Ytterbium ion doped samarium calcium oxyborate nonlinear optical crystal and preparation method and application thereof

Abstract

The invention discloses an ytterbium ion doped samarium calcium oxide borate nonlinear optical crystal and a preparation method and application thereof.The crystal belongs to a monoclinic system, an m point group and a Cm space group, the chemical formula is YbxSm1-xCa4O (BO3) 3, the chemical formula is 0.1-0.99, the cell parameters are as follows: a = 8.064-8.110, b = 16.045-16.062, c = 3.570-3.600, alpha = gamma = 90 degrees and beta = 100.80-101.38 degrees, and the ytterbium ion doped samarium calcium oxide borate nonlinear optical crystal has good crystal quality and transmittance as high as 87% and can be applied to high-power laser devices, such as laser devices, laser devices, laser devices and the like. The method is widely applied to the fields of photoetching machines, laser medical treatment, laser cutting and the like, and the preparation method has the advantages of being low in cost, high in quality, stable in performance, suitable for large-scale production and the like.

Description

Technical Field

[0001] The invention belongs to the technical fields of nonlinear optics and crystal growth, and in particular relates to an ytterbium ion-doped samarium calcium oxyborate nonlinear optical crystal and a preparation method and application thereof. Background Art

[0002] Since the birth of lasers, the research on nonlinear optical materials has developed rapidly. In order to expand the application wavelength of lasers, nonlinear optical effects such as second harmonic generation (SHG), sum frequency generation (SFG) and difference frequency generation (DFG) are used to achieve laser frequency conversion. As a medium for laser frequency conversion, nonlinear optical crystals play a key role in short-pulse, high-power lasers. Currently, practical nonlinear optical crystals include lithium niobate LNO (LiNbO 3 ), barium borate BBO (β-BaB 2 O 4 ), potassium dihydrogen phosphate (KDP) 2 PO 4 ), lithium triborate LBO (LiB 3 O 5 )wait.

[0003] Rare earth calcium borate crystals (RCa 4 O(BO 3 ) 3 , RCOB, R is a rare earth element) belongs to the monoclinic system and has a non-centrosymmetric structure. It can produce nonlinear optical effects and piezoelectric effects, so it can be used as a laser crystal and a piezoelectric crystal. As early as 1974, Kindermann et al. studied the rare earth calcium borate ternary system and synthesized a series of compound crystals. Subsequently, the preparation method and nonlinear optical properties of the rare earth calcium borate series crystals were studied and reported by scholars. SmCa 4 O(BO 3 ) 3 (SmCOB) and YCa 4 O(BO 3 ) 3 (abbreviated as YCOB) all belong to the monoclinic system and have high laser damage threshold, high transmittance, and high physical and chemical stability. 4 O(BO 3 ) 3 Compared to YCa 4 O(BO 3 ) 3 It has rich energy levels and more absorption peaks in the ultraviolet to near-infrared band. 3+ The doped YCOB crystal achieves the absorption of idler light in the quasi-parametric amplification system. Sm:YCOB has a seed intensity of 260 MW / cm2 Under the conditions of 70% pump loss and 41% signal efficiency, the energy conversion efficiency was greatly improved.

[0004] The inventors found that SmCOB crystal, as a nonlinear optical crystal with excellent performance, can be used as a matrix material by doping Yb 3+ Yb:SmCOB crystal can be formed. As a new type of nonlinear optical crystal with potential application value, the preparation method and optical and thermal properties of Yb:SmCOB have not been studied and reported, so it is necessary to design a preparation method of ytterbium ion doped samarium calcium oxyborate crystal. Summary of the invention

[0005] In view of the above problems, the present invention provides an ytterbium ion-doped samarium calcium oxyborate nonlinear optical crystal and a preparation method and use thereof.

[0006] The first aspect of the present invention provides an ytterbium ion-doped samarium calcium oxyborate nonlinear optical crystal, wherein the nonlinear optical crystal belongs to the monoclinic system. m Point group, C m Space group, chemical formula is Yb x Sm 1-x Ca 4 O(BO 3 ) 3 , x is 0.1 ~ 0.99, and the unit cell parameters are a =8.064 ~ 8.110 Å, b =16.045 ~ 16.062 Å, c = 3.570 ~ 3.600 Å, α = γ = 90°, β = 100.80° ~ 101.38°.

[0007] Optionally, in the nonlinear optical crystal, Sm, Yb, Ca, B and O coordinate to form SmO 6 Octahedron, YbO 6 Octahedron, CaO 6 Octahedron and BO 3 Triangular planar structure, SmO 6 Octahedron and YbO 6 Octahedrons are connected to CaO by sharing corners or edges. 6 Octahedron connected, BO 3 Triangular planes as bridges connecting SmO 6 Octahedron, YbO 6 Octahedron and CaO 6 Octahedral, SmO6 Octahedron, YbO 6 Octahedron, CaO 6 Octahedron and BO 3 Octahedrons are arranged periodically in three-dimensional space.

[0008] Optionally, the maximum half-peak width of the rocking curve of the nonlinear optical crystal is less than 70"; The transmittance of the nonlinear optical crystal at 500-900 nm, 1635-1965 nm and 2000-2400 nm is greater than or equal to 87%; The absorption peak range of the nonlinear optical crystal is 850-1050 nm; The thermal conductivity value of the nonlinear optical crystal at 300-600 K is 1.6-2.7 W / (m·K).

[0009] The second aspect of the present invention provides a method for preparing the ytterbium ion-doped samarium calcium oxyborate nonlinear optical crystal as described in any one of the first aspects above, comprising: Step 1, preparing a polycrystalline material of samarium calcium oxyborate doped with ytterbium ions; Step 2, placing a seed crystal of yttrium calcium oxyborate crystal or samarium calcium oxyborate crystal at the bottom of the crucible, filling the polycrystalline material on the top of the seed crystal and sealing the crucible; Step 3, placing the crucible into a crystal growth furnace, raising the temperature inside the crystal growth furnace to an inoculation temperature, melting the polycrystalline material and the top of the seed crystal in the crucible, and completing the inoculation; Step 4: Control the temperature gradient in the crystal growth furnace to decrease, so that the polycrystalline material in the crucible is crystallized and cooled to obtain ytterbium ion-doped samarium calcium oxyborate crystals.

