Guanidine phosphite nonlinear optical crystal and its preparation method and use

Abstract

The present invention provides a guanidine phosphite nonlinear optical crystal and a preparation method and use thereof. The chemical formula of the crystal is [C(NH2)3]2HPO3, the molecular weight is 200.15, and the crystal belongs to the monoclinic system with a space group of Cm , the unit cell parameters are a =13.0197(14)Å, b =7.3168(7)Å, c =11.7448(19)Å, α= 90°, β= 119.607(3)°, c= 90°, unit cell volume is 972.8(2)Å 3 The frequency doubling effect of the crystal is about 0.8 times that of KH2PO4 (KDP), and the ultraviolet cutoff edge is about 189nm. The crystal is grown by evaporation, hydrothermal or room temperature solution method. The crystal has good chemical stability and can be used as a short-wavelength ultraviolet nonlinear optical crystal in all-solid-state lasers.

Description

Technical Field

[0001] The present invention relates to a guanidine phosphite [C(NH2)3]2HPO3 nonlinear optical crystal, a preparation method and application thereof. Background Art

[0002] Short-wavelength nonlinear optical crystals can utilize their frequency conversion properties to convert lasers in near-infrared and visible bands into short-wavelength lasers, offering important applications in fields such as medicine, communications, and scientific research. Currently, Chinese-made short-wavelength nonlinear optical crystals include KBe2BO3F2 (KBBF), BaB2O4 (BBO), and LiB3O5 (LBO). However, these crystals suffer from limitations such as low birefringence and difficulty growing large crystals, which limit their applications. Therefore, the preparation and synthesis of novel short-wavelength nonlinear optical crystal materials with superior overall performance is of great significance and practical value.

[0003] When designing and developing new short-wavelength nonlinear optical crystals, people hope to obtain crystals with large second-order nonlinear coefficients, wide transmittance range, short cutoff edge, and moderate birefringence. Summary of the Invention

[0004] The present invention aims to provide a guanidine phosphite nonlinear optical crystal, the chemical formula of the crystal is [C(NH2)3]2HPO3, the molecular weight is 200.15, belongs to the monoclinic system, the space group is Cm, and the unit cell parameters are α=90°,β=119.607(3)°,γ=90°,the unit cell volume is

[0005] Another object of the present invention is to provide a method for preparing guanidine phosphite [C(NH2)3]2HPO3 nonlinear optical crystals, which uses a melt method, a high-temperature melt method or a vacuum packaging method to grow the crystals.

[0006] Another object of the present invention is to provide a use of guanidine phosphite [C(NH2)3]2HPO3 nonlinear optical crystal.

[0007] The present invention relates to a guanidine phosphite nonlinear optical crystal, the chemical formula of which is [C(NH2)3]2HPO3, the molecular weight is 200.15, belongs to the monoclinic system, the space group is Cm, and the unit cell parameters are α=90°,β=119.607(3)°,γ=90°,the unit cell volume is

[0008] The preparation method of the guanidine phosphite nonlinear optical crystal adopts an evaporation method, a hydrothermal method or a room temperature solution method to grow the crystal;

[0009] The evaporation method for growing guanidine phosphite crystals is specifically performed in the following steps:

[0010] a. Mix a compound containing [C(NH2)3] and a compound containing P in a molar ratio of [C(NH2)3]:P=2:1, add 5-25 ml of deionized water, and mix and dissolve them thoroughly to obtain a mixed solution, wherein the compound containing [C(NH2)3] is [C(NH2)3]2CO3, [C(NH2)3]NO3, [C(NH2)3]HF2 or [C(NH2)3]Cl, and the compound containing P is H3PO3 or K2HPO3;

[0011] b. Place the mixed solution in step a in a resistance furnace, heat it to 40-90°C at a rate of 10-20°C / h, keep it at this temperature for 5-15 days to evaporate the solvent, and wait until the crystal growth is complete to obtain a guanidine phosphite nonlinear optical crystal;

[0012] The hydrothermal method for growing guanidine phosphite crystals is specifically performed in the following steps:

[0013] a. Mix a compound containing [C(NH2)3] and a compound containing P in a molar ratio of [C(NH2)3]:P=2:1, add 10-30 ml of deionized water, mix and dissolve them thoroughly to obtain a mixed solution, wherein the compound containing [C(NH2)3] is [C(NH2)3]2CO3, [C(NH2)3]NO3, [C(NH2)3]HF2 or [C(NH2)3]Cl, and the compound containing P is H3PO3 or K2HPO3;

