A histidine hypophosphite inorganic-organic hybrid nonlinear optical crystal and its preparation and application

Abstract

The present invention relates to a histidine hypophosphite inorganic-organic hybrid nonlinear optical crystal and its preparation and application. The chemical formula of the optical crystal is A(H2PO2), wherein A is L-C6H 10 N3O2 or D‑C6H 10 N3O2; belongs to the monoclinic system, space group is P21, unit cell parameters are α=γ=90°, β=99.0~99.4°, Z=2. The crystal of the present invention (L-C6H 10 N3O2)(H2PO2) and (D‑C6H 10 The birefringence of N3O2 (H2PO2) at 546nm is 0.084 and 0.058. Under 1064nm laser irradiation, its powder SHG coefficient is 1 and 2 times that of KH2PO4 (KDP), and phase matching is achieved under 1064nm laser irradiation. Furthermore, the ultraviolet absorption cutoff edges of this crystal material are 233nm and 234nm, corresponding to optical band gaps of 5.32eV and 5.30eV, respectively, showing broad application prospects in the field of ultraviolet lasers.

Description

Technical Field

[0001] The invention belongs to the technical field of nonlinear optical crystals and relates to a histidine hypophosphite inorganic-organic hybrid nonlinear optical crystal and a preparation and application thereof. Background Art

[0002] Second-order nonlinear optical crystals are optoelectronic functional materials widely used in the laser field, with important applications in laser frequency conversion, optoelectronic modulation, holographic storage of laser signals, and laser communications. Currently, practically applied second-order nonlinear optical phosphate materials include potassium dihydrogen phosphate (KH2PO4), potassium titanyl phosphate (KTiOPO4), and L-arginine phosphate ((H2N)2CNH(CH2)3CH(NH3)COO·H2PO4·H2O). However, inorganic-organic hybrid nonlinear optical materials for ultraviolet applications often face limitations due to inherent property limitations. These research and applications have placed increasing demands on the physical and chemical properties of ultraviolet inorganic-organic hybrid nonlinear optical materials, driving their rapid development. A high-performance ultraviolet inorganic-organic hybrid nonlinear optical crystal material requires not only a noncentrosymmetric structure but also a strong harmonic response, a wide bandgap, an appropriate birefringence, and stable physical and chemical properties. However, wide bandgap and strong frequency doubling, as two mutually opposing key optical properties, are often difficult to achieve simultaneously in a nonlinear optical crystal.

[0003] In recent years, combining two types of functional units (such as organic chiral units and inorganic tetrahedral units) to construct materials with strong frequency-harmonic effects has become an effective strategy. Among them, organic chiral units have the characteristics of strong frequency-harmonic effects and high optical anisotropy, while inorganic tetrahedral units have the characteristics of wide transmission band and thermal stability. Through the secondary bond interaction between the units, it is expected to obtain inorganic-organic hybrid nonlinear optical crystal materials that take into account all of their characteristics. Currently, the only commercial organic-inorganic hybrid nonlinear optical L-arginine phosphate (LAP) crystal was first explored and grown by Jiang Minhua's team at Shandong University in the 1980s. However, its thermal decomposition temperature is 112°C, which limits its application in high-temperature areas. In addition, there is room for further development in other nonlinear optical properties. Summary of the Invention

[0004] The purpose of the present invention is to provide a histidine hypophosphite inorganic-organic hybrid nonlinear optical crystal and its preparation and application, by combining organic chiral primitives (L-C6H 10 N3O2) + or (D-C6H 10 N3O2) +and inorganic tetrahedral anions (H2PO2) - , obtaining an inorganic-organic hybrid nonlinear optical crystal material with both a large band gap and a strong frequency response.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] In one aspect, the present invention provides a histidine hypophosphite inorganic-organic hybrid nonlinear optical crystal, characterized in that its chemical formula is A(H2PO2), wherein A is L-C6H 10 N3O2 or D-C6H 10 N3O2(please).

[0007] Furthermore, the optical crystal belongs to the monoclinic system, the space group is P21, and the unit cell parameters are α=γ=90°, β=99.0~99.4°, Z=2.

