A molybdenum strontium peroxide second-order nonlinear optical crystal and its preparation and application

Abstract

The present invention relates to a molybdenum strontium peroxide second-order nonlinear optical crystal and its preparation and application. The chemical formula of the crystal material is SrMo2O3(O2)4(H2O)2·3H2O, the molecular weight is 545.58, it belongs to the tetragonal crystal system, its space group is , the unit cell parameters are α=β=γ=90°, Z=8, and the unit cell volume is . The molybdenum strontium peroxide crystal material of the present invention has excellent optical properties. Under 1064nm laser irradiation, the powder frequency harmonic intensity is about 3 times that of potassium dihydrogen phosphate crystal, and phase matching can be achieved. The crystal material is not only easy to grow, but also can effectively expand the wavelength range of coherent light sources through optical frequency conversion technologies such as second harmonic generation and optical parametric amplification. In the fields of laser lithography, laser processing, medical diagnosis and treatment, this crystal material shows important application prospects.

Description

Technical Field

[0001] The invention belongs to the technical field of nonlinear optical crystal materials and relates to a molybdenum strontium peroxide second-order nonlinear optical crystal and its preparation and application. Background Art

[0002] Nonlinear optical crystals (NLO) are key materials for solid-state lasers to generate continuously tunable coherent light through cascade frequency conversion and are widely used in optoelectronics. New NLO crystal materials are constantly emerging, and many NLO materials covering the wavelength range from ultraviolet to mid-infrared have been discovered. Research has shown that: π-conjugated peroxide [O2] 2- They contribute significantly to second-order nonlinear optical effects. However, because peroxides are generally highly hygroscopic in air, most peroxides have poor optical stability in air, which has led to their application as second-order nonlinear optical crystal materials being neglected. Therefore, the development of peroxide second-order nonlinear optical crystal materials with excellent performance and air stability is a hot topic and a challenge in current research. Summary of the Invention

[0003] The purpose of the present invention is to provide a molybdenum strontium peroxide second-order nonlinear optical crystal and its preparation and application, wherein the peroxide [O2] 2- The group significantly enhances the linear and nonlinear optical properties of molybdenum strontium peroxide. The resulting molybdenum strontium peroxide optical crystal exhibits a frequency-doubled-energy effect of 3×KH2PO4(KDP)@1064nm, a birefringence of 0.033@546nm, and a band gap of 2.9eV. Furthermore, the molybdenum strontium peroxide single crystal remains transparent after two weeks of exposure to air.

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

[0005] In one aspect, the present invention provides a second-order nonlinear optical crystal of molybdenum strontium peroxide, whose chemical formula is SrMo2O3(O2)4(H2O)2·3H2O, molecular weight is 545.58, belongs to the tetragonal system, and its space group is The unit cell parameters are α=β=γ=90°,Z=8,the unit cell volume is

[0006] Furthermore, the unit cell parameters of the optical crystal are α=β=γ=90°,Z=8. Further preferably, the unit cell parameters are α=β=γ=90°,Z=8. Most preferably, the unit cell parameters are α=β=γ=90°, Z=8.

[0007] The crystal structure of molybdenum strontium peroxide of the present invention is as follows Figure 1 As shown. Each Mo atom is bound to three oxygen atoms, two [O2] 2- The coordination forms the [Mo(O2)2O3] unit. The arrangement direction of the [Mo(O2)2O3] unit in the crystal is 90°, which leads to significant nonlinear optical effects. 2+ The atoms are connected to the [Mo(O2)2O3] unit through shared oxygen atoms to form a three-dimensional structure.

[0008] On the other hand, the present invention provides a method for preparing molybdenum strontium peroxide second-order nonlinear optical crystals, which comprises mixing an Sr source, a Mo source, and hydrogen peroxide and continuously stirring until a clear and transparent solution is obtained, and then naturally evaporating the solvent to finally obtain light yellow transparent block-shaped crystals, which are the target product.

[0009] Furthermore, the added amounts of the Sr source and the Mo source satisfy the following molar ratio of the Sr element to the Mo element: (1-10): (2-20).

[0010] Furthermore, the solution volatilizes at a temperature of 25 to 55° C., and the volatilization time is no less than one week.

[0011] Furthermore, the solution volatilizes at a temperature of 30-35° C. and for a volatilization time of no less than one week.

[0012] Furthermore, the Sr source is at least one of strontium carbonate, strontium nitrate or strontium chloride.

[0013] Furthermore, the Mo source is at least one of molybdenum oxide and molybdic acid.

[0014] In a third aspect, the present invention provides an application of a molybdenum strontium peroxide second-order nonlinear optical crystal in a laser frequency converter, an optical parametric oscillator, an optical parametric amplifier, and a photoelectric rectifier.

