Fluorinated biuret borate nonlinear optical crystal as well as preparation method and application thereof

Abstract

The invention relates to a fluorinated biuret borate nonlinear optical crystal and a preparation method and application thereof, the chemical formula of the crystal is [C2N3O2BF2H5] [BF4], the molecular weight is 238.71, and the crystal is prepared by a hydrothermal method or a room temperature solution method; the crystal belongs to a monoclinic system, the space group is P21, and the cell parameters are as follows: a = 6.0521 (11), b = 9.4651 (18), c = 7.1398 (12), beta = 91.267 (7), Z = 2, and V = 408.90 (13) 3. The [C2N3O2BF2H5] [BF4] nonlinear optical crystal obtained by the method is used for manufacturing a second harmonic generator, an upper frequency converter, a lower frequency converter, an optical parametric oscillator and the like; meanwhile, the crystal can also be used as a birefringent crystal for manufacturing a refractive index modulator, a phase modulator and a polarization device.

Description

Technical Field

[0001] This invention relates to a nonlinear optical crystal of fluorinated borate biuret, its preparation method, and its uses. Background Technology

[0002] Ultraviolet nonlinear optical materials are key materials for generating coherent ultraviolet light in solid-state lasers. To obtain nonlinear optical materials with nonlinear optical properties, the commonly used international method is to introduce nonlinear optical functional units that easily cause distortion into the structure. These units mainly contain d... 0 d 10 Transition metal cation polyhedra or metal cation polyhedra containing lone pairs of electrons have electronic structures. However, these structural units often cause a redshift of the ultraviolet cutoff edge, making them unsuitable for the ultraviolet region. Borates, on the other hand, are characterized by their ability to transmit ultraviolet radiation, and many excellent nonlinear optical crystals have been discovered among borates, such as BBO (…). β -BBO), LBO (LiB3O5) crystals, CBO (CsB3O5) crystals, CLBO (CsLiB6O) crystals 10 Nonlinear optical crystals include KBBF (KBe₂BO₃F₂) crystals. Although the crystal growth techniques for these materials have become increasingly mature, they still have significant drawbacks: such as hygroscopicity, long growth cycles, severe layered growth habits, and high cost. Therefore, synthesizing new nonlinear optical crystal materials remains a very important and challenging task.

[0003] Ultraviolet birefringent crystals can be applied in optical isolators, Glan prisms, polarizers / analyzers, circulators, photoelectric modulators, and laser polarization technology. Currently, commercially available birefringent materials include CaCO3, TiO2, LiNbO3, YVO4, α-BaB2O4, and MgF2. However, they still face challenges such as difficult processing, low refractive index, excessively high cutoff edges, and susceptibility to cracking. Therefore, discovering new and superior birefringent optical crystal materials remains a pressing issue, requiring extensive and in-depth research to continuously explore and discover birefringent crystals with better performance. Summary of the Invention

[0004] The purpose of this invention is to provide a nonlinear optical crystal of fluorinated borate biuret, which has no center of symmetry, is monoclinic, and has a space group of [missing information]. P 21, with unit cell parameters a = 6.0521(11) Å, b = 9.4651(18) Å, c = 7.1398(12) Å. β = 91.267(7), Z = 2, V = 408.90(13) Å 3 .

[0005] Another objective of this invention is to provide a method for preparing a nonlinear optical crystal of borate biuret fluoride, using a hydrothermal method or a room temperature solution method.

[0006] Another object of the present invention is to provide the use of a nonlinear optical crystal of fluorinated borate biuret.

[0007] The present invention discloses a nonlinear optical crystal of fluorinated borate biuret, the molecular formula of which is [C2N3O2BF2H5][BF4], it lacks a center of symmetry, belongs to the monoclinic crystal system, and has a space group of [missing information]. P 21, with unit cell parameters a = 6.0521(11) Å, b = 9.4651(18) Å, c = 7.1398(12) Å. β = 91.267(7), Z = 2, V = 408.90(13) Å 3 .

[0008] The method for preparing the aforementioned fluorinated borate biuret nonlinear optical crystal involves growing the crystal using a hydrothermal method or a room-temperature solution method. The hydrothermal growth of the fluorinated borate biuret nonlinear optical crystal is carried out according to the following steps: a. Mix biuret, fluorinated compounds HBF4, NH4BF4, NaBF4, LiBF4, KBF4, RbBF4, CsBF4, LiHF2, NaHF2, KHF2, RbHF2 or CsHF2, and B-containing compounds H3BO3 or HBO2 in a molar ratio of 1:2-3:0-2 until homogeneous. Add 5-10 mL of deionized water to fully mix and dissolve the mixture to obtain a solution. b. Transfer the mixed solution from step a into the polytetrafluoroethylene liner of a 50 mL hydrothermal reactor and tighten and seal the opening of the hydrothermal reactor. c. Place the hydrothermal reactor from step b in a constant temperature chamber, raise the temperature to 110°C at a rate of 10°C / h, keep it at the constant temperature for 3 days, and then lower it to room temperature at a rate of 1-3°C / h. d. Open the hydrothermal reactor, quickly wash the product in the polytetrafluoroethylene liner with deionized water, and air dry at room temperature to obtain the fluorinated borate biuret nonlinear optical crystal. The room temperature solution method for growing the fluorinated borate biuret nonlinear optical crystal is performed according to the following steps: a. Mix biuret, fluorinated compounds HBF4, NH4BF4, NaBF4, LiBF4, KBF4, RbBF4, CsBF4, LiHF2, NaHF2, KHF2, RbHF2 or CsHF2, and B-containing compound H3BO3 in a molar ratio of 1:2-3:0-2. Add the mixture to a 100mL polytetrafluoroethylene beaker and mix thoroughly. Add 60mL of water and stir until well mixed to obtain a mixture. b. The mixed solution from step a is ultrasonically treated to ensure thorough mixing and dissolution. It is then filtered with qualitative filter paper to obtain a clear solution. The solution is then sealed with a polyvinyl chloride film and placed in a static environment free from shaking, pollution, and air convection. Several small holes are punched in the seal to adjust the evaporation rate of the solvent in the solution. The solution is left to stand at room temperature. Subsequently, crystals precipitate in the solution and gradually grow. Once the growth is complete, a nonlinear optical crystal of fluorinated borate biuret with a size in the millimeter range is obtained.

