A ytterbium-doped silicate femtosecond laser crystal, a preparation method thereof and applications thereof

Abstract

The present invention discloses a ytterbium-doped silicate femtosecond laser crystal, a preparation method thereof and an application thereof, relating to the technical field of laser crystal gain materials. The chemical formula of the laser crystal is Yb 4x CaLa 4(1‑x) Si3O 13 , wherein x = 0.01-0.30. The laser crystal uses CaLa4Si3O 13 as a laser crystal matrix. By using the fact that La element occupies multiple lattice sites in the CaLa4Si3O 13 crystal, the incorporation of Yb can effectively replace multiple lattice sites of La, thereby enhancing the inhomogeneous broadening of Yb and forming broadband emission, which is beneficial to the generation of femtosecond laser. Using such a crystal as a gain medium and pumping with a laser having a central emission wavelength in the range of 940-980 nanometers, high-efficiency tunable and ultrashort pulse laser output near 1 micron can be achieved, and it has important application prospects in the fields of industrial applications, scientific research and national defense and military.

Description

Technical Field

[0001] The present invention relates to the technical field of laser crystal gain materials, and particularly relates to a ytterbium-doped silicate femtosecond laser crystal, a preparation method thereof, and an application thereof. Background Art

[0002] Among all the current ultrafast laser crystals capable of realizing LD-pumped all-solid-state femtosecond laser output, laser crystal materials doped with Yb 3+ have attracted much attention. The reasons are as follows: (1) Yb 3+ has only two electron energy levels (ground state 2 F 7 / 2 and excited state 2 F 5 / 2 ), and its laser operation belongs to a quasi-three-level system, which can effectively avoid defects such as concentration quenching, excited state absorption, and up-conversion; (2) due to the simple energy levels, it can emit a relatively wide fluorescence spectrum, supporting the generation of ultrashort pulses; (3) its absorption wavelength matches the output wavelength of semiconductor lasers, and semiconductor lasers can be directly used for pumping. And high-performance femtosecond laser crystal materials need to meet a basic requirement: a wide emission spectral bandwidth (which is beneficial to realizing ultrashort pulses).

[0003] In the internal structure of disordered crystals, since luminescent ions randomly occupy different positions in the lattice, compared with traditional ordered crystals, they have a wider inhomogeneous broadening fluorescence spectrum, which is beneficial to the generation of ultrashort pulses. At the same time, the absorption spectrum is also broadened to a certain extent compared with traditional ordered crystals, which makes disordered crystals have good application scenarios in the research of laser crystals. In addition, its own physical and chemical properties are also relatively excellent, attracting the attention of many researchers. Summary of the Invention

[0004] The first object of the present invention is to provide a ytterbium-doped silicate femtosecond laser crystal. This is a laser crystal material that generates 1-micron ultrashort pulses, and the material has a greater degree of disorder, and it is more conducive to generating ultrashort pulsed lasers through mode-locking technology.

[0005] The second object of the present invention is to provide a preparation method of the above-mentioned ytterbium-doped silicate femtosecond laser crystal.

[0006] The third object of the present invention is to provide an application of the above-mentioned ytterbium-doped silicate femtosecond laser crystal.

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

[0008] A ytterbium-doped silicate femtosecond laser crystal, the chemical formula of the laser crystal is Yb 4x CaLa 4(1-x) Si3O 13, where x = 0.01 - 0.30, preferably 0.1 - 0.15.

[0009] Further, in the laser crystal, the La element will be partially replaced by Yb 3+ and replaced.

[0010] The second object of the present invention can be achieved by the following technical solutions:

[0011] For the preparation method of the ytterbium-doped silicate femtosecond laser crystal, the laser crystal can be grown by the Czochralski method, including the following steps:

[0012] 1) Select Yb2O3, CaCO3, La2O3, SiO2 as raw materials, and proportion the raw materials according to the following chemical equation:

[0013] 2xYb2O3 + CaCO3 + 2(1 - x)La2O3 + 3SiO2 → Yb 4x CaLa 4(1-x) Si3O 13 + CO2↑;

[0014] 2) Mix the raw materials prepared in step 1) evenly, press them into blocks, and calcine to obtain a sintered material;

[0015] 3) Carry out crystal growth by the Czochralski method:

[0016] The operation is as follows: Place the sintered material obtained in step 2) in a reactor, heat it to above the melting point to completely melt it, perform constant temperature treatment, and then carry out crystal growth; after the crystal growth is completed, cool it to room temperature and take out the crystal to obtain the target product.