[0015] Furthermore, when the molybdenum strontium peroxide second-order nonlinear optical crystal material is applied to a laser frequency converter, it can generate 532nm green light output under the irradiation of a 1064nm laser.

[0016] Specifically, the application of molybdenum strontium peroxide crystal as a nonlinear optical crystal material can output a strong 532nm green light under 1064nm laser irradiation. Its powder frequency-doubled intensity is about three times that of KDP crystal, and it can achieve phase matching.

[0017] The present invention utilizes the distorted octahedron strategy to convert [O2] 2-By replacing oxygen atoms with molybdenum strontium peroxide (MoSrO2), they successfully constructed a [Mo(O2)2O3] moiety with strong polarizability anisotropy and hyperpolarizability. As a result, MoSrO2 exhibits a strong double-harmonic response (3×KDP) and a moderate birefringence (0.033@546nm).

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] (1) This application provides a new second-order nonlinear optical crystal, SrMo2O3(O2)4(H2O)2·3H2O. This crystal material has a large frequency-doubled effect, approximately three times the frequency-doubled intensity of a KDP crystal under 1064nm laser irradiation, and is capable of phase matching. In addition, this crystal material has high transmittance in the 427-1300nm spectral range, with an absorption cutoff wavelength of 427nm. Therefore, this crystal material has broad application prospects in the field of nonlinear optics.

[0020] (2) This application provides a method for preparing the nonlinear optical crystal SrMo2O3(O2)4(H2O)2·3H2O. A solution evaporation method is used to successfully grow pale yellow block crystals of SrMo2O3(O2)4(H2O)2·3H2O. This method is simple, operates under mild conditions, and can efficiently produce single crystals with high optical quality and purity, facilitating large-scale industrial production.

[0021] (3) The molybdenum strontium peroxide crystal material of the present invention can be applied to a laser frequency converter, and can be used to output a laser beam as a second harmonic. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the crystal structure of SrMo2O3(O2)4(H2O)2·3H2O;

[0023] Figure 2 The following are comparisons of X-ray diffraction patterns; (a) is the X-ray diffraction pattern obtained by analyzing and simulating the single crystal X-ray diffraction data of sample 1#; (b) is the pattern obtained by X-ray diffraction testing after grinding sample 1# into powder;

[0024] Figure 3 is the UV-visible-near-infrared absorption spectrum of sample 1#;

[0025] Figure 4 is the infrared spectrum of sample 1#;

[0026] Figure 5 This is the second harmonic signal diagram of sample 1# and KDP sample with size ranging from 105 to 150 μm;

[0027] Figure 6This is the second harmonic phase matching diagram of sample 1# at a wavelength of 1064nm;

[0028] Figure 7 This is the optical photograph of sample 1#. DETAILED DESCRIPTION

[0029] 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.

[0030] In the following examples, unless otherwise specified, raw materials or processing techniques are conventional commercially available raw materials or conventional processing techniques in the art.

[0031] Example 1:

[0032] Preparation of samples 1# to 8#

[0033] A mixture of Sr, Mo, and hydrogen peroxide (30% by mass) is placed in a polytetrafluoroethylene-lined container and stirred continuously until a clear, transparent solution is obtained. The solvent is then slowly evaporated at room temperature, ultimately yielding pale yellow, transparent, blocky SrMo2O3(O2)4(H2O)2·3H2O crystals.

[0034] The relationship between the types and ratios of raw materials in the initial mixture, volatilization temperature, volatilization time and sample numbers is shown in Table 1.

[0035] Table 1 Correspondence between samples, raw materials and synthesis conditions

[0036]

[0037] Crystal structure analysis of samples 1# to 8#

[0038] Single crystal X-ray diffraction and powder X-ray diffraction techniques were used to perform structural analysis and phase analysis on samples 1# to 8#, respectively.

[0039] Single crystal X-ray diffraction measurements were performed on a Bruker D8 VENTURE CMOS X-ray single crystal diffractometer from Germany. The data collection temperature was 298.15 K, 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 Olex2 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.

[0040] Single crystal X-ray diffraction results show that samples 1# to 8# have the same chemical formula and crystal structure, the chemical formula is SrMo2O3(O2)4(H2O)2·3H2O, the molecular weight is 545.58, and they belong to the tetragonal system. Their space group is The unit cell parameters are α=β=γ=90°,Z=8,the unit cell volume is

[0041] Taking sample 1# as a typical representative, its crystal structure data is α=β=γ=90°,Z=8. The crystal structure of SrMo2O3(O2)4(H2O)2·3H2O is as follows Figure 1 shown.

[0042] The powder X-ray diffraction test was carried out on a Bruker D8 X-ray powder diffractometer from Bruker, Germany. The test conditions were a fixed target monochromatic light source Cu-Kα, 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 10-70°, and the scanning step is 0.02°.

