Borate crystal, application of borate crystal as acousto-optic medium and acousto-optic device

Abstract

The embodiment of the invention discloses a borate crystal, application of the borate crystal as an acousto-optic medium and an acousto-optic device. In a specific embodiment, the chemical formula of the crystal is Ba3M (B3O6) 3, and M is one of Lu, Gd, Bi, Y and In. The borate crystal Ba3M (B3O6) 3 prepared by the embodiment not only can penetrate to a deep ultraviolet region, but also has a quite large elasto-optical coefficient, and the mechanical and optical properties of the borate crystal have high anisotropy, so that the propagation speed of sound waves in the c-axis direction of the borate crystal is slower, and compared with other crystals, the borate crystal also has quite large refractive index, and the refractive index of the borate crystal Ba3M (B3O6) 3 is greatly improved. The acousto-optic conversion efficiency of the acousto-optic device can be greatly improved, and the power of a driving power supply and the heating condition of the device are effectively reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of acousto-optic crystal materials. More specifically, it relates to borate crystals, their application as acousto-optic media, and acousto-optic devices. Background Art

[0002] Currently, most acousto-optic media are prepared from acousto-optic crystals. When light passes through an acousto-optic crystal, the acousto-optic effect occurs. The acousto-optic effect is the phenomenon that the refractive index of the medium is changed by ultrasonic waves, forming a distribution that varies periodically with time and space, equivalent to a phase grating. When the incident laser passes through the medium modulated by ultrasonic waves, diffraction occurs, and the frequency, intensity, direction, etc. of the diffracted laser will change with the change of ultrasonic waves. This phenomenon is called the acousto-optic effect. Under the action of sound waves, the acousto-optic medium deflects the propagation direction of the light beam, and the sound wave can be used to modulate the intensity and frequency of the light beam. Using the acousto-optic effect to control laser beams has wide applications in laser modulation, such as in optical modulators, beam deflection, optical information processing, and spectrum analysis. For acousto-optic materials, the figure of merit characterizing the acousto-optic coupling strength is usually related to the following parameters: the refractive index of the acousto-optic medium for light waves, the effective elasto-optic coefficient, the density of the acousto-optic medium, and the propagation speed of sound waves along a specific direction of the acousto-optic medium. Among them, the commonly used figure of merit is proportional to the seventh or sixth power of the refractive index, and the figure of merit will decrease sharply with the decrease of the refractive index of the acousto-optic medium.

[0003] However, the acousto-optic media in the prior art require high-power driving, generate a lot of heat and need to be cooled additionally, which seriously affects the use of the acousto-optic media. Summary of the Invention

[0004] The purpose of the present invention is to provide borate crystals, their application as acousto-optic media, and acousto-optic devices to solve at least one of the problems existing in the prior art.

[0005] To achieve the above purpose, the present invention adopts the following technical solutions:

[0006] The first purpose of the present invention is to provide a borate crystal;

[0007] The second purpose of the present invention is to provide a preparation method of a borate crystal;

[0008] The third purpose of the present invention is to provide an application of a borate crystal as an acousto-optic medium;

[0009] The fourth purpose of the present invention is to provide an acousto-optic device including the borate crystal described in any item of the first aspect;

[0010] The borate crystal Ba3M(B3O6)3 (M = Lu, Gd, Bi, Y, In) can transmit light up to the deep ultraviolet region. It has a relatively large elasto-optic coefficient, a slow sound wave propagation speed in the c-axis direction of this type of crystal, and a relatively large refractive index. Therefore, using this borate crystal as the acousto-optic medium in an acousto-optic device and applying it to an acousto-optic device with ultraviolet light as the corresponding light wave will greatly improve the acousto-optic conversion efficiency of the acousto-optic device, effectively reducing the driving power supply power and device heating of the acousto-optic device.