[0017] Further, in step 2), the calcination conditions are set as follows: the sintering temperature is 1200 - 1400 °C, and the sintering time is 2 - 24 hours.

[0018] Further, in step 3), heating to above the melting point specifically means heating to 40 - 120 °C above the melting point.

[0019] Further, in step 3), the time for constant temperature treatment is 1 - 12 hours.

[0020] Further, in step 3), during the crystal growth process, the pulling speed is 0.1 - 5.0 mm / h, and the rotation speed is 3 - 50 rpm.

[0021] Further, in step 3), during the cooling process, the annealing rate is 6 - 20 °C / h.

[0022] Further, in step 1), the purity of all raw materials reaches 99.999%.

[0023] The third object of the present invention can be achieved by the following technical solutions:

[0024] The application of the above ytterbium-doped silicate femtosecond laser crystal, wherein the laser crystal is used to generate ultrafast laser pulses in a 1-micron band all-solid-state mode-locked laser.

[0025] An all-solid-state mode-locked laser, using the above ytterbium-doped silicate femtosecond laser crystal as the laser working medium and a laser diode as the pump source.

[0026] Further, the central emission wavelength of the pump source is in the range of 940 to 980 nanometers.

[0027] Further, the output wavelength of the all-solid-state mode locking is in the 1-micron band.

[0028] The application of the above ytterbium-doped silicate femtosecond laser crystal or all-solid-state mode-locked laser, and the application is in the fields of industry, spectroscopy, biochemistry, medicine, military, national defense, etc.

[0029] The present invention has the following advantages and effects compared with the prior art:

[0030] This laser crystal uses CaLa4Si3O 13 as the laser crystal matrix, and utilizes the fact that La elements occupy multiple lattice sites in the CaLa4Si3O 13 crystal. The incorporation of Yb can effectively replace multiple lattice sites of La, thereby enhancing the inhomogeneous broadening of Yb and forming broadband emission, which is beneficial to the generation of femtosecond laser.

[0031] Using such a crystal as the gain medium and pumping with a laser having a central emission wavelength in the range of 940 to 980 nanometers, high-efficiency tunable and ultrashort pulse laser output near 1 micron can be achieved, which has important application prospects in the fields of industrial applications, scientific research, national defense and military, etc. Detailed implementation manners

[0032] The following combines examples to further describe in detail the specific implementation manners of the present invention. The following examples are used to illustrate the present invention but are not used to limit the scope of the present invention.

[0033] Example 1

[0034] Weigh the required mass of each raw material, namely Yb2O3 (99.999%), CaCO3 (99.999%), La2O3 (99.999%), and SiO2 (99.999%), according to the chemical equation of the ratio, where x = 0.1. Then put the prepared raw materials into a mixer to make them evenly mixed, and press the mixed sample into a block and place it in a crucible. Next, place the sample in a muffle furnace for calcination. The sintering temperature is 1250 °C and the sintering time is 9 hours to obtain the sintered material. Place the obtained sintered material in a pulling furnace, heat it up to 80 °C above the melting point, completely melt it, and keep it at a constant temperature for 6 hours. Then slowly lower the temperature to the crystallization point for crystal growth. The pulling speed is 1.2 mm / h and the rotation speed is 12 rpm. When the growth process ends, the crystal is pulled out of the melt and cooled to room temperature at an annealing rate of 16 °C / h, and then the crystal Yb is taken out. 0.4 CaLa 3.6 Si3O 13 。

[0035] Using such a crystal as the gain medium and pumping it with a laser whose central emission wavelength is in the range of 940 - 980 nm, high-efficiency tunable and ultrashort pulse laser output near 1 μm can be achieved, which has important application prospects in the fields of industrial applications, scientific research, national defense, and military, etc.

