Halogen esilate second-order nonlinear optical crystal and preparation and application thereof

Abstract

The invention relates to a 2-halogen ethane sulfonate second-order nonlinear optical crystal and preparation and application thereof, the chemical formula of the crystal material is Na [SO3 (CH2) 2X] (H2O), X = Cl or Br, the crystalline material belongs to a monoclinic system, the space group is Pc, and the cell parameters are alpha = gamma = 90 degrees, beta = 91.86-92.86 degrees, and Z = 2. The powder frequency doubling effects of the non-linear optical crystals Na [SO3 (CH2) 2Cl] (H2O) and Na [SO3 (CH2) 2Br] (H2O) under 1064nm laser irradiation are respectively 0.6 and 0.8 times of that of KH2PO4 (KDP), the powder frequency doubling intensities of the non-linear optical crystals Na [SO3 (CH2) 2Cl] (H2O) under 532nm laser irradiation are respectively 0.1 and 0.2 times of that of beta-BaB2O4 (BBO) crystals, and phase matching can be realized. In addition, Na [SO3 (CH2) 2Cl] (H2O) and Na [SO3 (CH2) 2Br] (H2O) have moderate birefringence (0.09 at-546 nm and 0.106 at-546 nm) and short ultraviolet absorption cut-off edges (190 nm and 208 nm), and millimeter-level single crystals are easy to grow. The wavelength range of the coherent light source can be expanded through optical frequency conversion technologies such as second harmonic generation and optical parametric amplification, and important application value is shown in the fields such as laser frequency conversion and photoelectric information storage.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of nonlinear optical crystalline materials, and relates to a 2-halogen ethane sulfonate second-order nonlinear optical crystalline material and a preparation method and application thereof. BACKGROUND

[0002] As the core material basis of modern optoelectronic technology, nonlinear optical materials have important applications in laser frequency conversion, electro-optic modulation, optical information storage, optical limiting and optical switching, etc. Especially in the short-wave ultraviolet region (wavelength λ < 280 nm), such materials show key application value in frontier technologies such as secure communication, high-efficiency sterilization processing and high-precision fire monitoring. Organic sulfonate salts have attracted widespread attention due to their significant second harmonic generation (SHG) effect. However, aromatic sulfonic acid-based organic sulfonate crystals have a common π-electron delocalization or electron-donating group effect in their structure, which narrows the energy gap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO), causing a significant red shift of the optical band gap, limiting their practical application potential in the ultraviolet and even deep ultraviolet bands. Therefore, developing sulfonate ultraviolet second-order nonlinear optical crystals with wide band gap and strong frequency doubling effect has become a key challenge and research frontier in this field. SUMMARY

[0003] The purpose of the present application is to provide a 2-halogen ethane sulfonate second-order nonlinear optical crystalline material and a preparation method and application thereof. The introduction of a flexible nonlinear optical functional group in the structure of the material helps to form a higher micro-polarizability and significant optical anisotropy, thereby making it have excellent second-order nonlinear optical performance. Experiments show that this kind of material can realize a strong powder frequency doubling effect (about 0.6-0.8 x KH2PO4 (KDP) @ 1064 nm), has a moderate birefringence (0.09 @ 546 nm and 0.106 @ 546 nm), and exhibits a large optical band gap (6.52 eV and 5.96 eV), which has potential application value in the field of ultraviolet nonlinear optics.

[0004] The purpose of the present application can be achieved by the following technical solutions:

[0005] One of the technical solutions of the present application provides a 2-halogen ethane sulfonate second-order nonlinear optical crystalline material, characterized in that the chemical formula of the crystalline material is Na[SO3(CH2)2X](H2O), wherein X = Cl or Br, the crystalline material belongs to a monoclinic system, the space group is Pc, and the unit cell parameters are a = 7.62 A, b = 5.62 A, c = 10.62 A, α = γ = 90°, β = 91.86-92.86°, and Z = 2. α = γ = 90°, β = 91.86-92.86°, and Z = 2.

