Rare earth fluoride laser crystal doped with trivalent luminous ions regulated and controlled by divalent alkaline earth ions as well as preparation and application of rare earth fluoride laser crystal

Abstract

The invention relates to a rare earth fluoride laser crystal doped with trivalent luminous ions regulated and controlled by divalent alkaline earth ions as well as preparation and application of the rare earth fluoride laser crystal. The laser crystal is expressed as xR, yMe: MF3, 0.001 < = x < = 0.3, and 0.01 < = y < = 0.2; r, Me, and M each represent a metal element, R is at least one of Nd, Pr, Er, Tm, Ho, Dy, or Eu, Me is at least one of Mg, Ca, Sr, or Ba, and M is at least one of Y, Lu, Sc, Gd, or La. The laser crystal grows by adopting a temperature gradient method and comprises the following steps: weighing RF3, MeF2 and MF3 raw materials, uniformly mixing, putting into a crucible, and grinding; and slowly cooling and growing in a vacuum atmosphere to obtain the rare earth fluoride laser crystal. The laser crystal can accelerate the application process of continuous and ultrafast laser in a new visible light wave band, shows a very wide fluorescent band and a new emission wavelength in visible orange red light and deep red light wave bands, can solve the problem that the fluorescent band of the existing praseodymium ion doped laser crystal is narrow, and promotes the development of the new visible light wave band.

Description

Technical Field

[0001] The present invention relates to the technical field of laser materials, and particularly relates to a divalent alkaline earth ion-regulated rare earth fluoride laser crystal doped with trivalent luminescent ions, and its preparation and application. Background Art

[0002] Visible light band lasers have significant application requirements in fields such as display, communication, sodium beacon, biomedicine, atomic optical clock, high-end manufacturing, etc. The emergence of high-efficiency blue light pump sources (such as InGaN laser diodes and frequency-doubled optical pump semiconductor lasers (2ω-OPSL)) has greatly promoted the development of visible light band laser output in rare earth ion-doped media. Currently, visible light rare earth ions mainly focus on Pr 3+ , Dy 3+ , Tb 3+ and Sm 3+ etc. Among them, the absorption cross-sections of Pr 3+ ions at 445 nm, 468 nm, and 486 nm reach the order of 10 -19 cm 2 . The fluorescence lifetime of the P0 upper energy level is about several tens of microseconds. Among them, the absorption peak at 445 nm is very consistent with the emission wavelength of the InGaN laser diode pump source, and the absorption peak at 468 nm is very consistent with the emission wavelength of the 2ω-OPSLs pump source. Compared with other rare earth ions, Pr 3 has a large number of radiative transitions, and the emission range almost covers red, orange, green, and blue light in the visible light band. The all-solid-state continuous laser output of Pr:LiYF4 has reached nearly 10 W, and the highest laser output slope efficiency is as high as 60%. Pr:LiYF4 in the 639 nm band was the first to obtain practical applications. Therefore, Pr 3+ doped laser materials are currently the most promising visible light band laser materials. 3+ 3+

[0003] The inventor's previous patents have provided some related visible light band laser materials. For example:

[0004] Patent CN115102022A relates to a praseodymium ion-doped calcium lithium fluoroaluminate type visible light band ultrafast laser crystal, its growth method and application. The chemical formula of this ultrafast laser crystal is Pr x LiM 1-xNF6, where the range of x is 0.003 - 0.03, M is at least one or a combination of two of Mg, Ca, Sr or Ba, and N is at least one of Al, Sc or Ga. It is grown by the Bridgman method, including the following steps: weighing PrF3, LiF, MF and NF raw materials according to the stoichiometric ratio, mixing them evenly, and then loading them into a crucible; placing the crucible in an inert atmosphere, heating to melt the materials and removing impurities, and then lowering the temperature for growth. After the growth is completed, it is cooled to room temperature to obtain a praseodymium ion-doped fluoroaluminocalcium lithium type visible-band ultrafast laser crystal; this ultrafast laser crystal is applied to accelerate the visible-band all-solid-state femtosecond ultrafast laser; this application exhibits a very wide fluorescence band in the visible orange-red and deep-red wavelength bands, which can solve the problem of narrow fluorescence bands of praseodymium ion-doped laser crystals. Patent CN116145254A provides a rare-earth ion-doped disordered high-entropy fluoride ultrafast laser crystal and its preparation method and application. The disordered high-entropy laser crystal is represented by Pr:CaSrBaF6, Pr:M1M2CaSrBaF 12 and Pr:M1M2CaSrBaF 12 where the doping range of praseodymium (Pr) ions is 0.003 - 0.05 (M1, M2 are one of trivalent non-luminescent ions such as Y, La, Lu, Gd, Sc, etc.). The doped rare-earth luminescent ions are not limited to Pr ions, but may also include other luminescent ions such as Yb, Nd, Er, Ho, Tm, Dy, Tb, etc. Taking Pr:CaSrBaF6, Pr:M1M2CaSrBaF 12 crystals as representatives, compared with other fluorides, they have a more disordered local structure, which can achieve 3 H6 and 3 F2, 3 F3 and 3 F4 to merge and overlap the lower energy levels, achieving the effect of overlapping and inhomogeneous broadening of the fluorescence spectrum; the crystal material of this application can achieve the ultra-wideband emission in the visible wavelength band of praseodymium ion-doped laser crystals, solve the problem of narrow fluorescence bands of current praseodymium ion-doped laser crystals, and accelerate the research and development of visible-band all-solid-state femtosecond ultrafast lasers and their applications in biomedicine and optical communication.

[0005] Currently, ultrafast pulsed lasers have characteristics such as ultrashort response time and high peak power, which are obviously the next development focus of visible-wavelength lasers. However, currently, the fluorescence spectra of each visible light channel of Pr 3+ -doped laser crystals are generally narrow (the full width at half maximum FWHM is about 0.7 - 3 nm), so it is difficult to achieve LD-pumped all-solid-state femtosecond ultrafast lasers. This bottleneck problem also seriously restricts the commercialization process of visible-wavelength femtosecond lasers. Summary of the Invention

[0006] The object of the present invention is to overcome the defects of the above-mentioned existing technologies and provide a divalent alkaline earth ion-regulated rare earth fluoride laser crystal doped with trivalent luminescent ions and its preparation and application.

[0007] The divalent alkaline earth ion-regulated praseodymium ion-doped rare earth fluoride laser crystal material provided by the present invention exhibits a very wide fluorescence band in the visible orange-red and deep red light bands under the excitation of a blue light diode. This material can solve the problem of the narrow fluorescence band of the currently praseodymium ion-doped laser crystal and can accelerate the research and application process of all-solid-state femtosecond ultrafast lasers in the visible band.

[0008] Rare earth fluorides can achieve large-size growth, have a weak lattice field, low phonon energy, and are also suitable as matrix materials doped with Pr 3+ ions. Taking LaF3 as representative, the melting point of the LaF3 crystal is 1493 °C. The lanthanum fluoride crystal is hexagonal, and the space group is P63 / mcm. La 3+ forms a 9-coordinated polyhedron with the surrounding F - ions. The rare earth ion spacing is large. This crystal has a weak lattice field and low phonon energy. In addition, LaF3 exhibits significant anisotropic characteristics, and there are large differences in the absorption and fluorescence spectra in different polarization directions. It can be seen that lasers with different wavelengths, different output powers, and slope efficiencies can be achieved in different polarization directions of the LaF3 crystal. Since the 1970s, LaF3 has been used as an excellent laser crystal matrix material, and the spectra and laser characteristics of lanthanum fluoride crystals doped with different rare earth ions have also been reported in large numbers. However, the research on Pr 3+ ion-doped LaF3 is less. Currently, laser outputs have only been obtained at two bands of orange light at 598.5 nm and deep red light at 718 nm, and the output power and slope efficiency are generally low. Therefore, it is very necessary to carry out co-doping of Pr 3+ ions and hetero-valence regulating ions in LaF3 crystals to achieve spectral performance regulation and high-efficiency laser output in other bands.

