NONLINEAR OPTICAL CRYSTAL FLUORINE BORON BERYLLIUM SALT AND ITS PREPARATION PROCESS AND USE

Abstract

Crystalline NH.sub.4Be.sub.2BO.sub.3F.sub.2 or Be.sub.2BO.sub.3F (abbreviated as BBF) has nonlinear optical effect, is not deliquescent in the air, is chemically stable. They can be used in a variety of nonlinear optical fields and will pioneer the nonlinear optical applications in the deep UV band.

Claims

1. A fluorine boron beryllium salt, characterized in that, the fluorine boron beryllium salt is ammonium beryllium borate fluoride (chemical formula I) compound, or beryllium borate fluoride (chemical formula II) compound:
Be.sub.2BO.sub.3F.NH.sub.4F,NH.sub.4Be.sub.2BO.sub.3F.sub.2(chemical formula II)
Be.sub.2BO.sub.3F(chemical formula III). Preferably, the beryllium borate fluoride compound is of a trigonal (rhombohedral) system structure. Preferably, the ammonium beryllium borate fluoride compound is of a trigonal (rhombohedral) system structure. Preferably, the ammonium beryllium borate fluoride compound or the beryllium borate fluoride compound is a nonlinear optical crystal.

2. A process for preparing the ammonium beryllium borate fluoride compound according to claim 1, comprising the following steps: preparing raw materials NH.sub.4F, BeO and H.sub.3BO.sub.3, adding the raw materials into a hydrothermal kettle, followed by addition of water, slowly raising the temperature to 150-240 C., keeping the temperature constant for 5 to 7 days; cooling followed by withdrawal and washing, to obtain the ammonium beryllium borate fluoride compound. Preferably, the molar ratio of NH.sub.4F, BeO and H.sub.3BO.sub.3 is (0.5-2.5):1:(0.5-2.0), preferably (1.0-2.5):1:(0.5-1.5). Preferably, the water is added in an amount of - (ml:ml), preferably - (ml:ml) of the volume of the hydrothermal kettle. Preferably, the solvent used for washing is water, ethanol or a mixture thereof, and multiple solvents shown above can be used for washing in multiple times. Preferably, the temperature is slowly raised to 180-220 C. Preferably, the cooling rate is 5-10 C./hour. Preferably, cooling is carried out to 20-30 C.

3. An ammonium beryllium borate fluoride nonlinear optical crystal, characterized in that, the crystal has the chemical formula of NH.sub.4Be.sub.2BO.sub.3F.sub.2; the crystal does not have a center of symmetry, and belongs to trigonal (rhombohedral) system, its space group is R32, cell parameters are a=4.4418 , b=4.4418 , c=19.9087 , ==90, =120, z=3, and unit cell volume is V=340.2 .sup.3.

4. A method for growing an ammonium beryllium borate fluoride nonlinear optical crystal according to claim 3, characterized by a hydrothermal method and using H.sub.3BO.sub.3NH.sub.4F as mineralizer system, and comprising the following steps: placing an ammonium beryllium borate fluoride compound and a mineralizer comprising H.sub.3BO.sub.3 and NH.sub.4F in a hydrothermal kettle, followed by addition of water, raising the temperature to 250-350 C., keeping the temperature constant, after 7-14 days, decreasing the temperature to 40-60 C., stopping heating, cooling the sample, followed by washing, to obtain the ammonium beryllium borate fluoride nonlinear optical crystal. Preferably, the molar ratio of the ammonium beryllium borate fluoride compound to the mineralizer is 1:(2-3). Preferably, the mass ratio of H.sub.3BO.sub.3 to NH.sub.4F in the mineralizer is between and . Preferably, the ammonium beryllium borate fluoride compound and the mineralizer are uniformly mixed and then placed in the hydrothermal kettle. Preferably, the water is added in an amount of - (ml:ml), preferably - (ml:ml) of the volume of the hydrothermal kettle. Preferably, the rate of cooling to 40-60 C. (preferably 50 C.) is 3-10 C. per hour, preferably 5 C. per hour. Preferably, the sample is subjected to washing after being cooled to 20-30 C. Preferably, the solvent used for washing is water, ethanol or a mixture thereof, and multiple solvents shown above can be used for washing in multiple times. Preferably, the prepared crystal has a volume greater than 2.0 mm.sup.3.