[0006] Further, the chemical formula of the crystalline material is Na[SO3(CH2)2Cl](H2O), which belongs to monoclinic system, space group Pc, and the cell parameters are α = γ = 90°, β = 91.76 ~ 91.96°, Z = 2. Further preferably, the cell parameters are α = γ = 90°, β = 91.81 ~ 92.91°, Z = 2. Further preferably, the cell parameters are

[0007] α = γ = 90°, β = 91.86 ~ 91.87°, Z = 2. Most preferably, the cell parameters are α = γ = 90°, β = 91.866°, Z = 2.

[0008] The crystal structure of the organic sulfonate Na[SO3(CH2)2Cl](H2O) of the present application is shown in Figure 1 Each Na atom is coordinated with 6 oxygen atoms to form a [NaO6] polyhedron. Each [NaO6] polyhedron and [SO3(CH2)2Cl] - group are connected by corner sharing to form a layered structure, and the [SO3(CH2)2Cl] - anions are arranged in an anti-parallel manner in the two-dimensional layer, and the directions of the dipole moments of adjacent anions are almost opposite. Such arrangement is not conducive to the generation of strong SHG response of the crystalline material, although the primitive has a large first hyperpolarizability.

[0009] Further, the chemical formula of the crystalline material is Na[SO3(CH2)2Br](H2O), which belongs to monoclinic system, space group Pc, and the cell parameters are α = γ = 90°, β = 92.39 ~ 92.59°, Z = 2.

[0010] Further preferably, the cell parameters are α = γ = 90°, β = 92.44 ~ 92.54°, Z = 2. Further preferably, the cell parameters are α = γ = 90°, β = 92.49 ~ 92.50°, Z = 2. Most preferably, the cell parameters are

[0011] α = γ = 90°, β = 92.498(2)°, Z = 2.

[0012] The crystal structure of the organic sulfonate Na[SO3(CH2)2Br](H2O) of the present application is shown in Figure 2As shown. Each Na atom coordinates with 6 oxygen atoms to form a [NaO6] polyhedron. Each [NaO6] polyhedron is associated with [SO3(CH2)2Br]. - The groups form a layered structure through angle-sharing connections, [SO3(CH2)2Br] - The anions are arranged in an antiparallel pattern within the two-dimensional layer, with the dipole moments of adjacent anions oriented in almost opposite directions. This arrangement is unfavorable for the crystal material to generate a strong SHG response, despite the high first hyperpolarizability of the building blocks themselves.

[0013] The second technical solution of this invention provides a method for preparing second-order nonlinear optical crystalline materials of 2-halogen ethane sulfonate. First, a halocarbon source, a sulfurous acid source, and a mixed solvent are mixed and added to a reaction vessel. After heating and reacting, the mixture is filtered while hot. The filtrate is concentrated under reduced pressure to obtain a white solid. Each white solid is dissolved in anhydrous ethanol to prepare a saturated solution. After slow evaporation for two weeks, a colorless and transparent single crystal is obtained, which is the target product.

[0014] Furthermore, the amounts of the halohydrocarbon source, the sulfurous acid source, and the mixed solvent added satisfy the following: the molar ratio of the halohydrocarbon source, the sulfurous acid source, and the mixed solvent is (1-10):(1-30):(20-40).

[0015] Furthermore, the halohydrocarbon source is 1,2-dichloroethane and 1,2-dibromoethane.

[0016] Furthermore, the sulfurous acid source is sodium sulfite.

[0017] Furthermore, the mixed solvent is a mixed solution of anhydrous ethanol and water in a volume ratio of (1-3):(1-3). Preferably, the volume ratio of anhydrous ethanol to water is more preferably 1:1.

[0018] Furthermore, the reaction time should be no less than 24 hours at a temperature of 100–120°C, followed by a solvent evaporation period of no less than one week.

[0019] The third technical solution of the present invention provides an application of a second-order nonlinear optical crystalline material of 2-haloethane sulfonate in laser frequency converters, optical parametric oscillators, optical parametric amplifiers, and photoelectric rectifiers.

[0020] Furthermore, this material is used in laser frequency converters to output 532nm laser under 1064nm laser irradiation and 266nm laser under 532nm laser irradiation.

[0021] Specifically, Na[SO3(CH2)2Cl](H2O) crystal, as a nonlinear optical crystalline material, outputs a strong 532nm laser under 1064nm laser irradiation. Its powder frequency doubling intensity is 0.6 times that of KDP crystal. Under 532nm laser irradiation, the powder frequency doubling intensity is about 0.1 times that of β-BaB2O4(BBO) crystal and can achieve phase matching.