[0009] The object of the present invention can be achieved by the following technical solutions:

[0010] One of the technical solutions of the present invention provides a divalent alkaline earth ion-regulated rare earth fluoride laser crystal doped with trivalent luminescent ions. The chemical composition of the laser crystal is expressed as xR,yMe:MF3, where the range of x is 0.001 ≤ x ≤ 0.3, and the range of y is 0.01 ≤ y ≤ 0.2; R, Me, and M all represent metal elements. Among them, R is a rare earth metal, selected from at least one of Nd, Pr, Er, Tm, Ho, Dy, or Eu, Me is at least any one of Mg, Ca, Sr, or Ba, and M is at least any one of Y, Lu, Sc, Gd, or La.

[0011] Further, R is preferably Pr, Me is preferably Sr, and M is preferably La. More preferably, the chemical formula of the laser crystal is xPr,ySr:LaF3, where the range of x is 0.001 ≤ x ≤ 0.3, and the range of y is 0.01 ≤ y ≤ 0.2; more preferably, the chemical formula of the laser crystal is preferably 0.6% Pr, 5% Sr:LaF3.

[0012] The LaF3 crystal belongs to the tetragonal crystal system. In addition to having a low phonon energy and a high 5d energy level position, it can greatly reduce the non-radiative transition probability caused by multi-phonon relaxation and the excited state absorption of the laser upper energy level caused by the low 5d energy level position. The inventors noticed that the two lower energy levels of Pr 3+ ions 3 H6 and 3 F2, 3 F3 and 3 F4 energy level positions are very close. For example, in the LiYF4 matrix, 3 H6 and 3 F2 and 3 F3 and 3 F4 energy level differences are 255 cm -1 and 232 cm -1 . respectively. By substituting trivalent La 2+ ions with divalent alkaline earth ions Me 3+ (Me = Mg, Ca, Sr, Ba), with the incorporation of Sr 2+ ions, the local symmetry is lower, the lattice distortion is more serious, the energy level splitting is larger, the local disorder is enhanced, and a truly formed La 3+ / Sr 2+ -Pr 3+ disordered distribution of the mixed composite fluoride is achieved, thereby realizing 3 the merging and overlapping of H6 and 3 F2, 3 F3 and 3 F4 adjacent lower energy levels, achieving the effect of overlapping and inhomogeneous broadening of the fluorescence spectrum. Thus, the key scientific problem of the narrow fluorescence spectrum (FWHM 0.7 - 3 nm at half peak width) of the existing Pr-doped 3+ crystals is solved. Combining with the research of femtosecond laser technology in the visible light band, it is expected to achieve all-solid-state femtosecond ultrafast laser output.

[0013] The second technical solution of the present invention provides a preparation method of a rare earth fluoride laser crystal doped with trivalent luminescent ions regulated by divalent alkaline earth ions. The crystal is grown by the temperature gradient method, including the following steps:

[0014] (1) Material preparation: Weigh the raw materials of RF3, MeF2, and MF3 according to the stoichiometric ratio, mix them evenly, then load them into the crucible and grind.

[0015] (2) Crystal growth: Place the crucible in a high-vacuum atmosphere, heat to melt the materials and remove impurities, and then start a slow cooling process for crystal growth. After the growth is completed, cool down to room temperature to obtain a rare-earth fluoride laser crystal doped with praseodymium ions regulated by divalent alkaline-earth ions.

[0016] Furthermore, the purity of the raw materials of RF3, MeF2 and MF3 in step (1) is 5N purity, and the state is single-crystal particles or powder; the grinding time is 40 - 60 min.

[0017] Furthermore, the vacuum atmosphere in step (2) is achieved by rough pumping with a mechanical pump and fine pumping with a molecular pump, and the vacuum degree is maintained below 8 Pa throughout the crystal growth process.

[0018] Furthermore, the heating to melt the materials in step (2) generally means that by raising the temperature, the solid materials are fully melted to convert the raw materials into the required molten state. The impurity removal refers to the process of removing impurities in the raw materials or generated during the chemical reaction; the impurities are other trace components that are not the desired components in the raw materials, including water vapor, existing inclusions, bubbles, etc.

[0019] Furthermore, the heating rate in step (2) is 200 - 300 °C / h, heating to 1500 °C, and maintaining a constant temperature for 5 - 8 h after heating to 1500 °C.

[0020] Furthermore, the slow cooling process in step (2) is: cooling from 1500 °C to 1350 °C at a rate of 1.5 °C / h.