[0036] Example 2

[0037] Weigh the required mass of each raw material, namely Yb2O3 (99.999%), CaCO3 (99.999%), La2O3 (99.999%), and SiO2 (99.999%), according to the chemical equation of the ratio, where x = 0.15. Then put the prepared raw materials into a mixer to make them evenly mixed, and press the mixed sample into a block and place it in a crucible. Next, place the sample in a muffle furnace for calcination. The sintering temperature is 1200 °C and the sintering time is 10 hours to obtain the sintered material. Place the obtained sintered material in a pulling furnace, heat it up to 60 °C above the melting point, completely melt it, and keep it at a constant temperature for 8 hours. Then slowly lower the temperature to the crystallization point for crystal growth. The pulling speed is 1.3 mm / h and the rotation speed is 15 rpm. When the growth process ends, the crystal is pulled out of the melt and cooled to room temperature at an annealing rate of 12 °C / h, and then the crystal Yb is taken out. 0.6 CaLa 3.4 Si3O 13 。

[0038] Using such a crystal as the gain medium and pumping it with a laser whose central emission wavelength is in the range of 940 - 980 nm, high-efficiency tunable and ultrashort pulse laser output near 1 μm can be achieved, which has important application prospects in the fields of industrial applications, scientific research, national defense, and military, etc.

[0039] The above-described embodiments merely represent several implementation manners of the present invention. The description thereof is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted 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, and these all fall within the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the appended claims.

Claims

1. A ytterbium-doped silicate femtosecond laser crystal, characterized in that: The chemical formula of the described laser crystal is Yb 4x CaLa 4(1-x) Si3O 13 , where x = 0.01 to 0.

30.

2. The preparation method of the ytterbium-doped silicate femtosecond laser crystal according to claim 1, characterized in that: It includes the following steps: 1) Select Yb2O3, CaCO3, La2O3, and SiO2 as raw materials, and proportion the raw materials according to the following chemical equation: 2xYb2O3 + CaCO3 + 2(1 - x)La2O3 + 3SiO2 → Yb 4x CaLa 4(1-x) Si3O 13 + CO2↑; 2) Mix the raw materials proportioned in step 1) evenly, press them into blocks, and calcine to obtain a sintered material; 3) Perform crystal growth by the Czochralski method: The operation is as follows: Place the sintered material obtained in step 2) in a reactor, heat it to above the melting point to completely melt it, perform isothermal treatment, and then carry out crystal growth; after the crystal growth is completed, cool it to room temperature and take out the crystal to obtain the target product.

3. The method for preparing a ytterbium-doped silicate femtosecond laser crystal according to claim 2, wherein: In step 2) described above, the calcination conditions are set as follows: the sintering temperature is 1200 - 1400 °C, and the sintering time is 2 - 24 hours.

4. The method for preparing a ytterbium-doped silicate femtosecond laser crystal according to claim 2, wherein: In step 3) described above, heating to above the melting point specifically means heating to 40 - 120 °C above the melting point; In step 3) described above, the isothermal treatment time is 1 - 12 hours; In step 3) described above, during the crystal growth process, the pulling speed is 0.1 - 5.0 mm / h, and the rotation speed is 3 - 50 rpm; In step 3) described above, during the cooling process, the annealing rate is 6 - 20 °C / h.

5. The method for preparing a ytterbium-doped silicate femtosecond laser crystal according to claim 2, wherein: In step 1) described above, the purity of all raw materials reaches 99.999%.

6. Use of the ytterbium-doped silicate femtosecond laser crystal according to claim 1, characterized in that: The laser crystal is used to generate ultrafast laser pulses in a 1-μm band all-solid-state mode-locked laser.

7. An all-solid-state mode-locked laser, characterized in that: It uses the ytterbium-doped silicate femtosecond laser crystal described in claim 1 as the laser working medium, and uses a laser diode as the pump source.

8. The all-solid-state mode-locked laser according to claim 7, wherein: The central emission wavelength of the pump source is 940 - 980 nm.

9. The all-solid-state mode-locked laser according to claim 7, wherein: The output wavelength of the all-solid-state mode-locked laser is in the 1-μm band.

10. The application of the ytterbium-doped silicate femtosecond laser crystal described in claim 1 or the all-solid-state mode-locked laser described in any one of claims 7 - 9 in the fields of industry, spectroscopy, biochemistry, medicine, military, or national defense.