[0022] Specifically, Na[SO3(CH2)2Br](H2O) crystal, as a nonlinear optical crystalline material, outputs a strong 532nm laser under 1064nm laser irradiation. Its powder frequency doubling intensity is 0.8 times that of KDP crystal, and under 532nm laser irradiation, the powder frequency doubling intensity is about 0.2 times that of BBO crystal and can achieve phase matching.

[0023] This invention combines alkali metal cations and flexible sulfonic acid anions [SO3(CH2)2X]. - Combined, a frequency-doubling crystal of 2-haloethane sulfonate, Na[SO3(CH2)2X](H2O) (X = Cl or Br), was prepared. The flexible sulfonate anion [SO3(CH2)2X]... - With large polarizability anisotropy and first hyperpolarizability, the crystal material exhibits moderate powder frequency doubling effect (0.6×KDP and 0.8×KDP), moderate birefringence (0.09@546nm and 0.106@546nm) and wide optical band gap (6.52eV and 5.96eV).

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

[0025] (1) This application provides a second-order nonlinear optical crystal, Na[SO3(CH2)2Cl](H2O), which exhibits a moderate powder frequency doubling effect. Under 1064 nm laser irradiation, its frequency doubling intensity is 0.6 times that of KDP crystal, and under 532 nm laser irradiation, its intensity is approximately 0.1 times that of BBO crystal, with phase matching achieved in both cases. Furthermore, the ultraviolet absorption cutoff edge of this crystalline material is 190 nm, and its birefringence at 546 nm is 0.09. This crystalline material has broad application prospects in the field of nonlinear optics.

[0026] (2) This application provides a second-order nonlinear optical crystal, Na[SO3(CH2)2Br](H2O). This crystalline material exhibits a moderate powder frequency doubling effect. Under 1064 nm laser irradiation, its frequency doubling intensity is 0.8 times that of KDP crystal, and under 532 nm laser irradiation, its powder frequency doubling intensity is approximately 0.2 times that of BBO crystal, both achieving phase matching. Furthermore, the ultraviolet absorption cutoff edge of this crystalline material is 208 nm, and its birefringence at 546 nm is 0.106. This crystalline material has broad application prospects in the field of nonlinear optics. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the crystal structure of Na[SO3(CH2)2Cl](H2O);

[0028] Figure 2 This is a schematic diagram of the crystal structure of Na[SO3(CH2)2Br](H2O);

[0029] Figure 3 The X-ray diffraction pattern of sample 1-1# obtained by fitting the crystal structure resolved by single-crystal X-ray diffraction is compared with the X-ray diffraction pattern obtained by grinding sample 1-1# into powder.

[0030] Figure 4 The X-ray diffraction pattern of sample 2-1# obtained by fitting the crystal structure resolved by single-crystal X-ray diffraction is compared with the X-ray diffraction pattern obtained by grinding sample 2-1# into powder.

[0031] Figure 5 This is the UV-Vis transmission spectrum of sample 1-1#;

[0032] Figure 6 This is the UV-Vis transmission spectrum of sample 2-1#;

[0033] Figure 7 This is the infrared spectrum of sample 1-1#;

[0034] Figure 8 This is the infrared spectrum of sample 2-1#;

[0035] Figure 9 This is the thermogravimetric analysis chromatogram of sample 1-1#;

[0036] Figure 10 This is the thermogravimetric analysis chromatogram of sample 2-1#;

[0037] Figure 11 The second harmonic signal diagrams are for samples 1-1#, 2-1# and standard KDP sample with dimensions in the range of 105 to 150 μm.

[0038] Figure 12 These are the second harmonic phase matching diagrams of samples 1-1# and 2-1# in the 1064nm band;

[0039] Figure 13 The second harmonic signal diagrams are for samples 1-1#, 2-1# and standard BBO sample with dimensions in the range of 105 to 150 μm.

[0040] Figure 14 These are the second harmonic phase matching diagrams of samples 1-1# and 2-1# in the 532nm band;

[0041] Figure 15 This is a birefringence test result of sample 1-1# at a wavelength of 546nm.

