A thulium-terbium co-doped yttrium calcium aluminate near-infrared waveband laser crystal, a preparation method and application thereof

Abstract

The application relates to a thulium-terbium co-doped calcium yttrium aluminate near-infrared waveband laser crystal and a preparation method and application thereof. x Tb y CaY 1‑x‑y AlO4, wherein the value range of x is 0.001-0.05, the value range of y is 0.0001-0.002, the space group is I4 / mmm, and the crystal is tetragonal. Compared with the prior art, the laser crystal can efficiently realize near-infrared waveband laser output near 1.5 microns and can be applied to the fields of medical treatment, military affairs, communication detection and the like.

Description

Technical Field

[0001] This invention relates to the field of laser materials technology, specifically to a thulium-terbium co-doped yttrium calcium aluminate near-infrared laser crystal, its preparation method, and its applications. Background Technology

[0002] With the advancement of information technology, the demand for lasers in specific wavelengths is increasing. This has prompted research in related fields to shift towards high-performance lasers in new wavelength bands. Among them, near-infrared lasers have received widespread attention due to their broad applications in daily life. The infrared spectrum is generally divided into three regions: near-infrared (0.75–2.5 μm), mid-infrared (2.5–25 μm), and far-infrared (25–300 μm). Due to different application requirements, different fields have different definitions for the range of infrared wavelengths. In the laser field, the near-infrared wavelength range is generally defined as 1–5 μm. Near-infrared lasers have important applications in medicine, military, communication, and detection.

[0003] Currently, the rare earth ions that produce laser output in the near-mid-infrared range of 1.5-3.5 μm mainly include thulium (Tm), holmium (Ho), erbium (Er), and dysprosium (Dy). Among these, Tm... 3+ The ion absorption energy at 1.5 μm matches that of commonly used pumps, and the wide gain bandwidth enables the laser to be tunable. Tm 3+ Ions are composed of Tm atoms (outer electron distribution 4f) 13 6s 2 The 4f electron shell loses one electron, and the 6s electron shell loses two electrons to form Tm. 3+ The main absorption band of the ion corresponds to 3 H6→ 3 The H4 transition, with a wavelength around 800 nm, closely matches the emission wavelength of GaAsAl laser diodes. Therefore, high-power GaAsAl lasers can be used as Tm... 3+ Ion-doped laser dielectric pump source. Tm 3+ The main luminescence of ions in the near-mid-infrared band includes transitions at 1.5 μm, 2 μm, and 2.3 μm, respectively. 3 H4→ 3 F4 3 F4→ 3 H6 3 H4→ 3 H5.

[0004] In Tm 3+ In ions, 3 H4 and 3 The energy level spacing of F4 and 3 F4 and 3The energy level spacing of H6 is relatively close, making it highly susceptible to cross relaxation (CR). The pump light then... 3 H6 population pumping to 3 The H4 energy level, through a cross-relaxation process 3 H4(Tm 3+ )+ 3 H6(Tm 3+ → 3 F4(Tm 3+ )+ 3 F4(Tm 3+ ),exist 3 The F4 energy level receives twice the number of particles, and then through 3 F4→ 3 The H6 emission transition produces a 2μm laser. Although cross-relaxation is highly favorable for Tm... 3+ The laser output at 2μm ion emission has the opposite effect on 1.5μm emission, resulting in a lower energy level at 1.5μm. 3 F4's lifetime relative to the upper energy level 3 H4 is an order of magnitude higher, which leads to the self-termination phenomenon of the 1.5μm laser. Summary of the Invention

[0005] The purpose of this invention is to provide a thulium-terbium co-doped calcium yttrium aluminate near-infrared laser crystal, its preparation method and application, to achieve near-infrared laser output near 1.5 μm.

[0006] The objective of this invention can be achieved through the following technical solution: a thulium-terbium co-doped calcium yttrium aluminate (CaYAlO4) near-infrared laser crystal, the chemical formula of which is Tm x Tb y CaY 1-x-y AlO4, where x ranges from 0.001 to 0.05 and y ranges from 0.0001 to 0.002, has a space group of I4 / mmm, and is tetragonal.

[0007] To achieve laser output at 1.5 μm, a crucial approach is to activate the lower energy level, thereby achieving population inversion. This invention also incorporates Tb doping. 3+ The Tm was significantly reduced after ionization. 3+ ion 3 The F4 level lifetime helps alleviate the self-termination problem of the 1.5μm level transition, effectively improving the efficiency of 1.5μm laser output. The CaYAlO4(CYA) crystal has a relatively low phonon energy of 756 cm⁻¹. -1 This helps reduce nonradiative transitions caused by multiphonon relaxation.

[0008] Preferably, the value of x is in the range of 0.001-0.01, and the value of y is in the range of 0.001-0.002.

