Sodium-magnesium-zinc hydroxycarbonate ultraviolet nonlinear optical crystal and preparation method and application thereof

Abstract

The invention relates to a sodium magnesium zinc hydroxycarbonate ultraviolet nonlinear optical crystal and a preparation method and application thereof, the chemical formula of the crystal is Na2Mg0. 34Zn0. 66C2O7H2, the crystal belongs to a tetragonal system, the space group is P-4 (No.81), and the crystal belongs to a non-centered space group; the cell parameters are as follows: a = 7.4555 (2), b = 7.4555 (2), c = 5.7592 (3), alpha = beta = gamma = 90 degrees, Z = 2, and unit cell volume V = 320.12 (2) 3. The sodium-magnesium-zinc hydroxycarbonate ultraviolet nonlinear optical crystal provided by the invention has a broad band gap of 5.65 eV, a corresponding ultraviolet cutoff edge of 219.64 nm, a birefringence of about 0.055 at 248nm, and good phase matching capability in an ultraviolet region; the theoretical frequency multiplication coefficient of the crystal is more than two times that of a KDP crystal, and the crystal is good in mechanical property, stable in air and not prone to deliquescence. Meanwhile, the crystal is simple in preparation process, relatively low in cost and environment-friendly in raw material, has good application potential in preparation of laser harmonic generators, optical parametric amplifiers and optical waveguide devices, and can realize output of deep ultraviolet laser with the wavelength less than 400nm.

Description

Technical Field

[0001] This invention relates to the field of nonlinear optical crystal technology. More specifically, it relates to a material with the molecular formula Na₂Mg. 0.34 Zn 0.66 Carbonate nonlinear optical crystals of C2O7H2, their preparation methods, and applications. Background Technology

[0002] Ultraviolet nonlinear optical crystals are crystals that can output ultraviolet laser light with wavelengths in the range of 200-400 nm by changing the frequency of incident light through nonlinear optical effects. These crystals have significant application value in cutting-edge fields such as optical communication, laser processing, optical sensing, and quantum optics. Nonlinear optical crystals suitable for the ultraviolet band must meet at least three basic conditions: first, a band gap of 3.1 eV or higher; second, a nonlinear optical coefficient no less than twice that of potassium dihydrogen phosphate (KDP) crystals; and third, a suitable birefringence (Δn) to achieve phase matching.

[0003] Currently, most existing ultraviolet nonlinear optical crystals still have shortcomings in terms of environmental stability, thermal stability, and water resistance, making it difficult to fully meet the needs of practical applications. This, to some extent, restricts the further development and application of such materials in the field of laser technology. The sodium magnesium zinc hydroxycarbonate ultraviolet nonlinear optical crystal provided by this invention has a wide bandgap of 5.65 eV, corresponding to an ultraviolet cutoff edge of 219.64 nm, and a birefringence of approximately 0.055 at 248 nm. It exhibits good phase matching ability in the ultraviolet region; its theoretical frequency doubling factor is more than twice that of KDP crystals, and it possesses good mechanical properties, is stable in air, and is not easily deliquescent. Furthermore, the crystal's preparation process is simple and low-cost, and the raw materials are environmentally friendly, demonstrating excellent application potential. Summary of the Invention

[0004] The purpose of this invention is to provide a sodium magnesium zinc hydroxycarbonate ultraviolet nonlinear optical crystal.

[0005] Another object of the present invention is to provide a method for preparing a sodium magnesium zinc hydroxycarbonate ultraviolet nonlinear optical crystal.

[0006] Another object of the present invention is to provide the use of a sodium magnesium zinc hydroxycarbonate ultraviolet nonlinear optical crystal.

[0007] The present invention discloses a sodium magnesium zinc hydroxycarbonate ultraviolet nonlinear optical crystal, the chemical formula of which is Na2Mg. 0.34 Zn 0.66C2O7H2 belongs to the tetragonal crystal system, space group P-4 (No. 81), and is a non-centered space group; its unit cell parameters are a = 7.4555(2) Å, b = 7.4555(2) Å, c = 5.7592(3) Å, α = β = γ = 90°, Z = 2, and unit cell volume V = 320.12(2) Å. 3 .

[0008] The hydrothermal growth of the sodium magnesium zinc hydroxycarbonate ultraviolet nonlinear optical crystal is carried out according to the following steps:

[0009] a. Weigh the raw materials under air conditions, according to the molar ratio of magnesium, zinc, and sodium elements of 1:(0.5-2):(1-2), and place them in a polytetrafluoroethylene liner. Add 5-10 ml of deionized water or purified water, cover the liner, and place the liner into the 304 stainless steel shell of the hydrothermal reactor and tighten it. The magnesium compound is selected from at least one of MgF2, MgO, Mg(OH)2, and MgCO3; the zinc compound is selected from at least one of ZnCl2, ZnO, Zn(OH)2, and Zn(NO3)26H2O; and the sodium compound is selected from at least one of Na2CO3 and NaHCO3.