5. A process for preparing the beryllium borate fluoride compound according to claim 1, comprising the following steps: preparing raw materials NH.sub.4F, BeO and H.sub.3BO.sub.3, adding the raw materials into a hydrothermal kettle, followed by addition of water, slowly raising the temperature to 180-240 C., keeping the temperature constant for 5-7 days; cooling followed by withdrawal and washing, to obtain the beryllium borate fluoride compound. Preferably, the molar ratio of NH.sub.4F, BeO and H.sub.3BO.sub.3 is (0.1-0.8):1:(0.5-2.5), preferably 0.5:1:(0.5-2.5). Preferably, the water is added in an amount of - (ml:ml), preferably - (ml:ml) of the volume of the hydrothermal kettle. Preferably, the temperature is slowly raised to 200-220 C. Preferably, the cooling rate is 5-10 C./hour; preferably, cooling is carried out to 20-30 C. Preferably, the solvent used for washing is water, ethanol or a mixture thereof, and multiple solvents shown above can be used for washing in multiple times.

6. A beryllium borate fluoride nonlinear optical crystal, characterized in that, the crystal has the chemical formula of Be.sub.2BO.sub.3F; the crystal does not have a center of symmetry and belongs to trigonal (rhombohedral) system, its space group is R32, cell parameters are a=4.4398 , b=4.4398 , c=12.4697 , ==90, =120, z=3, and unit cell volume is V=212.87 .sup.3. Preferably, the beryllium borate fluoride nonlinear optical crystal has the structure shown in FIG. 7.

7. A method for growing the beryllium borate fluoride nonlinear optical crystal according to claim 6, characterized by a hydrothermal method to growth and using H.sub.3BO.sub.3NH.sub.4F as mineralizer system, and comprising the following steps: placing a beryllium borate fluoride compound and a mineralizer comprising H.sub.3BO.sub.3 and NH.sub.4F into a hydrothermal kettle, followed by addition of water, raising the temperature to 250-350 C., keeping the temperature constant, after 7-14 days, decreasing the temperature to 40-60 C., stopping heating, cooling the sample, followed by washing, to obtain the beryllium borate fluoride nonlinear optical crystal. Preferably, the molar ratio of the beryllium borate fluoride compound to the mineralizer is 1:(2-3). Preferably, the mass ratio of NH.sub.4F to H.sub.3BO.sub.3 in the mineralizer is between and . Preferably, the beryllium borate fluoride compound and the mineralizer are uniformly mixed and then placed in a hydrothermal kettle. Preferably, the water is added in an amount of - (ml:ml), preferably - (ml:ml) of the volume of the hydrothermal kettle. Preferably, the rate of cooling to 40-60 C. (preferably 50 C.) is 3-10 C. per hour, preferably 5 C. per hour. Preferably, the sample is subjected to washing after being cooled to 20-30. Preferably, the solvent used for washing is water, ethanol or a mixture thereof, and multiple solvents shown above can be used for washing in multiple times. Preferably, the prepared crystal has a volume greater than 2.0 mm.sup.3. Preferably, the XRD structure of the beryllium borate fluoride crystals after being ground into powder is shown in FIG. 9.

