Thulium-zirconium co-doped gadolinium scandate near-middle infrared band laser crystal and preparation method and application thereof

Abstract

The invention relates to a thulium-zirconium co-doped gadolinium scandate near-middle infrared band laser crystal and a preparation method and application thereof, the chemical composition of the crystal is represented as TmxZryGd1-xSc1-yO3, the value range of x is more than or equal to 0.001 and less than or equal to 0.05, the value range of y is more than or equal to 0.005 and less than or equal to 0.05, and the space group of the crystal is Pnma and an orthorhombic system. The preparation method of the thulium-zirconium co-doped gadolinium scandate near-middle infrared band laser crystal is an edge-defined film-fed crystal method. Compared with the prior art, the laser crystal provided by the invention can efficiently realize output of near-middle infrared band laser near 1.5 microns and 2.3 microns, and can be applied to the fields of laser medical treatment, environmental monitoring, realization of output of near-middle infrared laser as an optical parametric oscillation (OPO) pumping source and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of laser materials, and particularly relates to a thulium-zirconium co-doped gadolinium scandate near-infrared laser crystal, a preparation method thereof, and an application thereof. Background Art

[0002] With the rapid development of the information age, people's demand for lasers in special wavelength bands is increasing day by day, especially in the near-infrared wavelength band (1.5 - 3.5 μm). Lasers in this wavelength band have important application values in the fields of medicine, military, communication detection, etc. At present, rare earth ions that can achieve near-infrared laser output mainly include thulium (Tm 3+ ), holmium (Ho 3+ ), erbium (Er 3+ ), and dysprosium (Dy 3+ ), etc. In order to meet the requirements of high-performance lasers, the research focus has gradually shifted to the development of new laser crystal materials. Among them, GdScO3 crystal has become one of the candidate materials that have received much attention due to its unique structural and performance advantages.

[0003] GdScO3 crystal belongs to the perovskite-like structure, has an orthorhombic crystal system, and the space group is Pnma. Compared with the ideal cubic Pm-3m perovskite structure, its structure is formed by the anti-phase tilt of adjacent ScO6 octahedrons. This structural characteristic enables it to match well with other perovskite-structured film materials and become an excellent substrate material. In addition, the phonon energy of GdScO3 crystal is relatively low (452 cm -1 ), much lower than that of other oxide crystals (such as YAP, SRA, etc.). This characteristic can effectively inhibit the non-radiative transition caused by multi-phonon relaxation, thereby significantly improving the output efficiency of near-infrared lasers. At the same time, the high disorder of GdScO3 crystal helps to achieve a wide gain spectrum and ultrafast laser output, while its high refractive index (2.1103) can reduce the thermo-optic birefringence phenomenon under high pump energy and reduce the loss. Therefore, GdScO3 crystal is not only an excellent substrate material but also a laser material with broad development prospects.

