in the solution. Let it stand at room temperature until the growth is complete, and you will get a guanidine nitrate nonlinear optical crystal with dimensions of Φ19 mm × 17 mm × 12 mm.

[0075] Example 4

[0076] This embodiment provides a guanidine nitrate nonlinear optical crystal and its preparation method.

[0077] The guanidine nitrate nonlinear optical crystal was prepared by room temperature solution growth, including the following steps:

[0078] (1) Mix guanidine phosphate and strontium nitrate at a molar ratio of 0.8:1 until homogeneous, and add 120 mL of deionized water to dissolve them thoroughly.

[0079] (2) Transfer the mixed solution from step (1) into a 250 mL beaker, treat it with ultrasound to ensure thorough mixing and dissolution, adjust the pH of the solution to 3, filter it with filter paper, seal it with a polyvinyl chloride film, and place it in a static environment free from shaking, pollution, and air convection. Make several small holes in the seal to adjust the evaporation rate of the solvent in the solution. Let it stand at room temperature until the growth is complete, and a guanidine nitrate nonlinear optical crystal with dimensions of Φ21 mm × 16 mm × 15 mm will be obtained.

[0080] Example 5

[0081] This embodiment provides a guanidine nitrate nonlinear optical crystal and its preparation method.

[0082] The guanidine nitrate nonlinear optical crystal was prepared by room temperature solution growth, including the following steps:

[0083] (1) Mix guanidine chloride and ammonium nitrate at a molar ratio of 1:1.2 until homogeneous, and add 200 mL of deionized water to dissolve them thoroughly;

[0084] (2) Transfer the mixed solution from step (1) into a 300 mL beaker, treat it with ultrasound to fully mix and dissolve it, adjust the pH of the solution to 9, filter it with filter paper, seal it with a polyvinyl chloride film, place it in a static environment without shaking, pollution, or air convection, punch several small holes in the seal to adjust the evaporation rate of the solvent in the solution, let it stand at room temperature until the growth is complete, and obtain a guanidine nitrate nonlinear optical crystal with dimensions of Φ25 mm × 20 mm × 14 mm.

[0085] Example 6

[0086] This embodiment provides a guanidine nitrate nonlinear optical crystal and its preparation method.

[0087] The guanidine nitrate nonlinear optical crystal was prepared by hydrothermal growth, including the following steps:

[0088] (1) Mix guanidine carbonate and ammonium nitrate in a molar ratio of 1:1 until homogeneous, and add 50 mL of deionized water to dissolve them thoroughly.

[0089] (2) Transfer the mixed solution from step (1) into the polytetrafluoroethylene liner of a 100 mL high-pressure reactor and seal the reactor opening tightly. Place the high-pressure reactor in a constant temperature chamber, raise the temperature to 120 °C at a rate of 20 °C / h, hold the temperature for 3 days, and then lower it to room temperature at a rate of 20 °C / day. Open the high-pressure reactor, and obtain a guanidine nitrate nonlinear optical crystal with dimensions of Φ30 mm × 20 mm × 16 mm in the colorless clear solution.

[0090] Example 7

[0091] This embodiment provides a guanidine nitrate nonlinear optical crystal and its preparation method.

[0092] The guanidine nitrate nonlinear optical crystal was prepared by hydrothermal growth, including the following steps:

[0093] (1) Mix guanidine phosphate and nitric acid in a molar ratio of 1:0.8 until homogeneous, and add 20 mL of deionized water to dissolve them thoroughly.

[0094] (2) Transfer the mixed solution from step (1) into the polytetrafluoroethylene liner of a 50 mL high-pressure reactor and seal the reactor opening tightly. Place the high-pressure reactor in a constant temperature chamber, raise the temperature to 160 °C at a rate of 40 °C / h, hold the temperature for 10 days, and then lower it to room temperature at a rate of 60 °C / day. Open the high-pressure reactor, and obtain a guanidine nitrate nonlinear optical crystal with dimensions of Φ17 mm × 16 mm × 13 mm in the colorless clear solution.

[0095] Example 8

[0096] This embodiment provides a guanidine nitrate nonlinear optical crystal and its preparation method.

[0097] The guanidine nitrate nonlinear optical crystal was prepared by hydrothermal growth, including the following steps:

[0098] (1) Mix guanidine sulfate and calcium nitrate in a molar ratio of 1:1 until homogeneous, and add 25 mL of deionized water to mix and dissolve them thoroughly.

[0099] (2) Transfer the mixed solution from step (1) into the polytetrafluoroethylene liner of a 50 mL high-pressure reactor and seal the reactor opening tightly. Place the high-pressure reactor in a constant temperature chamber, raise the temperature to 180 °C at a rate of 60 °C / h, maintain the temperature for 7 days, and then lower it to room temperature at a rate of 100 °C / day. Open the high-pressure reactor, and obtain a guanidine nitrate nonlinear optical crystal with dimensions of Φ22 mm × 14 mm × 12 mm in the colorless clear solution.

[0100] Example 9

[0101] This embodiment provides a guanidine nitrate nonlinear optical crystal and its preparation method.

[0102] The guanidine nitrate nonlinear optical crystal was prepared by hydrothermal growth, including the following steps:

[0103] (1) Mix guanidine sulfate and barium nitrate in a molar ratio of 0.8:1 until homogeneous, and add 5 mL of deionized water to mix and dissolve them thoroughly.