[0010] Optionally, step 1 includes: CaCO 3 or CaO, H 3 BO 3 、Sm 2 O 3 and Yb 2 O 3 Mixing to obtain a mixed material, pressing the mixed material into blocks and performing a first sintering to obtain a first sintered product; The first sintered product is ground to obtain a ground product, and the ground product is pressed into blocks and subjected to a second sintering to obtain the ytterbium ion-doped samarium calcium oxyborate polycrystalline material.

[0011] Optionally, the CaCO 3 or CaO, H 3 BO 3 、Sm 2 O3 and Yb 2 O 3 The molar ratio is 4: (3.03-3.09): (1-x) / 2: x / 2, wherein x is 0.1-0.99.

[0012] Optionally, the first sintering includes: heating the mixed material to a first temperature, keeping the temperature, continuing to heat the mixed material to a second temperature, keeping the temperature, continuing to heat the mixed material to a third temperature, keeping the temperature, and cooling; The second sintering includes: heating the ground product to the third temperature, keeping the temperature, continuing to heat the product to a fourth temperature, keeping the temperature, and cooling the product.

[0013] Optionally, the step 3 includes: placing the crucible in a furnace tube, and filling the space between the furnace tube and the crucible with alumina; Place the furnace tube containing the crucible on the descending device in the crystal growth furnace, adjust the height of the descending device so that the polycrystalline material in the crucible is in the high temperature zone of the crystal growth furnace, raise the temperature in the high temperature zone to the inoculation temperature and keep it warm, so that the polycrystalline material in the crucible and the top of the seed crystal are melted, and the inoculation is completed.

[0014] Optionally, step 4 includes: controlling the crucible to descend in the temperature gradient zone of the crystal growth furnace through the descending device, so that the polycrystalline material in a molten state in the crucible stops descending and cools after crystallization, thereby obtaining ytterbium ion-doped samarium calcium oxyborate crystals; wherein, along the descending direction of the crucible, the temperature of the temperature gradient zone decreases according to a gradient of 30 to 50 °C / cm.

[0015] The third aspect of the present invention provides a use of the ytterbium ion-doped samarium calcium oxyborate nonlinear optical crystal according to any one of the first aspect or the preparation method according to any one of the second aspect, and the use of the ytterbium ion-doped samarium calcium oxyborate nonlinear optical crystal in the preparation of laser frequency conversion devices, photolithography machines, frequency doubling generators, up or down frequency converters or optical parametric oscillators.

[0016] Compared with the prior art, the present invention is characterized in that: The present invention provides an ytterbium ion-doped samarium calcium oxyborate nonlinear optical crystal, a preparation method and use thereof, wherein gradient cooling is achieved through a crucible descent method, thereby achieving gradual growth of the ytterbium ion-doped samarium calcium oxyborate crystal, and finally preparing an ytterbium ion-doped samarium calcium oxyborate nonlinear optical crystal (hereinafter referred to as "Yb:SmCOB") having good size, quality and performance parameters, filling the gap in the field of ytterbium ion-doped samarium calcium oxyborate single crystal growth.

[0017] (1) The present invention uses a combination of a high temperature solid phase method and a crucible descent method to strictly control the preparation process, thereby preparing Yb:SmCOB with good size, quality and performance parameters.

[0018] (2) After the mixed raw materials are pressed into blocks, they are sintered twice through a specific process to improve the purity of the polycrystalline material, and finally a Yb:SmCOB with higher purity is prepared.

[0019] (3) The present invention uses yttrium calcium oxyborate crystal (SmCOB) or samarium calcium oxyborate crystal YCOB as a heterogeneous seed crystal, and melts, crystallizes, and cools the polycrystalline material in a crystal growth furnace under specific conditions of temperature increase and temperature gradient decrease to finally prepare Yb 0.1 Sm 0.9 Ca 4 O(BO 3 ) 3 and Yb 0.2 Sm 0.8 Ca 4 O(BO 3 ) 3 Crystal.

[0020] (4) The crucible used in the present invention has a size of Φ25 mm × 250 mm, and the crystal growth furnace has a size of 1.0 m × 1.0 m × 2.4 m. 0.1 Sm 0.9 Ca 4 O(BO 3 ) 3 and Yb 0.2 Sm 0.8 Ca 4 O(BO 3 ) 3 The crystal sizes are Φ25 mm × 50 mm and Φ25 mm × 70 mm respectively. The specific crucible size and crystal growth furnace size can produce specific temperature gradients and temperature fields, determine the crystal size, and have a specific impact on the performance of the crystal. The composition, structure, shape, and size of the crucible play an important and critical role in obtaining large-size, high-purity nonlinear optical crystals.

[0021] (5) The Yb:SmCOB crystal grown by the method of the present invention belongs to the monoclinic system, the maximum half-peak width of the rocking curve is less than 70", and the crystal has good crystal quality. 0.1 Sm 0.9 Ca 4 O(BO 3 ) 3 and Yb 0.2 Sm 0.8 Ca 4 O(BO3 ) 3 The effective segregation coefficients of Yb:SmCOB are 0.89 and 0.88, respectively, and the degree of segregation of the crystal is small. The transmittance of Yb:SmCOB at 500~900 nm, 1635~1965 nm and 2000~2400 nm is 87%, which meets the high transmittance requirements as a frequency doubling crystal or a self-frequency doubling crystal, and the absorption peak of Yb:SmCOB at 850~1050 nm is broadened, which is conducive to expanding the self-absorption wavelength range in self-frequency doubling laser applications. In addition, Yb:SmCOB has abundant absorption peaks in the near-infrared band, and is expected to achieve absorption of idler light in QPA systems and improve energy conversion efficiency. The thermal conductivity of Yb:SmCOB crystals at 300~600 K is 1.6~2.7 W / (m·K), indicating that Yb:SmCOB has a good laser damage threshold and can maintain stable laser output in laser applications.