8. A method for growing the beryllium borate fluoride nonlinear optical crystal according to claim 6, characterized by a flux method to growth and using B.sub.2O.sub.3NH.sub.4F as a flux system, and comprising the following steps: using BeO, NH.sub.4BF.sub.4, B.sub.2O.sub.3 and NH.sub.4F as raw materials, after mixing uniformly and grinding, placing the raw materials into a platinum tube, then sealing the platinum tube with oxyhydrogen flame; placing the sealed platinum tube into a reactor, filling alumina powder outside the platinum tube; raising the temperature of the reactor to 650 C.-800 C. in a resistance wire heating furnace, keeping the temperature constant for 10-15 days, then decreasing the temperature to 350-450 C. at a rate of 1-3 C. per hour, followed by decreasing the temperature to 40-60 C. at the rate of 5-10 C. per hour, stopping heating, cooling the sample to 20-30 C., followed by washing, to obtain the beryllium borate fluoride optical crystal. Preferably, the molar ratio of BeO, NH.sub.4BF.sub.4, B.sub.2O.sub.3 and NH.sub.4F is 3-8:1-2:6-16:2-5. Preferably, the solvent used for washing is water, ethanol or a mixture thereof, and multiple solvents shown above can be used for washing in multiple times. Preferably, the prepared crystal has a volume greater than 0.5 mm.sup.3. Preferably, the XRD of the beryllium borate fluoride crystal powder is shown in FIG. 10.

9. Use of the ammonium beryllium borate fluoride compound according to claim 1, wherein the compound or crystal is used for frequency conversion of a laser output by a laser; and for generating harmonic light output of double or triple or quadruple or quintuple or sextuple frequency for a laser beam having a wavelength of 1.064 m; or the crystal is used for generating a harmonic light output below 200 nm.

10. Use of the beryllium borate fluoride compound according to claim 1, the compound or the crystal is used for a harmonic generator, an optical parametric and amplifying device, and an optical waveguide device in the deep UV region; or the compound or the crystal is used for an optical parametric and amplifying device from the infrared to the deep UV region.

11. Use of the ammonium beryllium borate fluoride nonlinear optical crystal according to claim 3, wherein the compound or crystal is used for frequency conversion of a laser output by a laser; and for generating harmonic light output of double or triple or quadruple or quintuple or sextuple frequency for a laser beam having a wavelength of 1.064 m; or the crystal is used for generating a harmonic light output below 200 nm.

12. Use of the beryllium borate fluoride nonlinear optical crystal according to claim 6, the compound or the crystal is used for a harmonic generator, an optical parametric and amplifying device, and an optical waveguide device in the deep UV region; or the compound or the crystal is used for an optical parametric and amplifying device from the infrared to the deep UV region.

Description

DESCRIPTION OF DRAWINGS

[0088] FIG. 1 is a typical schematic drawing of the nonlinear optical effect of ABBF crystal as frequency doubling crystal, wherein 1 is a laser, 2 is an incident laser beam, 3 is ABBF single crystal after crystal post-treatment and optical processing, 4 is a generated exit laser beam, and 5 is a filter.

[0089] FIG. 2 is a schematic drawing of the structure of ABBF crystal.

[0090] FIG. 3 is an X-ray diffraction pattern of the ABBF powder raw material of Example 1.

[0091] FIG. 4 is an X-ray diffraction pattern of the ABBF powder raw material of Example 2.

[0092] FIG. 5 is an X-ray diffraction pattern of the ABBF single crystal of Example 3 after being ground into powder.

[0093] FIG. 6 is a typical schematic drawing of the nonlinear optical effect of BBF crystal as frequency doubling crystal, wherein 1 is a laser, 2 is an incident laser beam, 3 is BBF single crystal after crystal post-treatment and optical processing, 4 is a generated exit laser beam, and 5 is a filter.

[0094] FIG. 7 is a schematic drawing of the structure of BBF crystal.

[0095] FIG. 8 is an X-ray diffraction pattern of the BBF powder raw material of Example 8.

[0096] FIG. 9 is an X-ray diffraction pattern of the BBF single crystal of Example 9 after being ground into powder.

[0097] FIG. 10 is an X-ray diffraction pattern of the BBF single crystal of Example 10 after being ground into powder.

