CN1085612A - Cesium triborate single crystal growth method and nonlinear optical device made by it - Google Patents

Abstract

The invention relates to a method for extracting Cs from a sample containing Cs₂O and B₂O₃CsB growth in melt by pulling technique₃O₅Method for single-crystal growth, and CsB₃O₅A nonlinear optical device made of single crystal. CsB grown by the method₃O₅Single crystals, which can be used to make nonlinear optical devices; the nonlinear optical device has high conversion efficiency, excellent light damage resistance and can generate ultraviolet light with wavelength of 1700 AAAnd (6) discharging.

Description

Cesium triborate method for monocrystal growth and with the device for non-linear optical of its making

The present invention relates to a kind of compound monocrystal cesium triborate (CsB ₃O ₅) growth method and use CsB ₃O ₅The device for non-linear optical that single crystal is made.

When in laser has the crystal of non-zero secondary polarizability, propagating, can produce non-linear optical effects such as frequency multiplication and frequency, difference frequency, parameter amplification.Utilize the crystalline non-linear optical effect, can make second harmonic generator, device for non-linear optical such as upper and lower frequency converter, optical parametric oscillator.

The ideal non-linear optic crystal should possess following condition: non-linear susceptibility is big, the optical transmittance wide waveband, and the phase matched performance is good, the light injury threshold height.

The BBO(low-temperature phase barium metaborate, β-BaB ₂O ₄) and LBO(three lithium tetraborates, LiB ₃O ₅) be the outstanding non-linear optic crystal of finding in recent years, they especially (see " Chinese science " B28,235 tolerating in the powerful device for non-linear optical to be used widely in device for non-linear optical, 1985 and " Chinese invention patent ", application number 88102084).

But the too little (d of Clock Multiplier Factor z component of BBO ₃₁＜0.07d ₁₁), this has limited its application at the uv-absorbing wave band, its acceptance angle little (less than 1mrad-om) in addition, thereby very high to the requirement of crystal working accuracy; And effective Clock Multiplier Factor of LBO big not enough (be about BBO 3/5), this is restricted the efficiency of conversion of LBO.

Acta Crystallography magazine (Vol.13,889,1960 of Denmark; Vol.B30,1178,1974) reported CsB ₃O ₅Crystalline structure.This crystal belongs to P2 ₁2 ₁2 ₁Spacer is a biaxial crystal.According to above-mentioned magazine report, prepared CsB ₃O ₅Crystallite dimension only is 0.10 * 0.17 * 0.46mm ³The Physics and Chemistry of Glasses magazine (Vol.16,108,1975) of Britain has been reported with hot-stage microscope and has been studied CsB ₃O ₅Cross the kinetics of crystallization process in the sloppy heat body, the photo of being announced shows that what obtain is the polycrystal that several crystallites are polymerized.So far not seeing relevant preparation size as yet is enough to the report of the cesium triborate monocrystalline used for physical property measurement, also not about the test of cesium triborate monocrystalline non-linear optical property or the cesium triborate monocrystalline is used to make the report of device for non-linear optical.

The purpose of this invention is to provide a kind of growth method of cesium triborate monocrystalline and device for non-linear optical of making of the cesium triborate monocrystalline of preparing.

The present invention prepares CsB ₃O ₅The method of monocrystalline is the method for adopting czochralski technique growing crystal from melt.

To contain Cs ₂O and B ₂O ₃Mol ratio is after 1: 3 raw materials of compound mixes, to be heated to fusing in platinum crucible, and is being higher than CsB ₃O ₅Melting temperature insulation for some time; Drop to the temperature of a little higher than fusing point, seed crystal is fixed on the seed rod with platinum filament, seed crystal makes seed crystal contact with bath surface under the top; With less than 45 rev/mins rotating speed rotation seed crystal, and, treat CsB with 0～5 millimeter/hour the speed pulling crystal that makes progress ₃O ₅Single crystal growing strengthens pull rate behind the required yardstick, makes crystal break away from melt liquid level, is annealed to room temperature with the speed that is not more than 100 ℃/hour.Described raw materials of compound can be Cs ₂CO ₃With H ₃BO ₃Or B ₂O ₃, also can be CsNO ₃With H ₃BO ₃Or B ₂O ₃, can also be CsCl and H ₃BO ₃Or B ₂O ₃Utilize following any one reaction can obtain CsB ₂O ₅Melt:

Adopt aforesaid method can obtain to be of a size of the transparent CsB of centimetre-sized ₃O ₅Monocrystalline.