[0011] A borate crystal with the chemical formula Ba3M(B3O6)3, which has a centrosymmetric structure, belongs to the hexagonal crystal system, and has a space group of P63 / m(176), where M is one of Lu, Gd, Bi, Y, and In;

[0012] The unit cell parameters are α = β = 120°, γ = 90°, Z = 2,

[0013] Specifically, the elasto-optic coefficient of the crystal is 0.30 - 0.45; the refractive index of the crystal is 0.12 - 0.15.

[0014] A preparation method of the borate crystal as described in the first aspect,

[0015] The borate crystal is grown by the Czochralski method or the flux method,

[0016] The growth of the borate crystal by the Czochralski method includes the following steps,

[0017] Mix the Ba compound, M compound, and B compound evenly according to the molar ratio Ba:M:B = 6:1:18;

[0018] Heat to 500 - 600 °C, keep warm for 20 - 40 h, cool and grind, then heat to 1050 - 1150 °C again for material melting to obtain a mixed melt, add a seed rod with a bound seed crystal, and grow at a lifting speed of 0.03 - 0.06 cm / h;

[0019] Cool to obtain the borate crystal;

[0020] The growth of the borate crystal by the flux method includes the following steps,

[0021] Mix the Ba compound, M compound, and B compound evenly according to the molar ratio Ba:M:B = 6:1:18;

[0022] Heat to 500 - 600 °C, keep warm for 20 - 40 h, cool and grind, then heat to 750 - 850 °C again for sintering, keep warm for 20 - 30 h, to obtain polycrystalline powder of pure-phase compound Ba3M(B3O6)3;

[0023] The obtained polycrystalline powder of the compound Ba3M(B3O6)3 is uniformly mixed with a flux system in a molar ratio of 1:1 - 3 to obtain a crystal growth material;

[0024] The crystal growth material is heated until it completely melts and stirred evenly, cooled to the solution saturation point at a rate of 20 - 50 °C / d, a seed crystal is inserted, and crystal rotation is started, and the crystal is grown by cooling at a rate of 0.01 - 5 °C / h;

[0025] Cooling to obtain a borate crystal;

[0026] Wherein the Ba-containing compound is selected from one or more of BaCO3, BaO, and BaF2;

[0027] The B-containing compound is selected from one or more of H3BO3 and B2O3.

[0028] The flux is selected from one or more of BaCO3 and BaF2, or one or more of BaF2 and H3BO3.

[0029] It should be noted that when the flux includes two or more compounds, the molar amount of the flux refers to the sum of the molar amounts of all compounds in the flux.

[0030] An application of a borate crystal as described in any one of the first aspects as an acousto-optic medium.

[0031] An acousto-optic device includes a borate crystal as described in any one of the first aspects. An acoustic wave with a set frequency is incident along the c-axis direction of the crystal, and a laser is incident at an angle of α with respect to the b-axis of the crystal, causing the crystal to emit diffraction fringes, where the value range of α is 0° - 2°.

[0032] Preferably, the laser is selected from ultraviolet light, visible light, or infrared light, and preferably, the laser wavelength is less than 200 nm.

[0033] Preferably, the frequency of the acoustic wave is greater than 1 GHz.

[0034] Preferably, the acousto-optic device is one of an acousto-optic modulator, an acousto-optic deflector, an acousto-optic filter, an acousto-optic spectrum analyzer, an acousto-optic photodetector, and an acousto-optic fiber sensor.

[0035] The beneficial effects of the present invention are as follows:

[0036] The borate compounds prepared by the prior art are often in powder form, while the present invention can grow borate crystals by the Czochralski method or the flux method.