[0009] The fluorinated borate biuret nonlinear optical crystal is used in the preparation of harmonic output of 2nd, 3rd, or 4th harmonic light from the 1064 nm fundamental frequency light output by an Nd:YAG laser, with an output intensity approximately 3 times that of KDP under the same conditions.

[0010] The use of the fluorinated borate biuret nonlinear optical crystal in the fabrication of frequency multiplier generators, up or down frequency converters, or optical parametric oscillators.

[0011] The use of the fluorinated borate biuret nonlinear optical crystal in the fabrication of optical isolators, circulators, beam shifters, optical polarizers, or optical modulators.

[0012] The nonlinear optical crystal of fluorinated borate biuret obtained by the method described in this invention has a crystal size in the millimeter range, no obvious layered growth habit, and can be obtained by using a large-size container and extending the crystal growth period to obtain a correspondingly large crystal [C2N3O2BF2H5][BF4]. In the growth of the [C2N3O2BF2H5][BF4] nonlinear optical crystal, the crystal grows easily, is transparent and unencapsulated, and has the advantages of fast growth rate, low cost, and easy acquisition of large-size fluorinated borate biuret nonlinear optical crystals.

[0013] The large-size [C2N3O2BF2H5][BF4] nonlinear optical crystal obtained by the method described in this invention can be used as a nonlinear optical and birefringent device by orienting the crystal blank according to the crystallographic data, cutting the crystal according to the required angle, thickness and cross-sectional size, and polishing the light-transmitting surface of the crystal. This [C2N3O2BF2H5][BF4] nonlinear optical crystal has advantages such as a wide light transmission band, stable physicochemical properties, moderate mechanical hardness, not easy to break, and easy to cut, polish and store. Attached Figure Description

[0014] Figure 1 The powder XRD pattern of [C2N3O2BF2H5][BF4] of this invention; Figure 2 This is a structural diagram of the [C2N3O2BF2H5][BF4] nonlinear optical crystal of the present invention.

[0015] Figure 3 This is a schematic diagram of the working principle of the nonlinear optical device fabricated by the [C2N3O2BF2H5][BF4] nonlinear optical crystal of the present invention, wherein 1 is a laser, 2 is the emitted beam, 3 is the [C2N3O2BF2H5][BF4] nonlinear optical crystal, 4 is the emitted beam, and 5 is a filter. Figure 4 This is a schematic diagram of the working principle of the optical device made from the [C2N3O2BF2H5][BF4] nonlinear optical crystal of the present invention. In the diagram, 1 is the incident light, 2 is the polarizer, 3 is the bonding joint of two prisms made from processed [C2N3O2BF2H5][BF4] crystals, and 4 and 5 are two beams of light with different refractive indices, where 4 is the extraordinary light and 5 is the ordinary light. Detailed Implementation

[0016] The present invention will now be described in detail with reference to the accompanying drawings and embodiments: Example 1

[0017] According to the reaction formula: C2N3O2H5 + 2HBF4 → [C2N3O2BF2H5][BF4] + 2HF, the [C2N3O2BF2H5][BF4] nonlinear optical crystal was prepared by hydrothermal method. a. Mix C2N3O2H5 and HBF4 at a molar ratio of 1:2 until homogeneous, add 5mL of deionized water and mix thoroughly to dissolve, thus obtaining a mixed solution; b. Transfer the mixed solution from step a into the polytetrafluoroethylene liner of a 50 mL hydrothermal reactor and tighten and seal the opening of the hydrothermal reactor. c. Place the hydrothermal reactor from step b in a constant temperature chamber, raise the temperature to 110°C at a rate of 10°C / h, keep it at the constant temperature for 3 days, and then lower it to room temperature at a rate of 1°C / h. d. Open the hydrothermal reactor, quickly wash the product in the polytetrafluoroethylene liner with deionized water, and place it on filter paper to dry. This will yield a [C2N3O2BF2H5][BF4] nonlinear optical crystal with dimensions of 15mm×12mm×8mm. Example 2

[0018] According to the reaction formula: C2N3O2H5 + 2NH4BF4 → [C2N3O2BF2H5][BF4] + 2HF + 2NH3, the nonlinear optical crystal [C2N3O2BF2H5][BF4] is prepared by hydrothermal method. a. Mix C2N3O2H5 and NH4BF4 at a molar ratio of 1:2 until homogeneous, add 10 mL of deionized water and mix thoroughly to dissolve, thus obtaining a mixed solution; b. Transfer the mixed solution from step a into the polytetrafluoroethylene liner of a 50 mL hydrothermal reactor and tighten and seal the opening of the hydrothermal reactor. c. Place the hydrothermal reactor from step b in a constant temperature chamber, raise the temperature to 110°C at a rate of 10°C / h, keep it at the constant temperature for 3 days, and then lower it to room temperature at a rate of 3°C / h. d. Open the hydrothermal reactor, quickly wash the product in the polytetrafluoroethylene liner with deionized water, and place it on filter paper to dry. This will yield a [C2N3O2BF2H5][BF4] nonlinear optical crystal with dimensions of 9mm×7mm×3mm. Example 3