[0042] Figure 16 This is a birefringence test result of sample 2-1# at a wavelength of 546nm. Detailed Implementation

[0043] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0044] Example:

[0045] In the following embodiments, unless otherwise specified, the raw materials or processing techniques are conventional commercially available raw materials or conventional processing techniques in the art.

[0046] Example 1:

[0047] Preparation of samples 1# to 8#

[0048] A haloalkanes source, a sulfurous acid source, and a mixed solvent were added to a reaction vessel. The mixture was heated and filtered while hot. The filtrate was concentrated under reduced pressure to obtain a white solid. Each white solid was dissolved in anhydrous ethanol to prepare a saturated solution. After slow evaporation for two weeks, colorless, transparent, flaky single crystals of Na[SO3(CH2)2Cl](H2O) were obtained.

[0049] The relationship between the types and proportions of raw materials, isothermal temperature, isothermal time and sample number in the initial mixture is shown in Table 1.

[0050] Table 1. Correspondence between samples and raw materials and synthesis conditions.

[0051]

[0052]

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

[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] Single-crystal X-ray diffraction measurements were performed on a Bruker D8 VENTURE CMOS X-ray single-crystal diffractometer (Germany). Data was collected at 100 K, and the diffraction source was graphite-monochromatic Mo-Kα rays. The scanning mode was ω; the data underwent absorption correction processing using the Multi-Scan method. Structural analysis was performed using the SHELXTL-97 package; the positions of heavy atoms were determined using a direct method, and the coordinates of the remaining atoms were obtained using difference Fourier synthesis; F-based... 2 The full matrix least squares method is used to refine the coordinates and anisotropic thermal parameters of all atoms.

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

[0057] The single-crystal X-ray diffraction results show that samples 1-1# to 1-8# have the same chemical structural formula and crystal structure, with the chemical formula Na[SO3(CH2)2Cl](H2O), belonging to the monoclinic crystal system, space group Pc, and cell parameters of [missing information]. α=γ=90°, β=91.76~91.96°, Z=2.

[0058] Taking sample 1-1# as a typical example, its crystal structure data is as follows: α = γ = 90°, β = 91.866°, Z = 2. Its crystal structure is as follows: Figure 1 As shown.

[0059] The powder X-ray diffraction test results show that on the XRD patterns of samples 1-1# to 1-8#, the diffraction peaks of the samples and the diffraction peaks fitted by the single crystal data are in the same position, but the peak intensities are slightly different.

[0060] Taking sample 1-1# as a typical example, such as Figure 3 As shown, the X-ray diffraction pattern obtained by fitting the crystal structure determined by single-crystal X-ray diffraction is consistent with the X-ray diffraction pattern obtained after grinding sample 1-1# into powder. The peak positions are consistent, indicating that the obtained sample has high purity.

[0061] Ultraviolet-Visible Light Transmission Spectroscopy Test

[0062] The diffuse reflectance absorption spectra of samples 1-1# were measured using an Agilent Technologies Carry 5000 UV-Vis-NIR spectrophotometer. The results are as follows: Figure 5 As shown, the ultraviolet absorption cutoff edge of this compound is 190 nm.

[0063] Infrared spectroscopy test

[0064] Infrared spectroscopy measurements of samples 1-1# were performed using a Nicoleti S10 Fourier transform infrared spectrometer from Thermo Fisher Scientific, Inc., USA. The results are as follows: Figure 7 As shown, in the infrared spectrum (524 cm⁻¹) -1 796cm -1 1027cm -1 1170cm -1 1313cm -1 The characteristic absorption peaks confirmed the presence of [SO3(CH2)2Cl] in the crystal. - The presence of functional groups.

[0065] Thermogravimetric test

[0066] Thermogravimetric analysis (TGA) of samples 1-1# was performed on a Netzsch STA 409PC thermogravimetric analyzer from Netzsch GmbH, Germany. The results are as follows: Figure 9 As shown, by Figure 9 It can be seen that this compound is stable up to 80℃.