[0014] b. Transferring the mixed solution from step a into a polytetrafluoroethylene liner of a hydrothermal reactor with a volume of 23-100 ml, and tightening and sealing the reactor; then heating the mixture to 150-220° C. at a rate of 10-20° C. / h, keeping the temperature constant for 1-3 days, and then cooling the mixture to room temperature at a rate of 1-3° C. / h to obtain a guanidine phosphite nonlinear optical crystal;

[0015] The room temperature solution method for growing guanidine phosphite crystals is specifically performed in the following steps:

[0016] a. Mix a compound containing [C(NH2)3] and a compound containing P in a molar ratio of [C(NH2)3]:P=2:1, add 0-150 ml of deionized water, and mix and dissolve them thoroughly to obtain a mixed solution, wherein the compound containing [C(NH2)3] is [C(NH2)3]2CO3, [C(NH2)3]NO3, [C(NH2)3]HF2 or [C(NH2)3]Cl, and the compound containing P is H3PO3 or K2HPO3;

[0017] b. Ultrasonic treatment of the mixed solution in step a to fully mix and dissolve it to obtain a clear solution. The container is tightly sealed with a polyvinyl chloride film and placed in a static environment without shaking, pollution, or air convection. Several small holes are punched in the sealing film and the container is allowed to stand at room temperature for 10-15 days.

[0018] c. When crystals precipitate out of the solution and gradually grow, guanidine phosphite nonlinear optical crystals are obtained.

[0019] The guanidine phosphite nonlinear optical crystal is used in preparing harmonic light output of 1064nm fundamental frequency light output by an Nd:YAG laser for frequency doubling, tripling and quadrupling.

[0020] The guanidine phosphite nonlinear optical crystal is used in preparing ultraviolet frequency-doubled light output below 266 nm.

[0021] The guanidine phosphite nonlinear optical crystal is used in preparing a frequency doubling generator, an up- or down-frequency converter or an optical parametric oscillator.

[0022] The present invention discloses a method for preparing a guanidine phosphite nonlinear optical crystal. The container used during the preparation process is a polytetrafluoroethylene beaker lined with polytetrafluoroethylene and a stainless steel-lined hydrothermal kettle equipped with a platinum sleeve. Before use, the container must be cleaned with acid, rinsed with deionized water, and air-dried. The resistance furnace used is a muffle furnace or a drying oven.

[0023] The preparation method of the guanidine phosphite nonlinear optical crystal described in the present invention is adopted to obtain a centimeter-sized [C(NH2)3]2HPO3 nonlinear optical crystal. By using a large-sized container and extending the growth period of the crystal, a corresponding large-sized nonlinear optical crystal [C(NH2)3]2HPO3 can be obtained. During the growth of the [C(NH2)3]2HPO3 nonlinear optical crystal, the crystal is easy to grow, transparent and without wrapping, and has the advantages of fast growth rate, low cost, and easy acquisition of large-sized crystals.

[0024] By adopting the preparation method of the guanidine phosphite nonlinear optical crystal described in the present invention, a large-sized [C(NH2)3]2HPO3 nonlinear optical crystal is obtained. According to the crystallographic data of the crystal, the crystal blank is oriented, the crystal is cut according to the required angle, thickness and cross-sectional size, and the light-transmitting surface of the crystal is polished. Then, the crystal can be used as a nonlinear optical device. The [C(NH2)3]2HPO3 nonlinear optical crystal has the advantages of a wide light transmission band, stable physical and chemical properties, and is easy to process and preserve. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The powder XRD spectrum of the compound [C(NH2)3]2HPO3 of the present invention;

[0026] Figure 2 This is a structural diagram of the [C(NH2)3]2HPO3 crystal of the present invention;

[0027] Figure 3 This is a working principle diagram of the nonlinear optical device made of [C(NH2)3]2HPO3 crystal of the present invention, where 1 is the laser, 2 is the emitted light beam, 3 is the [C(NH2)3]2HPO3 crystal, 4 is the output light beam, and 5 is the filter. DETAILED DESCRIPTION

[0028] The present invention is further described below with reference to the following examples. It should be noted that the following examples are not intended to limit the scope of the present invention, and any improvements made based on the present invention do not violate the spirit of the present invention. Unless otherwise specified, the raw materials and equipment used in the present invention are commercially available.