[0008] Furthermore, the chemical formula of the crystal is (L-C6H 10 N3O2)(H2PO2) belongs to the monoclinic system, the space group is P21, and the unit cell parameters are α=γ=90°,β=99.0~99.4,Z=2。 Further preferably, the unit cell parameters are α=γ=90°,β=99.05~99.35°,Z=2。 Further preferably, the unit cell parameters are α=γ=90°,β=99.059~99.345,Z=2。More preferably, the unit cell parameters are α=γ=90°, β=99.185(2)°, Z=2.

[0009] Each asymmetric unit contains a chiral L-histidine cation, a hypophosphite tetrahedral anion and two hydrogen bonds (N2-H2···O4 and N3-H3B···O3) (e.g. Figure 1 a). The smallest asymmetric units are connected by hydrogen bonds (C1-H 1A O3 and N3-H 3C ···O4) forms a one-dimensional (1D) infinite spiral chain along the coordinate axis b (such as Figure 1 b). Adjacent helical chains form a two-dimensional wavy layered structure in plane ab through hydrogen bonds (N1-H1···O1) Figure 1 c). This final 3D framework is composed of 2D layers through hydrogen bonds (N3-H 3A ···O3 and C5-H5···O2) stacked ( Figure 1 d).

[0010] The inorganic-organic hybrid (L-C6H 10 The ultraviolet absorption cutoff wavelength of the (N3O2) (H2PO2) crystal is 233-237 nm. Preferably, the ultraviolet absorption cutoff wavelength of the inorganic-organic hybrid nonlinear optical crystal is 233 nm.

[0011] Furthermore, the chemical formula of the crystal is (D-C6H 10 N3O2)(H2PO2) belongs to the monoclinic system, the space group is P21, and the unit cell parameters are α=γ=90°,β=99.0~99.4°,Z=2. Further preferably, the unit cell parameters are α=γ=90°,β=99.05~99.35°,Z=2。 Further preferably, the unit cell parameters are α=γ=90°,β=99.059~99.345°,Z=2。More preferably, the unit cell parameters are α=γ=90°, β=99.193(2)°, Z=2.

[0012] Each asymmetric unit contains a chiral D-histidine cation, a hypophosphite tetrahedral anion and two hydrogen bonds (N2-H2···O4 and N3-H3B···O3) (e.g. Figure 9 a). The smallest asymmetric units are connected by hydrogen bonds (C1-H 1A O3 and N3-H 3C ···O4) forms a one-dimensional (1D) infinite spiral chain along the coordinate axis b (such as Figure 9 b). Adjacent helical chains form a two-dimensional wavy layered structure in plane ab through hydrogen bonds (N1-H1···O1) Figure 9 c). This final 3D framework is composed of 2D layers through hydrogen bonds (N3-H 3A ···O3 and C5-H5···O2) stacked ( Figure 9 d).

[0013] The inorganic-organic hybrid (D-C6H 10 The ultraviolet absorption cutoff wavelength of the (N3O2) (H2PO2) crystal is 234-238 nm. Preferably, the ultraviolet absorption cutoff wavelength of the inorganic-organic hybrid nonlinear optical crystal is 234 nm.

[0014] In a second aspect, the present invention provides a method for preparing a histidine hypophosphite inorganic-organic hybrid nonlinear optical crystal, comprising mixing raw materials containing a histidine source, hypophosphorous acid and water, placing the mixture in an open evaporation container, and volatilizing and crystallizing the mixture to obtain a target product.

[0015] Furthermore, the histidine source is L-histidine or D-histidine.

[0016] Furthermore, the molar ratio of the histidine source, hypophosphorous acid and water is 5:5-10:500-1500. Preferably, the molar ratio of the histidine source, hypophosphorous acid and water is 5:(5-10):500-750.

[0017] Furthermore, the temperature for volatilization and crystallization is 15 to 45°C, preferably 25 to 35°C.

[0018] Furthermore, the volatilization and crystallization time is not less than 14 days, preferably 14 to 21 days.

[0019] Furthermore, after the crystallization is completed, the temperature is lowered to room temperature at a cooling rate of 0.5° C. / h to 10° C. / h, preferably 0.5 to 3° C. / h.