[0004] Doping tetravalent ion Zr 4+ in GdScO3 crystal has important scientific significance and application potential. The ionic radius of Zr 4+ is similar to that of Sc 3+ , which can effectively reduce lattice distortion, enhance the stability of the crystal structure, and at the same time inhibit the formation of defects such as oxygen vacancies, thereby improving the crystal quality. In addition, Zr 4+ doping can adjust the carrier concentration, optimize the conductivity and dielectric properties of the material, and make it show more excellent electrical properties in electronic devices. In terms of optical properties, Zr 4+Doping can regulate the bandgap of crystals, improve light absorption and emission characteristics, enhance the luminescence efficiency, and provide potential advantages for the application of optoelectronic devices. In terms of thermal properties, Zr 4+ doping can adjust the thermal expansion coefficient and thermal conductivity, enhance the stability of the material in high-temperature environments, and make it more suitable for use in high-temperature devices. Generally speaking, Zr 4+ doping not only significantly improves the structural, electrical, optical, and thermal properties of GdScO3 crystals, but also opens up new possibilities for their applications in capacitors, sensors, lasers, LEDs, and high-temperature materials, etc., having important research value and technical prospects. Patent CN114108072B discloses a rare-earth ion-doped GdScO3 sesquioxide laser crystal that can be used as a gain medium for solid-state lasers in the infrared band, relating to the technical field of laser crystal gain materials; this crystal can grow single crystals by the melt method and has a low phonon energy (452 cm -1 and a wide fluorescence spectrum (~100 nm). After doping with Yb 3+ , Tm 3+ , Ho 3+ and other rare-earth activating ions, it is expected to achieve high-power, tunable continuous laser and ultrashort pulse laser output in the 1μm and 2μm bands; the crystal growth method provided by this invention can grow high-quality single crystals, and the all-solid-state infrared-band laser fabricated has characteristics such as wavelength tunability and ultrashort pulse width, having a wide range of applications. Patent CN116163018A relates to a thulium-doped gadolinium scandate near-infrared laser crystal and its preparation method and application. The chemical formula of this crystal is Tm x Gd 1-x ScO3, where the value range of x is 0.001~0.05, its space group is Pnma, orthorhombic system, and the unit cell parameters are a = 5.487, b = 5.756, c = 7.925. The laser crystal of this invention can efficiently achieve near-infrared laser output in the vicinity of 1.5μm and 2.3μm, and can be applied to laser medicine, environmental monitoring, and as an optical parametric oscillation (OPO) pump source to achieve near-infrared laser output and other fields.

[0005] However, at present, there is no report on the growth and spectral properties of Tm 3+ and Zr 4+ co-doped GdScO3 crystals. Therefore, developing a thulium-zirconium co-doped gadolinium scandate (Tm,Zr:GdScO3) near-infrared laser crystal and exploring its application in lasers have important innovative significance and practical value. This crystal material is expected to achieve high-performance output in the field of near-infrared lasers, providing new solutions for applications such as medical treatment, military, and communication detection. Summary of the Invention

[0006] The object of the present invention is to overcome the defects existing in the above-mentioned prior art, and to provide a thulium-zirconium co-doped gadolinium scandate near-infrared laser crystal, a preparation method and an application thereof, so as to achieve near-infrared laser output in the vicinity of 1.5μm and 2.3μm.

[0007] The object of the present invention can be achieved by the following technical solutions:

[0008] One of the technical solutions of the present invention provides a thulium-zirconium co-doped gadolinium scandate near-infrared laser crystal, and the chemical composition of the crystal is expressed as Tm x Zr y Gd 1-x Sc 1-y O3, that is, Tm ions and Zr ions are simultaneously doped in gadolinium scandate (GdScO3), wherein the value range of x is 0.001≤x≤0.05, the value range of y is 0.005≤y≤0.05, its space group is Pnma, orthorhombic system, and it belongs to a compound with a perovskite-like structure, having a low phonon energy (452cm -1 ), and a relatively high melting point (2150°C).

[0009] Preferably, the value range of x is 0.001≤x≤0.01, and the value range of y is 0.005≤y≤0.05.

[0010] More preferably, x is 0.005, and the value range of y is 0.01≤y≤0.03.

[0011] Compared with other rare earth ions, the absorption energy of Tm 3+ ions in the 1.5μm and 2.3μm bands matches the common pump, and the relatively wide gain bandwidth enables the laser to have tunable capabilities. Tm 3+ ions are formed by the loss of one electron from the 4f electron layer and two electrons from the 6s electron layer of a Tm atom (outer electron distribution 4f 13 6s 2 ). The main absorption band of Tm 3+ ions corresponds to 3 H6→ 3 H4 transition, with a wavelength of around 800nm, which is very consistent with the emission wavelength of a GaAsAl laser diode. Therefore, a high-power GaAsAl laser can be used as a pump source for a Tm 3+ ion-doped laser medium. The main luminescence of Tm 3+ ions in the near-infrared band are as follows: the transitions corresponding to 1.5μm, 2μm, and 2.3μm are 3 H4→ 3 F4, 3 F4→ 3 H6, 3 H4→3 H5。

