Symmetric trioxane nonlinear optical crystal as well as preparation method and application thereof

Abstract

The invention discloses a symmetric trioxane nonlinear optical crystal as well as a preparation method and application thereof. In the invention, a target crystal with a millimeter-level size is prepared by virtue of an aqueous solution cooling method, and the preparation method comprises the following steps: completely dissolving symmetric trioxane powder in water, then slowly cooling at a temperature 1-3 DEG C higher than a saturation point temperature, carrying out single crystal growth, and ending the crystal growth process when the temperature is reduced to 25 DEG C or lower, the symmetric trioxane single crystal is obtained; wherein the growth period of the crystal is 26 to 104 days. Tests show that the symmetric trioxane nonlinear optical crystal belongs to a trigonal system, the space group of the crystal is R3c, the cell parameters of the crystal are # imgabs 0 # alpha = beta = 90 degrees, gamma = 120 degrees, z = 6, the unit cell volume of the crystal is # imgabs 1 #, the ultraviolet absorption edge of the crystal can reach 155nm, and the crystal is colorless and transparent, is suitable for frequency conversion of laser output of a laser, is particularly suitable for the requirement of deep ultraviolet band laser frequency conversion, and has a wide application prospect. The material can be used for manufacturing deep ultraviolet nonlinear optical devices.

Description

Technical Field

[0001] The present invention relates to the technical field of novel optoelectronic functional materials. More specifically, it relates to a symmetric trioxane nonlinear optical crystal, a preparation method thereof, and an application thereof. Background Art

[0002] With the rapid development of scientific research and modern instruments such as micro-nano fine laser processing, ultra-high resolution photoelectron spectrometers, and photoelectron emission microscopes, the demand for deep ultraviolet coherent light sources (wavelength less than 200 nm) has become increasingly urgent. Currently, the means to generate deep ultraviolet lasers mainly rely on synchrotron radiation light sources and excimer lasers, but both of these methods have disadvantages such as poor beam monochromaticity and relatively wide linewidths, and the optical parameters cannot meet the requirements of precision instruments. Therefore, since the 1990s, how to obtain a deep ultraviolet coherent light source with high beam quality and narrow linewidth has become the primary task that scientists need to solve.

[0003] In recent years, solid-state lasers have become a research hotspot in the field of laser technology due to their advantages such as good beam quality, good coherence, and compact structure. However, due to the limitations of the matrix crystals in the lasers by the energy levels of the activated ions, it is currently very difficult for solid-state lasers to directly generate deep ultraviolet lasers. Currently, relying on nonlinear optical crystals to perform multi-stage frequency conversion on the lasers generated by near-infrared fundamental light sources such as Nd:YAG and Nd:YVO 4 etc. is still the main way for solid-state lasers to generate deep ultraviolet lasers, but the high number of frequency conversion times severely limits the conversion efficiency. With the development of nonlinear optical crystals and the development of two nonlinear optical crystals, namely KBe 2 BO 3 F 2 (KBBF) and Sr 2 Be 2 B 2 O 7 (SBBO), it has become possible to achieve the output of deep ultraviolet coherent light through direct frequency doubling technology. However, due to problems such as difficult crystal growth and structural polymorphism, it has not been widely used. Therefore, the research and development of practical deep ultraviolet nonlinear optical crystals play an important role in promoting academic progress and industrial technology development in related fields.

[0004] Symmetrical trioxane nonlinear optical crystals have shown broad application prospects in many fields due to their unique properties. In optics, symmetrical trioxane nonlinear optical crystals are high-quality raw materials for manufacturing optical lenses. They have good refraction and transmission properties for light, can accurately focus and disperse light, and are widely used in the manufacture of camera lenses, microscope eyepieces, and astronomical telescope lenses. However, since the symmetrical trioxane prepared at present is usually a uniaxial crystal, it is limited by the crystal size and crystal structure, and there are no reports on the use of symmetrical trioxane single crystals for the production of nonlinear optical devices. Summary of the invention

[0005] To solve the above problems, the first object of the present invention is to provide a method for preparing a symmetrical trioxane nonlinear optical crystal.

[0006] The second object of the present invention is to provide a symmetrical trioxane nonlinear optical crystal prepared by the preparation method as described above.

