CN1782144A

CN1782144A - Fs laser crystal of ytterbium doped strontium yttrium borate

Info

Publication number: CN1782144A
Application number: CN 200410101055
Authority: CN
Inventors: 王国富; 张彦; 林州斌; 胡祖树; 张莉珍
Original assignee: Fujian Institute of Research on the Structure of Matter of CAS
Current assignee: Fujian Institute of Research on the Structure of Matter of CAS
Priority date: 2004-12-03
Filing date: 2004-12-03
Publication date: 2006-06-07
Anticipated expiration: 2024-12-03
Also published as: CN100469950C

Abstract

The present invention relates to artificial crystal technology, and especially a kind of femtosecond laser crystal of Yb-doped strontium yttrium borate and its preparation process. The Yb-doped strontium yttrium borate crystal is prepared through Czochralski method at growth temperature of 1325 deg C, pulling speed of 0.7-2 mm/hr and crystal rotation speed of 15-30 rpm. The said process can grow high quality and large size femtosecond laser crystal of Yb-doped strontium yttrium borate.

Description

Femtosecond laser crystal doped with ytterbium strontium yttrium borate

The invention relates to the field of artificial crystals and crystal growth in the technical field of photoelectron functional materials, in particular to a femtosecond laser crystal material of a working substance in a solid femtosecond laser.

The femtosecond laser crystal in the background technology is a working substance of a solid femtosecond laser, and refers to a luminescent material which takes a crystal as a substrate, absorbs pump light energy through a discrete luminescent center and converts the pump light energy into laser output. Various physical and chemical properties of the femtosecond laser crystal are mainly determined by the host material, and spectral characteristics, fluorescence lifetime, and the like are determined by the energy level structure of the active ion. Since 1965, the pulse laser technology has rapidly developed since the picosecond level pulse is obtained by using a passive mode-locked ruby laser and enters an ultra-short range. In the 70 s, a team collided ring mode-locked dye laser appeared, and the pulse width of the laser entered the femtosecond stage. In the early 90 s, speeches et al at the university of san andelu, uk, first reported that ultrashort pulses of 60fs were generated using a self-mode-locked titanium-sapphire laser. The titanium gem solid laser has wide tunable range, large fluorescence bandwidth, simple structure, high reliability and no pollution, overcomes the defects of a dye laser, and raises the heat tide of developing a novel solid femtosecond laser internationally.

At present, the most widely used solid femtosecond laser crystal is a titanium gem crystal, which has various better physical and chemical properties and is easy to grow high-quality crystal with high optical quality and large size. However, it has the disadvantage of narrow absorption line, and is not suitable for pumping by LD, which will be the development direction of laser pumping source in future.

The active search for a high-quality laser crystal material with excellent physical, chemical and mechanical properties and high optical quality and large size, which is suitable for LD pumping, is currently ongoing work of scientists in various countries. Ytterbium ion is widely used as an active ion, Yb-doped, due to its superior spectral properties³⁺The laser crystal of the ion has high quantum efficiency and is suitable for InGaAs laser diode pumping; borate is also a popular choice for laser-based materials due to its good physicochemical and mechanical properties.

The invention aims to develop a novel laser crystal ytterbium-doped strontium yttrium borate[Yb:Sr₃Y₂(BO₃)₄]The laser crystal material can be directly used as a flash lamp and an LD pump and has higher conversion efficiency.

Sr is added into the grown Yb₃Y₂(BO₃)₄The crystal is obtained by collecting diffraction data on a four-circle diffractometer, and structural analysis shows that the crystal belongs to an orthorhombic system, the space group is Pnma, the unit cell parameters are that a is 8.713 Å, b is 16.003 Å, c is 7.406 Å and V is 1032.7 Å³And Z is 4, and the refractive index is 1.74. Wherein ytterbium ion is used as doping ion to replace lattice site of yttrium ionThe doping concentration of ytterbium is between 0.5 at% and 25 at%, the fluorescence lifetime (tau) is 3.55-1.03ms, the fluorescence lifetime is a function of the concentration of ytterbium ions, and ytterbium ions with different concentrations can be doped according to different requirements. The experimental result shows that the laser crystal can output laser with the wavelength of 1054nm and can be used as a laser crystal.

Yb:Sr₃Y₂(BO₃)₄The crystal is a molten compound with the same components, can be grown by a pulling method according to a chemical reaction formula: the Yb is weighed, mixed and tabletted according to the ratio₂O₃Then adding the raw materials according to the required concentration, wherein the raw materials are as follows: yb of₂O₃(purity 99.95%, institute of chemistry for Catharanthus of the Chinese academy of sciences), Y₂O₃(purity 99.99%, institute of applied chemistry of Catharanthus of Chinese academy of sciences), SrCO₃(purity 99.95%, Shanghai chemical reagent Co., Ltd., China pharmaceutical group), H₃BO₃(purity 99.99%, Beijing chemical plant), platinum crucible is used for growth in inert gas (such as N)₂Ar, etc.) under the atmosphere, the parameters of the crystal growth are about 1325-1370 ℃, the pulling speed is 0.7-2mm/h, the crystal rotating speed is 15-30rmp, and high-quality Yb and Sr are grown₃Y₂(BO₃)₄And (4) crystals.