[0067] Frequency doubling test experiment and results

[0068] The frequency doubling test experiment for sample 1-1# is as follows: A Q-switched Nd:YAG solid-state laser with a wavelength of 1064nm was used as the fundamental frequency light to irradiate the test crystal powder. The generated second harmonic intensity was detected by an Ocean Optics Maya2000 Pro spectrometer. The crystal sample, standard sample KDP, and standard sample BBO crystals were ground separately and sieved with standard sieves to separate crystals of different particle sizes, with particle size ranges of 26–50, 50–74, 74–105, 105–150, and 150–200 μm, respectively. The variation of the frequency doubling signal with particle size was observed to determine whether phase matching could be achieved. Under the same test conditions, the second harmonic intensity generated by the sample, standard sample KDP, and standard sample BBO crystals was compared to obtain the relative magnitude of the sample's frequency doubling effect. Using the same test method, the test crystal powder was irradiated with a fundamental frequency light with a wavelength of 532nm, and the generated second harmonic intensity was detected by an Ocean Optics Maya2000 Pro spectrometer. Observe the variation of the harmonic signal with particle size to determine whether phase matching can be achieved. Under the same test conditions, compare the second harmonic intensity generated by the sample and the standard sample BBO to obtain the relative magnitude of the harmonic effect of the sample.

[0069] Test results show that the powder frequency doubling effect of compound Na[SO3(CH2)2Cl](H2O) under 1064nm laser irradiation is approximately 0.6 times that of potassium dihydrogen phosphate crystal (KDP) (e.g., Figure 11 Under 532nm laser irradiation, the frequency doubling intensity of the powder is approximately 0.1 times that of the BBO crystal (e.g., Figure 13 ), and all can achieve phase matching ( Figure 12 and Figure 14 ).

[0070] Crystal birefringence test

[0071] The birefringence properties of crystal sample 1-1# were measured using a ZEISS AXIO Scope 5 polarizing microscope equipped with a Berek compensator. The light source wavelength was 546 nm. The birefringence was calculated using the following formula:

[0072] ΔR(retardation)=|n e -n o |×T=Δn×T

[0073] In the formula, ΔR represents the optical path difference, Δn represents birefringence, and T represents the crystal thickness. The compensated positive and negative rotations provide a relative delay.

[0074] The results are as follows Figure 15 As shown, Figure 15Image a shows a Na[SO3(CH2)2Cl](H2O) crystal after complete extinction using a Berek compensator. The optical path difference (R) is 4.50 μm, and the measured single crystal thickness (T) is 50.03 μm. Figure 15 b). The crystal planes identified by single-crystal XRD analysis are... ( Figure 15 c). Calculations were performed on Na[SO3(CH2)2Cl](H2O) crystals. The refractive index difference of the crystal plane at 546 nm is 0.09.

[0075] Example 2

[0076] Preparation of samples 1# to 8#

[0077] A haloalkanes source, a sulfurous acid source, and a mixed solvent were added to a reaction vessel. The mixture was heated and filtered while hot. The filtrate was concentrated under reduced pressure to obtain a white solid. Each white solid was dissolved in anhydrous ethanol to prepare a saturated solution. After slow evaporation for two weeks, colorless, transparent, flaky single crystals of Na[SO3(CH2)2Br](H2O) were obtained.

[0078] The relationship between the types and proportions of raw materials, constant temperature, constant temperature time and sample number in the initial mixture is shown in Table 2.

[0079] Table 2. Correspondence between samples and raw materials and synthesis conditions.

[0080]

[0081]

[0082] Crystal structure analysis of samples 2-1# to 2-8#

[0083] The structures of samples 2-1# to 2-8# were analyzed using single-crystal X-ray diffraction and powder X-ray diffraction methods.

[0084] Single-crystal X-ray diffraction measurements were performed on a Bruker D8 VENTURE CMOS X-ray single-crystal diffractometer (Germany). Data was collected at 100 K, and the diffraction source was graphite-monochromatic Mo-Kα rays. The scanning mode was ω; the data underwent absorption correction processing using the Multi-Scan method. Structural analysis was performed using the SHELXTL-97 package; the positions of heavy atoms were determined using a direct method, and the coordinates of the remaining atoms were obtained using difference Fourier synthesis; F-based... 2 The full matrix least squares method is used to refine the coordinates and anisotropic thermal parameters of all atoms.

[0085] Powder X-ray diffraction tests were performed on a Bruker D8 X-ray powder diffractometer from Bruker GmbH, Germany. The test conditions were a fixed target, a monochromatic Cu-Kα light source, and a wavelength of [missing information]. The voltage and current are 40kV / 20A, the slits DivSlit / RecSlit / SctSlit are 2.00deg / 0.3mm / 2.00deg respectively, the scanning range is 5~70°, and the scanning step size is 0.02°.