The present inventor finds after tested, CsB ₃O ₅Crystal has following nonlinear optical properties:

1. the transmission region of non-constant width: ultraviolet absorption edge is 170nm, and the infrared permeation wave band extends to 3000nm.

2. the Sellmeire equation that draws by least square fitting:

$n_x^2=2.2916+\frac{0.02105}{{\mathrm{\λ}}^2+0.06525}-3.1848\×{10}^{-8}\×{\mathrm{\λ}}_2$ $n_y^2=2.3731+\frac{0.03437}{{\mathrm{\λ}}^2+0.1160}-7.2632\×{10}^{-8}\×{\mathrm{\λ}}^2$ $n_z^2=2.4607+\frac{0.03202}{{\mathrm{\λ}}^2+0.08961}-5.6332\×{10}^{-8}\×{\mathrm{\λ}}^2$

3. effectively Clock Multiplier Factor is big, greater than LBO, with BBO about equally.

4. Clock Multiplier Factor z component is big.

5. the light injury threshold height is 20-28GW/cm ²(1ns, λ=1053nm).Be not less than BBO.

6. under the room temperature, in its whole transmission region scope, all can realize phase matched.Adopt the YAG laser apparatus, first-harmonic λ=1064nm, frequency multiplication ripple λ=532nm, phase matching angle θ=59.4 °, φ=0 ° (I class); θ=15.6 °, φ=0 ° (II class).

7. acceptance angle is greater than BBO.

8. walk-off angle is 1.76 ° (I classes), and 1.12 ° (II class) is less than BBO.

Therefore, chemical formula is CsB ₂O ₅Compound crystal be a kind of new non-linear optic crystal.Adopt the CsB of the inventive method growth ₃O ₅The device for non-linear optical that single crystal is made has the existing following advantage that adopts the device for non-linear optical that bbo crystal or lbo crystal make simultaneously: the efficiency of conversion height, beam divergence is required low, photodamage resistant superior performance, and can produce wavelength and be as short as 1700

UV-light output.

Accompanying drawing 1 is typical CsB of the present invention ₃O ₅The fundamental diagram of the device for non-linear optical that single crystal is made.Inject CsB by the light beam (2) that laser apparatus (1) sends ₂O ₅Crystal (3), the outgoing beam that is produced (4) passes through filter plate (5), thereby obtains needed laser beam.Be of the present invention with CsB ₃O ₅The device for non-linear optical that single crystal is made comprises a branch of at least incidence electromagnetic radiation by a CsB ₃O ₅Behind the monocrystalline, produce the device that a branch of at least frequency is different from the output radiation of incidence electromagnetic radiation.This device can be a second harmonic generator, upper and lower frequency converter, and optical parametric oscillator etc., the wavelength region of described incidence electromagnetic radiation is 0.34～3.0 μ m.

For second harmonic generator, (2) are fundamental waves, and outgoing beam (4) contains the composition of first-harmonic and frequency multiplication ripple, and the effect of spectral filter (5) is an elimination fundamental wave composition, only allows frequency doubled light to pass through.

CsB ₃O ₅The modes of emplacement of single crystal (3) is such: make light beam incident direction and crystal optics axle z(be equivalent to crystallographic axis b) and the axle x(be equivalent to crystallographic axis c) angle be respectively θ, φ, described θ, φ are CsB ₃O ₅The crystalline phase matching angle, about the problem of phase matching angle in the biaxial crystal, Hobden had done to go through (J.Appl.Phys., Vol.38,4365,1967).

Below be to adopt the inventive method growth CsB ₃O ₅The embodiment of monocrystalline:

Embodiment 1:

With 79.2gCs ₂CO ₃And 89.6gN ₃BO ₃Behind the uniform mixing, pack in the opening platinum crucible of φ 50mm * 40mm, crucible is put into monocrystal growing furnace, with lagging material the opening that is positioned at furnace roof portion is sealed up, stay an aperture that can supply seed rod to come in and go out in furnace roof portion and corresponding position, crucible central position, be rapidly heated to 1000 ℃, constant temperature fast cooling to 838 ℃ after 10 hours will be along the CsB of C axle cutting ₃O ₅Seed crystal is fixed on the seed rod lower end with platinum filament, from furnace roof portion aperture seed crystal is imported crucible, make it to contact with melt liquid level, 20 rev/mins of seed rod speed of rotation, pull rate is 0.5 millimeter/hour, accelerate pull rate when finishing growth and make crystal break away from bath surface, be cooled to room temperature, obtain to be of a size of the transparent CsB of φ=20mm * 20mm with 60 ℃/hour speed annealing ₃O ₅Monocrystalline.