[0104] (2) Transfer the mixed solution from step (1) into the polytetrafluoroethylene liner of a 25 mL high-pressure reactor and seal the reactor opening tightly. Place the high-pressure reactor in a constant temperature chamber, raise the temperature to 50 °C at a rate of 25 °C / h, maintain the temperature for 15 days, and then lower it to room temperature at a rate of 10 °C / day. d. Open the high-pressure reactor and obtain a guanidine nitrate nonlinear optical crystal with dimensions of Φ15 mm × 13 mm × 10 mm in the colorless clear solution.

[0105] Example 10

[0106] This embodiment provides a guanidine nitrate nonlinear optical crystal and its preparation method.

[0107] The guanidine nitrate nonlinear optical crystal was prepared by hydrothermal growth, including the following steps:

[0108] (1) Mix guanidine chloride and strontium nitrate in a molar ratio of 1.2:1 until homogeneous, and add 30 mL of deionized water to dissolve them thoroughly.

[0109] (2) Transfer the mixed solution from step (1) into the polytetrafluoroethylene liner of a 50 mL high-pressure reactor and seal the reactor opening tightly. Place the high-pressure reactor in a constant temperature chamber, raise the temperature to 150 °C at a rate of 30 °C / h, maintain the temperature for 10 days, and then lower it to room temperature at a rate of 70 °C / day. Open the high-pressure reactor, and obtain a guanidine nitrate nonlinear optical crystal with dimensions of Φ21 mm × 16 mm × 12 mm in the colorless clear solution.

[0110] X-ray powder diffraction was performed on the guanidine nitrate nonlinear optical crystals provided in Examples 1-10. The X-ray powder diffraction patterns are basically as follows: Figure 2 As shown.

[0111] The guanidine nitrate nonlinear optical crystals provided in Examples 1-10 were processed in matching directions, and then... Figure 3 As shown, the laser is positioned at position 3. At room temperature, a Q-switched Nd:YAG laser is used as the light source with an incident wavelength of 532nm. The infrared beam with a wavelength of 532nm emitted by the Q-switched Nd:YAG laser 1 is focused by the convex lens 2 and enters the nonlinear optical crystal 3, generating a frequency-doubled light with a wavelength of 266nm. After being split by the prism 4 and filtered by the filter 5, the output intensity is approximately 5 to 6 times that of KDP under the same conditions.

[0112] The above description is merely a preferred embodiment of this disclosure and is not intended to limit this disclosure. Any modifications, equivalent substitutions, or improvements made by those skilled in the art to the technical methods within the spirit and principles of this disclosure shall still be included within the protection scope of the technical solution of this disclosure.

Claims

1. A guanidine nitrate nonlinear optical crystal, wherein, The guanidine nitrate nonlinear optical crystal has the chemical formula C(NH2)3NO3, belongs to the monoclinic crystal system, has the space group Cm, and has the following unit cell parameters: a=12.69±0.02Å, b=7.27±0.02Å, c=3.63±0.02Å, alpha=90°, beta=120.85±0.02°, gamma=90°, and Z=2.

2. The guanidine nitrate nonlinear optical crystal according to claim 1, wherein, The guanidine nitrate nonlinear optical crystal includes one or more diffraction peaks at 14.6°±0.2°, 16.3°±0.2°, and 28.2°±0.2° in the X-ray powder diffraction pattern with a diffraction angle of 2θ.

3. The guanidine nitrate nonlinear optical crystal according to claim 1 or 2, wherein, The guanidine nitrate nonlinear optical crystal has a length dimension of 5~30mm; The phase matching direction of the guanidine nitrate nonlinear optical crystal includes the [100] direction.

4. A method for preparing a guanidine nitrate nonlinear optical crystal according to any one of claims 1 to 3, comprising: Dissolve compounds containing guanidine groups and compounds containing nitrate groups in water to obtain an aqueous solution of guanidine nitrate; Guanidine nitrate nonlinear optical crystals were obtained by crystallizing guanidine nitrate using a room temperature solution method or a hydrothermal method. The room temperature solution method includes: placing the guanidine nitrate aqueous solution in a sealed container, allowing the solvent in the solution to evaporate through a small hole at 15~40°C, thereby obtaining the guanidine nitrate nonlinear optical crystal; The hydrothermal method includes: placing the guanidine nitrate aqueous solution in a sealed container, heating it to 50-180°C at a rate of 20-60°C / h, maintaining the temperature for 3-15 days, and then cooling it to room temperature at a rate of 10-100°C / day to obtain the guanidine nitrate nonlinear optical crystal.

5. The preparation method according to claim 4, wherein, The molar ratio of the guanidine-containing compound to the nitrate-containing compound is (0.8~1.2):(0.8~1.2).

6. The preparation method according to claim 4 or 5, wherein, The guanidine-containing compound includes at least one of guanidine carbonate, guanidine sulfate, guanidine phosphate, and guanidine chloride; The nitrate-containing compounds include at least one of nitric acid, barium nitrate, calcium nitrate, strontium nitrate, and ammonium nitrate.

7. The application of the guanidine nitrate nonlinear optical crystal according to any one of claims 1 to 3 in an optical device.

8. The application according to claim 7, wherein, The optical devices include frequency multipliers, up- or down-frequency converters, or optical parametric oscillators.

9. The application according to claim 7, wherein, The guanidine nitrate nonlinear optical crystal is used for frequency doubling light output in the ultraviolet solar blind band.

10. The application according to claim 7, wherein, The guanidine nitrate nonlinear optical crystal outputs harmonic light of 2nd or 4th harmonic from the 1064nm fundamental frequency light of the Nd:YAG laser.

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