[0021] Furthermore, after the growth in step (2) (slow cooling process), cool from 1350 °C to room temperature at a rate of 30 - 50 °C / h.

[0022] In some specific embodiments of the present application, the RF3 is selected from PrF3, the MeF2 is selected from SrF2, and the MF3 is selected from LaF3, and specifically includes the following steps:

[0023] (1) Weigh the raw materials of PrF3, SrF2 and LaF3 according to the stoichiometric ratio, mix them evenly, and then load them into the crucible.

[0024] (2) Place the crucible in a high-vacuum atmosphere, heat to melt the materials and remove impurities, and then lower the temperature for growth. After the growth is completed, cool down to room temperature to obtain a visible-band ultrafast laser crystal of lanthanum fluoride co-doped with trivalent praseodymium ions and divalent strontium ions.

[0025] The third technical solution of the present invention provides an application of a divalent alkaline earth ion-regulated praseodymium ion-doped rare earth fluoride laser crystal. The laser crystal is used as a laser gain medium for an all-solid-state visible light ultrafast laser to accelerate the all-solid-state femtosecond ultrafast laser in the visible band.

[0026] Compared with the prior art, the present application has at least the following improvements and beneficial effects:

[0027] (1) In some specific embodiments provided by the present invention, the LaF3 crystal selected by the present invention belongs to the tetragonal crystal system. In addition to having a low phonon energy and a high 5d energy level position, it can greatly reduce the non-radiative transition probability caused by multi-phonon relaxation and the excited state absorption of the laser upper energy level caused by the low 5d energy level position. By using the substitution of a heterovalent alkaline earth ion Sr 2+ to obtain the crystal of xPr,yMe:LaF3 (Me = Mg, Ca, Sr, Ba, etc., 0.001 ≤ x ≤ 0.3, 0.01 ≤ y ≤ 0.2), with the incorporation of Sr 2+ ions, the lower the local symmetry, the more severe the lattice distortion, the greater the energy level splitting, and the enhanced local disorder, truly forming a mixed composite fluoride with a disordered distribution of La 3+ / Sr 2+ -Pr 3+ to achieve the merging and overlapping of the lower energy levels of H6 and 3 F2, 3 F3 and 3 F4 that are close to each other, achieving the effect of overlapping and inhomogeneous broadening of the fluorescence spectrum. Thus, the key scientific problem of the narrow fluorescence spectrum (FWHM of the half-peak width is 0.7 - 3 nm) of the existing Pr-doped 3 crystals is solved. Combining with the research on femtosecond laser technology in the visible band, it is expected to achieve all-solid-state femtosecond ultrafast laser output; 3+

[0028] (2) In some specific embodiments provided by the present invention, the crystal of xPr,yMe:LaF3 (Me = Mg, Ca, Sr, Ba, etc., 0.001 ≤ x ≤ 0.3, 0.01 ≤ y ≤ 0.2) can achieve a wider fluorescence band in the visible band than the existing xPr:LaF3 (0.001 ≤ x ≤ 0.3) and is a laser material that is more promising for achieving all-solid-state femtosecond laser output;

[0029] (3) The crystal material of the present invention can accelerate the research and application process of all-solid-state femtosecond ultrafast lasers in the visible band and can be applied to fields such as laser display, optical communication, deep-water detection, and biological medicine. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 For the 0.6% Pr, 5% Sr:LaF prepared in Examples 1 and 23； Room temperature fluorescence spectrum of 0.6% Pr, 8% Sr:LaF3 sample under 444 nm light excitation; among which (A) represents: the full fluorescence spectrum of the crystal in the visible light band, and (B) represents: the local fluorescence spectrum of the crystal in the red and orange light bands;

[0031] Figure 2 is 0.6% Pr, 5% Sr:LaF prepared in Examples 1 and 2 3； Fluorescence lifetime spectrum corresponding to the 640 nm emission peak of 0.6% Pr, 8% Sr:LaF3 sample under 444 nm light excitation; among which (A) represents: the lifetime of the P0 energy level of the 0.6% Pr:LaF3 crystal in the comparative case 3 The lifetime of the P0 energy level, and (B) represents: Example 1: 0.6% Pr, 5% Sr:LaF3 crystal 3 The lifetime of the P0 energy level; (C) represents: Example 2: 0.6% Pr, 8% Sr:LaF3 crystal 3 The lifetime of the P0 energy level. Detailed implementation manners

[0032] 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.