EMBODIMENTS

[0098] As described above, the present invention provides a novel ammonium beryllium borate fluoride nonlinear optical crystal, whose chemical formula is NH.sub.4Be.sub.2BO.sub.3F.sub.2. The crystal does not have a center of symmetry, and belongs to trigonal (rhombohedral) system, its space group is R32, cell parameters are a=4.4418 , b=4.4418 , c=19.9087 , ==90, =120, z=3, and unit cell volume is V=340.2 .sup.3. Its structure is shown in FIG. 2. Ammonium ions and fluoride ions are present in the crystal. Ammonium ion and fluoride ion can generate hydrogen bond, and the disadvantage of layered growth habit can be avoided or optimized through the hydrogen bond, thereby opening up the application of deep UV nonlinear optical crystals.

[0099] As described above, the present invention also provides a novel beryllium borate fluoride nonlinear optical crystal having the chemical formula of Be.sub.2BO.sub.3F. The crystal does not have a center of symmetry and belongs to trigonal (rhombohedral) system, its space group is R32, cell parameters are a=4.4398 , b=4.4398 , c=12.4697 , ==90, =120, z=3, and unit cell volume is V=212.87 .sup.3. This structure is as such: removing the potassium ion from the KBBF while keeping the structural features of KBBF, and directly linking the (Be.sub.2BO.sub.3) layers by fluorine atoms. Thus, the FO bond can be used to avoid or improve the layered growth habit of KBBF and the defect of uneasy growth in z direction, and can shorten the distance between the layers, thereby opening up the application of deep UV nonlinear optical crystals.

[0100] The present invention will be further described with reference to the following examples. It should be noted that the following examples are not intended to limit the protection scope of the present invention, and any improvements made on the basis of the present invention are not contrary to the spirit of the present invention. The raw materials or equipment used in the present invention are commercially available unless otherwise specified.

Example 1 Preparation of Ammonium Beryllium Borate Fluoride Compound by Hydrothermal Process

[0101] Raw materials used:

TABLE-US-00001 BeO 0.25 g (0.01 mol) H.sub.3BO.sub.3 0.93 g (0.015 mol) NH.sub.4F 0.925 g (0.025 mol)

[0102] Its chemical reaction equation is:

2BeO+H.sub.3BO.sub.3+2NH.sub.4F=NH.sub.4Be.sub.2BO.sub.3F.sub.2+NH.sub.3+2H.sub.2O

[0103] Specific steps were as follows: In an operation box, the above raw materials were weighed according to the above amounts, placed in a 23 ml hydrothermal kettle, followed by pouring of 10 ml of distilled water, the hydrothermal kettle was placed in an oven, the oven was slowly heated to 220 C., kept at constant temperature for 7 days, and then cooled to 30 C. at a cooling rate of 5 C. per hour. After cooling, the sample was washed with distilled water and alcohol to obtain pure NH.sub.4Be.sub.2BO.sub.3F.sub.2 compound. The product was subjected to X-ray analysis and the resulting pattern (FIG. 3) was consistent with the X-ray pattern of the ABBF single crystal after being ground into powder (FIG. 5).

Example 2 Preparation of Ammonium Beryllium Borate Fluoride Compound by Hydrothermal Process

[0104] Raw materials used:

TABLE-US-00002 BeO 2.5 g (0.1 mol) H.sub.3BO.sub.3 3.1 g (0.05 mol) NH.sub.4F 5.55 g (0.15 mol)

[0105] Its chemical reaction equation is:

2BeO+H.sub.3BO.sub.3+2NH.sub.4F=NH.sub.4Be.sub.2BO.sub.3F.sub.2+NH.sub.3+2H.sub.2O

[0106] Specific steps were as follows: In an operation box, the above raw materials were weighed according to the above amounts, placed in a 200 ml hydrothermal kettle, followed by pouring of 100 ml of distilled water, the hydrothermal kettle was placed in an oven, the oven was slowly heated to 180 C., kept at constant temperature for 7 days, and then cooled to 30 C. at a cooling rate of 5 C. per hour. After cooling, the sample was washed with distilled water and alcohol to obtain pure NH.sub.4Be.sub.2BO.sub.3F.sub.2 compound. The product was subjected to X-ray analysis and the resulting pattern (FIG. 4) was consistent with the X-ray pattern of the ABBF single crystal after being ground into powder (FIG. 5).