[0029] Example 1

[0030] According to the reaction formula: [C(NH2)3]2CO3+H3PO3→[C(NH2)3]2HPO3+H2O+CO2, [C(NH2)3]2HPO3 nonlinear optical crystal was prepared by evaporation method:

[0031] a. Mix [C(NH2)3]2CO3 and H3PO3 in a molar ratio of 1:1, add 5 ml of deionized water and dissolve them to obtain a mixed solution, and then treat the mixed solution with ultrasound to ensure that it is fully mixed and dissolved to obtain a clear solution;

[0032] b. Place the clarified solution in step a in a resistance furnace, raise the temperature to 90°C at a rate of 10°C / h, and keep it at this temperature for 10 days to evaporate the solvent. After crystal growth is completed, a guanidine phosphite nonlinear optical crystal with a size of Φ5 mm × 2 mm × 1.3 mm is obtained.

[0033] Example 2

[0034] According to the reaction formula: 2[C(NH2)3]Cl+H3PO3→[C(NH2)3]2HPO3+2HCl, [C(NH2)3]2HPO3 nonlinear optical crystal was prepared by evaporation method:

[0035] a. Mix [C(NH2)3]Cl and H3PO3 in a molar ratio of 2:1, add 20 ml of deionized water and mix and dissolve to obtain a mixed solution, and then treat the mixed solution with ultrasound to fully mix and dissolve to obtain a clear solution;

[0036] b. Place the clarified solution in step a in a resistance furnace, raise the temperature to 70°C at a rate of 20°C / h, and keep it at this temperature for 12 days to evaporate the solvent. After the crystal growth is completed, a guanidine phosphite nonlinear optical crystal with a size of Φ3mm×1mm×0.6mm is obtained.

[0037] Example 3

[0038] According to the reaction formula: 2[C(NH2)3]HF2+K2HPO3→[C(NH2)3]2HPO3+2KF+2HF, [C(NH2)3]2HPO3 nonlinear optical crystal was prepared by evaporation method:

[0039] a. Mix [C(NH2)3]HF2 and K2HPO3 in a molar ratio of 2:1, add 25 ml of deionized water, stir evenly to obtain a mixed solution, and ultrasonicate the mixed solution to ensure that it is fully mixed and dissolved to obtain a clear solution;

[0040] b. Place the clarified solution from step a in a resistance furnace, raise the temperature to 60°C at a rate of 10°C / h, and keep it at this temperature for 10 days to evaporate the solvent. Crystals will precipitate and gradually grow. When the crystal growth is complete, a [C(NH2)3]2HPO3 nonlinear optical crystal with a size of Φ6 mm × 2.5 mm × 2 mm is obtained.

[0041] Example 4

[0042] According to the reaction formula: 2[C(NH2)3]NO3+H3PO3→[C(NH2)3]2HPO3+2HNO3, [C(NH2)3]2HPO3 nonlinear optical crystal was prepared by evaporation method:

[0043] a. Mix [C(NH2)3]NO3 and H3PO3 in a molar ratio of 2:1, add 10 ml of deionized water, stir evenly to obtain a mixed solution, and then treat the mixed solution with ultrasound to ensure that it is fully mixed and dissolved to obtain a clear solution;

[0044] b. Place the clarified solution from step a in a resistance furnace, raise the temperature to 85°C at a rate of 10°C / h, and keep it at this temperature for 10 days to evaporate the solvent. Crystals will precipitate and gradually grow. When the crystal growth is complete, a [C(NH2)3]2HPO3 nonlinear optical crystal with a size of Φ4 mm × 1.5 mm × 0.4 mm is obtained.

[0045] Example 5

[0046] According to the reaction formula: [C(NH2)3]2CO3+H3PO3→[C(NH2)3]2HPO3+H2O+CO2, [C(NH2)3]2HPO3 nonlinear optical crystal was prepared by hydrothermal method:

[0047] a. Mix [C(NH2)3]2CO3 and H3PO3 in a molar ratio of 1:1, add 10 ml of deionized water, stir evenly, and mix and dissolve thoroughly to obtain a mixed solution;

[0048] b. The mixed solution in step a was transferred into a polytetrafluoroethylene liner of a 23 ml hydrothermal reactor, and the reactor was tightened and sealed; the temperature was then raised to 220° C. at a rate of 10° C. / h, kept at this temperature for 2 days, and then cooled to room temperature at a rate of 1° C. / h to obtain a guanidine phosphite nonlinear optical crystal with a size of 3 mm × 1.5 mm × 0.6 mm.