[0012] The second technical solution of the present invention provides a method for preparing the above-mentioned thulium-zirconium co-doped gadolinium scandate near-infrared laser crystal. The crystal is grown by the guided-mode method, and the specific steps are as follows:

[0013] (1) According to the stoichiometric ratio in Tm x Zr y Gd 1-x Sc 1-y O3, weigh the raw materials of Tm2O3, ZrO2, Gd2O3 and Sc2O3, grind and mix them evenly to obtain a mixed raw material;

[0014] (2) Compact the mixed raw material obtained in step (1), then sinter the compacted mixed raw material, and then load it into a crucible;

[0015] (3) Place the crucible of step (2) into a guided-mode furnace, fix the GdScO3 seed crystal in the seed crystal rod fixture, evacuate, and then fill with an inert gas, and heat up to ensure that all the raw materials in the crucible are melted;

[0016] (4) Keep the temperature for a period of time, and grow the crystal by the guided-mode method; after the crystal growth is completed, cool down to room temperature, take out the crystal to obtain the above-mentioned thulium-zirconium co-doped gadolinium scandate near-infrared laser crystal.

[0017] Furthermore, the raw materials of Tm2O3, ZrO2, Gd2O3 and Sc2O3 in step (1) are in the state of single crystal particles or powders, and the purity is 5N;

[0018] Furthermore, the grinding in step (1) is carried out in an agate mortar, and the grinding time is 60-120 min.

[0019] Furthermore, the pressure of the compaction in step (2) is 1.5-2.5 MPa, preferably 2 MPa; the sintering temperature is 1400-1600 °C, preferably 1500 °C; the sintering time is more than 24 hours.

[0020] Furthermore, the heating rate in step (3) is 300-400 °C / h, and the temperature is raised to 2100-2300 °C; preferably, the temperature is raised to 2200 °C at a rate of 350 °C / h.

[0021] Furthermore, the inert gas in step (3) is preferably high-purity argon;

[0022] Furthermore, the evacuation in step (3) is preferably carried out by a mechanical pump, and the vacuum is pumped to below 8 Pa.

[0023] Further, the temperature for heat preservation (i.e., crystal growth) in step (4) is 2100 - 2300 °C, preferably 2200 °C;

[0024] Further, the cooling time in step (4) is more than 24 hours.

[0025] The third technical solution of the present invention provides an application of the above-mentioned thulium-zirconium co-doped gadolinium scandate near-infrared laser crystal. The laser crystal is used as a gain medium to achieve near-infrared laser output near 1.5 μm and 2.3 μm.

[0026] Compared with the prior art, the present invention has the following advantages:

[0027] 1. The crystal material of the present invention can achieve efficient near-infrared laser output near 1.5 μm and 2.3 μm. Near-infrared lasers have important applications in medical, military, communication detection, etc. They cover 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 community, industrial community, and military community;

[0028] 2. The matrix phonon energy of the present invention is low (452 cm -1 ), and the output power is high. By co-doping Zr 4+ ions, the fluorescence at 1.5 μm and 2.3 μm is enhanced;

[0029] 3. The present invention only dopes Tm 3+ ions and Zr 4+ ions in the matrix GdScO3. The types of raw materials are few and the cost is low. Compared with Tm-Ho co-doping, near-infrared laser output near 1.5 μm and 2.3 μm can be achieved simultaneously

[0030] 4. The present invention can be applied to fields such as laser medical treatment, environmental monitoring, and realizing the output of near-infrared lasers as an optical parametric oscillation (OPO) pump source, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is the X-ray powder diffraction pattern of the sample prepared in Example 1 of the present invention;

[0032] Figure 2 is the room-temperature absorption coefficient spectrum of the sample prepared in Example 1 of the present invention;

[0033] Figure 3 is the room-temperature fluorescence spectrum of the samples prepared in Examples 1 - 3 and Comparative Example 1 of the present invention;

[0034] [[ID=%]] Figure 4 is the sample prepared in Example 1 of the present invention under 808 nm light excitation, 3 H4(a) and3 Fluorescence lifetime spectra corresponding to the F4(b) energy level;