[0009] Preferably, the thulium-terbium co-doped yttrium calcium aluminate near-infrared laser crystal has a thermal conductivity of 3.7 W / m / K in the a-direction and 3.3 W / m / K in the c-direction, and a phonon energy of 756 cm⁻¹. -1 .

[0010] A method for preparing the above-mentioned thulium-terbium co-doped calcium yttrium aluminate near-infrared laser crystal, wherein the crystal is grown by the Czochralski method.

[0011] Preferably, the preparation method of the thulium-terbium co-doped calcium yttrium aluminate near-infrared laser crystal includes the following steps:

[0012] (1) Weigh the single crystal particles or powders of Ca2O3, Y2O3, Al2O3, Tm2O3 and Tb2O3 according to the stoichiometric ratio, and then mix them thoroughly in a mixer.

[0013] (2) Press the mixed raw materials together, then sinter the pressed raw materials, and then put them into a crucible;

[0014] (3) Place the crucible into the ladle furnace, evacuate it, fill it with inert gas, and heat it to ensure that all the raw materials in the crucible are melted.

[0015] (4) The crystal is grown by the Czochralski method. After the growth is completed, the temperature is lowered to room temperature and the crystal is taken out to obtain the thulium-terbium co-doped calcium yttrium aluminate near-infrared laser crystal.

[0016] More preferably, the single crystal particles or powders of Ca2O3, Y2O3, Al2O3, Tm2O3 and Tb2O3 mentioned in step (1) have a purity of 5N.

[0017] More preferably, the mixing time in step (1) is 15-24 hours.

[0018] More preferably, the pressure of the compression in step (2) is 1.5-2.5 MPa.

[0019] More preferably, the sintering temperature in step (2) is 1100-1300℃ and the time is not less than 24 hours.

[0020] More preferably, the sintering temperature in step (2) is 1200°C.

[0021] More preferably, the vacuuming in step (3) is performed by using a mechanical pump to evacuate the vacuum to below 8 Pa.

[0022] More preferably, the inert gas in step (3) is high-purity nitrogen.

[0023] More preferably, in step (3), the heating rate in the pulling furnace is 200-300℃ / h, and the temperature is raised to 1700-1900℃.

[0024] More preferably, in step (3), the temperature inside the pulling furnace is raised to 1800°C.

[0025] More preferably, the cooling time in step (4) is no less than 60 hours.

[0026] An application of the above-mentioned thulium-terbium co-doped calcium yttrium aluminate near-infrared laser crystal is described, in which the laser crystal is used to achieve near-infrared laser output around 1.5 μm.

[0027] Compared with the prior art, the present invention has the following advantages:

[0028] 1. The laser crystal of this invention can achieve efficient near-infrared laser output around 1.5 micrometers. Near-infrared lasers have important applications in medical, military, and communication detection fields, covering the atmospheric communication window area and are suitable for atmospheric communication. Based on these excellent characteristics and pulsed lasers, they are widely used in the scientific, industrial, and military communities.

[0029] 2. This invention incorporates Tb 3+ The Tm was significantly reduced after ionization. 3+ ion 3 The F4 energy level lifetime helps to alleviate the self-termination problem of 1.5μm energy level transitions and can effectively improve the efficiency of 1.5μm laser output.

[0030] 3. The laser crystal of this invention has high thermal conductivity (3.7 W / m / K in the a-direction and 3.3 W / m / K in the c-direction), stable chemical structure, high mechanical hardness, and low phonon energy (756 cm⁻¹). -1 );

[0031] 4. The laser crystal matrix of this invention has low phonon energy and high output power. Attached Figure Description

[0032] Figure 1 This is the X-ray powder diffraction pattern of the sample prepared in Example 1 of this invention;

[0033] Figure 2 This is the room temperature absorption coefficient spectrum of the sample prepared in Example 1 of this invention;

[0034] Figure 3 This is the room temperature fluorescence spectrum of the sample prepared in Example 1 of this invention.

[0035] Figure 4 The sample prepared in Example 1 of this invention and Tm 3+Ion-doped CaYAlO4 crystal under 808nm light excitation 3 Comparison of fluorescence lifetime spectra corresponding to the H4 energy level.

[0036] Figure 5 The sample prepared in Example 1 of this invention and Tm 3+ Ion-doped CaYAlO4 crystal under 808nm light excitation 3 Comparison of fluorescence lifetime spectra corresponding to the F4 energy level. Detailed Implementation

[0037] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. The following embodiments are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures; however, the scope of protection of the present invention is not limited to the following embodiments.