[0049] Example 6

[0050] According to the reaction formula: 2[C(NH2)3]Cl+H3PO3→[C(NH2)3]2HPO3+2HCl, [C(NH2)3]2HPO3 nonlinear optical crystal was prepared by hydrothermal method:

[0051] a. Mix [C(NH2)3]Cl and H3PO3 in a molar ratio of 2:1, add 15 ml of deionized water to mix and dissolve them thoroughly to obtain a mixed solution;

[0052] b. Transfer the mixed solution in step a into the polytetrafluoroethylene liner of a hydrothermal reactor with a volume of 23 ml, and tighten and seal the mouth of the hydrothermal reactor. Place it in a constant temperature box, raise the temperature to 180°C at a rate of 20°C / h, keep the temperature constant for 3 days, and then cool it to room temperature at a rate of 1°C / h. Open the reactor to obtain a [C(NH2)3]2HPO3 nonlinear optical crystal with a size of 2.4 mm×1.4 mm×0.6 mm.

[0053] Example 7

[0054] According to the reaction formula: 2[C(NH2)3]HF2+K2HPO3→[C(NH2)3]2HPO3+2KF+2HF, the compound [C(NH2)3]2HPO3 nonlinear optical crystal was synthesized by hydrothermal method:

[0055] a. Mix [C(NH2)3]HF2 and K2HPO3 in a molar ratio of 2:1, add 30 ml of deionized water to mix and dissolve them thoroughly to obtain a mixed solution;

[0056] b. Transfer the mixed solution in step a into the polytetrafluoroethylene liner of a hydrothermal reactor with a volume of 100 ml, and tighten and seal the mouth of the hydrothermal reactor. Place it in a constant temperature box, heat it to 150°C at a rate of 15°C / h, keep it at this temperature for 3 days, and then cool it to room temperature at a rate of 2°C / h. Open the reactor to obtain a [C(NH2)3]2HPO3 nonlinear optical crystal with a size of 3.6 mm×1.9 mm×0.8 mm.

[0057] Example 8

[0058] According to the reaction formula: 2[C(NH2)3]NO3+H3PO3→[C(NH2)3]2HPO3+2HNO3, the compound [C(NH2)3]2HPO3 nonlinear optical crystal was synthesized by hydrothermal method:

[0059] a. Mix [C(NH2)3]NO3 and H3PO3 in a molar ratio of 2:1, add 25 ml of deionized water, stir evenly, and mix and dissolve thoroughly to obtain a mixed solution;

[0060] b. Transfer the mixed solution in step a into the polytetrafluoroethylene liner of a hydrothermal reactor with a volume of 80 ml. Place the reactor in a constant temperature box, heat it to 145°C at a rate of 15°C / h, keep it at this temperature for 2 days, then cool it to room temperature at a rate of 2°C / h. Open the high-pressure reactor to obtain a [C(NH2)3]2HPO3 nonlinear optical crystal with a size of 0.6 mm × 0.3 mm × 0.2 mm.

[0061] Example 9

[0062] According to the reaction formula: 2[C(NH2)3]Cl+H3PO3→[C(NH2)3]2HPO3+2HCl, [C(NH2)3]2HPO3 nonlinear optical crystal was prepared by room temperature solution method:

[0063] a. Mix [C(NH2)3]Cl and H3PO3 in a molar ratio of 2:1, add 150 ml of deionized water, stir evenly, and mix and dissolve thoroughly to obtain a mixed solution;

[0064] b. Ultrasonic treatment of the mixed solution in step a to fully mix and dissolve the solution to obtain a clear solution. The container is tightly sealed with a polyvinyl chloride film and placed in a static environment without shaking, pollution, or air convection. Several small holes are punched in the sealing film and the container is allowed to stand at room temperature for 10 days.

[0065] c. Wait for crystals to precipitate out of the solution and grow gradually. When the reaction is complete, a [C(NH2)3]2HPO3 nonlinear optical crystal with a size of 9mm×5mm×2mm is obtained.