Example 3 Growing Ammonium Beryllium Borate Fluoride Single Crystal by Hydrothermal Process

[0107] Crystal growth device was resistance wire heating furnace, and temperature control device was 908PHK20 type programmable automatic temperature control instrument.

[0108] Raw materials used:

TABLE-US-00003 NH.sub.4Be.sub.2BO.sub.3F.sub.2 2 g (0.015 mol) H.sub.3BO.sub.3 0.62 g (0.01 mol) NH.sub.4F 1.11 g (0.03 mol)

[0109] Specific steps were as follows: With H.sub.3BO.sub.3NH.sub.4F as mineralizer system, in an operation box, the above raw materials were weighed according to the above amounts, and loaded in a hydrothermal kettle having a capacity of 35 ml, followed by pouring of 20 ml of distilled water, the reaction kettle was placed in the resistance wire heating furnace and slowly heated to 250 C./330 C. (upper temperature/lower temperature), kept at constant temperature for 10 days, then cooled to 50 C. at a rate of 5 C. per hour, the furnace was turned off, after cooling, the sample was washed with water and alcohol to obtain ammonium beryllium borate fluoride optical crystal having a size of about 1.51.51.0 mm. The crystals were ground to powder for X-ray analysis, and the resulting pattern was shown in FIG. 5.

Example 4 Growing Ammonium Beryllium Borate Fluoride Single Crystal by Hydrothermal Process

[0110] Crystal growth device was resistance wire heating furnace, and temperature control device was 908PHK20 type programmable automatic temperature control instrument.

[0111] Raw materials used:

TABLE-US-00004 NH.sub.4Be.sub.2BO.sub.3F.sub.2 100 g (0.75 mol) H.sub.3BO.sub.3 31 g (0.5 mol) NH.sub.4F 55.5 g (1.5 mol)

[0112] Specific steps were as follows: With H.sub.3BO.sub.3NH.sub.4F as mineralizer system, in an operation box, the above raw materials were weighed according to the above amounts, and loaded in a hydrothermal kettle having a capacity of 2000 ml, followed by pouring of 1200 ml of distilled water, the reaction kettle was placed in the resistance wire heating furnace and slowly heated to 250 C./330 C. (upper temperature/lower temperature), kept at constant temperature for 40 days, then cooled to 50 C. at a rate of 5 C. per hour, the furnace was turned off, after cooling, the sample was washed with water and alcohol to obtain ammonium beryllium borate fluoride optical crystal having a size of about 5.05.03.0 mm.

Example 5

[0113] The crystal obtained in Example 4 was processed and then placed between the laser 1 and the filter 5 in the device shown in FIG. 1 (i.e., the position of reference sign 3), at room temperature, a Q-switched Nd:YAG laser was used as input light source, the incident wavelength was 1064 nm, an obvious 532 nm frequency doubling green light output was observed, the output intensity was about 1.5 times that of KDP under the same conditions.

Example 6

[0114] The crystal obtained in Example 4 was processed and then placed between the laser 1 and the filter 5 in the device shown in FIG. 1 (i.e., the position of reference sign 3), at room temperature, the frequency doubling light of the Q-switched Nd:YAG laser was used as input light source, the incident wavelength was 532 nm, an obvious 266 nm frequency doubling UV light output was observed.

Example 7

[0115] The crystal obtained in Example 4 was processed and then placed between the laser 1 and the filter 5 in the device shown in FIG. 1 (i.e., the position of reference sign 3), at room temperature, the frequency tripling light of the Q-switched Nd:YAG laser was used as input light source, the incident wavelength was 355 nm, a 177.3 nm frequency doubling deep UV light output was observed.