Sr is added into the grown Yb₃Y₂(BO₃)₄The crystal is analyzed and tested for absorption spectrum, fluorescence spectrum and fluorescence life, and the result shows that (5 at% Yb is doped³⁺Sr of₃Y₂(BO₃)₄Crystal as an example): yb of Sr₃Y₂(BO₃)₄The main absorption peak of the crystal is 977nm, the half-peak width is 8nm, and the absorption transition cross section is 2.07 x 10^-20cm²The larger half-peak width at 977nm is very suitable for pumping by InGaAs semiconductor laser, which is beneficial to the absorption of laser crystal to pump light and improves the pumping efficiency. Its emission transition cross section at 1054nm_emIs 0.70X 10^-19cm²The fluorescence lifetime is 1.18ms, since crystals with long fluorescence lifetime can accumulate more particles at the upper levelAnd the energy storage is increased, so that the output power and the output energy of the device are improved. Thus, Yb: Sr₃Y₂(BO₃)₄The crystal can obtain larger output, and has high conversion efficiency, low cost and high optical qualityThe amount and the laser crystal have practical application prospect and use value.

Yb:Sr₃Y₂(BO₃)₄The crystal can be very easily grown into a crystal with excellent quality by a Czochralski method, has high growth speed, hard texture, good heat-conducting property and excellent optical characteristics, can be easily pumped by a flash lamp and an LD to obtain laser output with the laser output wavelength of 1054nm, and can be used as a better laser crystal.

Yb: Sr of the invention₃Y₂(BO₃)₄The crystal is a molten compound with the same components, can be grown by adopting a pulling method, has short growth period and can obtain high-quality large-size crystals. In the experimental process, a proper solid-phase synthesis method and a better growth condition are found, and crystals with high optical quality and the size of phi 15mm multiplied by 25mm are grown by adopting a pulling method.

Detailed Description

Example 1: czochralski method for growing Yb with doping concentration of 2.0 at%³⁺Yb of (1)₃Y₂(BO₃)₄And (3) laser crystals. Accurately weighing SrCO according to the proportion₃、Y₂O₃、H₃BO₃、Yb₂O₃Mixing, grinding, tabletting, and adding 60 × 40mm³The platinum crucible of (2) was subjected to a solid-phase reaction in a muffle furnace at 900 ℃ for 12 hours, and then heated to 1100 ℃ for 10 hours. Putting the synthesized sample into a pulling furnace, and adopting a pulling method in N₂In the atmosphere, under the conditions of growth temperature of 1325 ℃, crystal rotation speed of 15rmp and pulling speed of 1mm/h, high-quality Yb with the size of phi 20mm multiplied by 30mm is grown³⁺2.0 at.% of Yb to Sr₃Y₂(BO₃)₄And (4) crystals.

Example 2: czochralski method for growing Yb with a doping concentration of 5.0 at%³⁺Yb of (1)₃Y₂(BO₃)₄And (3) laser crystals. Accurately weighing SrCO according to the proportion₃、Y₂O₃、H₃BO₃、Yb₂O₃Mixing, grinding, tabletting, and adding 60 × 40mm³The platinum crucible of (2) was subjected to solid-phase reaction in a muffle furnace at 1050 ℃ for 10 hours, and then heated to 1200 ℃ for 20 hours. Putting the synthesized sample into a pulling furnace, and growing high-quality Yb with the size of phi 15mm multiplied by 25mm by adopting a pulling method under the conditions that the growth temperature is 1350 ℃, the crystal rotating speed is 15rmp and the pulling speed is 0.5mm/h in Ar atmosphere³⁺5.0 at.% of Yb to Sr₃Y₂(BO₃)₄And (4) crystals.

Claims

An ytterbium-doped strontium yttrium borate femtosecond laser crystal is characterized in that: the molecular formula of the crystal is Yb: Sr₃Y₂(BO₃)₄Belongs to an orthorhombic system, the space group is Pnma, the unit cell parameters are a-8.713 Å, b-16.003 Å, c-7.406 Å and V-1032.7 Å³Z is 4, refractive index 1.74, Yb³⁺Ion as doping ion to replace Y in crystal³⁺The lattice sites of the ions have a doping concentration of between 0.5 at% and 25 at%. .
A method for producing the crystal of claim 1, characterized in that: the crystal is grown by adopting a pulling method, the growth temperature of the crystal is 1325-.
Use of a crystal according to claim 1, characterized in that: the crystal is used as a laser working substance in a solid femtosecond laser, and a flash lamp or a laser diode is used as a pumping source to excite and generate laser output with the wavelength of 1054 nm.
Use of a crystal according to claim 1, characterized in that: the solid femtosecond laser made of the crystal is used in the fields of informatics, biomedicine and ultrafast science.