[0086] The single-crystal X-ray diffraction results show that samples 2-1# to 2-8# have the same chemical structure and crystal structure, with the chemical formula Na[SO3(CH2)2Br](H2O), belonging to the monoclinic crystal system, space group Pc, and cell parameters of [missing information]. α=γ=90°, β=92.39~92.59°, Z=2.

[0087] Taking sample 2-1# as a typical example, its crystal structure data is as follows: α=γ=90°, β=92.498(2)°, Z=2. Its crystal structure is as follows: Figure 2 As shown.

[0088] The powder X-ray diffraction test results show that on the XRD patterns of samples 2-1# to 2-8#, the diffraction peaks of the samples and the diffraction peaks fitted by the single crystal data are in the same position, but the peak intensities are slightly different.

[0089] Taking sample 2-1# as a typical example, such as Figure 4 As shown, the X-ray diffraction pattern obtained by fitting the crystal structure determined by single-crystal X-ray diffraction is consistent with the X-ray diffraction pattern obtained after grinding sample 2-1# into powder. The peak positions are consistent, indicating that the obtained sample has high purity.

[0090] Ultraviolet-Visible Light Transmission Spectroscopy Test

[0091] The diffuse reflectance absorption spectrum of sample 2-1# was measured using an Agilent Technologies Carry 5000 UV-Vis-NIR spectrophotometer. The results are as follows: Figure 6 As shown, the ultraviolet absorption cutoff edge of this compound is 208 nm.

[0092] Infrared spectroscopy test

[0093] The infrared spectra of sample 2-1# were measured using a Nicoleti S10 Fourier transform infrared spectrometer from Thermo Fisher Scientific, Inc., USA. The results are as follows: Figure 8 As shown, in the infrared spectrum (520cm) -1 778cm -1 1027cm -11156cm -1 1276cm -1 The characteristic absorption peaks confirmed the presence of [SO3(CH2)2Br] in the crystal. - The presence of functional groups.

[0094] Thermogravimetric test

[0095] Thermogravimetric analysis (TGA) of sample 2-1# was performed on a Netzsch STA 409PC thermogravimetric analyzer from Netzsch GmbH, Germany. The results are as follows: Figure 10 As shown, by Figure 10 It can be seen that the compound is stable up to 82℃.

[0096] Frequency doubling test experiment and results

[0097] The frequency doubling test experiment for sample 2-1# is as follows: A Q-switched Nd:YAG solid-state laser with a wavelength of 1064 nm was used as the fundamental frequency light to irradiate the test crystal powder. The generated second harmonic intensity was detected by an Ocean Optics Maya2000 Pro spectrometer. The crystal sample, standard sample KDP, and standard sample BBO crystals were ground separately and sieved with standard sieves to separate crystals of different particle sizes, with particle size ranges of 26–50, 50–74, 74–105, 105–150, and 150–200 μm, respectively. The variation of the frequency doubling signal with particle size was observed to determine whether phase matching could be achieved. Under the same test conditions, the second harmonic intensity generated by the sample was compared with that of the standard sample KDP and standard sample BBO crystals to obtain the relative magnitude of the sample's frequency doubling effect. Using the same test method, the test crystal powder was irradiated with a fundamental frequency light with a wavelength of 532 nm, and the generated second harmonic intensity was detected by an Ocean Optics Maya2000 Pro spectrometer. Observe the variation of the harmonic signal with particle size to determine whether phase matching can be achieved. Under the same test conditions, compare the second harmonic intensity generated by the sample and the standard sample BBO to obtain the relative magnitude of the harmonic effect of the sample.

[0098] Test results show that the powder frequency doubling effect of compound Na[SO3(CH2)2Br](H2O) under 1064nm laser irradiation is approximately 0.8 times that of potassium dihydrogen phosphate crystals (e.g., Figure 11 Under 532nm laser irradiation, the frequency doubling intensity of the powder is approximately 0.2 times that of the BBO crystal (e.g., Figure 13 ), and all can achieve phase matching ( Figure 12 and Figure 14 ).