[0035] Figure 5 These are fluorescence lifetime spectra corresponding to the H4(a) and 3 H4(a) and 3 F4(b) energy levels of the sample prepared in Example 2 of the present invention under 808 nm light excitation;

[0036] Figure 6 These are fluorescence lifetime spectra corresponding to the H4(a) and 3 H4(a) and 3 F4(b) energy levels of the sample prepared in Example 3 of the present invention under 808 nm light excitation;

[0037] Figure 7 These are fluorescence lifetime spectra corresponding to the H4(a) and 3 H4(a) and 3 F4(b) energy levels of the sample prepared in Comparative Example 1 of the present invention under 808 nm light excitation. Detailed implementation manners

[0038] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be described in detail below with reference to specific embodiments. It should be noted that the following embodiments will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be pointed out that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made. These all belong to the protection scope of the present invention.

[0039] There are no special restrictions on the sources of all raw materials of the present invention, and those purchased on the market or prepared according to the conventional methods well-known to those skilled in the art are all acceptable.

[0040] Example 1

[0041] This example provides a Tm 0.02 Zr 0.03 Gd 0.98 Sc 0.97 O3 crystal. The initial raw materials of this crystal are polycrystalline powders of Tm2O3, ZrO2, Gd2O3, and Sc2O3 with 5N purity. After selecting specific concentrations of Tm ions to dope and replace Gd ions, and Zr ions to dope and replace Sc ions, the mass of each raw material required is calculated according to the chemical formula Tm 0.02 Zr 0.03 Gd 0.98 Sc 0.97 O3, and accurately weighed, and then grown to obtain the crystal. The specific steps are as follows:

[0042] (1) According to the stoichiometric ratio, weigh the single crystal particles of Tm2O3, ZrO2, Gd2O3, and Sc2O3 with a purity of 5N, and then use an agate mortar to grind and mix them evenly; the total mass of the above raw materials is 250 g;

[0043] (2) Compress the mixed raw materials under a pressure of 2 MPa, then sinter the compressed raw materials at 1500 °C for 24 h, and then load them into a crucible;

[0044] (3) Place the crucible in a guided mold furnace, fix the GdScO3 seed crystal in the seed crystal rod fixture, evacuate to below 8 Pa, and then fill it with high-purity argon gas, and heat it to 2200 °C at a rate of 350 °C / h to ensure that all the raw materials in the crucible are melted;

[0045] (4) Lower the GdScO3 seed crystal to contact the melt at the top of the mold (i.e., the melted raw materials in step (3)), after seeding and necking down, the pulling speed is 3 mm / h, and when the crystal fills up to the width of the mold, carry out equal-diameter growth;

[0046] (5) Grow the crystal by the guided mold method, after the growth is completed, cool it down to room temperature, and the cooling time is not less than 24 hours, then take out the crystal to obtain Tm 0.02 Zr 0.03 Gd 0.98 Sc 0.97 O3 crystal.

[0047] As Figure 1 shown is the X-ray powder diffraction pattern of the prepared Tm 0.02 Zr 0.03 Gd 0.98 Sc 0.97 O3 sample. It can be seen that the co-doped GdScO3 of Tm and Zr is still a pure GdScO3 single crystal phase. The characteristic diffraction peaks of the sample provided in Example 1 in the pattern are highly consistent with the database card of the standard GdScO3 single crystal phase, and no additional diffraction peaks belonging to other impurity phases appear. This strongly proves that in this doping system, the lattice structure maintains the singularity of GdScO3 and the crystal structure integrity is good.