[0066] Example 10

[0067] According to the reaction formula: [C(NH2)3]2CO3+H3PO3→[C(NH2)3]2HPO3+H2O+CO2, [C(NH2)3]2HPO3 nonlinear optical crystal was prepared by room temperature solution method:

[0068] a. Mix [C(NH2)3]2CO3 and H3PO3 in a molar ratio of 1:1, add 60 ml of deionized water, stir evenly, and mix and dissolve thoroughly to obtain a mixed solution;

[0069] b. Ultrasonic treatment of the mixed solution in step a to fully mix and dissolve the solution to obtain a clear solution. The container is tightly sealed with a polyvinyl chloride film and placed in a static environment without shaking, pollution, or air convection. Several small holes are punched in the sealing film and the container is allowed to stand at room temperature for 12 days.

[0070] c. When crystals precipitate out of the solution and gradually grow, the reaction is complete, and a [C(NH2)3]2HPO3 nonlinear optical crystal with a size of 5 mm × 2 mm × 1 mm is obtained.

[0071] Example 11

[0072] According to the reaction formula: 2[C(NH2)3]NO3+H3PO3→[C(NH2)3]2HPO3+2HNO3, [C(NH2)3]2HPO3 nonlinear optical crystal was prepared by room temperature solution method:

[0073] a. Mix [C(NH2)3]NO3 and H3PO3 in a molar ratio of 2:1, add 20 ml of deionized water, stir evenly, and mix and dissolve them thoroughly to obtain a mixed solution;

[0074] b. Ultrasonic treatment of the mixed solution in step a to fully mix and dissolve the solution to obtain a clear solution. The container was tightly sealed with a polyvinyl chloride film and placed in a static environment without shaking, pollution, or air convection. Several small holes were punched in the sealing film and the container was left standing at room temperature for 13 days.

[0075] c. When crystals precipitate out of the solution and gradually grow, the reaction is completed, and a [C(NH2)3]2HPO3 nonlinear optical crystal with a size of 2 mm × 1.2 mm × 0.7 mm is obtained.

[0076] Example 12

[0077] According to the reaction formula: 2[C(NH2)3]HF2+K2HPO3→[C(NH2)3]2HPO3+2KF+2HF, [C(NH2)3]2HPO3 nonlinear optical crystal was prepared by room temperature solution method:

[0078] a. Mix [C(NH2)3]HF2 and KH2PO3 in a molar ratio of 2:1, add 30 ml of deionized water, stir evenly, and mix and dissolve thoroughly to obtain a mixed solution;

[0079] b. Ultrasonic treatment of the mixed solution in step a to fully mix and dissolve the solution to obtain a clear solution. The container is tightly sealed with a polyvinyl chloride film and placed in a static environment without shaking, pollution, or air convection. Several small holes are punched in the sealing film and the container is allowed to stand at room temperature for 14 days.

[0080] c. Wait for crystals to precipitate out of the solution and gradually grow. When the reaction is complete, a [C(NH2)3]2HPO3 nonlinear optical crystal with a size of 3.2 mm × 1.3 mm × 0.7 mm is obtained.

[0081] Example 13

[0082] According to the reaction formula: 2[C(NH2)3]HF2+H3PO3→[C(NH2)3]2HPO3+4HF, [C(NH2)3]2HPO3 nonlinear optical crystal was prepared by room temperature solution method:

[0083] a. Mix [C(NH2)3]HF2 and H3PO3 in a molar ratio of 2:1, add 70 ml of deionized water, stir evenly, and mix and dissolve thoroughly to obtain a mixed solution;

[0084] b. Ultrasonic treatment of the mixed solution in step a to fully mix and dissolve the solution to obtain a clear solution. The container is tightly sealed with a polyvinyl chloride film and placed in a static environment without shaking, pollution, or air convection. Several small holes are punched in the sealing film and the container is allowed to stand at room temperature for 15 days.

[0085] c. Wait for crystals to precipitate out of the solution and gradually grow. When the reaction is complete, a [C(NH2)3]2HPO3 nonlinear optical crystal with a size of 6.2 mm × 4.7 mm × 2 mm is obtained.