[0010] b. Place the hydrothermal reactor from step a into a stepped temperature-controlled forced-air drying oven, raise the temperature to 240°C at 0.5°C / min, hold for 24 hours, then lower the temperature to 220°C and hold for 24 hours, then lower the temperature to 180°C and hold for 24 hours, and finally lower to room temperature.

[0011] c. Open the polytetrafluoroethylene liner, rinse the product with deionized water, and dry the cleaned crystal product in a drying oven to obtain sodium magnesium zinc hydroxycarbonate ultraviolet nonlinear optical crystal.

[0012] Preferably, the molar ratio of magnesium, zinc, and sodium in the magnesium-containing compound, zinc-containing compound, and sodium-containing compound can also be, but is not limited to, 1:0.5:1, 1:0.5:1.5, 1:0.5:2, 1:1:1, 1:1:1.5, 1:1:2, 1:1.5:1, 1:1.5:1.5, 1:1.5:2, 1:2:1, 1:2:1.5, and 1:2:2.

[0013] The sodium magnesium zinc hydroxycarbonate ultraviolet nonlinear optical crystal is used for frequency conversion of laser output in lasers.

[0014] The sodium magnesium zinc hydroxycarbonate ultraviolet nonlinear optical crystal is used to generate harmonic output with a minimum wavelength of 219.64 nm.

[0015] The sodium magnesium zinc hydroxy carbonate ultraviolet nonlinear optical crystal is used to prepare ultraviolet harmonic generators, optical parametric oscillators and optical parametric amplifiers, and optical waveguide devices.

[0016] The sodium magnesium zinc hydroxycarbonate ultraviolet nonlinear optical crystal is used to prepare optical parametric oscillation and optical parametric amplification devices from the infrared to the ultraviolet region.

[0017] The application of the sodium magnesium zinc hydroxycarbonate ultraviolet nonlinear optical crystal described in this invention in the field of laser technology includes its use in the preparation of ultraviolet band laser frequency conversion crystals, ultraviolet lasers, ultraviolet electro-optic devices, ultraviolet communication devices, laser medicine, ultraviolet lithography devices, and ultraviolet micro-nano fabrication devices.

[0018] The beneficial effects of this invention are as follows: The sodium magnesium zinc hydroxycarbonate ultraviolet nonlinear optical crystal provided by this invention has a wide bandgap of 5.65 eV, corresponding to an ultraviolet cutoff edge of 219.64 nm, thus making it suitable for optical applications in the ultraviolet band; its birefringence is approximately 0.055 at 248 nm, exhibiting good phase matching capability in the ultraviolet region; its theoretical frequency doubling factor is more than twice that of KDP crystal, and it possesses good mechanical properties. A high-yield preparation of colorless and transparent crystals can be achieved using a hydrothermal synthesis method. This preparation method is simple, efficient, clean, environmentally friendly, low-cost, and time-saving. The raw materials are environmentally friendly, and the prepared crystals are stable in air and not easily deliquescent, demonstrating good application potential in the preparation of laser harmonic generators, optical parametric amplifiers, and optical waveguide devices. It can achieve the output of deep ultraviolet lasers with wavelengths less than 400 nm. Attached Figure Description

[0019] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0020] Figure 1 The present invention is Na2Mg 0.34 Zn 0.66 Schematic diagram of X-ray diffraction (XRD) of C2O7H2 crystal theory;

[0021] Figure 2 The present invention is Na2Mg 0.34 Zn 0.66 A schematic diagram of the single-cell structure of C2O7H2 crystal;

[0022] Figure 3 The present invention is Na2Mg 0.34 Zn 0.66 Schematic diagram of the band gap values ​​of C2O7H2 crystal;

[0023] Figure 4 The present invention is Na2Mg 0.34 Zn 0.66 A schematic diagram of the theoretically calculated refractive index and birefringence of C2O7H2 crystal;

[0024] Figure 5 The present invention is Na2Mg 0.34 Zn 0.66 A schematic diagram of the theoretically calculated shortest phase-matching wavelength for C2O7H2 crystal;

[0025] Figure 6 The present invention is Na2Mg 0.34 Zn 0.66 A schematic diagram of the frequency doubling coefficients calculated theoretically for C2O7H2 crystals under different scissors operations (SO).