[0019] According to the reaction formula: C2N3O2H5 + 2LiBF4 → [C2N3O2BF2H5][BF4] + 2LiF2, the nonlinear optical crystal [C2N3O2BF2H5][BF4] is prepared by hydrothermal method. a. Mix C2N3O2H5 and LiBF4 at a molar ratio of 1:2 until homogeneous, add 8 mL of deionized water to fully mix and dissolve them to obtain a mixed solution; b. Transfer the mixed solution from step a into the polytetrafluoroethylene liner of a 50 mL hydrothermal reactor and tighten and seal the opening of the hydrothermal reactor. c. Place the hydrothermal reactor from step b in a constant temperature chamber, raise the temperature to 110°C at a rate of 10°C / h, keep it at the constant temperature for 3 days, and then lower it to room temperature at a rate of 2°C / h. d. Open the hydrothermal reactor, quickly wash the product in the polytetrafluoroethylene liner with deionized water, and place it on filter paper to dry. This will yield a [C2N3O2BF2H5][BF4] nonlinear optical crystal with dimensions of 8mm×7mm×2mm. Example 4

[0020] According to the reaction formula: C2N3O2H5 + 2NaBF4 → [C2N3O2BF2H5][BF4] + 2NaF2, the nonlinear optical crystal [C2N3O2BF2H5][BF4] is prepared by hydrothermal method. a. Mix C2N3O2H5 and NaBF4 at a molar ratio of 1:2 until homogeneous, add 9 mL of deionized water and mix thoroughly to dissolve, thus obtaining a mixed solution; b. Transfer the mixed solution from step a into the polytetrafluoroethylene liner of a 50 mL hydrothermal reactor and tighten and seal the opening of the hydrothermal reactor. c. Place the hydrothermal reactor from step b in a constant temperature chamber, raise the temperature to 110°C at a rate of 10°C / h, keep it at the constant temperature for 3 days, and then lower it to room temperature at a rate of 2°C / h. d. Open the hydrothermal reactor, quickly wash the product in the polytetrafluoroethylene liner with deionized water, and place it on filter paper to dry. This will yield a [C2N3O2BF2H5][BF4] nonlinear optical crystal with dimensions of 10mm×6mm×3mm. Example 5

[0021] According to the reaction formula: C2N3O2H5 + 2KBF4 → [C2N3O2BF2H5][BF4] + 2KF2, the nonlinear optical crystal [C2N3O2BF2H5][BF4] is prepared by hydrothermal method. a. Mix C2N3O2H5 and KBF4 at a molar ratio of 1:2 until homogeneous, add 10 mL of deionized water and mix thoroughly to dissolve, thus obtaining a mixed solution; b. Transfer the mixed solution from step a into the polytetrafluoroethylene liner of a 50 mL hydrothermal reactor and tighten and seal the opening of the hydrothermal reactor. c. Place the hydrothermal reactor from step b in a constant temperature chamber, raise the temperature to 110°C at a rate of 10°C / h, keep it at the constant temperature for 3 days, and then lower it to room temperature at a rate of 2°C / h. d. Open the hydrothermal reactor, quickly wash the product in the polytetrafluoroethylene liner with deionized water, and place it on filter paper to dry. This will yield a [C2N3O2BF2H5][BF4] nonlinear optical crystal with dimensions of 7mm×4mm×4mm. Example 6

[0022] According to the reaction formula: C2N3O2H5 + 2RbBF4 → [C2N3O2BF2H5][BF4] + 2RbF2, the nonlinear optical crystal [C2N3O2BF2H5][BF4] is prepared by hydrothermal method. a. Mix C2N3O2H5 and RbBF4 at a molar ratio of 1:2 until homogeneous, add 7 mL of deionized water and mix thoroughly to dissolve, thus obtaining a mixed solution; b. Transfer the mixed solution from step a into the polytetrafluoroethylene liner of a 50 mL hydrothermal reactor and tighten and seal the opening of the hydrothermal reactor. c. Place the hydrothermal reactor from step b in a constant temperature chamber, raise the temperature to 110°C at a rate of 10°C / h, keep it at the constant temperature for 3 days, and then lower it to room temperature at a rate of 2°C / h. d. Open the hydrothermal reactor, quickly wash the product in the polytetrafluoroethylene liner with deionized water, and place it on filter paper to dry. This will yield a [C2N3O2BF2H5][BF4] nonlinear optical crystal with dimensions of 7mm×4mm×4mm. Example 7

[0023] According to the reaction formula: C2N3O2H5 + 2CsBF4 → [C2N3O2BF2H5][BF4] + 2CsF2, the nonlinear optical crystal [C2N3O2BF2H5][BF4] is prepared by hydrothermal method. a. Mix C2N3O2H5 and CsBF4 at a molar ratio of 1:2 until homogeneous, add 8 mL of deionized water to fully mix and dissolve them to obtain a mixed solution; b. Transfer the mixed solution from step a into the polytetrafluoroethylene liner of a 50 mL hydrothermal reactor and tighten and seal the opening of the hydrothermal reactor. c. Place the hydrothermal reactor from step b in a constant temperature chamber, raise the temperature to 110°C at a rate of 10°C / h, keep it at the constant temperature for 3 days, and then lower it to room temperature at a rate of 2°C / h. d. Open the hydrothermal reactor, quickly wash the product in the polytetrafluoroethylene liner with deionized water, and place it on filter paper to dry. This will yield a [C2N3O2BF2H5][BF4] nonlinear optical crystal with dimensions of 8mm×5mm×3mm. Example 8

[0024] According to the reaction formula: C2N3O2H5 + 3NH4HF2 + 2H3BO3 → [C2N3O2BF2H5][BF4] + 3NH3 + 6H2O, the nonlinear optical crystal [C2N3O2BF2H5][BF4] is prepared by hydrothermal method. a. Mix C2N3O2H5, NH4HF2, and H3BO3 in a molar ratio of 1:3:2 until homogeneous, add 10 mL of deionized water and mix thoroughly to obtain a mixed solution; b. Transfer the mixed solution from step a into the polytetrafluoroethylene liner of a 50 mL hydrothermal reactor and tighten and seal the opening of the hydrothermal reactor. c. Place the hydrothermal reactor from step b in a constant temperature chamber, raise the temperature to 110°C at a rate of 10°C / h, keep it at the constant temperature for 3 days, and then lower it to room temperature at a rate of 1°C / h. d. Open the hydrothermal reactor, quickly wash the product in the polytetrafluoroethylene liner with deionized water, and place it on filter paper to dry. This will yield a [C2N3O2BF2H5][BF4] nonlinear optical crystal with dimensions of 9mm×4mm×2mm. Example 9