[0043] The powder X-ray diffraction test results show that in the XRD spectra of samples 1# to 8#, the peak positions of each sample are basically the same, but the peak intensities are slightly different.

[0044] Take sample 1# as a typical example. Figure 2 As shown in the figure, the peak positions of the fitted X-ray diffraction pattern obtained based on the crystal structure analyzed by single crystal X-ray diffraction are consistent with the pattern obtained by X-ray diffraction testing of sample 1 after grinding into powder. This indicates that the obtained sample has a high purity.

[0045] UV-Vis-NIR diffuse reflectance spectroscopy test

[0046] The diffuse reflectance spectrum of sample 1# was tested on a Cary 5000 UV-visible-near infrared spectrophotometer from Agilent Technologies, USA. Figure 3 As shown, the compound has no obvious absorption in the range of 427nm to 1300nm, and its optical band gap is 2.90eV.

[0047] Infrared spectrum test

[0048] The infrared spectrum test of sample 1# was conducted on a Nicolet iS10 Fourier infrared spectrometer from Thermo Fisher Scientific Inc., USA. Figure 4 As shown, 968 cm in the infrared spectrum -1The characteristic absorption peak of [O2] 2- The presence of groups.

[0049] Frequency doubling test experiment and results

[0050] The SHG test experiment for sample 1# was conducted as follows: a Q-switched Nd:YAG solid-state laser with 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 spectrometer, and the harmonic intensity was displayed using an oscilloscope. The crystal sample and a control KDP crystal were ground separately and sieved using a standard sieve to produce crystals of varying particle sizes: less than 26 μm, 26–50 μm, 50–74 μm, 74–105 μm, and 105–150 μm. The SHG signal intensity 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 KDP sample were compared to determine the relative magnitude of the SHG effect.

[0051] The test results show that the compound molybdenum strontium peroxide crystal has a large frequency doubling effect. Under 1064nm wavelength laser irradiation, the frequency doubling signal intensity is 3 times that of the control sample KDP crystal (such as Figure 5 ), phase matching can be achieved (such as Figure 6 ).

[0052] Sample air stability test and results

[0053] The newly prepared crystals were exposed to air for two weeks. (a) is a picture of the newly prepared crystals, and (b) is a picture of the crystals after being exposed to air for two weeks. The results are shown in Figure 2. Figure 7 As shown, the MoSnO single crystals retained high transparency after being exposed to air for two weeks.

[0054] 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 molybdenum strontium peroxide second-order nonlinear optical crystal, characterized in that: Its chemical formula is SrMo2O3(O2)4(H2O)2·3H2O, its molecular weight is 545.58, it belongs to the tetragonal system, and its space group is I 2 d , the unit cell parameters are a = b = 17.18~17.38 Å, c = 8.48~8.68 Å, α = β = γ = 90°, Z = 8, the unit cell volume is V = 2561.9~2571.9Å 3 .

2. The method for preparing a molybdenum strontium peroxide second-order nonlinear optical crystal according to claim 1, wherein: Mix the Sr source, Mo source, and hydrogen peroxide and stir continuously until a clear and transparent solution is obtained. Then, the solvent is naturally evaporated to finally obtain light yellow transparent block crystals, which are the target product.

3. The method for preparing a molybdenum strontium peroxide second-order nonlinear optical crystal according to claim 2, characterized in that: The added amounts of the Sr source and the Mo source satisfy the molar ratio of the Sr element to the Mo element of (1-10): (2-20).

4. The method for preparing a molybdenum strontium peroxide second-order nonlinear optical crystal according to claim 2, characterized in that: The temperature of the solution is 25~55 o C. The volatilization time is not less than one week.

5. The method for preparing a molybdenum strontium peroxide second-order nonlinear optical crystal according to claim 3, characterized in that: The temperature of the solution is 30~35 o C. The volatilization time is not less than one week.

6. The method for preparing a molybdenum strontium peroxide second-order nonlinear optical crystal according to claim 2, characterized in that: The Sr source is at least one of strontium carbonate, strontium nitrate or strontium chloride.

7. The method for preparing a molybdenum strontium peroxide second-order nonlinear optical crystal according to claim 2, characterized in that: The Mo source is at least one of molybdenum oxide and molybdic acid.

8. Use of the molybdenum strontium peroxide second-order nonlinear optical crystal as claimed in claim 1 in a laser frequency converter, an optical parametric oscillator, an optical parametric amplifier and a photoelectric rectifier.

9. The use of the molybdenum strontium peroxide second-order nonlinear optical crystal according to claim 8, characterized in that: When the molybdenum strontium peroxide second-order nonlinear optical crystal material is used in a laser frequency converter, it can generate 532 nm green light output under the irradiation of a 1064 nm laser.

Images