[0037] The borate crystals Ba3M(B3O6)3 (M = Lu, Gd, Bi, Y, In) prepared by the present invention can not only transmit light up to the deep ultraviolet region, but also have a relatively large elasto-optic coefficient, and their mechanical and optical properties are highly anisotropic. As a result, the propagation speed of sound waves in the c-axis direction of such crystals is relatively slow. Compared with other crystals, they also have a relatively large refractive index (0.12 - 0.15). If such crystals are used to make the acousto-optic medium in acousto-optic devices, their figure of merit can reach 6 - 10.3. Particularly importantly, the figure of merit characterizing the acousto-optic diffraction efficiency is nearly 5 times higher than that of fused quartz. Therefore, using this borate crystal as the acousto-optic medium in acousto-optic devices corresponding to ultraviolet light will greatly improve the acousto-optic conversion efficiency of the acousto-optic device, effectively reducing the driving power supply power and the device heating situation. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The following further describes in detail the specific embodiments of the present invention with reference to the drawings.

[0039] Figure 1 The structural schematic diagram of the acousto-optic device provided by an embodiment of the present invention is shown.

[0040] Figure 2 The three-dimensional structural schematic diagram of the incident laser and sound waves on the acousto-optic medium provided by an embodiment of the present invention is shown.

[0041] Figure 3 The acousto-optic modulation spectrogram of the acousto-optic medium provided by an embodiment of the present invention is shown. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0042] To more clearly illustrate the present invention, the present invention will be further described below in conjunction with 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 specific content described below is illustrative rather than restrictive, and should not be used to limit the protection scope of the present invention.

[0043] Example 1

[0044] Growing the borate crystal by the Czochralski method includes the following steps: uniformly mixing a BaCO3 compound, a Lu2O3 compound, and an H3BO3 compound in a molar ratio of Ba:Lu:B = 6:1:18;

[0045] Heating to 500 °C for sintering, holding for 24 h, cooling and grinding, then heating to 1100 °C again for material melting, adding a seed rod for binding the seed crystal, and growing at a lifting speed of 0.05 cm / h, with a growth period of 20 - 30 days.

[0046] After cooling, the Ba3Lu(B3O6)3 crystal is obtained.

[0047] The crystal has a centrosymmetric structure, belongs to the hexagonal crystal system, and has a space group of P63 / m(176);

[0048] The unit cell parameters are α = β = 120°, γ = 90°, Z = 2.

[0049] Example 2

[0050] Growing the borate crystal by the Czochralski method includes the following steps: Mixing a BaCO3 compound, a Gd2O3 compound, and an H3BO3 compound evenly in a molar ratio of Ba:Gd:B = 6:1:18;

[0051] Heating to 550 °C for sintering, holding for 20 h, cooling and grinding, then heating to 1150 °C again for material melting, adding a seed rod with a bonded seed crystal, and growing at a lifting speed of 0.06 cm / h, with a growth period of 20 - 30 days.

[0052] The obtained crystal after cooling is the Ba3Gd(B3O6)3 crystal.

[0053] The crystal has a centrosymmetric structure, belongs to the hexagonal crystal system, and has a space group of P63 / m(176); The unit cell parameters are α = β = 120°, γ = 90°, Z = 2.

[0054] Example 3

[0055] Growing the borate crystal by the Czochralski method includes the following steps: Mixing a BaCO3 compound, a Bi2O3 compound, and an H3BO3 compound evenly in a molar ratio of Ba:Bi:B = 6:1:18;

[0056] Heating to 600 °C for sintering, holding for 30 h, cooling and grinding, then heating to 1050 °C again for material melting, adding a seed rod with a bonded seed crystal, and growing at a lifting speed of 0.03 cm / h, with a growth period of 20 - 30 days.

[0057] The obtained crystal after cooling is the Ba3Bi(B3O6)3 crystal.

[0058] The crystal has a centrosymmetric structure, belongs to the hexagonal crystal system, and has a space group of P63 / m(176); The unit cell parameters are α = β = 120°, γ = 90°, Z = 2.

[0059] Example 4

[0060] Growing borate crystals by the Czochralski method includes the following steps: Mixing a BaCO3 compound, a Y2O3 compound, and an H3BO3 compound evenly in a molar ratio of Ba:Y:B = 6:1:18;

[0061] Heating to 500 °C for sintering, holding for 40 h, cooling and grinding, then heating to 1100 °C again for material melting, adding a seed rod with a bonded seed crystal, and growing at a lifting speed of 0.04 cm / h for a growth period of 20 - 30 days.