[0025] According to the reaction formula: C2N3O2H5 + 3LiHF2 + 2H3BO3 → [C2N3O2BF2H5][BF4] + 3LiOH + 3H2O, the nonlinear optical crystal [C2N3O2BF2H5][BF4] is prepared by hydrothermal method. a. Mix C2N3O2H5, LiHF2, and H3BO3 in a molar ratio of 1:3:2 until homogeneous, add 10 mL of deionized water and mix thoroughly to obtain a mixed solution; b. Transfer the mixed solution from step a into the polytetrafluoroethylene liner of a 50 mL hydrothermal reactor and tighten and seal the opening of the hydrothermal reactor. c. Place the hydrothermal reactor from step b in a constant temperature chamber, raise the temperature to 110°C at a rate of 10°C / h, keep it at the constant temperature for 3 days, and then lower it to room temperature at a rate of 1°C / h. d. Open the hydrothermal reactor, quickly wash the product in the polytetrafluoroethylene liner with deionized water, and place it on filter paper to dry. This will yield a [C2N3O2BF2H5][BF4] nonlinear optical crystal with dimensions of 7mm×3mm×2mm. Example 10

[0026] According to the reaction formula: C2N3O2H5 + 3NaHF2 + 2H3BO3 → [C2N3O2BF2H5][BF4] + 3NaOH + 3H2O, the nonlinear optical crystal [C2N3O2BF2H5][BF4] is prepared by hydrothermal method. a. Mix C2N3O2H5, NaHF2, and H3BO3 in a molar ratio of 1:3:2 until homogeneous, add 10mL of deionized water and mix thoroughly to obtain a mixed solution; b. Transfer the mixed solution from step a into the polytetrafluoroethylene liner of a 50 mL hydrothermal reactor and tighten and seal the opening of the hydrothermal reactor. c. Place the hydrothermal reactor from step b in a constant temperature chamber, raise the temperature to 110°C at a rate of 10°C / h, keep it at the constant temperature for 3 days, and then lower it to room temperature at a rate of 1°C / h. d. Open the hydrothermal reactor, quickly wash the product in the polytetrafluoroethylene liner with deionized water, and place it on filter paper to dry. This will yield a [C2N3O2BF2H5][BF4] nonlinear optical crystal with a size of 6mm×2mm×2mm. Example 11

[0027] According to the reaction formula: C2N3O2H5 + 3KHF2 + 2H3BO3 → [C2N3O2BF2H5][BF4] + 3KOH + 3H2O, the nonlinear optical crystal [C2N3O2BF2H5][BF4] is prepared by hydrothermal method. a. Mix C2N3O2H5, KHF2, and H3BO3 in a molar ratio of 1:3:2 until homogeneous, add 10 mL of deionized water and mix thoroughly to obtain a mixed solution; b. Transfer the mixed solution from step a into the polytetrafluoroethylene liner of a 50 mL hydrothermal reactor and tighten and seal the opening of the hydrothermal reactor. c. Place the hydrothermal reactor from step b in a constant temperature chamber, raise the temperature to 110°C at a rate of 10°C / h, keep it at the constant temperature for 3 days, and then lower it to room temperature at a rate of 1°C / h. d. Open the hydrothermal reactor, quickly wash the product in the polytetrafluoroethylene liner with deionized water, and place it on filter paper to dry. This will yield a [C2N3O2BF2H5][BF4] nonlinear optical crystal with a size of 8mm×3mm×3mm. Example 12

[0028] According to the reaction formula: C2N3O2H5 + 3RbHF2 + 2H3BO3 → [C2N3O2BF2H5][BF4] + 3RbOH + 3H2O, the nonlinear optical crystal [C2N3O2BF2H5][BF4] is prepared by hydrothermal method. a. Mix C2N3O2H5, RbHF2, and H3BO3 in a molar ratio of 1:3:2 until homogeneous, add 10mL of deionized water and mix thoroughly to obtain a mixed solution; b. Transfer the mixed solution from step a into the polytetrafluoroethylene liner of a 50 mL hydrothermal reactor and tighten and seal the opening of the hydrothermal reactor. c. Place the hydrothermal reactor from step b in a constant temperature chamber, raise the temperature to 110°C at a rate of 10°C / h, keep it at the constant temperature for 3 days, and then lower it to room temperature at a rate of 1°C / h. d. Open the hydrothermal reactor, quickly wash the product in the polytetrafluoroethylene liner with deionized water, and place it on filter paper to dry. This will yield a [C2N3O2BF2H5][BF4] nonlinear optical crystal with dimensions of 10mm×4mm×3mm. Example 13

[0029] According to the reaction formula: C2N3O2H5 + 3CsHF2 + 2H3BO3 → [C2N3O2BF2H5][BF4] + 3CsOH + 3H2O, the nonlinear optical crystal [C2N3O2BF2H5][BF4] is prepared by hydrothermal method. a. Mix C2N3O2H5, CsHF2, and H3BO3 in a molar ratio of 1:3:2 until homogeneous, add 10 mL of deionized water and mix thoroughly to dissolve, thus obtaining a mixed solution; b. Transfer the mixed solution from step a into the polytetrafluoroethylene liner of a 50 mL hydrothermal reactor and tighten and seal the opening of the hydrothermal reactor. c. Place the hydrothermal reactor from step b in a constant temperature chamber, raise the temperature to 110°C at a rate of 10°C / h, keep it at the constant temperature for 3 days, and then lower it to room temperature at a rate of 1°C / h. d. Open the hydrothermal reactor, quickly wash the product in the polytetrafluoroethylene liner with deionized water, and place it on filter paper to dry. This will yield a [C2N3O2BF2H5][BF4] nonlinear optical crystal with dimensions of 7mm×5mm×2mm. Example 14