[0048] As Figure 2 shown is the prepared Tm 0.02 Zr 0.03 Gd 0.98 Sc 0.97The room-temperature absorption coefficient spectrum of the Tm 0.02 Zr 0.03 Gd 0.98 Sc 0.97 O3 sample shows a very good match with the emission wavelength of the GaAsAl laser diode, as can be seen from the curve trend and the distribution of absorption peaks in the figure. In the range of 750 - 850 nm, the sample exhibits significant absorption characteristics. The position of the absorption peak corresponds precisely to the main emission wavelength of the GaAsAl laser diode in this band, and the peak absorption coefficient at 793 nm has a very high matching degree with the diode emission intensity. This excellent fit means that the Tm 0.02 Zr 0.03 Gd 0.98 Sc 0.97 O3 sample can achieve effective energy conversion with the GaAsAl laser diode in terms of light absorption. When their spectra are aligned, the photoelectric conversion efficiency can be greatly improved, effectively avoiding energy loss and thermal effects, providing strong support for the construction of efficient optoelectronic devices. 0.02 Zr 0.03 Gd 0.98 Sc 0.97 As shown in

[0049] is the room-temperature fluorescence spectrum of the prepared Tm 0.02 Zr 0.03 Gd 0.98 Sc 0.97 O3 sample. It can be seen that after co-doping with Zr ions, the emission at 1.5 μm and 2.3 μm in the crystal is enhanced, while the emission at 2 μm is weakened. The emission cross-section at 1464 nm calculated by the following formula (Eq.1) is 1.05×10 Figure 3 As shown in 0.02 Zr 0.03 Gd 0.98 Sc 0.97 O3 sample. It can be seen that after co-doping with Zr ions, the emission at 1.5 μm and 2.3 μm in the crystal is enhanced, while the emission at 2 μm is weakened. The emission cross-section at 1464 nm calculated by the following formula (Eq.1) is 1.05×10 -20 cm 2 , and the full width at half maximum (FHWM) is 85.12 nm; the emission cross-section at 2 μm decreases to 0.64×10 -20 cm 2 . The above results indicate that the incorporation of Zr ions improves the fluorescence emission characteristics of Tm ions, enhances the emission ability in the infrared band, and may simultaneously lead to an increase in non-radiative transitions in the 2-μm band, thus suppressing the corresponding emission performance.

[0050]

[0051] As shown in Figure 4 is the fluorescence lifetime spectrum of the prepared Tm 0.02 Zr 0.03 Gd 0.98 Sc 0.97 O3 sample under 808-nm light excitation. 0.02 Zr 0.03 Gd 0.98 Sc 0.97 O3 sample under 808-nm light excitation. 3 H4 and 3 F4 energy level corresponding fluorescence lifetime spectrum. It can be seen that the lifetime of the sample 3 H4 energy level is 320 μs, 3 F4 energy level is 4.71 ms. The above results indicate that Tm ions in 3The long fluorescence lifetime of the H4 energy level indicates its strong radiative transition ability and low non-radiative conversion probability, which is consistent with the potential advantages shown in optoelectronic applications. At the same time, the short 3 lifetime of the F4 energy level is very beneficial to the laser output at 1.5 μm and 2.3 μm.

[0052] Example 2

[0053] This example provides a Tm 0.02 Zr 0.02 Gd 0.98 Sc 0.98 O3 crystal. The initial raw materials of this crystal are polycrystalline powders of Tm2O3, ZrO2, Gd2O3, and Sc2O3 with a purity of 5N. After selecting specific concentrations of Tm ions to dope and replace Gd ions, and Zr ions to dope and replace Sc ions, according to the chemical formula Tm 0.02 Zr 0.02 Gd 0.98 Sc 0.98 O3, calculate the required mass of each raw material and accurately weigh it, and then grow to obtain the crystal, which specifically includes the following steps:

[0054] (1) According to the stoichiometric ratio, weigh the single crystal powders of Tm2O3, ZrO2, Gd2O3, and Sc2O3 with a purity of 5N, and then use an agate mortar to fully grind and mix them evenly; the total mass of the above several raw materials is 250 g;

[0055] (2) Compact the mixed raw materials under a pressure of 1.5 MPa, then sinter the compacted raw materials at 1400 °C for 30 h, and then load them into a crucible;