[0022] (6) The preparation method can grow multiple ytterbium ion-doped samarium calcium oxyborate crystals in one furnace, which is helpful for realizing mass production. At the same time, the preparation method can control the shape and direction of the grown ytterbium ion-doped samarium calcium oxyborate single crystal according to requirements, which greatly reduces the later processing loss and working hours. The ytterbium ion-doped samarium calcium oxyborate single crystal grown by the present invention is not easy to crack and has a high yield. The crystal can realize ultra-short and ultra-strong pulse laser output in quasi-parametric amplification technology and has potential application in laser self-frequency doubling. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the principle of growing crystals by the crucible descent method of the present invention; Figure 2 is a photograph of the crystal of the present invention, wherein (a) is Yb 0.1 Sm 0.9 Ca 4 O(BO 3 ) 3 Crystal, (b) is Yb 0.2 Sm 0.8 Ca 4 O(BO 3 ) 3 Crystals; Figure 3 is the crystal structure of the crystal of the present invention, wherein the labeling of the Yb atom is omitted; Figure 4 is the XRD spectrum of the crystal of the present invention; Figure 5 The wafer is obtained after the crystal processing of the present invention, and the wafer size is 10 mm × 10 mm × 1 mm. (a) is Yb 0.1 Sm0.9 Ca 4 O(BO 3 ) 3 Chip, (b) is Yb 0.2 Sm 0.8 Ca 4 O(BO 3 ) 3 Wafer; Figure 6 is the transmission spectrum of the crystal of the present invention, wherein (a) is Yb 0.1 Sm 0.9 Ca 4 O(BO 3 ) 3 The transmission spectrum of the crystal, (b) is Yb 0.2 Sm 0.8 Ca 4 O(BO 3 ) 3 Transmission spectrum of the crystal; Figure 7 is the rocking curve of the crystal of the present invention, wherein (a) is Yb 0.1 Sm 0.9 Ca 4 O(BO 3 ) 3 The rocking curve of the crystal, (b) is Yb 0.2 Sm 0.8 Ca 4 O(BO 3 ) 3 Rocking curve of a crystal. DETAILED DESCRIPTION

[0024] The present application provides an ytterbium ion-doped samarium calcium oxyborate nonlinear optical crystal.

[0025] Ytterbium ion doped samarium calcium oxyborate nonlinear optical crystal belongs to the monoclinic system. m Point group, C m Space group, chemical formula is Yb x Sm 1-x Ca 4 O(BO 3 ) 3 (hereinafter referred to as "Yb:SmCOB"), x is 0.1 ~ 0.99, and the unit cell parameters are a =8.064 ~8.110 Å, b =16.045 ~ 16.062 Å, c = 3.570 ~ 3.600 Å, α = γ = 90°, β= 100.80° ~101.38°.

[0026] In the nonlinear optical crystal, Sm, Yb, Ca, B and O coordinate to form SmO 6 Octahedron, YbO 6 Octahedron, CaO 6 Octahedron and BO 3 Triangular planar structure, SmO 6 Octahedron and YbO 6 Octahedrons are connected to CaO by sharing corners or edges. 6 Octahedron connected, BO 3 Triangular planes as bridges connecting SmO 6 Octahedron, YbO 6 Octahedron and CaO 6 Octahedral, SmO 6 Octahedron, YbO 6 Octahedron, CaO 6 Octahedron and BO 3 Octahedrons are arranged periodically in three-dimensional space.

[0027] The maximum half-peak width of the rocking curve of the nonlinear optical crystal is less than 70"; The transmittance of the nonlinear optical crystal at 500-900 nm, 1635-1965 nm and 2000-2400 nm is greater than or equal to 87%; The absorption peak range of the nonlinear optical crystal is 850-1050 nm; The thermal conductivity value of the nonlinear optical crystal at 300-600 K is 1.6-2.7 W / (m·K).

[0028] Compared with SmCOB crystal, Yb:SmCOB will introduce a new absorption peak at 850~1050 nm, while SmCOB has inherent absorption at 900~980nm, so the absorption peak of Yb:SmCOB at 850~1050 nm is Sm 3+ and Yb 3+ The result of the superposition of energy level transitions. 3+ , which can not only increase the absorption bandwidth in the range of 850~1050 nm, but also enhance the absorption intensity, which is beneficial for Yb:SmCOB to cover a wider wavelength range of idle light and improve the efficiency of absorbing idle light. 3+There are emission peaks at 1020-1026 nm and 1089 nm, and green light output at 510-513 nm and 544.5 nm can be achieved through laser self-doubling. Yb:SmCOB has a high transmittance of more than 80% at 990-1030 nm, and is expected to achieve narrow-bandwidth green light output at 510-515 nm in the laser self-doubling system.

[0029] The present application also provides a method for preparing an ytterbium ion-doped samarium calcium oxyborate nonlinear optical crystal, comprising: Step 1, preparing a polycrystalline material of samarium calcium oxyborate doped with ytterbium ions; Step 2, placing a seed crystal of yttrium calcium oxyborate crystal or samarium calcium oxyborate crystal at the bottom of the crucible, filling the polycrystalline material on the top of the seed crystal and sealing the crucible; Step 3, placing the crucible into a crystal growth furnace, raising the temperature inside the crystal growth furnace to an inoculation temperature, melting the polycrystalline material and the top of the seed crystal in the crucible, and completing the inoculation; Step 4: Control the temperature gradient in the crystal growth furnace to decrease, so that the polycrystalline material in the crucible is crystallized and cooled to obtain ytterbium ion-doped samarium calcium oxyborate crystals.

[0030] In some embodiments, step 1 comprises: Mixing CaCO3 or CaO, H3BO3, Sm2O3 and Yb2O3 to obtain a mixture, pressing the mixture into blocks and performing a first sintering to obtain a first sintering product; The first sintered product is ground to obtain a ground product, and the ground product is pressed into blocks and subjected to secondary sintering to obtain the ytterbium ion-doped samarium calcium oxyborate polycrystalline material.

[0031] In some embodiments, the molar ratio of CaCO3 or CaO, H3BO3, Sm2O3 and Yb2O3 is 4: (3.03~3.09): (1-x) / 2: x / 2, wherein x is 0.1~0.99.

[0032] In some embodiments, the first sintering includes: heating the mixed material to a first temperature, keeping the temperature, continuing to heat the mixed material to a second temperature, keeping the temperature, continuing to heat the mixed material to a third temperature, keeping the temperature, and cooling; The second sintering includes: heating the ground product to the third temperature, keeping the temperature, continuing to heat the product to a fourth temperature, keeping the temperature, and cooling the product.