[0086] Example 14

[0087] The [C(NH2)3]2HPO3 nonlinear optical crystals obtained in Examples 1-14 are processed in the matching direction, and the attached Figure 3As shown, it is placed at position 3. At room temperature, a Q-switched Nd:YAG laser is used as the light source with an incident wavelength of 1064 nm. The infrared beam 2 with a wavelength of 1064 nm emitted by the Q-switched Nd:YAG laser 1 is incident on the [C(NH2)3]2HPO3 single crystal 3, generating green frequency-doubled light with a wavelength of 532 nm. The output intensity is about 0.8 times that of KDP under the same conditions. At the same time, under the same experimental setup, purple frequency-doubled light with a wavelength of 266 nm is generated, and the output intensity is 0.1 times that of BBO under the same conditions.

Claims

1. A guanidine phosphite nonlinear optical crystal, characterized in that The chemical formula of the crystal is [C(NH2)3]2HPO3, the molecular weight is 200.15, it belongs to the monoclinic system, and the space group is Cm , the unit cell parameters are a =13.0197(14) Å, b =7.3168(7) Å, c =11.7448(19) Å, α= 90°, β= 119.607(3)°, γ= 90°, unit cell volume is 972.8(2)Å 3 .

2. The method for preparing the guanidine phosphite nonlinear optical crystal according to claim 1, characterized in that Growing crystals using evaporation, hydrothermal, or room temperature solution methods; The evaporation method for growing guanidine phosphite crystals is specifically performed in the following steps: a. Mix a compound containing [C(NH2)3] and a compound containing P in a molar ratio of [C(NH2)3]:P=2:1, add 5-25 ml of deionized water, and mix and dissolve them thoroughly to obtain a mixed solution, wherein the compound containing [C(NH2)3] is [C(NH2)3]2CO3, [C(NH2)3]NO3, [C(NH2)3]HF2 or [C(NH2)3]Cl, and the compound containing P is H3PO3 or K2HPO3; b. Place the mixed solution in step a in a resistance furnace, heat it to 40-90°C at a rate of 10-20°C / h, keep it at this temperature for 5-15 days to evaporate the solvent, and wait until the crystal growth is complete to obtain a guanidine phosphite nonlinear optical crystal; The hydrothermal method for growing guanidine phosphite crystals is specifically performed in the following steps: a. Mix a compound containing [C(NH2)3] and a compound containing P in a molar ratio of [C(NH2)3]:P=2:1, add 10-30 ml of deionized water, mix and dissolve them thoroughly to obtain a mixed solution, wherein the compound containing [C(NH2)3] is [C(NH2)3]2CO3, [C(NH2)3]NO3, [C(NH2)3]HF2 or [C(NH2)3]Cl, and the compound containing P is H3PO3 or K2HPO3; b. Transferring the mixed solution from step a into a polytetrafluoroethylene liner of a hydrothermal reactor with a volume of 23-100 ml, and tightening and sealing the reactor; then heating the mixture to 150-220° C. at a rate of 10-20° C. / h, keeping the temperature constant for 1-3 days, and then cooling the mixture to room temperature at a rate of 1-3° C. / h to obtain a guanidine phosphite nonlinear optical crystal; The room temperature solution method for growing guanidine phosphite crystals is specifically performed in the following steps: a. Mix a compound containing [C(NH2)3] and a compound containing P in a molar ratio of [C(NH2)3]:P=2:1, add 0-150 ml of deionized water, and mix and dissolve them thoroughly to obtain a mixed solution, wherein the compound containing [C(NH2)3] is [C(NH2)3]2CO3, [C(NH2)3]NO3, [C(NH2)3]HF2 or [C(NH2)3]Cl, and the compound containing P is H3PO3 or K2HPO3; b. Ultrasonic treatment of the mixed solution in step a to fully mix and dissolve it to obtain a clear solution. The container is tightly sealed with a polyvinyl chloride film and placed in a static environment without shaking, pollution, or air convection. Several small holes are punched in the sealing film and the container is allowed to stand at room temperature for 10-15 days. c. When crystals precipitate out of the solution and gradually grow, guanidine phosphite nonlinear optical crystals are obtained.

3. Use of the guanidine phosphite 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 frequency doubling, tripling and quadrupling.

4. Use of the guanidine phosphite nonlinear optical crystal according to claim 1 in preparing an ultraviolet frequency-doubled light output below 266 nm.

5. Use of the guanidine phosphite nonlinear optical crystal according to claim 1 in preparing a frequency doubling generator, an up- or down-frequency converter, or an optical parametric oscillator.

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