[0026] Figure 7 The present invention is Na2Mg 0.34 Zn 0.66 The working principle diagram of C2O7H2 crystal shows that 1 is the laser, 2 is the fundamental frequency laser beam, 3 is the convex lens, 4 is the incident laser beam, 5 is the sodium magnesium zinc hydroxy carbonate ultraviolet nonlinear optical crystal, 6 is the output frequency-doubled laser beam and the remaining fundamental frequency beam, 7 is the prism, and 8 is the output light separated from the fundamental frequency beam. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described below with reference to the accompanying drawings. These are merely examples and should not be construed as limiting the scope of protection of this invention.

[0028] Example 1: Preparation of Na₂Mg by hydrothermal crystallization 0.34 Zn 0.66 C2O7H2 crystals, including the following steps:

[0029] a. Weigh 0.561 g of MgF2, 1.227 g of ZnCl2 and 2.862 g of Na2CO3 under air conditions, put them into a polytetrafluoroethylene liner, add 5 ml of deionized water, cover the liner, and put the liner into the 304 stainless steel shell of the hydrothermal reactor and tighten it.

[0030] b. Place the hydrothermal reactor from step a into a stepped temperature-controlled forced-air drying oven, raise the temperature to 240°C at 0.5°C / min, hold for 24 hours, then lower the temperature to 220°C and hold for 24 hours, then lower the temperature to 180°C and hold for 24 hours, and finally lower to room temperature.

[0031] c. Open the polytetrafluoroethylene liner, rinse the product with deionized water, and dry the cleaned crystal product in a drying oven to obtain sodium magnesium zinc hydroxycarbonate ultraviolet nonlinear optical crystal.

[0032] Single-crystal X-ray diffraction was performed on the crystal sample. The single crystal was treated with quenching and collected at 150(2) K. The instrument used was a Bruker D8 VENTURE dual-wavelength (Mo / Cu) three-circle diffractometer equipped with a micro-focal sealed X-ray tube, a mirror monochromator, and a Bruker PHOTON III detector. The diffractometer was equipped with an Oxford Cryostream 800 cryogenic instrument and used Mo Kα radiation (λ = 0.71073 Å). All data were integrated and restored using the SAINT program and corrected for multi-scan absorption using the SADABS program. The structure was solved directly using the SHELXT program and based on the F-axis using the SHELXL-2019 / 2 program. 2 A full-matrix least squares refinement was performed, with all non-hydrogen atoms refined using anisotropic displacement parameters. All hydrogen atoms underwent free refinement, with their isotropic displacement parameters U... iso The constraint is: terminal sp 3 Carbon atom is the bonded atom U eq 1.5 times that, with the remaining carbon atoms being bonded atoms U eq 1.2 times. The disordered structural fragments were refined using bond length constraints and displacement parameter constraints. The crystallographic data of this invention has been submitted to the Cambridge Crystallographic Data Centre (CCDC), CCDC number: 2479651, containing supplemental crystallographic data for this paper. This data is freely available from the Cambridge Crystallographic Data Centre at www.ccdc.cam.ac.uk / structures. A schematic diagram of the theoretical X-ray diffraction (XRD) obtained from the crystal structure is shown below. Figure 1 As shown, a schematic diagram of the unit cell structure of the crystal is as follows. Figure 2 As shown, the structural data of the crystals prepared in Example 1 are shown in Table 1.

[0033] Table 1. Nonlinear optical crystal Na₂Mg 0.34 Zn 0.66 Crystal structure data of C2O7H2

[0034]

[0035] Example 2:

[0036] The electronic band structure, refractive index, birefringence, shortest phase-matching wavelength, and frequency doubling coefficient of the crystal obtained in Example 1 were determined through theoretical calculations. Figure 3As shown, the crystal has a wide bandgap of 5.65 eV, corresponding to an ultraviolet cutoff edge of 219.64 nm; Figure 4 As shown, the crystal exhibits a moderate birefringence (Δn), with a birefringence of approximately 0.055 at 248 nm, and good phase-matching capability in the ultraviolet region; Figure 5 As shown, the theoretical shortest phase-matching wavelength of this crystal using the birefringence phase-matching method can reach 279.56 nm; Figure 6 As shown, the range of the harmonic coefficients calculated by the crystal theory under different scissors operations (SO) is [0.88, 1.17] pm / V, which is KDP(d 36 =0.39 pm / V) is 2.25 to 3 times that of V.