[0033] In some embodiments, step 3 comprises: placing the crucible in a furnace tube, and filling the space between the furnace tube and the crucible with alumina powder; Place the furnace tube containing the crucible on the descending device in the crystal growth furnace, adjust the height of the descending device so that the polycrystalline material in the crucible is in the high temperature zone of the crystal growth furnace, raise the temperature in the high temperature zone to the inoculation temperature and keep it warm, so that the polycrystalline material in the crucible and the top of the seed crystal are melted, and the inoculation is completed.

[0034] In some embodiments, step 4 includes: controlling the crucible to descend in the temperature gradient zone of the crystal growth furnace through the descending device, so that the polycrystalline material in a molten state in the crucible stops descending and cools after crystallization, thereby obtaining ytterbium ion-doped samarium calcium oxyborate crystals; wherein, along the descending direction of the crucible, the temperature of the temperature gradient zone decreases according to a gradient of 30 to 50 °C / cm.

[0035] In specific implementation, the preparation method comprises the following steps: Step 1, synthesizing polycrystalline material of samarium calcium oxyborate; Step 2: placing a seed crystal of yttrium calcium oxyborate YCOB crystal or samarium calcium oxyborate SmCOB crystal at the bottom of a platinum crucible, then loading ytterbium ion-doped samarium calcium oxyborate polycrystalline material, and sealing the platinum crucible; Step 3, placing the crucible in the high temperature zone of the crystal growth furnace, and uniformly increasing the temperature in the crystal growth furnace to the inoculation temperature, so that the polycrystalline material and the top of the seed crystal in the crucible are melted, and the inoculation is completed; Step 4, controlling the crucible to descend in the temperature gradient zone of the crystal growth furnace, so that the polycrystalline material in the crucible begins to crystallize from the position in contact with the seed crystal, and stops descending after the ytterbium ion-doped samarium calcium oxyborate polycrystalline material is completely crystallized, and then gradually lowers the temperature in the furnace to room temperature to obtain ytterbium ion-doped samarium calcium oxyborate crystals; and testing the crystal structure with a single crystal X-ray diffractometer; Step 5: Use a crystal orientation instrument to determine the crystal orientation of the crystal, and then obtain a crystal sample of the crystal for optical performance testing through cutting and polishing.

[0036] Wherein, the step 1 comprises: doping the samarium calcium oxyborate crystal with ytterbium ions according to the chemical formula Yb x Sm 1-x Ca 4 O(BO 3 ) 3 , ( x = 0.1~0.99), weigh the raw material CaCO with a purity of more than 99.99% according to the stoichiometric ratio 3 or CaO, H 3 BO 3 、Sm 2 O 3 and Yb 2 O 3 , and then add excess H 3 BO3 , wherein the additional addition of excess H 3 BO 3 The proportion of H 3 BO 3 1% to 3% of the mass of the substance. After the raw materials are evenly mixed, they are pressed into blocks and sintered. The temperature is raised to 400°C in a muffle furnace after 4 hours and kept warm for 4 hours; the temperature is raised to 900°C after 4 hours and kept warm for 4 hours; the temperature is raised to 1100-1300°C after 4 hours, kept warm for 12 hours, and cooled to room temperature to obtain a polycrystalline material for the first sintering; the polycrystalline material after the first sintering is fully ground and pressed into blocks, and placed in a sintering crucible for secondary sintering, the temperature is raised to 1300°C after 12 hours, kept warm for 12 hours; the temperature is raised to 1300-1500°C after 4 hours, kept warm for 20 hours, and finally cooled to room temperature after 20 hours to obtain a polycrystalline material of ytterbium ion doped with samarium calcium oxyborate after the second sintering.

[0037] Wherein, the seed crystal orientation of step 2 is <010> The cross-sectional shape of the seed crystal is circular, and its size is Φ 7× 50 mm; the crucible consists of four parts: the seed crystal well at the bottom is a hollow cylinder with a size of Φ 8 × 50 mm, which is used to place the seed crystal; the shoulder part is a hollow truncated cone with a size of Φ 8 × Φ25 ×50 mm, which is the transition zone where the crystal diameter changes from small to large; the uppermost equal-diameter part is a hollow cylinder with a diameter of Φ25 mm and a height of 250 mm. This part realizes the equal-diameter growth of large-sized crystals; in addition, each platinum crucible is also equipped with a lid, which is sealed according to experimental requirements to prevent the external environment from affecting the crystal growth.

[0038] Among them, in the step 3, the crucible is first placed in a corundum ceramic furnace tube, and the space between the corundum furnace tube and the crucible is filled with alumina powder; then the corundum furnace tube equipped with the crucible is placed on the descending device in the crystal growth furnace; the height of the descending device is adjusted so that the polycrystalline material in the crucible is in the high temperature zone of the crystal growth furnace, and after 12 hours, the temperature is uniformly raised to 1500°C and kept warm for 12 hours, and then the height of the crucible is adjusted so that the top of the seed crystal in the crucible is melted to complete the inoculation.

[0039] Wherein, in the step 4, the temperature in the crystal growth furnace is maintained at a constant 1500°C, and the platinum crucible is controlled to descend in the temperature gradient zone of the crystal growth furnace, so that the polycrystalline material in the crucible in a molten state gradually crystallizes in the temperature field as the crucible descends. During the crystal growth process, the temperature gradient of the temperature gradient zone is 30 to 50°C / cm along the descending direction of the crucible, and the crucible is controlled to descend in the temperature gradient zone of the crystal growth furnace at a rate of 10 to 15 mm / day until all the polycrystalline materials in the crucible are crystallized and the crucible is stopped from descending; then the temperature in the crystal growth furnace is reduced to 500°C at a cooling rate of 20 to 40°C / hour, and then naturally cooled to room temperature, and the platinum crucible is peeled off to obtain Yb:SmCOB crystal.

[0040] The present application also provides a use of the ytterbium ion-doped samarium calcium oxyborate nonlinear optical crystal described in any of the above items, and the use of the ytterbium ion-doped samarium calcium oxyborate nonlinear optical crystal in the preparation of laser frequency conversion devices, photolithography machines, frequency doubling generators, up or down frequency converters or optical parametric oscillators.