Example 8 Preparation of Beryllium Borate Fluoride Compound by Hydrothermal Process

[0116] Raw materials used:

TABLE-US-00005 BeO 0.25 g (0.01 mol) H.sub.3BO.sub.3 1.55 g (0.025 mol) NH.sub.4F 0.185 g (0.005 mol)

[0117] Its chemical reaction equation is:

2BeOH.sub.3BO.sub.3+NH.sub.4F=Be.sub.2BO.sub.3F+NH.sub.3+2H.sub.2O

[0118] Specific steps were as follows: In an operation box, the above raw materials were weighed according to the above amounts, placed in a 23 ml hydrothermal kettle, followed by pouring of 10 ml of distilled water, the hydrothermal kettle was placed in an oven, the oven was slowly heated to 220 C., kept at constant temperature for 7 days, and then cooled to 30 C. at a cooling rate of 5 C. per hour. After cooling, the sample was washed with distilled water and alcohol to obtain Be.sub.2BO.sub.3F compound. The product was subjected to X-ray analysis and the resulting pattern (FIG. 8) was consistent with the X-ray pattern of the BBF single crystal after being ground into powder (FIG. 10).

Example 9 Growing Beryllium Borate Fluoride Single Crystal by Hydrothermal Process

[0119] Crystal growth device was resistance wire heating furnace, and temperature control device was 908PHK20 type programmable automatic temperature control instrument.

[0120] Raw materials used:

TABLE-US-00006 Be.sub.2BO.sub.3F 2.5 g (0.026 mol) H.sub.3BO.sub.3 1.86 g (0.03 mol) NH.sub.4F 0.555 g (0.015 mol)

[0121] Specific steps were as follows: With H.sub.3BO.sub.3NH.sub.4F as mineralizer system, in an operation box, the above raw materials were weighed according to the above amounts, and loaded in a hydrothermal kettle having a capacity of 35 ml, followed by pouring of 20 ml of distilled water, the reaction kettle was placed in the resistance wire heating furnace and slowly heated to 250 C./330 C. (upper temperature/lower temperature), kept at constant temperature for 12 days, then cooled to 50 C. at a rate of 5 C. per hour, the furnace was turned off, after cooling, the sample was washed with water and alcohol to obtain beryllium borate fluoride optical crystal having a size of about 1.21.20.8 mm. The crystals were ground to powder for X-ray analysis, and the resulting pattern was shown in FIG. 9.

Example 10 Growing Beryllium Borate Fluoride Single Crystal by Hydrothermal Process

[0122] Crystal growth device was resistance wire heating furnace, and temperature control device was 908PHK20 type programmable automatic temperature control instrument.

[0123] Raw materials used:

TABLE-US-00007 Be.sub.2BO.sub.3F 72 g (0.75 mol) H.sub.3BO.sub.3 93 g (1.5 mol) NH.sub.4F 27.75 g (0.75 mol)

[0124] Specific steps were as follows: With H.sub.3BO.sub.3NH.sub.4F as mineralizer system, in an operation box, the above raw materials were weighed according to the above amounts, and loaded in a hydrothermal kettle having a capacity of 2000 ml, followed by pouring of 1200 ml of distilled water, the reaction kettle was placed in the resistance wire heating furnace and slowly heated to 250 C./330 C. (upper temperature/lower temperature), kept at constant temperature for 40 days, then cooled to 50 C. at a rate of 5 C. per hour, the furnace was turned off, after cooling, the sample was washed with water and alcohol to obtain beryllium borate fluoride optical crystal having a size of about 4.54.53 mm (FIG. 10).

Example 11 Growing Beryllium Borate Fluoride Single Crystal by Flux Process

[0125] Crystal growth device was resistance wire heating furnace, and temperature control device was 908PHK20 type programmable automatic temperature control instrument. B.sub.2O.sub.3NH.sub.4F was selected as flux, and through spontaneous nucleation, crystals were obtained.