[0007] The third object of the present invention is to provide a symmetrical trioxane nonlinear optical crystal for use as an ultraviolet nonlinear optical crystal in the preparation of nonlinear optical devices.

[0008] In order to achieve the above first object, the present invention adopts the following technical scheme:

[0009] The present invention discloses a method for preparing a symmetrical trioxane nonlinear optical crystal, comprising the following steps:

[0010] The symmetrical trioxane powder is completely dissolved in water, and then the temperature is slowly lowered from 1-3°C above the saturation point temperature to grow a single crystal. The crystal growth process ends when the temperature drops below 25°C to obtain the symmetrical trioxane single crystal.

[0011] Among them, the crystal growth process is carried out in a crystal growth device, and the cooling rate is controlled by means of a high-precision temperature controller in the crystal growth device. The cooling rate is controlled by setting the time from the starting temperature to the end temperature. It is generally believed that the cooling process is uniform under the control of the equipment.

[0012] Further, the symmetric trioxane powder and water are formulated into a solution of the crystallization system according to their mass-volume ratio of (100-120) g: 500 mL. Exemplarily, the mass-volume ratio can be 100 g: 500 mL, 101 g: 500 mL, 102 g: 500 mL, 103 g: 500 mL, 104 g: 500 mL, 105 g: 500 mL, 106 g: 500 mL, 107 g: 500 mL, 108 g: 500 mL, 109 g: 500 mL, 110 g: 500 mL, 111 g: 500 mL, 112 g: 500 mL, 113 g: 500 mL, 114 g: 500 mL, 115 g: 500 mL, 116 g: 500 mL, 117 g: 500 mL, 118 g: 500 mL, 119 g: 500 mL, 120 g: 500 mL, etc. When the concentration of the crystallization system solution is different, its saturation point temperature is slightly different. Under the above mass-volume ratio relationship, the saturation point temperature is between 30-35 °C.

[0013] Generally, when the temperature drops below 25 °C, it is considered that the crystal growth is basically completed. In a specific embodiment, the crystal growth period is 26-104 days.

[0014] Further, the size range of the symmetric trioxane single crystal is in the millimeter level. The so-called "millimeter level" means that the length of any side of the crystal reaches at least 1 mm or more, such as 1 mm - 20 mm, such as 1 mm, 2 mm, 3 mm, 5 mm, 8 mm, 10 mm, 11 mm, 12 mm, 13 mm, 14 mm, 15 mm, 17 mm, 20 mm or any value between the two listed data.

[0015] To achieve the above second object, the present invention adopts the following technical solution:

[0016] The present invention discloses a symmetric trioxane nonlinear optical crystal prepared by the preparation method as described above.

[0017] Further, the chemical formula of the symmetric trioxane nonlinear optical crystal is C 3 H 6 O 3 , belonging to the trigonal crystal system, its space group is R3c, and its unit cell parameters are: α = β = 90°, γ = 120°, z = 6, and the unit cell volume is

[0018] Further, the symmetric trioxane nonlinear optical crystal is a colorless transparent crystal, its input wavelength range is 355-1064 nm, and its output wavelength range is 177-532 nm.

[0019] Further, the ultraviolet absorption edge of the symmetric trioxane nonlinear optical crystal is 155 ± 3 nm, for example, 155 nm.

[0020] Further, the symmetric trioxane nonlinear optical crystal can achieve second harmonic generation or fourth harmonic generation output of Nd:YAG (λ = 1.064 μm).

[0021] Further, the powder second harmonic generation effect of the symmetric trioxane nonlinear optical crystal is 3.0 times that of KH 2 PO 4 (KDP) and 0.7 times that of BaB 2 O 4 (BBO).

[0022] Further, the size of the symmetric trioxane nonlinear optical crystal is between (1 - 20) mm × (2 - 4) mm × (1 - 4) mm.

[0023] To achieve the above third object, the present invention adopts the following technical solution:

[0024] The present invention discloses the application of the symmetric trioxane nonlinear optical crystal as described above as an ultraviolet nonlinear optical crystal in the preparation of nonlinear optical devices, preferably the application of the symmetric trioxane nonlinear optical crystal as described above as an ultraviolet nonlinear optical crystal in the preparation of nonlinear optical devices.

[0025] Further, the nonlinear optical device is one of a frequency conversion optical device, a harmonic generator in the ultraviolet region, an optical parametric device, an optical amplification device, and an optical waveguide device.