[0041] The present invention is further described in detail below with reference to the embodiments.

[0042] Embodiment 1: According to the chemical formula of ytterbium ion doped samarium calcium oxyborate crystal Yb 0.1 Sm 0.9 Ca 4 O(BO 3 ) 3 Stoichiometric ratio, weigh 99.99% high purity CaCO 3 (400 g, 4 mol), H 3 BO 3 (185.49 g, 3 mol), Sm 2 O 3 (156.924 g, 0.45 mol) and Yb 2 O 3 (19.704 g, 0.05 mol) powder was used as the raw material, and 1% of H 3 BO 3(1.8549 g, 0.03 mol); then the weighed raw materials were mixed and pressed into blocks, and placed in a corundum crucible for sintering. The temperature was raised to 400°C in a muffle furnace for 4 hours and kept warm for 4 hours; then raised to 900°C for 4 hours and kept warm for 4 hours; then raised to 1100°C for 4 hours and kept warm for 12 hours, and then cooled to room temperature to obtain a polycrystalline material sintered for the first time; the polycrystalline material sintered once was ground and pressed into blocks, and placed in a crucible for secondary sintering, and the temperature was raised to 1100°C for 12 hours and kept warm for 12 hours; then raised to 1300°C for 4 hours and kept warm for 20 hours, and finally cooled to room temperature for 20 hours to obtain ytterbium ion-doped samarium calcium oxyborate Yb 0.1 Sm 0.9 Ca 4 O(BO 3 ) 3 of polycrystalline material.

[0043] A Φ7 × 50 mm oriented <010> The polycrystalline material is loaded into a platinum crucible with a thickness of 0.2 mm, a seed crystal well of Φ8 × 50 mm, a shoulder part of Φ8 × Φ25 × 50 mm, and an equal diameter part of Φ25 mm × 250 mm. Finally, the crucible is sealed with a platinum cover. Place the sealed platinum crucible into the corundum furnace tube, fill the gap between the furnace tube and the crucible with high-purity alumina powder, and place the corundum furnace tube on the descending device in the crystal growth furnace ( Figure 1 ), adjust the height of the descending device so that the polycrystalline material in the crucible is in the high temperature zone of the crystal growth furnace, and raise the temperature to 1500°C at a uniform speed after 12 hours and keep it for 12 hours, then adjust the height of the crucible so that the top of the seed crystal in the crucible melts, completing the inoculation.

[0044] After the inoculation is completed, the crystal growth of ytterbium ion doped samarium calcium oxyborate is carried out, the temperature in the crystal growth furnace is maintained at a constant 1500 ℃, and the platinum crucible is controlled to descend in the temperature gradient zone of the crystal growth furnace (the temperature gradient zone is Figure 1 The transition zone and low temperature zone in the crucible are collectively referred to as the transition zone and low temperature zone in the crucible), so that the polycrystalline material in the molten state in the crucible gradually crystallizes in the temperature field as the crucible descends. During the crystal growth process, the crucible is controlled to descend at a speed of 10 mm / day until all the polycrystalline material in the crucible is crystallized and the crucible is stopped from descending; then the temperature in the crystal growth furnace is reduced to 500℃ at a rate of 20℃ / hour, and then naturally cooled to room temperature, and the crucible is taken out to obtain ytterbium ion-doped samarium calcium oxyborate crystal Yb 0.1 Sm 0.9 Ca 4 O(BO 3 ) 3, the crystal size is Φ25 mm × 50 mm ( Figure 2 (as shown in (a)).

[0045] The crystal was tested by a powder X-ray diffractometer. The XRD data of the crystal was measured by a Bruker D8 Focus X-ray powder diffractometer at room temperature. Cu Kα (λ=0.1546 Å) was used as the excitation source, the working current was 40 mA, the working voltage of the X-ray tube was 40 kV, the scanning range was 10~80°, the step was 0.02°, and the scanning speed was 10° / min. The results showed that the crystal belonged to the monoclinic system. m The point group and space group are C m , chemical formula is Yb 0.1 Sm 0.9 Ca 4 O(BO 3 ) 3 , unit cell parameters a = 8.103 Å, b = 16.047Å, c = 3.571 Å, α = γ = 90°, β = 101.26°; Sm, Yb, Ca, B and O coordinate to form SmO 6 Octahedron, YbO 6 Octahedron, CaO 6 Octahedron and BO 3 Triangular planar structure; SmO 6 and YbO 6 The octahedron is connected to CaO by sharing corners or edges. 6 Octahedron connected, BO 3 Triangular planes as bridges connecting SmO 6 , YbO 6 and CaO 6 Octahedral, SmO 6 , YbO 6 , CaO 6 and BO 3 Periodically arranged in three-dimensional space ( Figure 3 ), the crystal is abbreviated as Yb:SmCOB; the measured crystal X-ray diffraction peak is consistent with SmCOB PDF79-1378 ( Figure 4 ).

[0046] Use the YX-2H8A embedded X-ray orientation instrument to orient the crystal. Start the YX-2H8A orientation instrument. After preheating, calibrate the orientation instrument with a quartz standard (Y-plane diffraction angle 2θ = 26.40°) to ensure the accuracy of its parameters and measurement data. Then place the Yb:SmCOB crystal on the sample stage of the orientation instrument. Select SmCa 4 O(BO 3 ) 3 Crystalline <060> The crystal direction (2θ = 33.54°) and the <-201> crystal direction (2θ = 37.77°) are taken as the undetermined crystal directions. Adjust the detector 2θ to the corresponding position, and shake the goniometer handwheel until the microampere display is deflected. When the crystal plane is rotated 90°, 180°, and 270° around the normal axis of the sample stage, and the microampere display is still deflected, it means that the crystal plane is the crystal direction corresponding to 2θ. Use a diamond wire cutting machine to cut the oriented crystal. The sample stage of the cutting machine can move back and forth and up and down under the control of the control system, and the fast-moving diamond wire can cut the crystal. At the same time, the sample stage is a wheel with an angle scale, which is convenient for adjusting the angle when cutting the crystal. Finally, several 10 mm × 10 mm × 1.0 mm X, Y, and Z chips ( Figure 5 The sample was then polished on a UNIPOL-830 metallographic grinding and polishing machine to meet the requirements of optical testing.