[0030] According to the reaction formula: C2N3O2H5 + 3LiHF2 + 2HBO2 → [C2N3O2BF2H5][BF4] + 3LiOH + H2O, the nonlinear optical crystal [C2N3O2BF2H5][BF4] is prepared by hydrothermal method. a. Mix C2N3O2H5, LiHF2, and HBO2 in a molar ratio of 1:3:2 until homogeneous, add 6 mL of deionized water and mix thoroughly to obtain a mixed solution; b. Transfer the mixed solution from step a into the polytetrafluoroethylene liner of a 50 mL hydrothermal reactor and tighten and seal the opening of the hydrothermal reactor. c. Place the hydrothermal reactor from step b in a constant temperature chamber, raise the temperature to 110°C at a rate of 10°C / h, keep it at the constant temperature for 3 days, and then lower it to room temperature at a rate of 2°C / h. d. Open the hydrothermal reactor, quickly wash the product in the polytetrafluoroethylene liner with deionized water, and place it on filter paper to dry. This will yield a [C2N3O2BF2H5][BF4] nonlinear optical crystal with dimensions of 5mm×2mm×1mm. Example 15

[0031] According to the reaction formula: C2N3O2H5 + 3NaHF2 + 2HBO2 → [C2N3O2BF2H5][BF4] + 3NaOH + H2O, the nonlinear optical crystal [C2N3O2BF2H5][BF4] is prepared by hydrothermal method. a. Mix C2N3O2H5, NaHF2, and HBO2 in a molar ratio of 1:3:2 until homogeneous, add 9 mL of deionized water and mix thoroughly to obtain a mixed solution; b. Transfer the mixed solution from step a into the polytetrafluoroethylene liner of a 50 mL hydrothermal reactor and tighten and seal the opening of the hydrothermal reactor. c. Place the hydrothermal reactor from step b in a constant temperature chamber, raise the temperature to 110°C at a rate of 10°C / h, keep it at the constant temperature for 3 days, and then lower it to room temperature at a rate of 2°C / h. d. Open the hydrothermal reactor, quickly wash the product in the polytetrafluoroethylene liner with deionized water, and place it on filter paper to dry. This will yield a [C2N3O2BF2H5][BF4] nonlinear optical crystal with dimensions of 6mm×2mm×1mm. Example 16

[0032] According to the reaction formula: C2N3O2H5 + 3KHF2 + 2HBO2 → [C2N3O2BF2H5][BF4] + 3KOH + H2O, the nonlinear optical crystal [C2N3O2BF2H5][BF4] is prepared by hydrothermal method. a. Mix C2N3O2H5, KHF2, and HBO2 in a molar ratio of 1:3:2 until homogeneous, add 7 mL of deionized water and mix thoroughly to obtain a mixed solution; b. Transfer the mixed solution from step a into the polytetrafluoroethylene liner of a 50 mL hydrothermal reactor and tighten and seal the opening of the hydrothermal reactor. c. Place the hydrothermal reactor from step b in a constant temperature chamber, raise the temperature to 110°C at a rate of 10°C / h, keep it at the constant temperature for 3 days, and then lower it to room temperature at a rate of 2°C / h. d. Open the hydrothermal reactor, quickly wash the product in the polytetrafluoroethylene liner with deionized water, and place it on filter paper to dry. This will yield a [C2N3O2BF2H5][BF4] nonlinear optical crystal with dimensions of 7mm×4mm×2mm. Example 17

[0033] According to the reaction formula: C2N3O2H5 + 3RbHF2 + 2HBO2 → [C2N3O2BF2H5][BF4] + 3RbOH + H2O, the nonlinear optical crystal [C2N3O2BF2H5][BF4] is prepared by hydrothermal method. a. Mix C2N3O2H5, RbHF2, and HBO2 in a molar ratio of 1:3:2 until homogeneous, add 9 mL of deionized water and mix thoroughly to dissolve, thus obtaining a mixed solution; b. Transfer the mixed solution from step a into the polytetrafluoroethylene liner of a 50 mL hydrothermal reactor and tighten and seal the opening of the hydrothermal reactor. c. Place the hydrothermal reactor from step b in a constant temperature chamber, raise the temperature to 110°C at a rate of 10°C / h, keep it at the constant temperature for 3 days, and then lower it to room temperature at a rate of 2°C / h. d. Open the hydrothermal reactor, quickly wash the product in the polytetrafluoroethylene liner with deionized water, and place it on filter paper to dry. This will yield a [C2N3O2BF2H5][BF4] nonlinear optical crystal with dimensions of 6mm×3mm×2mm. Example 18

[0034] According to the reaction formula: C2N3O2H5 + 3CsHF2 + 2HBO2 → [C2N3O2BF2H5][BF4] + 3CsOH + H2O, the nonlinear optical crystal [C2N3O2BF2H5][BF4] is prepared by hydrothermal method. a. Mix C2N3O2H5, CsHF2, and HBO2 in a molar ratio of 1:3:2 until homogeneous, add 8 mL of deionized water and mix thoroughly to dissolve, thus obtaining a mixed solution; b. Transfer the mixed solution from step a into the polytetrafluoroethylene liner of a 50 mL hydrothermal reactor and tighten and seal the opening of the hydrothermal reactor. c. Place the hydrothermal reactor from step b in a constant temperature chamber, raise the temperature to 110°C at a rate of 10°C / h, keep it at the constant temperature for 3 days, and then lower it to room temperature at a rate of 2°C / h. d. Open the hydrothermal reactor, quickly wash the product in the polytetrafluoroethylene liner with deionized water, and place it on filter paper to dry. This will yield a [C2N3O2BF2H5][BF4] nonlinear optical crystal with dimensions of 8mm×4mm×3mm. Example 19