[0020] In a third aspect, the present invention provides an application of a histidine hypophosphite inorganic-organic hybrid nonlinear optical crystal in a laser frequency converter.

[0021] Furthermore, the laser frequency converter is used to output 532nm green light under 1064nm laser irradiation.

[0022] Specifically, (L-C6H 10 N3O2)(H2PO2) crystals are used as nonlinear optical crystal materials. They emit a strong 532nm green light under 1064nm laser irradiation. Their powder SHG coefficient is twice that of KH2PO4 (KDP) and can achieve phase matching.

[0023] (D-C6H 10 N3O2) (H2PO2) crystals are used as nonlinear optical crystal materials. They emit strong 532nm green light under 1064nm laser irradiation. Their powder SHG coefficient is twice that of KH2PO4 (KDP) and can achieve phase matching.

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] (1) This application provides a new inorganic-organic hybrid nonlinear optical crystal (L-C6H 10N3O2) (H2PO2) crystal material exhibits a significant frequency-doubled effect, approximately double the frequency-doubled intensity of KH2PO4 crystal under 1064nm laser irradiation, enabling phase matching. Furthermore, this crystal material exhibits a UV absorption cutoff edge of 233nm and an optical band gap of 5.32eV. This crystal material achieves an effective balance between strong frequency-doubled response and a wide band gap, and has broad application prospects in UV laser frequency conversion, optoelectronic modulation, and holographic storage of laser signals.

[0026] (2) The present application also provides the inorganic-organic hybrid nonlinear optical crystal material (L-C6H 10 The preparation method of N3O2)(H2PO2) adopts the slow volatilization method of aqueous solution, takes 50% hypophosphorous acid aqueous solution as raw material and reaction solvent at 15-45°C, and obtains high-purity and high-crystallization inorganic-organic hybrid (L-C6H 10 N3O2)(H2PO2) nonlinear optical crystal material.

[0027] (3) This application provides a new inorganic-organic hybrid nonlinear optical crystal (D-C6H 10 N3O2) (H2PO2) crystal material exhibits a significant frequency-doubled effect, approximately twice the frequency-doubled intensity of KH2PO4 crystal under 1064nm laser irradiation, enabling phase matching. Furthermore, this crystal material exhibits a UV absorption cutoff edge of 234nm and an optical band gap of 5.30eV. This crystal material achieves an effective balance between strong frequency-doubled response and a wide band gap, and has broad application prospects in UV laser frequency conversion, optoelectronic modulation, and holographic storage of laser signals.

[0028] (4) The present application also provides the inorganic-organic hybrid nonlinear optical crystal (D-C6H 10 The preparation method of N3O2)(H2PO2) adopts the slow volatilization method of aqueous solution, takes 50% hypophosphorous acid aqueous solution as raw material and reaction solvent at 15-45°C, and obtains high-purity and high-crystallization inorganic-organic hybrid (D-C6H 10 N3O2)(H2PO2) nonlinear optical crystal material.

[0029] (5) The thermal decomposition temperature of the histidine hypophosphite inorganic-organic hybrid nonlinear optical crystal of the present invention can reach 203° C., which greatly improves the stability of the inorganic-organic hybrid nonlinear optical crystal. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Yes (L-C6H 10Schematic diagram of the crystal structure of N3O2)(H2PO2); (a) asymmetric unit; (b) one-dimensional chain structure; (c) two-dimensional layer structure; (d) three-dimensional structure;

[0031] Figure 2 The X-ray diffraction pattern of sample 1-1# obtained by fitting the crystal structure analyzed by single crystal X-ray diffraction is compared with the X-ray diffraction pattern of sample 1-1# after it was ground into powder;

[0032] Figure 3 is the UV transmittance spectrum of sample 1-1#;

[0033] Figure 4 is the infrared vibration spectrum of sample 1-1#;

[0034] Figure 5 This is the thermogravimetric analysis spectrum of sample 1-1#;

[0035] Figure 6 This is the second harmonic signal diagram of sample 1-1# and standard KDP sample with sample size ranging from 105 to 150 μm;

[0036] Figure 7 This is the second harmonic phase matching diagram of sample 1-1# in the 1064nm band;