[0047] The transmission spectrum of the crystal obtained above was tested. The results showed that the transmission bands of the X, Y, and Z crystal planes of Yb:SmCOB were not offset, and the transmittance at 500-900 nm, 1635-1965 nm, and 2000-2400 nm was 87% ( Figure 6 (a) shows that the crystal can meet the transmittance requirements of nonlinear optical crystals; and the absorption peak of Yb:SmCOB at 850~1050 nm becomes wider, which is conducive to expanding the self-absorption wavelength range in self-frequency doubling laser applications. In addition, Yb:SmCOB has abundant absorption peaks in the near-infrared band, which is expected to achieve absorption of idler light in QPA systems and improve energy conversion efficiency. The thermal conductivity of Yb:SmCOB crystals at 300~600 K is 1.6~2.7 W / (m·K), indicating that Yb:SmCOB has a good laser damage threshold and can maintain stable laser output in laser applications.

[0048] The rocking curve test of the crystal obtained above showed that the maximum half-peak width of the rocking curve of Yb:SmCOB was 57.4" and ( Figure 7 As shown in (a) above, it shows that the Yb:SmCOB crystal grown by the method of the present invention has high crystalline quality.

[0049] Embodiment 2: According to the chemical formula of ytterbium ion doped samarium calcium oxyborate crystal Yb 0.2 Sm 0.8 Ca 4 O(BO 3 ) 3 Stoichiometric ratio, weigh 99.99% high purity CaCO 3 (400 g, 4 mol), H 3 BO 3 (185.49 g, 3 mol), Sm 2 O 3 (139.488 g, 0.4 mol) and Yb 2 O 3 (39.408 g, 0.1 mol) powder was used as the raw material, and 3% of H 3 BO 3 (5.5647 g, 0.09 mol); then the raw materials were fully mixed and pressed into blocks, and then placed in a corundum crucible for sintering. The temperature was raised to 400°C in a muffle furnace for 4 hours and kept warm for 4 hours; then raised to 900°C for 4 hours and kept warm for 4 hours; then raised to 1300°C for 4 hours and kept warm for 12 hours, and then cooled to room temperature to obtain a polycrystalline material for the first sintering; the polycrystalline material after the first sintering was ground and pressed into blocks, and placed in a crucible for secondary sintering, and the temperature was raised to 1300°C for 12 hours and kept warm for 12 hours; then raised to 1500°C for 4 hours and kept warm for 20 hours, and finally cooled to room temperature for 20 hours to obtain ytterbium ion-doped samarium calcium oxyborate Yb for the second sintering 0.2 Sm 0.8 Ca 4 O(BO 3 ) 3 of polycrystalline material.

[0050] A Φ7 × 50 mm oriented <010> The seed crystal of samarium calcium oxyborate SmCOB crystal is prepared by loading the above polycrystalline material into a Φ25 × 250 mm platinum crucible with a crucible thickness of 0.2 mm, and finally covering the crucible with a platinum cover to seal the crucible.

[0051] The sealed platinum crucible is placed in the corundum furnace tube, and the gap between the furnace tube and the crucible is filled with high-purity alumina powder. The corundum furnace tube is placed on the descending device in the crystal growth furnace, and the height of the descending device is adjusted so that the polycrystalline material in the crucible is in the high temperature zone of the crystal growth furnace. After 12 hours, the temperature is uniformly raised to 1500°C and kept warm for 12 hours, and then the height of the crucible is adjusted so that the top of the seed crystal in the crucible is melted to complete the inoculation.

[0052] After the inoculation is completed, the crystal growth of ytterbium ion doped samarium calcium oxyborate is carried out, the temperature in the crystal growth furnace is maintained at a constant 1500 ℃, and the platinum crucible is controlled to descend in the temperature gradient zone of the crystal growth furnace, so that the polycrystalline material in the crucible in a molten state gradually crystallizes in the temperature field as the crucible descends. During the crystal growth process, the crucible is controlled to descend at a rate of 15 mm / day until all the polycrystalline material in the crucible is crystallized and the crucible stops descending; then the temperature in the crystal growth furnace is reduced to 500 ℃ at a rate of 40 ℃ / hour, and then the temperature is naturally cooled to room temperature, and the crucible is taken out to obtain ytterbium ion doped samarium calcium oxyborate crystals, whose structural formula is Yb 0.2 Sm 0.8 Ca 4 O(BO 3 ) 3 , the crystal size is Φ25 mm × 70 mm ( Figure 2 (as shown in (b)).

[0053] The crystal was tested by a powder X-ray diffractometer. The XRD data of the crystal was measured by a Bruker D8 Focus X-ray powder diffractometer at room temperature. Cu Kα (λ=0.1546 Å) was used as the excitation source, the working current was 40 mA, the working voltage of the X-ray tube was 40 kV, the scanning range was 10~80°, the step was 0.02°, and the scanning speed was 10° / min. The results showed that the crystal belonged to the monoclinic system. m The point group and space group are C m , chemical formula is Yb 0.2 Sm 0.8 Ca 4 O(BO 3 ) 3 , unit cell parameters a = 8.107 Å, b = 16.051Å, c = 3.582 Å, α = γ = 90°, β = 101.30°; Sm, Yb, Ca, B and O coordinate to form SmO 6 Octahedron, YbO 6 Octahedron, CaO 6 Octahedron and BO 3 Triangular planar structure; SmO 6 and YbO 6 The octahedron is connected to CaO by sharing corners or edges. 6 Octahedron connected, BO 3 Triangular planes as bridges connecting SmO 6 , YbO 6and CaO 6 Octahedral, SmO 6 , YbO 6 , CaO 6 and BO 3 The crystal is periodically arranged in three-dimensional space and is abbreviated as Yb:SmCOB. The measured X-ray diffraction peak of the crystal is consistent with SmCOBPDF79-1378 ( Figure 4 ).