[0033] There is no special limitation on the sources of all raw materials of the present invention, and those purchased on the market or prepared by conventional methods well-known to those skilled in the art are all acceptable.

[0034] All raw materials are purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0035] The chemical formula of a divalent cation-regulated trivalent luminescent ion-doped rare earth fluoride laser crystal (a divalent alkaline earth ion-regulated praseodymium ion-doped rare earth fluoride laser crystal) is xR, yMe:MF3, where the range of x is 0.001 ≤ x ≤ 0.3, the range of y is 0.01 ≤ y ≤ 0.2, R is one of Nd, Pr, Er, Tm, Ho, Dy, Eu, Me is one of Mg, Ca, Sr, Ba, and M is one of Y, Lu, Sc, Gd or La. The rare earth fluoride laser crystal is represented by Pr,Sr:LaF3 and is grown by the temperature gradient method. This method mainly includes the following steps:

[0036] (1) Using PrF3, SrF2, and LaF3 single-crystal particles or powders with a purity of 5N as raw materials, calculate the required mass of each raw material according to the stoichiometric ratio and accurately weigh them.

[0037] (2) Thoroughly grind the weighed raw material powders to make them evenly mixed, then load them into a graphite crucible and cover the lid; the grinding is carried out thoroughly in an agate mortar, and the grinding time is 40 - 60 min; put the ground raw materials into the graphite crucible and cover the crucible lid to prevent a large amount of volatilization of the raw materials and the entry of an oxygen-containing environment.

[0038] (3) Place the graphite crucible filled with materials in the hot field for vacuum pumping until the vacuum degree reaches below 8 Pa, raise the temperature to ensure complete melting of the materials and removal of impurities, then slowly cool down to carry out crystal growth. After the growth is completed, cool down to room temperature and then take out the crystal. The vacuum pumping is carried out by rough vacuum pumping with a mechanical pump and fine vacuum pumping with a molecular pump. The entire process of crystal growth is carried out under high vacuum. The heating rate to ensure complete melting of the materials and removal of impurities is 200 - 300 °C / h, raise the temperature to 1500 °C, and keep it at a constant temperature of 1500 °C for 5 - 8 h after reaching 1500 °C. The slow cooling procedure is to slowly cool down at a temperature rate of 1.5 °C / h from 1500 °C to 1350 °C, and the temperature range of cooling is 150 °C. After the slow cooling growth is completed, quickly cool down from 1350 °C to room temperature at a rate of 30 - 50 °C / h.

[0039] The rare-earth fluoride laser crystal provided by the present invention can accelerate the R & D and application processes of new bands of all-solid-state visible light and femtosecond ultrafast lasers. Based on the above steps, the present application provides the following specific embodiments:

[0040] Example 1

[0041] Growing 0.6% Pr, 5% Sr:LaF3 crystal by the temperature gradient method, which is specifically prepared by the following method:

[0042] Using the temperature gradient method to grow 0.6% Pr, 5% Sr:LaF3 crystal, put 150 g of raw materials (weighed according to the stoichiometric ratio in the chemical formula) into a graphite crucible, then cover the crucible lid, load the furnace and pump vacuum until it reaches below 8 Pa, then raise the temperature at a rate of 200 °C / h to ~1500 °C, keep it at a constant temperature of 8 h until the raw materials are completely melted and impurities are fully removed, then slowly cool down from 1500 °C to 1350 °C at a rate of 1.5 °C / h, and carry out crystal growth during the slow cooling process. After the slow cooling growth is completed, quickly cool down from 1350 °C to room temperature at a rate of 30 °C / h. The entire growth process is carried out under high vacuum, and then take out the crystal to obtain a 0.6% Pr, 5% Sr:LaF3 crystal with good optical quality.