[0062] The crystal obtained after cooling is the Ba3Y(B3O6)3 crystal.

[0063] This crystal has a centrosymmetric structure, belongs to the hexagonal crystal system, and the space group is P63 / m(176);

[0064] The unit cell parameters are α = β = 120°, γ = 90°, Z = 2.

[0065] Example 5

[0066] Growing borate crystals by the Czochralski method includes the following steps: Mixing a BaCO3 compound, an In2O3 compound, and an H3BO3 compound evenly in a molar ratio of Ba:In:B = 6:1:18;

[0067] Heating to 580 °C for sintering, holding for 24 h, cooling and grinding, then heating to 1100 °C again for material melting, adding a seed rod with a bonded seed crystal, and growing at a lifting speed of 0.04 cm / h for a growth period of 20 - 30 days.

[0068] The crystal obtained after cooling is the Ba3In(B3O6)3 crystal.

[0069] This crystal has a centrosymmetric structure, belongs to the hexagonal crystal system, and the space group is P63 / m(176);

[0070] The unit cell parameters are α = β = 120°, γ = 90°, Z = 2.

[0071] Example 6

[0072] The growth of borate crystals by the flux method includes the following steps

[0073] Mixing a BaCO3 compound, a Lu2O3 compound, and an H3BO3 compound evenly in a molar ratio of Ba:Lu:B = 6:1:18;

[0074] Heat to 500 °C for sintering, hold for 20 h, cool and grind, then heat to 750 °C again for sintering, hold for 24 h to obtain polycrystalline powder of pure-phase compound Ba3M(B3O6)3;

[0075] Mix the obtained polycrystalline powder of compound Ba3Lu(B3O6)3 with the flux system in a molar ratio of 1:1 - 3 and mix evenly to obtain crystal growth material;

[0076] Heat the crystal growth material until it completely melts and stir evenly, cool to the solution saturation point at a rate of 20 °C / d, lower the seed crystal and start crystal rotation, and cool at a rate of 2 °C / h to promote crystal growth; the growth period is 50 - 100 days, and after cooling, Ba3Lu(B3O6)3 crystal is obtained.

[0077] This crystal has a centrosymmetric structure, belongs to the hexagonal crystal system, and the space group is P63 / m(176);

[0078] The unit cell parameters are α = β = 120°, γ = 90°, Z = 2.

[0079] Example 7

[0080] The growth of borate crystal by the flux method includes the following steps,

[0081] Mix the BaCO3 compound, the compound containing Gd2O3 and the compound containing H3BO3 evenly in a molar ratio of Ba:Gd:B = 6:1:18;

[0082] Heat to 550 °C for sintering, hold for 24 h, cool and grind, then heat to 750 °C again for sintering, hold for 24 h to obtain polycrystalline powder of pure-phase compound Ba3Gd(B3O6)3;

[0083] Mix the obtained polycrystalline powder of compound Ba3Gd(B3O6)3 with the flux system in a molar ratio of 1:1 - 3 and mix evenly to obtain crystal growth material;

[0084] Heat the crystal growth material until it completely melts and stir evenly, cool to the solution saturation point at a rate of 20 °C / d, lower the seed crystal and start crystal rotation, and cool at a rate of 5 °C / h to promote crystal growth; the growth period is 50 - 100 days, and after cooling, Ba3Gd(B3O6)3 crystal is obtained.

[0085] This crystal has a centrosymmetric structure, belongs to the hexagonal crystal system, and the space group is P63 / m(176); the unit cell parameters are α = β = 120°, γ = 90°, Z = 2.