Embodiment 2:

With 118.2gCs ₂CO ₃And 133.8gH ₃BO ₃Behind the uniform mixing, pack in the opening platinum crucible of φ 50mm * 55mm, crucible is put into the vertical process furnace, with lagging material the opening that is positioned at furnace roof portion is sealed up, stay one can be rapidly heated to 950 ℃ for the aperture of seed rod discrepancy in furnace roof portion and corresponding position, crucible central position, constant temperature is after 12 hours, fast cooling to 837 ℃ will be along the CsB of C axle cutting ₃O ₅Seed crystal is fixed on the seed rod lower end with platinum filament, from furnace roof portion aperture seed crystal is imported crucible, make it to contact with melt liquid level, 30 rev/mins of seed rod speed of rotation, with 0.2 ℃/day speed cooling, crystal growth finishes after 14 days, and crystal is lifted from liquid level, speed annealing with 50 ℃/hour is cooled to room temperature, and the acquisition size is 21 * 25 * 20mm ³Transparent CsB ₃O ₅Monocrystalline.

Embodiment 3:

With 88.2gCsNO ₃And 84.0gH ₃BO ₃Behind the uniform mixing, pack in the opening platinum crucible of φ 45mm * 50mm, crucible is put into the vertical process furnace, with lagging material fire door is sealed up, stay an aperture at the furnace roof place corresponding with the crucible central position, 900 ℃ of constant temperature are cooled to 837 ℃ after 12 hours, by the top aperture, with seed rod seed crystal is imported crucible, make it to contact with liquid level, with 0.1 ℃/day speed cooling, and rotary seed crystal rod, 20 rev/mins of rotating speeds, sense of rotation with 1 minute be the cycle by clockwise with counterclockwise hocket, crystal growth finishes after 20 days, and crystal is lifted from liquid level, speed annealing with 60 ℃/hour is cooled to room temperature, obtains to be of a size of 27 * 17 * 14mm ³Transparent CsB ₃O ₅Monocrystalline.

Embodiment 4:

CsB with embodiment 1 acquisition ₃O ₅Monocrystalline is pressed crystallographic axis a, b, c orientation, and according to θ=59.4 °, the orientation of φ=0 ° cuts out 6 * a 6 * 6mm ³Crystal, press accompanying drawing 1 shown device on the position of non-linear optic crystal 3.At room temperature, with transferring Q YAG laser apparatus as light source, input optical wavelength is 1064nm, obtains the frequency multiplication output light of λ=532nm.

Claims (4)

1. A nonlinear optical device, which is a device that generates at least one beam of output radiation with a frequency different from that of the incident electromagnetic radiation after passing through a nonlinear optical crystal containing at least one beam of incident electromagnetic radiation, characterized in that the nonlinear The optical crystal is CsB ₃ O ₅ single crystal. 2. The nonlinear optical device according to claim 1, characterized in that the optical device can generate wavelengths as short as 1700

UV light output. 3. The nonlinear optical device according to claim 1, characterized in that the optical device can withstand a power density up to 20GW/CM ² . 4. A CsB ₃ O ₅ single crystal growth method, characterized in that the crystal is grown by pulling technology in a compound melt containing Cs ₂ O and B ₂ O ₃ in a molar ratio of 1:3, that is, in a platinum crucible Heat the raw material until it melts, when it is slightly higher than the melting point of CsB ₃ O ₅ , lower the seed crystal from the top to make it contact with the liquid surface, rotate the seed crystal at a speed of less than 45 rpm, and at the same time, rotate the seed crystal at a speed of 0 to 5 mm/min. Pull the crystal up at a speed of 1 hour, so that the CsB ₃ O ₅ single crystal grows to the desired size; the compound raw material can be Cs ₂ CO ₃ and H ₃ BO ₃ or B ₂ O ₃ , or CsNO ₃ and H ₃ BO ₃ or B ₂ O ₃ , or CsCl with H ₃ BO ₃ or B ₂ O ₃ .