[0043] Through fluorescence spectrum testing (the results are shown in Figure 1 and Figure 2) and spectral calculations (fitting the full width at half maximum of fluorescence using Origin software). For 3 P0→ 3 H6, 3 P0→ 3 F2 and 3 P0→ 3 F3+ 3 F4 transitions, the full widths at half maximum are 18.4 nm, 8.22 nm, and 11.2 nm respectively. Compared with the full widths at half maximum of 15.3 nm, 6.86 nm, and 5.78 nm for pure Pr:LaF3, there is a certain improvement. The emission peaks gradually broaden from the original double peaks and multiple sharp peaks into a smooth emission band, truly forming a La 3+ / Sr 2+ -Pr 3+ -disordered distribution of mixed composite fluoride. This should be the result of the merging and overlapping of the lower energy levels of Pr ions 3 H6 and 3 F2 and 3 F3 and 3 F4 being close. The wide fluorescence band is very beneficial for the output of ultrafast femtosecond lasers.

[0044] Example 2

[0045] Growing 0.6% Pr, 8% Sr:LaF3 crystal by the temperature gradient method. The specific preparation method is as follows:

[0046] Using the temperature gradient method to grow 0.6% Pr, 8% Sr:LaF3 crystal. Put 150 g of raw materials (weighed according to the stoichiometric ratio in the chemical formula) in a graphite crucible, then cover the crucible lid, load the furnace and evacuate to below 8 Pa, then heat at a rate of 200 °C / h to ~1500 °C, keep the temperature constant for 8 h until the raw materials are completely melted and impurities are fully removed, and then slowly cool from 1500 °C to 1350 °C at a rate of 1.5 °C / h. Crystal growth is carried out during the slow cooling process. After the slow cooling growth is completed, quickly cool from 1350 °C to room temperature at a rate of 30 °C / h. The whole growth process is carried out under high vacuum, and then the crystal is taken out. Obtain a 0.6% Pr, 8% Sr:LaF3 crystal with good optical quality.

[0047] Through fluorescence spectrum testing (the results are shown in Figure 1 and Figure 2 ) and spectral calculations (fitting the full width at half maximum of fluorescence using Origin software). For 3 P0→ 3 H6, 3 P0→ 3 F2 and 3 P0→ 3 F3+ 3The full widths at half maximum (FWHMs) of the F4 transitions are 16.5 nm, 8.06 nm, and 11.6 nm respectively. Compared with those of pure Pr:LaF3 which are 15.3 nm, 6.86 nm, and 5.78 nm, there is a certain improvement. For the 0.6% Pr, 8% Sr:LaF3 sample under 444 nm optical excitation, the 3 lifetime of the P0 energy level corresponding to the 640 nm emission peak is 44.0 μs.

[0048] Comparative Example 1

[0049] The 0.6% Pr:LaF3 crystal was grown by the temperature gradient method (i.e., without doping Sr), and it was specifically prepared by the following method:

[0050] Using the temperature gradient method to grow the 0.6% Pr:LaF3 crystal, put 150 g of raw materials (weighed according to the stoichiometric ratio in the chemical formula) in a graphite crucible, then cover the crucible lid, load the furnace and evacuate to below 8 Pa, and then heat at a rate of 200 °C / h to ~1500 °C, keep the temperature constant for 8 h until the raw materials are completely melted and fully remove impurities, and then slowly cool from 1500 °C to 1350 °C at a rate of 1.5 °C / h. Crystal growth occurs during the slow cooling process. After the slow cooling growth is completed, quickly cool to room temperature at a rate of 30 °C / h. The whole growth process is carried out under high vacuum, and then the crystal is taken out. A 0.6% Pr:LaF3 crystal with good optical quality is obtained.

[0051] Through fluorescence spectrum testing (the results are shown in Figure 1 and Figure 2 ) and spectral calculation (using Origin software to fit the fluorescence full width at half maximum), for 3 P0→ 3 H6, 3 P0→ 3 F2 and 3 P0→ 3 F3+ 3 F4 transitions, the full widths at half maximum are 15.3 nm, 6.86 nm, and 5.78 nm respectively. For the 0.6% Pr:LaF3 sample under 444 nm excitation, the 3 lifetime of the P0 energy level corresponding to the 640 nm emission peak is 49.3 μs.

[0052] As Figure 1 shown are the room temperature fluorescence spectra of the 0.6% Pr, 5% Sr:LaF3 samples and 0.6% Pr, 8% Sr:LaF3 samples prepared in Examples 1 - 2, and the 0.6% Pr:LaF3 sample prepared in Comparative Example 1. It can be seen that the two crystals provided in Examples 1 - 2 have 3 H6 and 3 in the orange - red light band of F2 and 3 F3 and 3The emission band in the deep red light band of F4 has a certain improvement compared with that of Pr:LaF3 doped singly.