[0035] According to the reaction formula: C2N3O2H5 + 2HBF4 → [C2N3O2BF2H5][BF4] + 2HF, the nonlinear optical crystal [C2N3O2BF2H5][BF4] was prepared by a room temperature solution method. a. Mix C2N3O2H5 and HBF4 at a molar ratio of 1:2 until homogeneous, add to a 100mL polytetrafluoroethylene beaker, add 60mL of water, stir and mix until homogeneous to obtain a mixture; b. The mixed solution from step a is ultrasonically treated to ensure thorough mixing and dissolution. Filter the solution using qualitative filter paper to obtain a clear solution. Seal the solution 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 for 10 days to allow the solvent to evaporate. [C2N3O2BF2H5][BF4] crystals precipitate and gradually grow. Once the crystal growth is complete, a [C2N3O2BF2H5][BF4] nonlinear optical crystal with dimensions of 5mm × 2mm × 1mm is obtained. Example 20

[0036] According to the reaction formula: C2N3O2H5 + 2NH4BF4 → [C2N3O2BF2H5][BF4] + 2HF + 2NH3, the nonlinear optical crystal [C2N3O2BF2H5][BF4] is prepared by room temperature solution method. a. Mix C2N3O2H5 and NH4BF4 at a molar ratio of 1:2 until homogeneous, add to a 100mL polytetrafluoroethylene beaker, add 60mL of water, stir and mix until homogeneous to obtain a mixture; b. The mixed solution from step a is ultrasonically treated to ensure thorough mixing and dissolution. Filter the solution using qualitative filter paper to obtain a clear solution. Seal the solution 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 for 10 days to allow the solvent to evaporate. [C2N3O2BF2H5][BF4] crystals precipitate and gradually grow. Once the crystal growth is complete, a [C2N3O2BF2H5][BF4] nonlinear optical crystal with dimensions of 3mm × 1.5mm × 1mm is obtained. Example 21

[0037] According to the reaction formula: C2N3O2H5 + 2LiBF4 → [C2N3O2BF2H5][BF4] + 2LiF2, the nonlinear optical crystal [C2N3O2BF2H5][BF4] was prepared by room temperature solution method. a. Mix C2N3O2H5 and LiBF4 at a molar ratio of 1:2 until homogeneous, add to a 100mL polytetrafluoroethylene beaker, add 60mL of water, stir and mix until homogeneous to obtain a mixture; b. The mixed solution from step a is ultrasonically treated to ensure thorough mixing and dissolution. Filter the solution using qualitative filter paper to obtain a clear solution. Seal the solution 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 for 10 days to allow the solvent to evaporate. [C2N3O2BF2H5][BF4] crystals precipitate and gradually grow. Once the crystal growth is complete, a [C2N3O2BF2H5][BF4] nonlinear optical crystal with dimensions of 4mm × 2mm × 1.5mm is obtained. Example 22

[0038] According to the reaction formula: C2N3O2H5 + 2NaBF4 → [C2N3O2BF2H5][BF4] + 2NaF2, the nonlinear optical crystal [C2N3O2BF2H5][BF4] was prepared by room temperature solution method. a. Mix C2N3O2H5 and NaBF4 at a molar ratio of 1:2 until homogeneous, add to a 100mL polytetrafluoroethylene beaker, add 60mL of water, stir and mix until homogeneous to obtain a mixture; b. The mixed solution from step a is ultrasonically treated to ensure thorough mixing and dissolution. Filter the solution using qualitative filter paper to obtain a clear solution. Seal the solution 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 for 10 days to allow the solvent to evaporate. [C2N3O2BF2H5][BF4] crystals precipitate and gradually grow. Once the crystal growth is complete, a [C2N3O2BF2H5][BF4] nonlinear optical crystal with dimensions of 3mm × 1.6mm × 1.2mm is obtained. Example 23

[0039] According to the reaction formula: C2N3O2H5 + 2KBF4 → [C2N3O2BF2H5][BF4] + 2KF2, the nonlinear optical crystal [C2N3O2BF2H5][BF4] was prepared by room temperature solution method. a. Mix C2N3O2H5 and KBF4 at a molar ratio of 1:2 until homogeneous, add to a 100mL polytetrafluoroethylene beaker, add 60mL of water, stir and mix until homogeneous to obtain a mixture; b. The mixed solution from step a is ultrasonically treated to ensure thorough mixing and dissolution. Filter the solution using qualitative filter paper to obtain a clear solution. Seal the solution 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 for 10 days to allow the solvent to evaporate. [C2N3O2BF2H5][BF4] crystals precipitate and gradually grow. Once the crystal growth is complete, a [C2N3O2BF2H5][BF4] nonlinear optical crystal with dimensions of 5mm × 3mm × 2mm is obtained. Example 24

[0040] According to the reaction formula: C2N3O2H5 + 2RbBF4 → [C2N3O2BF2H5][BF4] + 2RbF2, the nonlinear optical crystal [C2N3O2BF2H5][BF4] was prepared by room temperature solution method. a. Mix C2N3O2H5 and RbBF4 at a molar ratio of 1:2 until homogeneous, add to a 100mL polytetrafluoroethylene beaker, add 60mL of water, stir and mix until homogeneous to obtain a mixture; b. The mixed solution from step a is ultrasonically treated to ensure thorough mixing and dissolution. Filter the solution using qualitative filter paper to obtain a clear solution. Seal the solution 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 for 10 days to allow the solvent to evaporate. [C2N3O2BF2H5][BF4] crystals precipitate and gradually grow. Once the crystal growth is complete, a [C2N3O2BF2H5][BF4] nonlinear optical crystal with dimensions of 2.5mm × 1mm × 1.2mm is obtained. Example 25