[0037] Figure 8 is a graph of birefringence test, where (a)(L-C6H 10 N3O2)(H2PO2) without extinction; (b)(L-C6H 10 Complete extinction of N3O2)(H2PO2); (c)(L-C6H 10 N3O2)(H2PO2) crystal thickness;

[0038] Figure 9 Yes (D-C6H 10 Schematic diagram of the crystal structure of N3O2)(H2PO2); (a) asymmetric unit; (b) one-dimensional chain structure; (c) two-dimensional layer structure; (d) three-dimensional structure;

[0039] Figure 10 The X-ray diffraction pattern of sample 2-1# obtained by fitting the crystal structure analyzed by single crystal X-ray diffraction is compared with the X-ray diffraction pattern of sample 2-1# after it was ground into powder;

[0040] Figure 11 This is the UV transmittance spectrum of sample 2-1#;

[0041] Figure 12 This is the infrared vibration spectrum of sample 2-1#;

[0042] Figure 13 This is the thermogravimetric analysis spectrum of sample 2-1#;

[0043] Figure 14 This is the second harmonic signal diagram of sample 2-1# and standard KDP sample with sample size ranging from 105 to 150 μm;

[0044] Figure 15 This is the second harmonic phase matching diagram of sample 2-1# in the 1064nm band;

[0045] Figure 16 is a graph of birefringence test, where (a)(D-C6H 10 N3O2)(H2PO2) without extinction; (b)(D-C6H 10 Complete extinction of N3O2)(H2PO2); (c)(D-C6H 10 N3O2)(H2PO2) crystal thickness. DETAILED DESCRIPTION

[0046] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0047] Example 1

[0048] Preparation of samples 1# to 8#

[0049] Mix the histidine source, hypophosphorous acid (added in the form of a solution with a concentration of 50 wt%) and water in a certain proportion to form a raw material, place it in an evaporating dish, heat it to the crystallization temperature, keep it constant for a period of time, and then slowly cool the system temperature to room temperature at a certain rate. Filter and wash to obtain colorless block (L-C6H 10 N3O2)(H2PO2) crystals.

[0050] The relationship between the types and ratios of the raw materials in the initial mixture, the crystallization temperature, the crystallization time and the sample number is shown in Table 1.

[0051] Table 1 Correspondence between samples, raw materials and synthesis conditions

[0052]

[0053] Crystal structure analysis of samples 1# to 8#

[0054] The structures of samples 1-1# to 1-8# were analyzed using single crystal X-ray diffraction and powder X-ray diffraction methods.

[0055] The single crystal X-ray diffraction was performed on a Bruker D8 VENTURE CMOS X-ray single crystal diffractometer in Germany. The data collection temperature was 293K and the diffraction light source was graphite monochromatized Mo-Kα radiation. The scanning mode was ω; the data were processed for absorption correction using the Multi-Scan method. The structure was solved using the SHELXTL-2017 program package; the positions of heavy atoms were determined by direct method, and the coordinates of the remaining atoms were obtained by difference Fourier synthesis method; the F-based 2 The coordinates of all atoms and anisotropic thermal parameters were refined using the full-matrix least-squares method.

[0056] Powder X-ray diffraction was performed on a Bruker D8 X-ray powder diffractometer from Bruker, Germany, using a fixed-target monochromatic light source of Cu-Kα and a wavelength of The voltage and current are 40 kV / 20 A, the slits DivSlit / RecSlit / SctSlit are 2.00 deg / 0.3 mm / 2.00 deg respectively, the scanning range is 5 to 70°, and the scanning step is 0.02°.

[0057] Among them, the single crystal X-ray diffraction results show that samples 1-1# to 1-8# have the same chemical formula and crystal structure, and the chemical formula is (L-C6H 10 N3O2)(H2PO2) belongs to the monoclinic system, the space group is P21, and the unit cell parameters are α=γ=90°, β=99.059~99.345°, Z=2.

[0058] Take sample 1-1# as a typical example, its crystal structure data is α=γ=90°,β=99.185(2)°,Z=2,the unit cell volume is Its crystal structure is Figure 1 shown.