[0086] Example 8

[0087] The flux method for growing borate crystals includes the following steps:

[0088] Mix the BaCO3 compound, the Bi2O3-containing compound, and the H3BO3-containing compound evenly in a molar ratio of Ba:Bi:B = 6:1:18;

[0089] Heat to 600 °C for sintering, hold for 30 h, cool and grind, then heat to 800 °C again for sintering, hold for 24 h, to obtain the pure-phase compound Ba3Bi(B3O6)3 polycrystalline powder;

[0090] Mix the obtained Ba3Bi(B3O6)3 polycrystalline powder with the flux system in a molar ratio of 1:1 - 3 evenly to obtain the crystal growth material;

[0091] Heat the crystal growth material until it melts completely and stir evenly, cool to the solution saturation point at a rate of 50 °C / day, lower the seed crystal and start crystal rotation, and cool at a rate of 3 °C / h to promote crystal growth; the growth period is 50 - 100 days, and after cooling, the Ba3Bi(B3O6)3 crystal is obtained.

[0092] This crystal has a centrosymmetric structure, belongs to the hexagonal crystal system, and the space group is P63 / m(176); the unit cell parameters are α = β = 120°, γ = 90°, Z = 2.

[0093] Example 9

[0094] The flux method for growing borate crystals includes the following steps:

[0095] Mix the BaCO3-containing compound, the Y2O3-containing compound, and the H3BO3-containing compound evenly in a molar ratio of Ba:Y:B = 6:1:18;

[0096] Heat to 500 °C for sintering, hold for 40 h, cool and grind, then heat to 850 °C again for sintering, hold for 30 h, to obtain the pure-phase compound Ba3Y(B3O6)3 polycrystalline powder;

[0097] Mix the obtained Ba3Y(B3O6)3 polycrystalline powder with the flux system in a molar ratio of 1:1 - 3 evenly to obtain the crystal growth material;

[0098] Heat the crystal growth material until it melts completely and stir evenly, cool to the solution saturation point at a rate of 30 °C / day, lower the seed crystal and start crystal rotation, and cool at a rate of 3 °C / h to promote crystal growth; the growth period is 50 - 100 days, and after cooling, the Ba3Y(B3O6)3 crystal is obtained.

[0099] This crystal has a centrosymmetric structure, belongs to the hexagonal crystal system, and the space group is P63 / m(176);

[0100] The unit cell parameters are α = β = 120°, γ = 90°, Z = 2.

[0101] Example 10

[0102] The growth of borate crystals by the flux method comprises the following steps:

[0103] Mix a BaCO3 compound, an In2O3 compound, and an H3BO3 compound uniformly in a molar ratio of Ba:In:B = 6:1:18;

[0104] Heat to 500 °C for sintering, hold for 24 h, cool and grind, then heat to 750 °C again for sintering, hold for 20 h to obtain polycrystalline powder of pure-phase compound Ba3In(B3O6)3;

[0105] Mix the obtained polycrystalline powder of compound Ba3In(B3O6)3 with the flux system in a molar ratio of 1:1 - 3 uniformly to obtain a crystal growth material;

[0106] Heat the crystal growth material until it is completely melted and stir evenly, cool to the solution saturation point at a rate of 20 °C / d, lower the seed crystal and start crystal rotation, and cool at a rate of 0.05 °C / h to promote crystal growth; the growth period is 50 - 100 days, and Ba3In(B3O6)3 crystals are obtained after cooling.

[0107] This crystal has a centrosymmetric structure, belongs to the hexagonal crystal system, and the space group is P63 / m (176);

[0108] The unit cell parameters are α = β = 120°, γ = 90°, Z = 2.

[0109] In Examples 1 to 10, the Ba compound can also be selected from one or more of BaCO3, BaO, and BaF2; the B compound can also be selected from one or more of H3BO3 and B2O3.