[0041] According to the reaction formula: C2N3O2H5 + 2CsBF4 → [C2N3O2BF2H5][BF4] + 2CsF2, the nonlinear optical crystal [C2N3O2BF2H5][BF4] was prepared by room temperature solution method. a. Mix C2N3O2H5 and CsBF4 at a molar ratio of 1:2 until homogeneous, add to a 100mL polytetrafluoroethylene beaker, add 60mL of water, stir and mix until homogeneous to obtain a mixture; b. The mixed solution from step a is ultrasonically treated to ensure thorough mixing and dissolution. Filter the solution using qualitative filter paper to obtain a clear solution. Seal the solution 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 for 10 days to allow the solvent to evaporate. [C2N3O2BF2H5][BF4] crystals precipitate and gradually grow. Once the crystal growth is complete, a [C2N3O2BF2H5][BF4] nonlinear optical crystal with dimensions of 4mm × 2mm × 1mm is obtained. Example 26

[0042] According to the reaction formula: C2N3O2H5 + 3NH4HF2 + 2H3BO3 → [C2N3O2BF2H5][BF4] + 3NH3 + 6H2O, the nonlinear optical crystal [C2N3O2BF2H5][BF4] is prepared by room temperature solution method. a. Mix C2N3O2H5, NH4HF2, and H3BO3 in a molar ratio of 1:3:2 until homogeneous, add the mixture to a 100mL polytetrafluoroethylene beaker, add 60mL of water, stir and mix until homogeneous to obtain a mixture. b. The mixed solution from step a is ultrasonically treated to ensure thorough mixing and dissolution. Filter the solution using qualitative filter paper to obtain a clear solution. Seal the solution 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 for 10 days to allow the solvent to evaporate. [C2N3O2BF2H5][BF4] crystals precipitate and gradually grow. Once the crystal growth is complete, a [C2N3O2BF2H5][BF4] nonlinear optical crystal with dimensions of 2mm × 2mm × 1mm is obtained. Example 27

[0043] According to the reaction formula: C2N3O2H5 + 3LiHF2 + 2H3BO3 → [C2N3O2BF2H5][BF4] + 3LiOH + 3H2O, the nonlinear optical crystal [C2N3O2BF2H5][BF4] is prepared by room temperature solution method. a. Mix C2N3O2H5, LiHF2, and H3BO3 in a molar ratio of 1:3:2 until homogeneous, add the mixture to a 100mL polytetrafluoroethylene beaker, add 60mL of water, stir and mix until homogeneous to obtain a mixture. b. The mixed solution from step a is ultrasonically treated to ensure thorough mixing and dissolution. Filter the solution using qualitative filter paper to obtain a clear solution. Seal the solution 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 for 10 days to allow the solvent to evaporate. [C2N3O2BF2H5][BF4] crystals precipitate and gradually grow. Once the crystal growth is complete, a [C2N3O2BF2H5][BF4] nonlinear optical crystal with dimensions of 5mm × 3mm × 2mm is obtained. Example 28

[0044] According to the reaction formula: C2N3O2H5 + 3NaHF2 + 2H3BO3 → [C2N3O2BF2H5][BF4] + 3NaOH + 3H2O, the nonlinear optical crystal [C2N3O2BF2H5][BF4] is prepared by room temperature solution method. a. Mix C2N3O2H5, NaHF2, and H3BO3 in a molar ratio of 1:3:2 until homogeneous, add the mixture to a 100mL polytetrafluoroethylene beaker, add 60mL of water, stir and mix until homogeneous to obtain a mixture. b. The mixed solution from step a is ultrasonically treated to ensure thorough mixing and dissolution. Filter the solution using qualitative filter paper to obtain a clear solution. Seal the solution 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 for 10 days to allow the solvent to evaporate. [C2N3O2BF2H5][BF4] crystals precipitate and gradually grow. Once the crystal growth is complete, a [C2N3O2BF2H5][BF4] nonlinear optical crystal with dimensions of 4mm × 2mm × 2mm is obtained. Example 29

[0045] According to the reaction formula: C2N3O2H5 + 3KHF2 + 2H3BO3 → [C2N3O2BF2H5][BF4] + 3KOH + 3H2O, the nonlinear optical crystal [C2N3O2BF2H5][BF4] is prepared by room temperature solution method. a. Mix C2N3O2H5, KHF2, and H3BO3 in a molar ratio of 1:3:2 until homogeneous, add the mixture to a 100mL polytetrafluoroethylene beaker, add 60mL of water, stir and mix until homogeneous to obtain a mixture. b. The mixed solution from step a is ultrasonically treated to ensure thorough mixing and dissolution. Filter the solution using qualitative filter paper to obtain a clear solution. Seal the solution 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 for 10 days to allow the solvent to evaporate. [C2N3O2BF2H5][BF4] crystals precipitate and gradually grow. Once the crystal growth is complete, a [C2N3O2BF2H5][BF4] nonlinear optical crystal with dimensions of 3mm × 1.5mm × 1mm is obtained. Example 30

[0046] According to the reaction formula: C2N3O2H5 + 3RbHF2 + 2H3BO3 → [C2N3O2BF2H5][BF4] + 3RbOH + 3H2O, the nonlinear optical crystal [C2N3O2BF2H5][BF4] is prepared by room temperature solution method. a. Mix C2N3O2H5, RbHF2, and H3BO3 in a molar ratio of 1:3:2 until homogeneous, add the mixture to a 100mL polytetrafluoroethylene beaker, add 60mL of water, stir and mix until homogeneous to obtain a mixture. b. The mixed solution from step a is ultrasonically treated to ensure thorough mixing and dissolution. Filter the solution using qualitative filter paper to obtain a clear solution. Seal the solution 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 for 10 days to allow the solvent to evaporate. [C2N3O2BF2H5][BF4] crystals precipitate and gradually grow. Once the crystal growth is complete, a [C2N3O2BF2H5][BF4] nonlinear optical crystal with dimensions of 5mm × 3mm × 1mm is obtained. Example 31