[0099] Crystal birefringence test

[0100] The birefringence properties of crystal sample 2-1# were measured using a ZEISS AXIO Scope 5 polarizing microscope equipped with a Berek compensator. The light source wavelength was 546 nm. The birefringence was calculated using the following formula:

[0101] ΔR(retardation)=|n e -n o |×T=Δn×T

[0102] In the formula, ΔR represents the optical path difference, Δn represents birefringence, and T represents the crystal thickness. The compensated positive and negative rotations provide a relative delay.

[0103] The results are as follows Figure 16 As shown, Figure 16 Image a shows a Na[SO3(CH2)2Br](H2O) crystal after complete extinction using a Berek compensator. The optical path difference (R) is 6.15 μm, and the measured single crystal thickness (T) is 57.99 μm. Figure 16 b). The crystal planes identified by single-crystal XRD analysis are... ( Figure 16 c). Calculations were performed on the Na[SO3(CH2)2Br](H2O) crystal. The refractive index difference of the crystal plane at 546 nm is 0.106.

[0104] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any 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 invention should be within the protection scope of the present invention.

Claims

1. A second-order nonlinear optical crystalline material of 2-haloethane sulfonate, characterized in that, The chemical formula of this crystalline material is Na[SO3(CH2)2X](H2O), where X = Cl or Br. This crystalline material belongs to the monoclinic crystal system, with space group Pc and cell parameters of [missing information]. α=γ=90°, β=91.86~92.86°, Z=2.

2. The second-order nonlinear optical crystalline material of 2-haloethane sulfonate according to claim 1, characterized in that, The chemical formula of this crystalline material is Na[SO3(CH2)2Cl](H2O), it belongs to the monoclinic crystal system, space group Pc, and its unit cell parameters are as follows: α=γ=90°, β=91.76~91.96°, Z=2; Alternatively, the chemical formula of this crystalline material may be Na[SO3(CH2)2Br](H2O), which belongs to the monoclinic crystal system, space group Pc, and cell parameters are... α=γ=90°, β=92.39~92.59°, Z=2.

3. The method for preparing the second-order nonlinear optical crystalline material of 2-haloethane sulfonate as described in claim 1 or 2, characterized in that, First, the haloalkanes, sulfurous acid, and a mixed solvent are mixed and added to a reaction vessel. After heating and reacting, the mixture is filtered while hot. The filtrate is concentrated under reduced pressure to obtain a white solid. Each white solid is dissolved in anhydrous ethanol to prepare a saturated solution. After slow evaporation for two weeks, colorless and transparent single crystals are obtained, which is the target product.

4. The method for preparing the second-order nonlinear optical crystalline material of 2-haloethane sulfonate according to claim 3, characterized in that, The amounts of the halogenated hydrocarbon source, the sulfurous acid source, and the mixed solvent added satisfy the following: the molar ratio of the halogenated hydrocarbon source, the sulfurous acid source, and the mixed solvent is (1-10):(1-30):(20-40).

5. The method for preparing the second-order nonlinear optical crystalline material of 2-haloethane sulfonate according to claim 3, characterized in that, The halohydrocarbon source is 1,2-dichloroethane and 1,2-dibromoethane.

6. The method for preparing the second-order nonlinear optical crystalline material of 2-haloethane sulfonate according to claim 3, characterized in that, The sulfurous acid source is sodium sulfite.

7. The method for preparing the second-order nonlinear optical crystalline material of 2-haloethane sulfonate according to claim 3, characterized in that, The mixed solvent is a mixed solution of anhydrous ethanol and water in a volume ratio of (1-3):(1-3).

8. The method for preparing the second-order nonlinear optical crystalline material of 2-haloethane sulfonate according to claim 3, characterized in that, The reaction time should be no less than 24 hours at a temperature of 100–120°C, followed by a solvent evaporation period of no less than one week.

9. The application of the 2-haloethane sulfonate second-order nonlinear optical crystalline material as described in claim 1 or 2 in laser frequency converters, optical parametric oscillators, optical parametric amplifiers, and photoelectric rectifiers.

10. The application of the 2-haloethane sulfonate second-order nonlinear optical crystalline material according to claim 9, characterized in that, This material is used in laser frequency converters to output 532nm laser under 1064nm laser irradiation and 266nm laser under 532nm laser irradiation.

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