[0056] (3) Put the crucible into a guiding mold furnace, fix the GdScO3 seed crystal in the seed crystal rod fixture, evacuate to below 8 Pa, and then fill it with high-purity argon gas, and heat it to 2100 °C at a rate of 300 °C / h to ensure that all the raw materials in the crucible are melted;

[0057] (4) Lower the GdScO3 seed crystal to contact the melt at the top of the mold (i.e., the melted raw materials in step (3)), after seeding and necking down, the pulling speed is 4 mm / h, and when the crystal fills up to the width of the mold, carry out equal-diameter growth;

[0058] (5) Grow the crystal by the guiding mold method. After the growth is completed, cool it down to room temperature. The cooling time is not less than 24 hours, take out the crystal, and obtain the Tm 0.02 Zr 0.02 Gd 0.98 Sc 0.98 O3 crystal.

[0059] As Figure 3 shown, the prepared Tm 0.02 Zr0.02 Gd 0.98 Sc 0.98 The emission of O3 crystal at 1.5μm and 2.3μm is enhanced, while that at 2μm is weakened. The emission cross section at 1465nm is calculated by formula (Eq.1) to be 0.87×10 -20 cm 2 , FHWM is 89.63nm; the emission cross section at 2μm is reduced to 0.68×10 -20 cm 2 The above results show that the optimization of zirconium ion doping significantly improves the excitation emission characteristics of the sample in the 1.5μm and 2.3μm bands, demonstrating its application potential at these wavelengths.

[0060] like Figure 5 Shown is the Tm of the preparation 0.02 Zr 0.02 Gd 0.98 Sc 0.98 The O3 sample was excited by 808nm light. 3 H4 and 3 The fluorescence lifetime spectrum corresponding to the F4 energy level shows that the sample 3 The lifetime of the H4 level is 329μs. 3 The lifetime of F4 energy level is 5.22ms. The above results show that: 3 The H4 level has a long fluorescence lifetime, indicating that the Tm ion 3 The long lifetime of the H4 level indicates its high radiative transition capability, giving it good performance potential in laser and optoelectronic applications, and is beneficial for Tm ion lasing at 1.5μm and 2.3μm.

[0061] Example 3

[0062] This embodiment provides a Tm 0.02 Zr 0.01 Gd 0.98 Sc 0.99 O3 crystal, the initial raw material of the crystal is 5N purity Tm2O3, ZrO2, Gd2O3, Sc2O3 polycrystalline powder, after selecting a specific concentration of Tm ion doping to replace Gd ion, Zr ion doping to replace Sc ion, according to the chemical formula Tm 0.02 Zr 0.01 Gd 0.98 Sc 0.99 O3 calculates the required mass of each raw material and weighs it accurately, grows it, and obtains crystals, specifically including the following steps:

[0063] (1) Weigh single crystal particles of Tm2O3, ZrO2, Gd2O3, and Sc2O3 with a purity of 5N according to the stoichiometric ratio, and then use an agate mortar to grind and mix them evenly; the total mass of the above raw materials is 250 g;

[0064] (2) Compact the mixed raw materials under a pressure of 2.5 MPa, then sinter the compacted raw materials at 1600 °C for 24 h, and then load them into a crucible;

[0065] (3) Place the crucible in a guide mold furnace, fix the GdScO3 seed crystal in the seed crystal rod fixture, evacuate to below 8 Pa, and then fill it with high-purity argon gas. Heat it to 2100 °C at a rate of 300 °C / h to ensure that all the raw materials in the crucible are melted;

[0066] (4) Lower the GdScO3 seed crystal to contact the melt at the top of the mold (i.e., the melted raw materials in step (3)). After seeding and necking down, the pulling speed is 3 mm / h. When the crystal fills up to the width of the mold, carry out equal-diameter growth;

[0067] (5) Grow the crystal by the guide mold method. After the growth is completed, cool it down to room temperature. The cooling time is not less than 24 hours, and then take out the crystal to obtain Tm 0.02 Zr 0.01 Gd 0.98 Sc 0.99 O3 crystal.