[0059] Take sample 1-1# as a typical example. Figure 2 As shown in the figure, the X-ray diffraction pattern obtained by fitting the crystal structure analyzed by single crystal X-ray diffraction is consistent with the peak position and peak intensity of the X-ray diffraction pattern obtained by X-ray diffraction testing of sample 1-1# after grinding into powder, indicating that the obtained samples are of high purity.

[0060] UV transmittance spectrum test

[0061] The UV transmittance spectrum of sample 1-1# was tested on a Carry 5000 UV-visible-near infrared spectrophotometer from Agilent Technologies, USA. Figure 3 As shown by Figure 3It can be seen that the ultraviolet absorption cutoff edge of the compound is 233nm and the optical band gap is 5.32eV.

[0062] Infrared spectrum test

[0063] The infrared spectrum test of sample 1-1# was conducted on a Nicolet iS10 Fourier infrared spectrometer from Thermo Fisher Scientific Inc., USA. Figure 4 As shown by Figure 4 The group characteristic peaks of the compound can be seen, further confirming the accuracy of the crystal structure.

[0064] Thermogravimetric testing

[0065] The thermogravimetric test of sample 1-1# was conducted on a TGA / DSC1 / 1100SF thermogravimetric analyzer manufactured by Mettler-Toledo International Trading (Shanghai) Co., Ltd. The results are shown in the figure below. Figure 5 As shown, the compound is stable up to 203°C.

[0066] Frequency doubling test experiment and results

[0067] The SHG test experiment for sample 1-1# was conducted as follows: a Q-switched Nd:YAG solid-state laser, each generating a 1064nm wavelength as the fundamental frequency, was used to illuminate the crystal powder under test. The generated second harmonics were detected using a photomultiplier tube, and the harmonic intensity was displayed on an oscilloscope. The sample crystal and a standard KDP crystal were ground separately and sieved using a standard sieve to produce crystals of varying particle sizes: less than 50-74μm, 74-105μm, 105-150μm, 150-200μm, and 200-280μm. The SHG signal was observed as a function of particle size to determine whether phase matching was achieved. Under the same test conditions, the second harmonic intensities generated by the sample and the reference KDP crystal under 1064nm laser irradiation were compared to determine the relative magnitude of the SHG effect.

[0068] The test results showed that the compound (L-C6H 10 N3O2)(H2PO2) crystal has a large frequency doubling effect. Under 1064nm wavelength laser irradiation, the frequency doubling signal intensity is 1 times that of KDP crystal (such as Figure 6 ).like Figure 7 As shown, the crystal material can achieve phase matching in the 1064nm laser band.

[0069] Birefringence experiments and results

[0070] The birefringence test experiment of sample 1-1# is as follows:

[0071] (L-C6H 10The birefringence of N3O2)(H2PO2) was evaluated using a ZEISS Axio Scope 5 polarizing microscope equipped with a Berek compensator under a 546 nm light source. e -N o |×T=Δn×T to determine birefringence, the optical path difference is R, the measured birefringence is Δn, and the crystal thickness is T.

[0072] The test results show that Figure 8 a, (L-C6H 10 N3O2)(H2PO2) is not extinguished, Figure 8 b, (L-C6H 10 N3O2)(H2PO2) is completely extinguished, and its optical path difference is 1.93μm. (L-C6H 10 The crystal thickness of N3O2)(H2PO2 is 23.016μm( Figure 8 c). According to the formula R=Δn×T, (L-C6H 10 The birefringence of (N3O2)(H2PO2) is 0.084.

[0073] Example 2

[0074] Preparation of samples 1# to 8#

[0075] Mix the histidine source, hypophosphorous acid (added in the form of a solution with a concentration of 50 wt%) and water in a certain proportion to form a raw material, place it in an evaporating dish, heat it to the crystallization temperature, keep it constant for a period of time, and then slowly cool the system temperature to room temperature at a certain rate. Filter and wash to obtain colorless block (D-C6H 10 N3O2)(H2PO2) crystals.

[0076] The relationship between the types and ratios of the raw materials in the initial mixture, the crystallization temperature, the crystallization time and the sample number is shown in Table 2.