[0054] Use the YX-2H8A embedded X-ray orientation instrument to orient the crystal. Start the YX-2H8A orientation instrument. After preheating, calibrate the orientation instrument with a quartz standard (Y-plane diffraction angle 2θ = 26.40°) to ensure the accuracy of its parameters and measurement data. Then place the Yb:SmCOB crystal on the sample stage of the orientation instrument. Select SmCa 4 O(BO 3 ) 3 Crystalline <060> The crystal direction (2θ = 33.54°) and the <-201> crystal direction (2θ = 37.77°) are taken as the undetermined crystal directions. Adjust the detector 2θ to the corresponding position, and shake the goniometer handwheel until the microampere display is deflected. When the crystal plane is rotated 90°, 180°, and 270° around the normal axis of the sample stage, and the microampere display is still deflected, it means that the crystal plane is the crystal direction corresponding to 2θ. Use a diamond wire cutting machine to cut the oriented crystal. The sample stage of the cutting machine can move back and forth and up and down under the control of the control system, and the fast-moving diamond wire can cut the crystal. At the same time, the sample stage is a wheel with an angle scale, which is convenient for adjusting the angle when cutting the crystal. Finally, several 10 mm × 10 mm × 1.0 mm X, Y, and Z chips ( Figure 5 The sample was then polished on a UNIPOL-830 metallographic grinding and polishing machine to meet the requirements of optical testing.

[0055] The transmission spectrum of the crystal obtained above was tested. The results showed that the transmission bands of the X, Y, and Z crystal planes of Yb:SmCOB were not offset, and the transmittance at 500-900 nm, 1635-1965 nm, and 2000-2400 nm was 88% ( Figure 6(b) shows that the crystal can meet the transmittance requirements of nonlinear optical crystals; and the absorption peak of Yb:SmCOB at 850~1050 nm becomes wider, which is conducive to expanding the self-absorption wavelength range in self-frequency doubling laser applications. In addition, Yb:SmCOB has abundant absorption peaks in the near-infrared band, which is expected to achieve absorption of idler light in QPA systems and improve energy conversion efficiency. The thermal conductivity of Yb:SmCOB crystals at 300~600 K is 1.6~2.7 W / (m·K), indicating that Yb:SmCOB has a good laser damage threshold and can maintain stable laser output in laser applications.

[0056] The rocking curve test of the crystal obtained above showed that the maximum half-peak width of the rocking curve of Yb:SmCOB was 62.9" and ( Figure 7 As shown in (b) above, it shows that the Yb:SmCOB crystal grown by the method of the present invention has high crystalline quality.

[0057] Embodiment 3: According to the chemical formula of ytterbium ion doped samarium calcium oxyborate crystal Yb 0.9 Sm 0.1 Ca 4 O(BO 3 ) 3 Stoichiometric ratio, weigh 99.99% high purity CaCO 3 (400 g, 4 mol), H 3 BO 3 (185.49 g, 3 mol), Sm 2 O 3 (156.924 g, 0.05 mol) and Yb 2 O 3 (19.704 g, 0.45 mol) powder was used as the raw material, and 2% of H 3 BO 3 (3.8098 g, 0.06 mol); then the weighed raw materials were fully mixed and pressed into blocks, and then placed in a corundum crucible for sintering. The temperature was raised to 400°C in a muffle furnace for 4 hours and kept warm for 4 hours; then the temperature was raised to 900°C for 4 hours and kept warm for 4 hours; then the temperature was raised to 1200°C for 4 hours and kept warm for 12 hours, and then the temperature was lowered to room temperature to obtain a polycrystalline material sintered for the first time; the raw materials after the first sintering were fully ground and pressed into blocks, and then placed in a sintering crucible for secondary sintering, and the temperature was raised to 1200°C for 12 hours and kept warm for 12 hours; then the temperature was raised to 1450°C for 4 hours and kept warm for 20 hours, and finally the temperature was lowered to room temperature after 20 hours to obtain ytterbium ion-doped samarium calcium oxyborate Yb after the second sintering 0.9 Sm0.1 Ca 4 O(BO 3 ) 3 of polycrystalline material.

[0058] A Φ7 × 50 mm oriented <010> The seed crystal of yttrium calcium oxyborate YCOB crystal is prepared by placing the above polycrystalline material into a Φ25 × 250 mm platinum crucible with a crucible thickness of 0.2 mm, and finally covering the crucible with a platinum cover to seal the crucible.

[0059] The sealed platinum crucible is placed in the corundum furnace tube, and the gap between the furnace tube and the crucible is filled with high-purity alumina powder. The corundum furnace tube is placed on the descending device in the crystal growth furnace, and the height of the descending device is adjusted so that the polycrystalline material in the crucible is in the high temperature zone of the crystal growth furnace. After 12 hours, the temperature is uniformly raised to 1500°C and kept warm for 12 hours, and then the height of the crucible is adjusted so that the top of the seed crystal in the crucible is melted to complete the inoculation.

[0060] After the inoculation is completed, the crystal growth of ytterbium ion doped samarium calcium oxyborate is carried out, the temperature in the crystal growth furnace is maintained at a constant 1500 ℃, and the crucible is controlled to descend in the temperature gradient zone of the crystal growth furnace, so that the polycrystalline material in the crucible in a molten state gradually crystallizes in the temperature field as the crucible descends. During the growth process of the crystal, the crucible is controlled to descend at a speed of 12mm / day until all the polycrystalline material in the crucible is crystallized and the crucible stops descending; it is lowered to 500℃ at a rate of 30℃ / hour, and then naturally cooled to room temperature, and the crucible is taken out to obtain <010> Oriented ytterbium ion doped samarium calcium oxyborate crystal, the structural formula of which is Yb 0.9 Sm 0.1 Ca 4 O(BO 3 ) 3 .