[0026] Further, the nonlinear optical device includes a device that generates at least one output radiation with a frequency different from the incident electromagnetic radiation after passing at least one incident electromagnetic radiation through at least one nonlinear optical crystal, wherein the nonlinear optical crystal is selected from the symmetric trioxane nonlinear optical crystal as described above.

[0027] Further, the wavelength range of the incident electromagnetic radiation is 355 nm - 1064 nm, for example, 2 times, 3 times, or 4 times the wavelength of the output radiation.

[0028] Further, the wavelength range of the output radiation is 177.5 nm - 532 nm.

[0029] Further, the nonlinear optical device is an optical parametric device and can generate an optical output with a wavelength of 177 to 532 nm.

[0030] Further, the nonlinear optical device includes a device that passes at least one output incident electromagnetic radiation with a wavelength of 532 nm through at least one of the symmetric trioxane nonlinear optical crystals to generate at least one output radiation of second harmonic generation ultraviolet light with a wavelength of 266 nm.

[0031] Further, the nonlinear optical device includes a device that passes at least one output incident electromagnetic radiation with a wavelength of 355 nm through at least one of the symmetric trioxane nonlinear optical crystals to generate at least one output radiation of second harmonic generation deep ultraviolet light with a wavelength of 177.3 nm.

[0032] The beneficial effects of the present invention are as follows:

[0033] The present invention provides a symmetric trioxane nonlinear optical crystal, a preparation method thereof, and an application thereof, especially an application in a deep ultraviolet nonlinear optical device. In this preparation method, the present invention precisely controls the cooling rate of the aqueous solution cooling method by using a temperature control device produced by Fuzhou Kelsi Experimental Equipment Co., Ltd., and controls the concentration of the crystallization system to prepare a symmetric trioxane single crystal in a growth device. The size of the obtained symmetric trioxane single crystal has reached the millimeter level, meeting the requirements of physical property testing, and providing feasibility for further studying the properties and applications of this crystal. The powder second harmonic generation test method was used to measure the phase matching ability of the C 3 H 6 O 3 single crystal. The test results prove that the C 3 H 6 O 3 single crystal can achieve second harmonic generation or fourth harmonic generation output of Nd:YAG (λ = 1.064 μm), and its powder second harmonic generation effect is 3.0 times that of KH 2 PO 4 (KDP) and 0.7 times that of BaB 2 O 4 (BBO). In addition, the ultraviolet absorption edge of the C 3 H 6 O 3 crystal of the present invention can reach 155 nm. The crystal is colorless and transparent, suitable for frequency conversion of laser output of a laser, especially suitable for the needs of laser frequency conversion in the deep ultraviolet band, and can be used to make a deep ultraviolet nonlinear optical device. It is found that at room temperature, using the third harmonic generation second harmonic generation light of a Q-switched Nd:YAG laser as the input light source, with an incident wavelength of 355 nm, the incident laser beam with a wavelength of 355 nm emitted by the third harmonic generation second harmonic generation light of the Q-switched Nd:YAG laser is incident on the C 3 H 6 O 3 single crystal, and obvious output of second harmonic generation deep ultraviolet light with a wavelength of 177.3 nm can be generated, greatly broadening the types of crystals applicable to the preparation of deep ultraviolet nonlinear optical devices. Description of the Drawings

[0034] The following further elaborates on the specific embodiments of the present invention in conjunction with the drawings.

[0035] Figure 1 Photograph of the C 3 H 6 O 3 single crystal prepared in Example 1.

[0036] Figure 2 Schematic diagram of the C 3 H 6 O 3 crystal unit cell structure of the present invention.

[0037] Figure 3 Diffraction pattern of the C 3 H 6 O 3 single crystal ground into powder prepared in Example 1.

[0038] Figure 4 Schematic diagram showing the non-linear optical device of the present invention, where 1 - Nd:YAG laser, 2 - incident laser beam, 3 - frequency doubling crystal, 4 - outgoing laser beam, 5 - filter. Specific Embodiments

[0039] To more clearly illustrate the present invention, the following further describes the present invention in conjunction with preferred embodiments and the drawings. Similar components in the drawings are denoted by the same reference numerals. Those skilled in the art should understand that the content specifically described below is illustrative rather than restrictive, and should not be used to limit the protection scope of the present invention.