[0110] Example 11

[0111] Acousto-optic devices have very wide applications in many fields of science, engineering, and technology. For the acousto-optic medium 1 in acousto-optic devices, the quality factor is an important parameter characterizing the acousto-optic interaction of the acousto-optic medium 1. Currently, the quality factor directly related to the driving source power of acousto-optic devices is mainly M2:

[0112] According to Equation 1

[0113]

[0114] Wherein, n is the refractive index of the acousto-optic medium 1 for light waves of a specific wavelength; p is the effective elasto-optic coefficient of the acousto-optic medium 1; ρ is the density of the acousto-optic medium 1; υ is the propagation speed of the acoustic wave 5 in a specific direction along the acousto-optic medium 1.

[0115] It can be seen that for the acousto-optic medium 1, its quality factor for light waves of a specific wavelength is positively correlated with the refractive index n and the effective elasto-optic coefficient p of the light wave, and negatively correlated with the density ρ of the acousto-optic medium 1 and the propagation speed υ of the acoustic wave 5 in a specific direction along the acousto-optic medium 1.

[0116] The quality factor is a physical quantity that describes the transmission ability of a medium for light or electromagnetic waves of a specific frequency. The higher the quality factor, the stronger the transmission ability of the medium for light or electromagnetic waves of a specific frequency.

[0117] When considering the transmission of ultraviolet light, if the quality factor of the medium is larger, then the transmission ability of the medium for ultraviolet light is stronger. Therefore, the larger the quality factor, the stronger the transmission of ultraviolet light.

[0118] For optical devices, short-wavelength ultraviolet light means high resolution and sensitivity. This is mainly because short-wavelength light has higher energy and frequency, and can better excite certain substances or generate stronger signals. Therefore, the acousto-optic medium 1 that can transmit short-wavelength light has incomparable advantages in improving the performance of acousto-optic devices. Ultraviolet fused quartz or hydrothermal quartz single crystal is the most commonly used acousto-optic medium 1 in acousto-optic devices. However, when using ultraviolet fused quartz or hydrothermal quartz single crystal (both with the chemical formula SiO2) as the acousto-optic medium 1, its maximum quality factor is only 2.38. This results in poor transmission ability of ultraviolet light, and a large amount of ultraviolet light is absorbed by the acousto-optic medium 1 to generate a large amount of heat. At the same time, to ensure that the acousto-optic medium 1 outputs diffraction fringes 4 of sufficient intensity, a laser 3 emission device with a larger power needs to be used, which brings troubles to the use.

[0119] In addition, LiNbO3 is another existing acousto-optic medium 1 used in acousto-optic devices. The maximum quality factor of this acousto-optic medium 1 is about 4.6. Similarly, the TeO2 crystal has a very large acousto-optic quality factor, and its maximum quality factor can reach 793. However, the latter two crystals have a low laser 3 damage threshold and a low transmittance in the ultraviolet region, and are often used at low power in the visible near-infrared region, and are not suitable for use in the ultraviolet region and high-power lasers 3.

[0120] This embodiment uses a borate crystal as described in any one of Embodiments 1 to 10 as the acousto-optic medium in an acousto-optic device;

[0121] The acousto-optic device is one of an acousto-optic modulator, an acousto-optic deflector, an acousto-optic filter, an acousto-optic spectrum analyzer, an acousto-optic photodetector, and an acousto-optic fiber sensor.

[0122] In the acousto-optic medium 1 (i.e., borate crystal), Ba3M(B3O6)3 (M = Lu, Gd, Bi, Y, In) all belong to the hexagonal crystal system, the P63 / m space group, and are uniaxial crystals. The c-axis direction is its three-fold symmetry axis. The a-axis direction and the b-axis direction of the Ba3M(B3O6)3 crystal form a 120-degree angle, and the plane where the a-axis direction and the b-axis direction are located is perpendicular to the c direction.