[0126] Raw materials used:

TABLE-US-00008 BeO 2.25 g (0.09 mol) NH.sub.4BF.sub.4 1.575 g (0.015 mol) NH.sub.4F 5.55 g (0.15 mol) B.sub.2O.sub.3 2.1 g (0.03 mol)

[0127] Its chemical reaction equation is:

6BeO+NH.sub.4BF.sub.4+B.sub.2O.sub.3=3Be.sub.2BO.sub.3F+NH.sub.4F

[0128] Specific steps were as follows: In an operation box, the above raw materials were weighed according to the above amounts, mixed uniformly, and loaded in a platinum tube, then the platinum tube was sealed with oxyhydrogen flame. The sealed platinum tube was placed in a reactor with alumina powder filling the outside part of the platinum tube. The reactor was placed in a growth furnace, heated to 750 C., kept at constant temperature for 12 days, and then cooled to 400 C. at a rate of 2 C. per hour, subsequently to 50 C. at a rate of 10 C. per hour, the furnace was turned off, after cooling to room temperature, the sample was washed with water and alcohol, to obtain beryllium borate fluoride optical crystal having a size of about 1.01.00.6 mm.

Example 12 Growing Beryllium Borate Fluoride Single Crystal by Flux Process

[0129] Crystal growth device was resistance wire heating furnace, and temperature control device was 908PHK20 type programmable automatic temperature control instrument. B.sub.2O.sub.3NH.sub.4F was selected as flux, and through spontaneous nucleation, crystals were obtained.

[0130] Raw materials used:

TABLE-US-00009 BeO 22.5 g (0.9 mol) NH.sub.4BF.sub.4 15.75 g (0.15 mol) NH.sub.4F 55.5 g (1.5 mol) B.sub.2O.sub.3 21 g (0.3 mol)

[0131] Its chemical reaction equation is:

6BeONH.sub.4BF.sub.4+B.sub.2O.sub.3=3Be.sub.2BO.sub.3F+NH.sub.4F

[0132] Specific steps were as follows: In an operation box, the above raw materials were weighed according to the above amounts, mixed uniformly, and loaded in a platinum tube, then the platinum tube was sealed with oxyhydrogen flame. The sealed platinum tube was placed in a reactor with alumina powder filling the outside part of the platinum tube. The reactor was placed in a growth furnace, heated to 750 C., kept at constant temperature for 40 days, and then cooled to 400 C. at a rate of 2 C. per hour, subsequently to 50 C. at a rate of 10 C. per hour, the furnace was turned off, after cooling to room temperature, the sample was washed with water and alcohol, to obtain beryllium borate fluoride optical crystal having a size of about 3.53.52.5 mm.

Example 13

[0133] The crystal obtained in Example 11 was processed and then placed between the laser 1 and the filter 5 in the device shown in FIG. 6 (i.e., the position of reference sign 3), at room temperature, a Q-switched Nd:YAG laser was used as input light source, the incident wavelength was 1064 nm, an obvious 532 nm frequency doubling green light output was observed, the output intensity was about 2.2 times that of KDP under the same conditions.

Example 14

[0134] The crystal obtained in Example 11 was processed and then placed between the laser 1 and the filter 5 in the device shown in FIG. 6 (i.e., the position of reference sign 3), at room temperature, the frequency doubling light of the Q-switched Nd:YAG laser was used as input light source, the incident wavelength was 532 nm, an obvious 266 nm frequency doubling UV light output was observed.

Example 15

[0135] The crystal obtained in Example 11 was processed and then placed between the laser 1 and the filter 5 in the device shown in FIG. 6 (i.e., the position of reference sign 3), at room temperature, the frequency tripling light of the Q-switched Nd:YAG laser was used as input light source, the incident wavelength was 355 nm, a 177.3 nm frequency doubling deep UV light output was observed.