[0040] Unless otherwise specified, the raw materials and reagents used in the following examples are all commercially available products or can be prepared by known methods.

[0041] Example 1

[0042] The C 3 H 6 O 3 single crystal was prepared by the aqueous solution cooling method. The specific operating steps of the preparation method are as follows:

[0043] After weighing 110.5 g of the symmetric trioxane powder sample (manufacturer: Adamas, purity 99%) in the operating box, it was poured into the crystal growth device. The water bath temperature was slowly raised to 35°C, and 500 ml of deionized water was added thereto. After the powder sample was completely dissolved, the temperature was slowly decreased. After 70 days, the temperature was decreased to 25°C to end the crystal formation process, and the C Figure 1The shown crystal can produce multiple symmetric trioxane nonlinear optical crystals in the entire growth device, with their sizes ranging from 1 to 13 millimeters, and the maximum crystal size obtained being 13 mm × 4 mm × 3 mm. From Figure 1 it can be seen that the C 3 H 6 O 3 crystal prepared by the present invention is a colorless and transparent crystal.

[0044] Figure 2 shows the schematic diagram of the unit cell structure of the C 3 H 6 O 3 crystal of the present invention.

[0045] The C 3 H 6 O 3 crystal obtained in this example has an X-ray powder diffraction pattern as Figure 3 shown. From Figure 3 it can be known that the C 3 H 6 O 3 crystal obtained in this example is a single crystal of a single pure phase. This crystal does not have a center of symmetry, belongs to the trigonal crystal system, its space group is R3c, and its unit cell parameters are: α = β = 90°, γ = 120°, z = 6, and the unit cell volume is

[0046] The structures of the nonlinear optical devices in Application Examples 1 - 3 below are as Figure 4 shown, where the Nd:YAG laser 1 emits an incident laser beam 2, which passes through the frequency doubling crystal 3 to generate at least one outgoing laser beam 4 with a frequency different from that of the incident laser beam, and is output through the filter 5.

[0047] Example 2

[0048] The C 3 H 6 O 3 single crystal is prepared by the aqueous solution cooling method, and the specific operation steps of the preparation method are as follows:

[0049] After weighing 120 g of the symmetric trioxane powder sample (manufacturer: Adamas, purity 99%) in the operating box, pour it into the crystal growth device, slowly raise the water bath temperature to 35°C, add 500 ml of deionized water to it, and after the powder sample is completely dissolved, start to slowly cool down. After 52 days, the temperature drops to 25°C to end the crystal formation process. Multiple symmetric trioxane crystals can be produced in the entire growth device, with their sizes ranging from 1 to 10 millimeters, and the maximum crystal size obtained being 10 mm × 4 mm × 3 mm.

[0050] Example 3

[0051] Prepare C 3 H 6 O 3 single crystal by the method of cooling the aqueous solution. The specific operation steps of the preparation method are as follows:

[0052] After weighing 100 g of symmetric trioxane powder sample (manufacturer: Adamas, purity 99%) in the operating box, pour it into the crystal growth device. Slowly raise the water bath temperature to 30 °C, add 500 ml of deionized water to it. After the powder sample is completely dissolved, start to slowly cool down. After 104 days, the temperature drops to 25 °C to end the crystal formation process. Multiple symmetric trioxane crystals can be produced in the entire growth device, and their sizes are between 5 and 20 mm. The largest crystal size obtained is 20 mm × 4 mm × 4 mm.

[0053] Application Example 1

[0054] Take the C 3 H 6 O 3 single crystal prepared in Example 1, process, cut, orient, and polish it according to the matching direction to obtain a single crystal with a size of 3 mm × 3 mm × 2 mm as the Figure 4 second harmonic generation crystal in the optical device shown.

[0055] At room temperature, use a Q-switched Nd:YAG laser as the input light source, the incident wavelength is 1064 nm, and the incident laser beam 2 with a wavelength of 1064 nm emitted by the Q-switched Nd:YAG laser 1 is incident on C 3 H 6 O 3 single crystal 3, generating an obvious second harmonic generation green light output with a wavelength of 532 nm. The output intensity of the C 3 H 6 O 3 single crystal is about 3.0 times that of KDP under the same conditions.