[0123] The acousto-optic device includes the acousto-optic medium 1. A sound wave 5 with a set frequency is incident along the c-axis direction of the acousto-optic medium 1 (i.e., the borate crystal Ba3M(B3O6)3 where M is one of Lu, Gd, Bi, Y, In), and a sound wave 5 with a set frequency is incident along the c-axis direction of the acousto-optic medium 1. A laser 3 is incident at an angle α with respect to the b-axis of the acousto-optic medium 1, causing the acousto-optic medium 1 to emit diffraction fringes. Here, the value range of α is 0° - 2°.

[0124] In this embodiment, the laser 3 can be ultraviolet light, visible light, near-infrared light, etc. For ultraviolet light with a wavelength less than 200 nm, obvious technical effects are achieved. Therefore, the present invention preferably uses ultraviolet light with a wavelength less than 200 nm.

[0125] The direction of the laser 3 incident on the acousto-optic medium 1 is perpendicular or nearly perpendicular to the c-axis direction of the acousto-optic medium 1 (the light wave can deviate from the perpendicular by a small angle, which is beneficial for separating the incident light and the outgoing light). Therefore, the value range of α is preferably 0° - 2°.

[0126] In the present invention, the sound wave 5 can be emitted by the sound wave generator 2, and the sound wave 5 emitted by the sound wave generator 2 is a high-frequency sound wave 5. The acousto-optic medium 1 can be used within the frequency range of 1 KHz - 1 GHz and greater than 1 GHz of the sound wave 5. In the present invention, the acousto-optic medium 1 preferably uses a sound wave 5 frequency greater than 1 GHz.

[0127] During the research and testing process, the inventors found that the borate crystal Ba3M(B3O6)3 (M = Lu, Gd, Bi, Y, In) can not only transmit light up to the deep ultraviolet region (wavelength about 170 nm), but also has a relatively large photoelastic coefficient (p33 = 0.30 - 0.45), and its mechanical and optical properties are highly anisotropic. As a result, the propagation speed of the sound wave 5 in the c-axis direction of this type of crystal is slower. Compared with other crystals, it also has a relatively large refractive index (0.12 - 0.15). If this type of crystal is used to make the acousto-optic medium 1 in the acousto-optic device, its figure of merit M2 can reach 6 - 10.3. Particularly importantly, the figure of merit M2 characterizing the acousto-optic diffraction efficiency is nearly 5 times higher than that of fused quartz. Therefore, using this borate crystal as the acousto-optic medium 1 and applying it to the acousto-optic device with ultraviolet light as the corresponding light wave will greatly improve the acousto-optic conversion efficiency of the acousto-optic device, effectively reduce the driving power supply power and the device heating situation.

[0128] Example 12

[0129] This example is similar in principle to Example 11. The difference is that in this example, as Figure 2 shown, a sound wave 5 with a set frequency is incident along the c-axis direction of the acou-optic medium 1, and a laser 3 is incident at an angle α with respect to the b-axis of the acou-optic medium 1, causing the acou-optic medium 1 to emit diffraction fringes. Here, the value of α is 2°.

[0130] Example 13

[0131] As Figure 3 shown, this is the acou-optic modulation spectrogram obtained according to the acou-optic media in Example 11 and Example 12 in the present invention. Here, the abscissa is time, and the ordinate is intensity. Then, this figure mainly focuses on the variation of intensity with time.

[0132] The following are the features that should be mainly focused on:

[0133] Periodic variation of intensity: Due to the modulation of the sound wave 5, the intensity will show a periodic variation. Analyzing the period of this variation can help understand the frequency of the sound wave 5.

[0134] Amplitude of intensity: The amplitude of intensity can reflect the intensity of the modulated light. Analyzing the amplitude variation of intensity can help understand the interaction degree between the sound wave 5 and the light.

[0135] Stability of intensity: It can be seen from the figure that the intensity is stable, with small fluctuations or noise. It can be seen that the acou-optic medium 1 (i.e., borate crystal) has good stability and high measurement accuracy.

[0136] It can be seen from the figure that the speed of intensity change is fast. Through the fast response of intensity, it can be seen that the acou-optic medium has high sensitivity.