[0037] Example 3:

[0038] The sodium magnesium zinc hydroxycarbonate ultraviolet nonlinear optical crystal obtained in step 1 will be used according to... Figure 7 As shown, a Q-switched Nd:YAG laser 1, positioned at position 5, is used as the input light source. A fundamental frequency laser beam 2 with an incident wavelength of 1064 nm is emitted. This beam is focused by a convex lens 3, resulting in an incident laser beam 4 that enters the sodium magnesium zinc hydroxycarbonate ultraviolet nonlinear optical crystal 5. The output wavelength is a frequency-doubled laser beam of 532 nm. This beam, along with the remaining fundamental frequency beam 6, is separated into output beam 8 by a prism 7, thus obtaining the desired frequency-doubled laser. A distinct 532 nm frequency-doubled green light output can be observed, indicating that the Na2Mg... 0.34 Zn 0.66 C2O7H2 crystals exhibit second-order nonlinear optical properties.

[0039] Example 4:

[0040] The sodium magnesium zinc hydroxycarbonate ultraviolet nonlinear optical crystal of the present invention can be used to prepare harmonic generators, frequency multipliers, optical parametric oscillators, optical parametric amplifiers, optical waveguides, and frequency up-converters / down-converters in the infrared to ultraviolet regions.

[0041] Example 5:

[0042] The sodium magnesium zinc hydroxycarbonate ultraviolet nonlinear optical crystal of the present invention is used to generate harmonic outputs with wavelengths as short as 219.64 nm.

[0043] Finally, it should be noted that the above-described embodiments are only for illustrating the technical content, objectives, and effects of the present invention, and are not intended to limit the patent scope of the present invention. Any modifications or equivalent transformations made using the present invention's specification and drawings, or direct or indirect applications in related technical fields, do not depart from the spirit and scope of the present invention's technical solution, and are similarly included within the patent protection scope of the present invention.

Claims

1. A sodium magnesium zinc hydroxycarbonate ultraviolet nonlinear optical crystal, characterized in that, The chemical formula of this crystal is Na₂Mg. 0.34 Zn 0.66 C2O7H2 belongs to the tetragonal crystal system, space group P-4 (NO.81), and is a non-centered space group; its unit cell parameters are a=7.4555(2) Å, b=7.4555(2) Å, c=5.7592(3) Å, α=β=γ=90°, Z=2, and unit cell volume V=320.12(2) Å. 3 .

2. The method for preparing a sodium magnesium zinc hydroxycarbonate ultraviolet nonlinear optical crystal according to claim 1, characterized in that, The crystal was prepared using a hydrothermal method, and the specific operation was carried out according to the following steps: a. Weigh the raw materials under air conditions, according to the molar ratio of magnesium, zinc, and sodium elements of (0.5-1):(0.5-2):(1-2), and place them in a polytetrafluoroethylene liner. Add 5-10 ml of deionized water or purified water, cover the liner, and place the liner into the 304 stainless steel shell of the hydrothermal reactor and tighten it. The magnesium compound is selected from at least one of MgF2, MgO, Mg(OH)2, and MgCO3; the zinc compound is selected from at least one of ZnCl2, ZnO, Zn(OH)2, and Zn(NO3)26H2O; and the sodium compound is selected from at least one of Na2CO3 and NaHCO3. b. Place the hydrothermal reactor from step a into a stepped temperature-controlled forced-air drying oven, raise the temperature to 240°C at 0.5°C / min, keep it at that temperature for 24 hours, then lower the temperature to 220°C and keep it at that temperature for 24 hours, then lower the temperature to 180°C and keep it at that temperature for 24 hours, and finally lower it to room temperature. c. Open the polytetrafluoroethylene liner, rinse the product with deionized water, and dry the cleaned crystal product in a drying oven to obtain sodium magnesium zinc hydroxycarbonate ultraviolet nonlinear optical crystal.

3. The sodium magnesium zinc hydroxycarbonate ultraviolet nonlinear optical crystal according to claim 1 is used to prepare ultraviolet harmonic generators, optical parametric oscillators and optical parametric amplifiers, and optical waveguide devices.

4. The use of the sodium magnesium zinc hydroxycarbonate ultraviolet nonlinear optical crystal according to claim 1, wherein the ultraviolet nonlinear optical crystal is used to generate harmonic output with a minimum wavelength of 219.64 nm.

5. The use of the sodium magnesium zinc hydroxycarbonate ultraviolet nonlinear optical crystal according to claim 1, wherein the ultraviolet nonlinear optical crystal is used to prepare ultraviolet harmonic generators, optical parametric oscillators and optical parametric amplifiers, and optical waveguide devices.

6. The application of the sodium magnesium zinc hydroxycarbonate ultraviolet nonlinear optical crystal according to claim 1 in the field of laser technology includes its use in the preparation of ultraviolet band laser frequency conversion crystals, ultraviolet lasers, ultraviolet electro-optic devices, ultraviolet communication devices, laser medicine, ultraviolet lithography devices, and ultraviolet micro-nano fabrication devices.

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