[0053] Such as Figure 2 Shown are the fluorescence lifetime spectra corresponding to the emission peak at 640 nm of the 0.6% Pr, 5% Sr:LaF3 sample (b) and 0.6% Pr, 8% Sr:LaF3 sample (c) prepared in Examples 1 - 2, and the 0.6% Pr:LaF3 sample (a) prepared in Comparative Example 1 under 444 nm light excitation. The lifetime of the P0 energy level of the 0.6% Pr, 5% Sr:LaF3 sample 3 is 45.6 μs, and the lifetime of the P0 energy level of the 0.6% Pr, 8% Sr:LaF3 sample 3 is 44.0 μs, and the lifetime of the P0 energy level of the 0.6% Pr:LaF3 sample 3 is 49.3 μs.

[0054] Example 3

[0055] The 0.6% Pr, 5% Ca:LaF3 crystal is grown by the temperature gradient method, and is specifically prepared by the following method:

[0056] Using the temperature gradient method to grow the 0.6% Pr, 5% Ca:LaF3 crystal, put 150 g of raw materials in a graphite crucible, then cover the crucible lid, load the furnace and evacuate to below 8 Pa, then heat at a rate of 200 °C / h to ~1500 °C, keep the temperature constant for 8 h until the raw materials are completely melted and impurities are fully removed, and then slowly cool from 1500 °C to 1350 °C at a rate of 1.5 °C / h. Crystal growth is carried out during the slow cooling process. After the slow cooling growth is completed, quickly cool to room temperature at a rate of 30 °C / h. The whole growth process is carried out under high vacuum, and then the crystal is taken out. A 0.6% Pr, 5% Ca:LaF3 crystal with good optical quality is obtained.

[0057] Through fluorescence spectrum testing, it can be found that the emission bandwidths in the orange - red light band and the deep red light band both increase compared with those of the 0.6% Pr:LaF3.

[0058] Example 4

[0059] The 0.6% Pr, 5% Ba:LaF3 crystal is grown by the temperature gradient method, and is specifically prepared by the following method:

[0060] The 0.6% Pr, 5% Ba:LaF3 crystal was grown by the temperature gradient method. 150 g of raw materials were placed in a graphite crucible, and then the crucible lid was covered. The furnace was evacuated to below 8 Pa, and then heated at a rate of 200 °C / h to ~1500 °C and held at a constant temperature for 8 h until the raw materials were completely melted and impurities were fully removed. Then, it was slowly cooled from 1500 °C to 1350 °C at a rate of 1.5 °C / h, and crystal growth was carried out during the slow cooling process. After the slow cooling growth was completed, it was quickly cooled to room temperature at a rate of 30 °C / h. The entire growth process was carried out under high vacuum, and then the crystal was taken out. A 0.6% Pr, 5% Ba:LaF3 crystal with good optical quality was obtained.

[0061] Through fluorescence spectrum testing, it can be found that the emission bandwidths in the orange-red light band and the deep red light band are both increased compared with the emission bandwidth of 0.6% Pr:LaF3.

[0062] Example 5

[0063] Growth of 0.6% Pr, 5% Sr:Y 0.5 Gd 0.5 F3 crystal, which is specifically prepared by the following method:

[0064] The 0.6% Pr, 5% Sr:Y 0.5 Gd 0.5 F3 crystal was grown by the temperature gradient method. 150 g of raw materials were placed in a graphite crucible, and then the crucible lid was covered. The furnace was evacuated to below 8 Pa, and then heated at a rate of 200 °C / h to ~1250 °C and held at a constant temperature for 8 h until the raw materials were completely melted and impurities were fully removed. Then, it was slowly cooled from 1500 °C to 1350 °C at a rate of 1.5 °C / h, and crystal growth was carried out during the slow cooling process. After the slow cooling growth was completed, it was quickly cooled to room temperature at a rate of 30 °C / h. The entire growth process was carried out under high vacuum, and then the crystal was taken out. A 0.6% Pr, 5% Sr:Y 0.5 Gd 0.5 F3 crystal.