[0068] As Figure 3 shown, the prepared Tm 0.02 Zr 0.01 Gd 0.98 Sc 0.99 O3 crystal has enhanced emission at 1.5 μm and 2.3 μm and weakened emission at 2 μm. The emission cross-section at 1465 nm calculated by the formula (Eq. 1) is 0.94×10 -20 cm 2 , and the FHWM is 90.68 nm; the emission cross-section at 2 μm decreases to 1.07×10 -20 cm 2 . The above results show that the doping of Zr ions has a significant impact on the optical properties of Tm ions in the infrared band, especially the emission performance at 1.5 μm and 2.3 μm is improved, which is suitable for applications such as lasers and optical amplifiers.

[0069] As Figure 6 shown is the fluorescence lifetime spectra corresponding to the H4 and 0.02 Zr 0.01 Gd 0.98 Sc 0.99 O3 sample under 808 nm optical excitation. 3 H4 and 3 F4 energy levels. It can be seen that the sample3 The lifetime of the H4 energy level is 220 μs, 3 and the lifetime of the F4 energy level is 5.32 ms. The above results indicate that: in this sample 3 the H4 energy level has a relatively long fluorescence lifetime, indicating that the excited state of Tm ions can effectively retain energy, support strong radiative transitions, and thus is beneficial for efficient infrared luminescence applications.

[0070] Comparative Example 1

[0071] This example provides a Tm 0.02 Gd 0.98 ScO3 crystal. The initial raw materials of this crystal are polycrystalline powders of Tm2O3, Gd2O3, and Sc2O3 with a purity of 5N. After selecting a specific concentration of Tm ion doping to replace Gd ions, the mass of each raw material required is calculated according to the chemical formula Tm 0.02 Gd 0.98 ScO3 and accurately weighed, and then grown to obtain the crystal. The specific steps are as follows:

[0072] (1) According to the stoichiometric ratio, single crystal particles of Tm2O3, Gd2O3, and Sc2O3 with a purity of 5N are weighed and then thoroughly ground and mixed evenly using an agate mortar; the total mass of the above several raw materials is 250 g;

[0073] (2) The mixed raw materials are compacted under a pressure of 2.5 MPa, and then the compacted raw materials are sintered at 1600 °C for 24 h and then loaded into a crucible;

[0074] (3) The crucible is placed in a guiding mold furnace, and the GdScO3 seed crystal is fixed in the seed crystal rod fixture. After evacuating to below 8 Pa, high-purity argon is filled, and the temperature is raised to 2100 °C at a rate of 300 °C / h to ensure that all the raw materials in the crucible are melted;

[0075] (4) Lower the GdScO3 seed crystal to contact the melt at the top of the mold (i.e., the melted raw materials in step (3)). After seeding and necking down, the pulling speed is 3 mm / h. After the crystal fills up to the width of the mold, isodiametric growth is carried out;

[0076] (5) The crystal is grown by the guiding mold method. After the growth is completed, it is cooled to room temperature, and the cooling time is not less than 24 hours. The crystal is taken out to obtain the Tm 0.02 Gd 0.98 ScO3 crystal.

[0077] As Figure 3 shown, the prepared Tm 0.02 Gd 0.98 ScO3 crystal emits weakly at 1.5 μm and 2.3 μm and strongly at 2 μm. The emission cross-section at 1465 nm is calculated by formula (Eq.1) to be 0.83×10-20 cm 2 The full width at half maximum (FHWM) is 60.22 nm; the emission cross-section at 2 μm is 1.33×10 -20 cm 2 .

[0078] As Figure 7 shown is the fluorescence lifetime spectra corresponding to the 0.02 H4 and 0.98 F4 energy levels of the prepared Tm 3 Gd 3 ScO3 sample under 808 nm optical excitation. It can be seen that the lifetime of the 3 H4 energy level of the sample is 80.98 μs, and the lifetime of the 3 F4 energy level is 5.84 ms. The above results indicate that the emission cross-section and lifetime of this crystal at 2 μm are relatively strong, which is not conducive to the laser output at 1.5 μm and 2.3 μm. It is necessary to further adjust the material composition and structural design to optimize the performance in the 1.5 μm and 2.3 μm wavelength bands.