[0061] Use the YX-2H8A embedded X-ray orientation instrument to orient the crystal. Start the YX-2H8A orientation instrument. After preheating, calibrate the orientation instrument with a quartz standard (Y-plane diffraction angle 2θ = 26.40°) to ensure the accuracy of its parameters and measurement data. Then place the Yb:SmCOB crystal on the sample stage of the orientation instrument. Select SmCa 4 O(BO 3 ) 3Crystalline <060> The crystal direction (2θ = 33.54°) and <-201> crystal direction (2θ = 37.77°) are used as the undetermined crystal directions. Adjust the detector 2θ to the corresponding position and shake the goniometer handwheel until the microampere display is deflected. When the crystal plane rotates 90°, 180°, and 270° around the normal axis of the sample stage, and the microampere display still deflects, it means that the crystal plane is the crystal direction corresponding to 2θ. The oriented crystal is cut using a diamond wire cutting machine. The sample stage of the cutting machine can move forward and backward and up and down under the control of the control system, and the fast-moving diamond wire can cut the crystal. At the same time, the sample stage is a wheel with an angle scale, which is convenient for adjusting the angle when cutting the crystal. Finally, several 10 mm × 10 mm × 1.0 mm X, Y, and Z wafers were obtained from the Yb:SmCOB crystal. They were then polished on a UNIPOL-830 metallographic grinding and polishing machine to meet the requirements of optical testing.

[0062] The structure of the crystals was tested by X-ray diffractometer, and the transmission spectrum and rocking curve were tested.

Claims

1. A Ytterbium ion doped Samarium Calcium Oxyborate nonlinear optical crystal, characterized in that: The nonlinear optical crystal belongs to the monoclinic system, m Point group, C m Space group, chemical formula is Yb x Sm 1-x Ca4O(BO3)3, x is 0.1 ~ 0.99, unit cell parameters are a =8.064 ~ 8.110 Å, b =16.045 ~ 16.062 Å, c = 3.570 ~ 3.600 Å, α = γ = 90°, β =100.80° ~ 101.38°.

2. The ytterbium ion-doped samarium calcium oxyborate nonlinear optical crystal according to claim 1, characterized in that: In the nonlinear optical crystal, Sm, Yb, Ca, B and O are coordinated to form SmO6 octahedron, YbO6 octahedron, CaO6 octahedron and BO3 triangular plane structures; the SmO6 octahedron and YbO6 octahedron are connected with the CaO6 octahedron by sharing angles or edges; the BO3 triangular plane serves as a bridge to connect the SmO6 octahedron, YbO6 octahedron and CaO6 octahedron; the SmO6 octahedron, YbO6 octahedron, CaO6 octahedron and BO3 octahedron are periodically arranged in three-dimensional space.

3. The ytterbium ion-doped samarium calcium oxyborate nonlinear optical crystal according to claim 1, characterized in that: The maximum half-peak width of the rocking curve of the nonlinear optical crystal is less than 70"; The transmittance of the nonlinear optical crystal at 500-900 nm, 1635-1965 nm and 2000-2400 nm is greater than or equal to 87%; The absorption peak range of the nonlinear optical crystal is 850-1050 nm; The thermal conductivity value of the nonlinear optical crystal at 300-600 K is 1.6-2.7 W / (m·K).

4. A method for preparing the ytterbium ion-doped samarium calcium oxyborate nonlinear optical crystal according to any one of claims 1 to 3, characterized in that: include: Step 1, preparing a polycrystalline material of samarium calcium oxyborate doped with ytterbium ions; Step 2, placing a seed crystal of yttrium calcium oxyborate crystal or samarium calcium oxyborate crystal at the bottom of the crucible, filling the polycrystalline material on the top of the seed crystal and sealing the crucible; Step 3, placing the crucible into a crystal growth furnace, raising the temperature inside the crystal growth furnace to an inoculation temperature, melting the polycrystalline material and the top of the seed crystal in the crucible, and completing the inoculation; Step 4: Control the temperature gradient in the crystal growth furnace to decrease, so that the polycrystalline material in the crucible is crystallized and cooled to obtain ytterbium ion-doped samarium calcium oxyborate crystals.

5. The preparation method according to claim 4, characterized in that: The step 1 comprises: CaCO3 or CaO, H3BO3, Sm2O3 and Yb2O3 are mixed to obtain a mixture, the mixture is pressed into blocks and subjected to a first sintering to obtain a first sintering product; The first sintered product is ground to obtain a ground product, and the ground product is pressed into blocks and subjected to a second sintering to obtain the ytterbium ion-doped samarium calcium oxyborate polycrystalline material.

6. The preparation method according to claim 5, characterized in that: The molar ratio of CaCO3 or CaO, H3BO3, Sm2O3 and Yb2O3 is 4: (3.03-3.09): (1-x) / 2: x / 2, wherein x is 0.1-0.

99.

7. The preparation method according to claim 5, characterized in that: The first sintering comprises: heating the mixed material to a first temperature, keeping the temperature, continuing to heat the mixed material to a second temperature, keeping the temperature, continuing to heat the mixed material to a third temperature, keeping the temperature, and cooling the mixed material; The second sintering includes: heating the ground product to the third temperature, keeping the temperature, continuing to heat the product to a fourth temperature, keeping the temperature, and cooling the product.

8. The preparation method according to claim 4, characterized in that: The step 3 comprises: placing the crucible in a furnace tube, and filling the space between the furnace tube and the crucible with alumina powder; Place the furnace tube containing the crucible on the descending device in the crystal growth furnace, adjust the height of the descending device so that the polycrystalline material in the crucible is in the high temperature zone of the crystal growth furnace, raise the temperature in the high temperature zone to the inoculation temperature and keep it warm, so that the polycrystalline material in the crucible and the top of the seed crystal are melted, and the inoculation is completed.

9. The preparation method according to claim 8, characterized in that: The step 4 comprises: controlling the crucible to descend in the temperature gradient zone of the crystal growth furnace by the descending device, so that the polycrystalline material in a molten state in the crucible stops descending and cools after crystallization, thereby obtaining ytterbium ion-doped samarium calcium oxyborate crystals; wherein, along the descending direction of the crucible, the temperature of the temperature gradient zone decreases according to a gradient of 30 to 50 °C / cm.

10. Use of the ytterbium ion-doped samarium calcium oxyborate nonlinear optical crystal according to any one of claims 1 to 3 or the ytterbium ion-doped samarium calcium oxyborate nonlinear optical crystal prepared by the preparation method according to any one of claims 4 to 9, characterized in that: The ytterbium ion-doped samarium calcium oxyborate nonlinear optical crystal is used in the preparation of laser frequency conversion devices, photolithography machines, frequency doubling generators, up or down frequency converters or optical parametric oscillators.

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