[0077] Table 2 Correspondence between samples, raw materials and synthesis conditions

[0078]

[0079]

[0080] Crystal structure analysis of samples 1# to 8#

[0081] The structures of samples 2-1# to 2-8# were analyzed using single crystal X-ray diffraction and powder X-ray diffraction methods.

[0082] The single crystal X-ray diffraction was performed on a Bruker D8 VENTURE CMOS X-ray single crystal diffractometer in Germany. The data collection temperature was 293K and the diffraction light source was graphite monochromatized Mo-Kα radiation. The scanning mode was ω; the data were processed for absorption correction using the Multi-Scan method. The structure was solved using the SHELXTL-2017 program package; the positions of heavy atoms were determined by direct method, and the coordinates of the remaining atoms were obtained by difference Fourier synthesis method; the F-based 2 The coordinates of all atoms and anisotropic thermal parameters were refined using the full-matrix least-squares method.

[0083] Powder X-ray diffraction was performed on a Bruker D8 X-ray powder diffractometer from Bruker, Germany, using a fixed-target monochromatic light source of Cu-Kα and a wavelength of The voltage and current are 40 kV / 20 A, the slits DivSlit / RecSlit / SctSlit are 2.00 deg / 0.3 mm / 2.00 deg respectively, the scanning range is 5 to 70°, and the scanning step is 0.02°.

[0084] Among them, the single crystal X-ray diffraction results show that samples 2-1# to 2-8# have the same chemical formula and crystal structure, and the chemical formula is (D-C6H 10 N3O2)(H2PO2) belongs to the monoclinic system, the space group is P21, and the unit cell parameters are α=γ=90°, β=99.059~99.345°, Z=2.

[0085] Take sample 2-1# as a typical example, its crystal structure data is α=γ=90°,β=99.193(2)°,Z=2,the unit cell volume is Its crystal structure is Figure 9 shown.

[0086] Take sample 2-1# as a typical example. Figure 10 As shown in the figure, the X-ray diffraction pattern obtained by fitting the crystal structure analyzed by single crystal X-ray diffraction is consistent with the peak position and peak intensity of the X-ray diffraction pattern of sample 2-1# after grinding into powder, indicating that the obtained samples are of high purity.

[0087] UV transmittance spectrum test

[0088] The UV transmittance spectrum of sample 2-1# was tested on a Carry 5000 UV-visible-near infrared spectrophotometer from Agilent Technologies, USA. Figure 11 As shown by Figure 11It can be seen that the ultraviolet absorption cutoff edge of the compound is 234 nm and the optical band gap is 5.30 eV.

[0089] Infrared spectrum test

[0090] The infrared spectrum test of sample 2-1# was conducted on a Nicolet iS10 Fourier infrared spectrometer from Thermo Fisher Scientific Inc., USA. Figure 12 As shown by Figure 12 The group characteristic peaks of the compound can be seen, further confirming the accuracy of the crystal structure.

[0091] Thermogravimetric testing

[0092] The thermogravimetric test of sample 2-1# was conducted on a TGA / DSC1 / 1100SF thermogravimetric analyzer manufactured by Mettler-Toledo International Trading (Shanghai) Co., Ltd. Figure 13 As shown by Figure 13 It can be seen that the compound is stable up to 203°C.

[0093] Frequency doubling test experiment and results

[0094] The SHG test experiment for sample 2-1# was conducted as follows: a Q-switched Nd:YAG solid-state laser, generating a wavelength of 1064 nm, was used as the fundamental frequency to illuminate the crystal powder under test. The generated second harmonics were detected using a photomultiplier tube, and the harmonic intensity was displayed on an oscilloscope. The sample crystal and a standard KDP crystal were ground separately and sieved using a standard sieve to produce crystals of varying particle sizes: less than 50-74 μm, 74-105 μm, 105-150 μm, 150-200 μm, and 200-280 μm, respectively. The SHG signal was observed as a function of particle size to determine whether phase matching was achieved. Under the same test conditions, the second harmonic intensities of the sample and the reference KDP crystal, irradiated at 1064 nm, were compared to determine the relative magnitude of the SHG effect.