[0047] According to the reaction formula: C2N3O2H5 + 3CsHF2 + 2H3BO3 → [C2N3O2BF2H5][BF4] + 3CsOH + 3H2O, the nonlinear optical crystal [C2N3O2BF2H5][BF4] is prepared by room temperature solution method. a. Mix C2N3O2H5, CsHF2, and H3BO3 in a molar ratio of 1:3:2 until homogeneous, add the mixture to a 100mL polytetrafluoroethylene beaker, add 60mL of water, stir and mix until homogeneous to obtain a mixture. b. The mixed solution from step a is ultrasonically treated to ensure thorough mixing and dissolution. Filter the solution using qualitative filter paper to obtain a clear solution. Seal the solution 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 for 10 days to allow the solvent to evaporate. [C2N3O2BF2H5][BF4] crystals precipitate and gradually grow. Once the crystal growth is complete, a [C2N3O2BF2H5][BF4] nonlinear optical crystal with dimensions of 4mm × 2.5mm × 1.4mm is obtained. Example 32

[0048] The arbitrary [C2N3O2BF2H5][BF4] nonlinear optical crystals obtained in Examples 1-31 are processed in a matching direction, and then... Figure 3 As shown, the [C2N3O2BF2H5][BF4] single crystal 3 is positioned at location 3. At room temperature, a Q-switched Nd:YAG laser is used as the light source with an incident wavelength of 1064 nm. An infrared beam 2 with a wavelength of 1064 nm is emitted from the Q-switched Nd:YAG laser 1 and enters the [C2N3O2BF2H5][BF4] single crystal 3, producing green frequency-doubled light with a wavelength of 532 nm. The output intensity is about 3 times that of KDP under the same conditions. The outgoing beam 4 contains infrared light with a wavelength of 1064 nm and green light with a wavelength of 532 nm. After being filtered by the filter 5, a green laser with a wavelength of 532 nm is obtained. Example 33

[0049] Two single-crystal devices were obtained by directional cutting and polishing of any [C2N3O2BF2H5][BF4] nonlinear optical crystals obtained in Examples 1-31, and then attached to the substrate. Figure 4 As shown, at position 3, incident light 1 is incident through polarizer 2 into the prism bonding joint 3, which contains two processed [C2N3O2BF2H5][BF4] crystals, producing two beams of light with different refractive indices: extraordinary light 4 and ordinary light 5.

Claims

1. A nonlinear optical crystal of fluorinated borate biuret, characterized in that, The crystal has the molecular formula [C2N3O2BF2H5][BF4], lacks a center of symmetry, belongs to the monoclinic crystal system, and has a space group of [BF4]. P 21, with unit cell parameters a = 6.0521(11) Å, b = 9.4651(18) Å, c = 7.1398(12) Å. β = 91.267(7), Z = 2, V = 408.90(13) Å 3 .

2. The method for preparing the nonlinear optical crystal of fluorinated borate biuret according to claim 1, characterized in that... Crystals are grown using either hydrothermal or room temperature solution methods. The hydrothermal growth of the fluorinated borate biuret nonlinear optical crystal is carried out according to the following steps: a. Mix biuret, fluorinated compounds HBF4, NH4BF4, NaBF4, LiBF4, KBF4, RbBF4, CsBF4, LiHF2, NaHF2, KHF2, RbHF2 or CsHF2, and B-containing compounds H3BO3 or HBO2 in a molar ratio of 1:2-3:0-2 until homogeneous. Add 5-10 mL of deionized water to fully mix and dissolve the mixture to obtain a solution. b. Transfer the mixed solution from step a into the polytetrafluoroethylene liner of a 50 mL hydrothermal reactor and tighten and seal the opening of the hydrothermal reactor. c. Place the hydrothermal reactor from step b in a constant temperature chamber, raise the temperature to 110°C at a rate of 10°C / h, keep it at the constant temperature for 3 days, and then lower it to room temperature at a rate of 1-3°C / h. d. Open the hydrothermal reactor, quickly wash the product in the polytetrafluoroethylene liner with deionized water, and air dry at room temperature to obtain the fluorinated borate biuret nonlinear optical crystal. The room temperature solution method for growing the fluorinated borate biuret nonlinear optical crystal is performed according to the following steps: a. Mix biuret, fluorinated compounds HBF4, NH4BF4, NaBF4, LiBF4, KBF4, RbBF4, CsBF4, LiHF2, NaHF2, KHF2, RbHF2 or CsHF2, and B-containing compound H3BO3 in a molar ratio of 1:2-3:0-2. Add the mixture to a 100mL polytetrafluoroethylene beaker and mix thoroughly. Add 60mL of water and stir until well mixed to obtain a mixture. b. The mixed solution from step a is ultrasonically treated to ensure thorough mixing and dissolution. It is then filtered with qualitative filter paper to obtain a clear solution. The solution is then sealed with a polyvinyl chloride film and placed in a static environment free from shaking, pollution, and air convection. Several small holes are punched in the seal to adjust the evaporation rate of the solvent in the solution. The solution is left to stand at room temperature. Subsequently, crystals precipitate in the solution and gradually grow. Once the growth is complete, a nonlinear optical crystal of fluorinated borate biuret with a size in the millimeter range is obtained.

3. The use of the fluorinated borate biuret nonlinear optical crystal according to claim 1 in preparing harmonic light output of the 1064 nm fundamental frequency light output by an Nd:YAG laser for 2nd, 3rd, or 4th harmonic output, wherein the output intensity is approximately 3 times that of KDP under the same conditions.

4. The use of the fluorinated borate biuret nonlinear optical crystal according to claim 1 in the preparation of frequency multiplier generators, up or down frequency converters, or optical parametric oscillators.

5. The use of the fluorinated borate biuret nonlinear optical crystal according to claim 1 in the fabrication of optical isolators, circulators, beam shifters, optical polarizers, or optical modulators.

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