[0137] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by terms such as "upper", "lower", etc. is based on the orientation or positional relationship shown in the drawings. This is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention. Unless otherwise clearly specified and defined, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0138] It should also be noted that in the description of the present invention, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variation thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising an..." does not exclude the presence of additional identical elements in the process, method, article or device comprising the element.

[0139] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, rather than limitations on the implementation manners of the present invention. For those of ordinary skill in the art, based on the above description, other different forms of changes or variations can be made. It is impossible to enumerate 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 borate crystal, characterized in that, The chemical formula of the crystal is Ba3M(B3O6)3, which has a centrosymmetric structure, belongs to the hexagonal crystal system, and has a space group of P63 / m(176), where M is one of Lu, Gd, Bi, Y, and In; The unit cell parameters are α = β = 120°, γ = 90°, Z = 2, 2. The crystal according to claim 1, characterized in that, The elasto-optic coefficient of the crystal is 0.30 - 0.

45.

3. The crystal according to claim 1, wherein The refractive index of the crystal is 0.12 - 0.

15.

4. A method for preparing a borate crystal according to any one of claims 1-3, characterized in that, The borate crystal is grown by the Czochralski method or the flux method. The growth of the borate crystal by the Czochralski method includes the following steps. Mix the Ba compound, the M compound, and the B compound evenly according to the molar ratio of Ba:M:B = 6:1:

18. Heat to 500 - 600 °C, keep warm for 20 - 40 h, cool and grind, then heat again to 1050 - 1150 °C for material melting to obtain a mixed melt, add a seed rod with a bound seed crystal, and grow at a lifting speed of 0.03 - 0.06 cm / h. Cool to obtain the borate crystal. The growth of the borate crystal by the flux method includes the following steps. Mix the Ba compound, the M compound, and the B compound evenly according to the molar ratio of Ba:M:B = 6:1:

18. Heat to 500 - 600 °C, keep warm for 20 - 40 h, cool and grind, then heat again to 750 - 850 °C for sintering, keep warm for 20 - 30 h, to obtain polycrystalline powder of pure-phase compound Ba3M(B3O6)3. Mix the obtained polycrystalline powder of compound Ba3M(B3O6)3 with the flux system according to the molar ratio of 1:1 - 3, and mix evenly to obtain the crystal growth material. Heat the crystal growth material until it melts completely and stir evenly, cool to the solution saturation point at a rate of 20 - 50 °C / d, lower the seed crystal and start crystal rotation, and cool at a rate of 0.01 - 5 °C / h to grow the crystal. Cool to obtain the borate crystal. Wherein the Ba compound is selected from one or more of BaCO3, BaO, and BaF2; The B compound is selected from one or more of H3BO3 and B2O3.

5. According to the method described in claim 4, characterized in that The flux is selected from one or more of BaCO3 and BaF2, or one or more of BaF2 and H3BO3.

6. Application of a borate crystal as described in any one of claims 1 - 3 as an acousto-optic medium.

7. An acousto-optic device, characterized in that, Including a borate crystal as described in any one of claims 1 - 3, Incident with sound waves of a set frequency along the c-axis direction of the crystal, and incident with laser light at an angle of α with the b-axis of the crystal, so that the crystal emits diffraction fringes, where the value range of α is 0° - 2°.

8. The acousto-optic device according to claim 7, characterized in that, The laser is selected from ultraviolet light, visible light, or infrared light. Preferably, the laser wavelength is less than 200 nm.

9. The acousto-optic device according to claim 7, characterized in that, The frequency of the sound wave is greater than 1 GHz.

10. The acousto-optic device according to claim 7, characterized in that, The acousto-optic device is one of an acousto-optic modulator, an acousto-optic deflector, an acousto-optic filter, an acousto-optic spectrum analyzer, an acousto-optic photodetector, and an acousto-optic fiber sensor.

Images