[0095] The test results showed that the compound (D-C6H 10 N3O2)(H2PO2) crystal has a large frequency doubling effect. Under 1064nm wavelength laser irradiation, the frequency doubling signal intensity is twice that of KDP crystal (such as Figure 14 ).like Figure 15 As shown, the crystal material can achieve phase matching in the 1064nm laser band.

[0096] Birefringence experiments and results

[0097] The birefringence test experiment of sample 2-1# is as follows:

[0098] (D-C6H 10The birefringence of N3O2)(H2PO2) was evaluated using a ZEISS Axio Scope 5 polarizing microscope equipped with a Berek compensator under a 546 nm light source. e -N o |×T=Δn×T to determine birefringence, the optical path difference is R, the measured birefringence is Δn, and the crystal thickness is T.

[0099] The test results show that Figure 16 a, (D-C6H 10 N3O2)(H2PO2) is not extinguished, Figure 16 b, (L-C6H 10 N3O2)(H2PO2) is completely extinguished, and its optical path difference is 1.40μm. (D-C6H 10 The crystal thickness of N3O2)(H2PO2 is 24.138μm( Figure 16 c). According to the formula R=Δn×T, (D-C6H 10 The birefringence of (N3O2)(H2PO2) is 0.058.

[0100] In the above embodiments, unless otherwise specified, materials or processing techniques are conventional commercial products or conventional techniques in the art.

[0101] The above description of the embodiments is intended to facilitate understanding and use of the invention by those skilled in the art. It will be apparent that those skilled in the art can readily make various modifications to these embodiments and apply the general principles described herein to other embodiments without requiring inventive effort. Therefore, the present invention is not limited to the above-described embodiments. Improvements and modifications made by those skilled in the art based on the disclosure of the present invention, without departing from the scope of the present invention, should be within the scope of protection of the present invention.

Claims

1. A histidine hypophosphite inorganic-organic hybrid nonlinear optical crystal, characterized in that: Its chemical formula is A(H2PO2), where A is L-C6H 10 N3O2 or D-C6H 10 N3O2.

2. The histidine hypophosphite inorganic-organic hybrid nonlinear optical crystal according to claim 1, characterized in that: The optical crystal belongs to the monoclinic system, the space group is P21, and the unit cell parameters are α=γ=90°, β=99.0~99.4°, Z=2.

3. The histidine hypophosphite inorganic-organic hybrid nonlinear optical crystal according to claim 2, characterized in that: The chemical formula of the optical crystal is (L-C6H 10 N3O2)(H2PO2) belongs to the monoclinic system, the space group is P21, and the unit cell parameters are α=γ=90°, β=99.183~99.187°, Z=2; Or, the chemical formula of the optical crystal is (D-C6H 10 N3O2)(H2PO2) belongs to the monoclinic system, the space group is P21, and the unit cell parameters are α=γ=90°, β=99.191~99.195°, Z=2.

4. The method for preparing the histidine hypophosphite inorganic-organic hybrid nonlinear optical crystal according to any one of claims 1 to 3, characterized in that: The raw materials containing histidine source, hypophosphorous acid and water are mixed and placed in an open evaporation container for volatilization and crystallization to obtain the target product.

5. The method for preparing the histidine hypophosphite inorganic-organic hybrid nonlinear optical crystal according to claim 4, characterized in that: The histidine source is L-histidine or D-histidine.

6. The method for preparing the histidine hypophosphite inorganic-organic hybrid nonlinear optical crystal according to claim 4, characterized in that: The molar ratio of the histidine source, hypophosphorous acid and water is 5:5-10:500-1500.

7. The method for preparing the histidine hypophosphite inorganic-organic hybrid nonlinear optical crystal according to claim 4, characterized in that: The temperature of volatilization and crystallization is 15-45°C.

8. The method for preparing the histidine hypophosphite inorganic-organic hybrid nonlinear optical crystal according to claim 4, characterized in that: The time for volatilization and crystallization shall not be less than 14 days.

9. Use of the histidine hypophosphite inorganic-organic hybrid nonlinear optical crystal according to any one of claims 1 to 3 in a laser frequency converter.

10. The use of the histidine hypophosphite inorganic-organic hybrid nonlinear optical crystal according to claim 9, characterized in that: The laser frequency converter is used to output 532nm green light under 1064nm laser irradiation.

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