[0056] Application Example 2

[0057] Take the C 3 H 6 O 3 single crystal prepared in Example 1, process, cut, orient, and polish it according to the matching direction to obtain a single crystal with a size of 3 mm × 3 mm × 2 mm as the Figure 4 second harmonic generation crystal in the optical device shown.

[0058] At room temperature, use the second harmonic generation light of a Q-switched Nd:YAG laser as the input light source, the incident wavelength is 532 nm, and the incident laser beam 2 with a wavelength of 532 nm emitted by the second harmonic generation light 1 of the Q-switched Nd:YAG laser is incident on C 3 H6 O 3 Single crystal 3 generates obvious second harmonic green light output with a wavelength of 266 nm, C 3 H 6 O 3 The output intensity of the single crystal is about 0.7 times that of BBO under the same conditions.

[0059] Application Example 3

[0060] Take the C prepared in Example 1 3 H 6 O 3 Single crystal, which is processed, cut, oriented and polished according to the matching direction to obtain a single crystal with dimensions of 3 mm × 3 mm × 2 mm, as Figure 4 The second harmonic crystal in the optical device shown.

[0061] At room temperature, the third harmonic second harmonic light of a Q-switched Nd:YAG laser is used as the input light source, the incident wavelength is 355 nm, and the incident laser beam 2 with a wavelength of 355 nm emitted by the third harmonic second harmonic light 1 of the Q-switched Nd:YAG laser is incident on C 3 H 6 O 3 Single crystal 3 generates obvious second harmonic deep ultraviolet light output with a wavelength of 177.3 nm.

[0062] Therefore, the C prepared by the present invention 3 H 6 O 3 Single crystal is suitable for frequency conversion of laser output of lasers, especially for the need of laser frequency conversion in the deep ultraviolet band, and can be used to manufacture deep ultraviolet nonlinear optical devices.

[0063] Obviously, the above embodiments of the present invention are only examples for clearly explaining the present invention, and are not limitations on the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or variations can be made based on the above description. It is impossible to list all the implementation manners here. Any obvious changes or variations derived from the technical solutions of the present invention still fall within the protection scope of the present invention.

Claims

1. A method for preparing a symmetrical trioxane nonlinear optical crystal, characterized in that: The steps include: The symmetrical trioxane powder is completely dissolved in water, and then the temperature is slowly lowered from 1-3°C above the saturation point temperature to grow a single crystal. The crystal growth process ends when the temperature drops below 25°C, thereby obtaining the symmetrical trioxane single crystal; Wherein, the crystal growth period is 26-104 days.

2. The preparation method according to claim 1, characterized in that: The mass volume ratio of the symmetrical trioxane powder and water is (100-120) g:500 mL.

3. The preparation method according to claim 2, characterized in that: The saturation point temperature is 30-35°C.

4. Symmetric trioxane nonlinear optical crystal, characterized in that: The preparation method is described in any one of claims 1 to 3.

5. The symmetrical trioxane nonlinear optical crystal according to claim 4, characterized in that: The chemical formula of the symmetrical trioxane nonlinear optical crystal is C3H6O3, which belongs to the trigonal crystal system, its space group is R3c, and its unit cell parameters are: α=β=90°,γ=120°,z=6,the unit cell volume is 6. The symmetrical trioxane nonlinear optical crystal according to claim 4, characterized in that: The input wavelength range of the symmetrical trioxane nonlinear optical crystal is 355-1064 nm, and the output wavelength range is 177-532 nm.

7. The symmetrical trioxane nonlinear optical crystal according to claim 4, characterized in that: The ultraviolet absorption edge of the symmetrical trioxane nonlinear optical crystal is 155±3nm.

8. The symmetrical trioxane nonlinear optical crystal according to claim 4, characterized in that: The size of the symmetrical trioxane nonlinear optical crystal is between (1-20) mm×(2-4) mm×(1-4) mm.

9. Use of the symmetrical trioxane nonlinear optical crystal as claimed in any one of claims 4 to 8 as an ultraviolet nonlinear optical crystal in the preparation of nonlinear optical devices.

10. The use according to claim 9, characterized in that: The nonlinear optical device comprises a device for generating at least one beam of output radiation having a frequency different from that of the incident electromagnetic radiation after at least one beam of incident electromagnetic radiation passes through at least one nonlinear optical crystal, wherein the nonlinear optical crystal is selected from the symmetrical trioxane nonlinear optical crystal described in any one of claims 4 to 8.

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