[0038] Example 1

[0039] Tm 0.005 Tb 0.001 CaY 0.994 AlO4 crystals:

[0040] The initial raw materials were polycrystalline powders of Tm₂O₃, CaO, Tb₂O₃, Y₂O₃, and Al₂O₃ with a purity of 5N. After selecting a specific concentration of Tm ions to replace Y ions, the powders were then processed according to the chemical formula Tm₂O₃. 0.005 Tb 0.001 CaY 0.994 The AlO4 process involves calculating and accurately weighing the required mass of each raw material, growing it, and obtaining crystals, specifically including the following steps:

[0041] (1) Weigh the single crystal powders of Ca2O3, Y2O3, Al2O3, Tm2O3 and Tb2O3 according to the stoichiometric ratio, and then mix them thoroughly in a mixer.

[0042] (2) The mixed raw materials were pressed under a pressure of 2MPa, and then the pressed raw materials were sintered at 1200℃ for 24h and then loaded into a crucible.

[0043] (3) Place the crucible into the Czochralski furnace, tie the seed crystal to the seed crystal rod, and use c-direction pure CYA crystal for the seed crystal. After evacuating to below 8 Pa, fill with high-purity nitrogen and heat to 1800℃ at 250℃ to ensure that all the raw materials in the crucible are melted.

[0044] (4) After the raw material melts, slowly lower the seed crystal to contact the melt. When the head shows signs of melting, reduce the power and slowly pull up the seed crystal rod. The pulling speed is 1 mm / h and the rotation speed is 18 rpm. After the necking, shoulder expansion and equal diameter growth stages.

[0045] (5) Grow crystals using the Czochralski method. After growth, cool to room temperature for at least 60 hours, then remove the crystals to obtain Tm. 0.005 Tb 0.001 CaY 0.994 AlO4 crystals.

[0046] like Figure 1 The image shows the prepared Tm. 0.005 Tb 0.001 CaY 0.994 The X-ray powder diffraction pattern of the AlO4 sample shows that the Tm and Tb co-doped CaYAlO4 is still a pure CaYAlO4 single crystal phase.

[0047] like Figure 2 The image shows the prepared Tm. 0.005 Tb 0.001 CaY 0.994 The room temperature absorption coefficient spectrum of the AlO4 sample shows that it is very consistent with the emission wavelength of the GaAsAl laser diode.

[0048] like Figure 3 The image shows the prepared Tm. 0.005 Tb 0.001 CaY 0.994 The room-temperature fluorescence spectrum of the AlO4 sample shows that the crystal exhibits strong emission at 1.5 μm. The calculated emission cross-section at 1464 nm is 1.13 × 10⁻⁶. -21 cm 2 The FHWM is 169.3nm.

[0049] like Figure 4 The image shows the prepared Tm. 0.005 Tb 0.001 CaY 0.994 AlO4 sample and Tm 3+ Ion-doped CaYAlO4 crystal under 808nm light excitation 3 A comparison of the fluorescence lifetime spectra corresponding to the H4 energy level shows that Tm 0.005 Tb 0.001 CaY 0.994 AlO4 sample 3 The lifetime of the H4 level is 105 μs, and it is related to Tm. 3+ ion-doped CaYAlO4 crystals 3 The lifetime of the H4 level has decreased.

[0050] like Figure 5 The image shows the prepared Tm. 0.005 Tb 0.001 CaY 0.994 AlO4 sample and Tm 3+Ion-doped CaYAlO4 crystal under 808nm light excitation 3 A comparison of the fluorescence lifetime spectra corresponding to the F4 energy level shows that, with co-doping of Tb... 3+ After ionization, 3 The lifetime of the F4 level decreased from 3.86 ms to 259 μs, which greatly alleviated the self-termination problem of the 1.5 μm level transition and can effectively improve the efficiency of 1.5 μm laser output.

[0051] Example 2

[0052] Tm 0.01 Tb 0.001 CaY 0.989 AlO4 crystals:

[0053] The initial raw materials were polycrystalline powders of m2O3, CaO, Tb2O3, Y2O3, and Al2O3 with a purity of 5N. After selecting a specific concentration of Tm ions to replace Y ions, the powders were then processed according to the chemical formula Tm... 0.01 Tb 0.001 CaY 0.989 The AlO4 process involves calculating and accurately weighing the required mass of each raw material, growing it, and obtaining crystals, specifically including the following steps:

[0054] (1) Weigh the single crystal powders of Ca2O3, Y2O3, Al2O3, Tm2O3 and Tb2O3 according to the stoichiometric ratio, and then mix them thoroughly in a mixer.

[0055] (2) The mixed raw materials are pressed under a pressure of 1.5MPa, and then the pressed raw materials are sintered at 1100℃ for 30h and then loaded into a crucible.

[0056] (3) Place the crucible into the ladle furnace, evacuate to below 8 Pa, fill with high-purity nitrogen, and heat to 1700°C from 200°C to ensure that all the raw materials in the crucible are melted.