[0079] The above description of the embodiments is to enable those of ordinary skill in the art to understand and use the invention. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative efforts. Therefore, the present invention is not limited to the above embodiments, and the improvements and modifications made by those skilled in the art without departing from the scope of the present invention should be within the protection scope of the present invention.

Claims

1. A thulium- and zirconium-codoped gadolinium scandate near-infrared laser crystal, characterized in that, The chemical composition of the crystal is expressed as Tm x Zr y Gd 1-x Sc 1-y O3, where the value range of x is 0.001 ≤ x ≤ 0.05, the value range of y is 0.005 ≤ y ≤ 0.05, and its space group is Pnma, orthorhombic system.

2. A thulium-zirconium co-doped gadolinium scandate near-infrared laser crystal according to claim 1, characterized in that, The value range of x is 0.001 ≤ x ≤ 0.01, and the value range of y is 0.005 ≤ y ≤ 0.

05.

3. A thulium-zirconium co-doped gadolinium scandate near-infrared laser crystal according to claim 2, characterized in that, The value of x is 0.005, and the value range of y is 0.01 ≤ y ≤ 0.

03.

4. A method for preparing a thulium-zirconium co-doped gadolinium scandate near-infrared band laser crystal as described in any one of claims 1 to 3, characterized in that, The preparation method uses the edge-defined film-fed growth (EFG) method to grow crystals, and the method specifically includes the following steps: (1) According to the stoichiometric ratio of Tm x Zr y Gd 1-x Sc 1-y in O3, weigh the raw materials of Tm2O3, ZrO2, Gd2O3 and Sc2O3, grind them thoroughly and mix them evenly to obtain the mixed raw materials; (2) Compact the mixed raw materials obtained in step (1), then sinter the compacted mixed raw materials, and then load them into a crucible; (3) Place the crucible of step (2) into an EFG furnace, fix the GdScO3 seed crystal in the seed crystal rod clamp, evacuate, and then fill with an inert gas, and raise the temperature to ensure that all the raw materials in the crucible are melted; (4) Keep the temperature for a period of time, and grow crystals by the EFG method; after crystal growth is completed, cool down to room temperature, take out the crystals, and obtain the thulium-zirconium co-doped gadolinium scandate near-infrared band laser crystal.

5. The preparation method of the thulium-zirconium co-doped gadolinium scandate near-infrared laser crystal according to claim 4, characterized in that, The states of the Tm2O3, ZrO2, Gd2O3, and Sc2O3 raw materials in step (1) are single crystal particles or powders, and the purity is 5N purity.

6. The preparation method of the thulium-zirconium co-doped gadolinium scandate near-infrared band laser crystal according to claim 4, characterized in that, The grinding time in step (1) is 60 - 120 min.

7. The preparation method of the thulium-zirconium co-doped gadolinium scandate near-infrared laser crystal according to claim 4, characterized in that, The pressure for compaction in step (2) is 1.5 - 2.5 MPa, the sintering temperature is 1400 - 1600 °C, and the sintering time is more than 24 hours.

8. The preparation method of the thulium-zirconium co-doped gadolinium scandate near-infrared laser crystal according to claim 4, characterized in that, The heating rate in step (3) is 300 - 400 °C / h, the inert gas is high-purity argon; the evacuation is to evacuate to below 8 Pa.

9. The preparation method of the thulium-zirconium co-doped gadolinium scandate near-infrared band laser crystal according to claim 4, wherein, The temperature for heat preservation in step (4) is 2100 - 2300 °C, during the heat preservation process, crystal growth occurs; the cooling time is more than 24 hours.

10. Application of a thulium-zirconium co-doped gadolinium scandate near-infrared band laser crystal as described in any one of claims 1 to 3, characterized in that, The laser crystal is used as a gain medium to achieve near-infrared band laser output at 1.5 μm and 2.3 μm.

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