[0065] Through fluorescence spectrum testing, it can be found that the emission bandwidths in the orange-red light band and the deep red light band are both increased compared with the emission bandwidth of 0.6% Pr:LaF3.

[0066] As described above, it is only the preferred embodiment of the present invention, and it is not a limitation to the present invention in other forms. Any person skilled in the art may use the disclosed technical content to make changes or modifications into equivalent embodiments with equivalent changes. However, any simple modification, equivalent change, and modification made to the above embodiments based on the technical essence of the present invention without departing from the technical solution content of the present invention still belong to the protection scope of the technical solution of the present invention.

Claims

1. A divalent alkaline earth ion-regulated rare earth fluoride laser crystal doped with trivalent luminescent ions, characterized in that, The chemical composition of the laser crystal is expressed as xR,yMe:MF3, where the range of x is 0.001≤x≤0.3, and the range of y is 0.01≤y≤0.2; R is at least any one of Nd, Pr, Er, Tm, Ho, Dy or Eu, Me is at least any one of Mg, Ca, Sr or Ba, and M is at least any one of Y, Lu, Sc, Gd or La.

2. A divalent alkaline earth ion-regulated rare earth fluoride laser crystal doped with trivalent luminescent ions according to claim 1, characterized in that, The chemical formula of the laser crystal is xPr,ySr:LaF3, where the range of x is 0.001≤x≤0.3, and the range of y is 0.01≤y≤0.

2.

3. A divalent alkaline earth ion-regulated trivalent luminescent ion-doped rare earth fluoride laser crystal according to claim 2, characterized in that, The chemical formula of the laser crystal is 0.6%Pr,5%Sr:LaF3.

4. The preparation method of a divalent alkaline earth ion-regulated trivalent luminescent ion-doped rare earth fluoride laser crystal according to any one of claims 1 to 3, characterized in that, The crystal is grown by the temperature gradient method, including the following steps: (1) Material preparation: Weigh the raw materials of RF3, MeF2 and MF3 according to the stoichiometric ratio, mix them evenly, then put them into a crucible and grind. (2) Crystal growth: Place the crucible in a high vacuum atmosphere, heat up to melt the materials and remove impurities, and then start a slow cooling program for crystal growth. After the growth is completed, cool down to room temperature to obtain a divalent alkaline earth ion-regulated praseodymium ion-doped rare earth fluoride laser crystal.

5. The preparation method of a divalent alkaline earth ion-regulated trivalent luminescent ion-doped rare earth fluoride laser crystal according to claim 4, characterized in that, The purity of the raw materials of RF3, MeF2 and MF3 described in step (1) is 5N purity, and the state is single crystal particles or powder; the grinding time is 40-60 min.

6. The preparation method of a divalent alkaline earth ion-regulated trivalent luminescent ion-doped rare earth fluoride laser crystal according to claim 4, characterized in that, The vacuum atmosphere described in step (2) is that the vacuum degree is maintained below 8 Pa throughout the crystal growth process.

7. The preparation method of a divalent alkaline earth ion-regulated trivalent luminescent ion-doped rare earth fluoride laser crystal according to claim 4, characterized in that, The heating rate described in step (2) is 200-300 °C / h, heat up to 1500 °C, and keep it at a constant temperature for 5-8 h after heating up to 1500 °C.

8. The preparation method of a divalent alkaline earth ion-regulated trivalent luminescent ion-doped rare earth fluoride laser crystal according to claim 4, characterized in that, The slow cooling program described in step (2) is to cool from 1500 °C to 1350 °C at a rate of 1.5 °C / h.

9. The preparation method of a divalent alkaline earth ion-regulated trivalent luminescent ion-doped rare earth fluoride laser crystal according to claim 4, characterized in that, After the slow cooling growth described in step (2) is completed, cool from 1350 °C to room temperature at a rate of 30-50 °C / h.

10. Use of a divalent alkaline earth ion-regulated trivalent luminescent ion-doped rare earth fluoride laser crystal according to any one of claims 1 to 3, characterized in that, As a laser gain medium for an all-solid-state visible light ultrafast laser, it is used to accelerate the all-solid-state femtosecond ultrafast laser in the visible band.

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