[0057] (4) The crystal was grown by the Czochralski method. After growth, the temperature was lowered to room temperature for at least 60 hours. The crystal was then removed to obtain Tm. 0.01 Tb 0.001 CaY 0.989 AlO4 crystals.

[0058] Example 3

[0059] Tm 0.01 Tb 0.002 CaY 0.988 AlO4 crystals:

[0060] The initial raw materials were polycrystalline powders of m2O3, CaO, Tb2O3, Y2O3, and Al2O3 with a purity of 5N. After selecting a specific concentration of Tm ions to replace Y ions, the powders were then processed according to the chemical formula Tm... 0.01 Tb 0.002 CaY 0.988 The AlO4 process involves calculating and accurately weighing the required mass of each raw material, growing it, and obtaining crystals, specifically including the following steps:

[0061] (1) Weigh the single crystal powders of Ca2O3, Y2O3, Al2O3, Tm2O3 and Tb2O3 according to the stoichiometric ratio, and then mix them thoroughly in a mixer.

[0062] (2) The mixed raw materials are pressed under a pressure of 2.5 MPa, and then the pressed raw materials are sintered at 1300℃ for 24 hours and then loaded into a crucible.

[0063] (3) Place the crucible into the ladle furnace, evacuate to below 8 Pa, fill with high-purity nitrogen, and heat to 1900°C from 300°C to ensure that all the raw materials in the crucible are melted.

[0064] (4) The crystal was grown by the Czochralski method. After growth, the temperature was lowered to room temperature for at least 60 hours. The crystal was then removed to obtain Tm. 0.01 Tb 0.002 CaY 0.988 AlO4 crystals.

[0065] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A thulium-terbium co-doped calcium yttrium aluminate near-infrared laser crystal, characterized in that, The laser crystal described above is used to achieve near-infrared laser output around 1.5 μm, and the chemical formula of the crystal is Tm. x Tb y CaY 1-x-y AlO4, where x ranges from 0.001 to 0.01 and y ranges from 0.001 to 0.002, has a space group of I4 / mmm, and is a tetragonal crystal system.

2. The thulium-terbium co-doped calcium yttrium aluminate near-infrared laser crystal according to claim 1, characterized in that, The thulium-terbium co-doped yttrium calcium aluminate near-infrared laser crystal has a thermal conductivity of 3.7 W / m / K in the a-direction and 3.3 W / m / K in the c-direction, with a phonon energy of 756 cm⁻¹. -1 .

3. A method for preparing a thulium-terbium co-doped calcium yttrium aluminate near-infrared laser crystal as described in any one of claims 1 or 2, characterized in that, Crystals were grown using the Czochralski method.

4. The method for preparing a thulium-terbium co-doped yttrium calcium aluminate near-infrared laser crystal according to claim 3, characterized in that, Includes the following steps: (1) Weigh the single crystal particles or powders of Ca2O3, Y2O3, Al2O3, Tm2O3 and Tb2O3 according to the stoichiometric ratio, and then mix them thoroughly in a mixer. (2) Press the mixed raw materials together, then sinter the pressed raw materials, and then put them into a crucible; (3) Place the crucible into the ladle furnace, evacuate it, fill it with inert gas, and heat it to ensure that all the raw materials in the crucible are melted. (4) The crystal is grown by the Czochralski method. After the growth is completed, the temperature is lowered to room temperature and the crystal is taken out to obtain the thulium-terbium co-doped calcium yttrium aluminate near-infrared laser crystal.

5. The method for preparing a thulium-terbium co-doped yttrium calcium aluminate near-infrared laser crystal according to claim 4, characterized in that, The pressure of the compression in step (2) is 1.5-2.5 MPa.

6. The method for preparing a thulium-terbium co-doped calcium yttrium aluminate near-infrared laser crystal according to claim 4, characterized in that, The sintering temperature in step (2) is 1100-1300℃, and the time is not less than 24 hours.

7. The method for preparing a thulium-terbium co-doped yttrium calcium aluminate near-infrared laser crystal according to claim 4, characterized in that, Step (3) The heating rate inside the pulling furnace is 200-300℃ / h, and the temperature is raised to 1700-1900℃.

8. The method for preparing a thulium-terbium co-doped yttrium calcium aluminate near-infrared laser crystal according to claim 4, characterized in that, The vacuuming in step (3) is performed by using a mechanical pump to evacuate the vacuum to below 8 Pa.

9. An application of the thulium-terbium co-doped calcium yttrium aluminate near-infrared laser crystal as described in any one of claims 1 or 2, characterized in that, The laser crystal described above is used to achieve laser output in the near-infrared band around 1.5 μm.

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