Growth And Properties Of CNAGS And Nd:CNAGS Crystals

Laser has the characteristics of good direction,high brightness,good monochrome,and good coherence.It has important application value in the fields of data storage,medical treatment,information communication,and the military.Solid state laser has the advantages of small size,high output power,and ease to use.Using crystal as laser matrix material,doping a small amount of rare earth active ions,and realizing laser output is a research hotspot of solidstate laser.Langasite(La3GasSiO14,LGS)series crystals have good piezoelectric,optical,and thermal properties,is a kind of laser,frequency doubling,piezoelectric and other functions in one multifunctional crystal Ca3Nb(Al0.5Ga0.5)Si2O14(CNAGS)crystal,as a member of langasite series crystals,has reduced the development cost-effectively due to the introduction of aluminum ion.The crystal has good thermal and spectral characteristics,better resistance performance at high temperature,and is expected to become a composite functional material with excellent performance.It has potential applications in electro-optic modulation and acousto-optic modulation.In recent years,the research on the crystal are mainly focused on the field of high-temperature piezoelectricity.Rare earth ion doped Ca3Nb(Al0.5Ga0.5)Si2O14 crystal have not been reported.By designing and growing rare earth ion doped CNAGS crystals and studying their optical,thermal,and laser properties,it is expected that laser crystal materials with excellent performance can be obtained to achieve high-efficiency laser output.By integrating piezoelectric,elastic-optical,acoustic-optical,and other characteristics,the miniaturization of composite devices can be realized.In this paper,the growth of Ca3Nb(Al0.5Ga0.5)Si2O14 and Nd:Ca3Nb(Al0.5Ga0.5)Si2O14 crystals was carried out.The basic physical properties,thermal,optical,and laser properties of the crystals were deeply studied.The main contents include:1)Optical grade CNAGS and Nd:CNAGS crystals doped with different concentrations of Nd3+ ions were grown by the Czochralski method.The growth process of the crystals were optimized,reducing defects,improving the crystal quality,and obtaining high-quality single crystals.2)The crystal structure was analyzed using powder X-ray diffraction(PXRD);The elements in the crystal were analyzed by X-ray fluorescence(XRF);The actual density of the crystal was measured using the drainage method.3)The specific heat,thermal expansion,and thermal diffusion of CNAGS and Nd:CNAGS crystals were measured,and the thermal conductivity was calculated.The results show that low-concentration doping has little effect on the thermal properties of the crystal;The thermal expansion coefficient of the anisotropy difference is small,which can effectively prevent crystal cracking caused by uneven thermal stress inside the crystal during growth and use;The thermal diffusion coefficient and thermal conductivity gradually decrease as the concentration of doped ions increases.4)The refractive index of CNAGS crystal was measured,and the corresponding refractive index dispersion equation and dispersion curve were obtained by fitting the Sellmeier equation.According to the curve,no is less than ne,and the crystal belongs to a positive uniaxial crystal;At 1066 nm,the refractive indices no and ne of CNAGS crystals are 1.7521 and 1.8170,respectively.The phase matching angle of type I and type Ⅱ is calculated,which are 39.86° and 62.90° respectively.5)The absorption and transmission spectra of the crystal were measured,and the absorption coefficient and absorption cross-section were calculated.The absorption and emission parameters related to the crystal were calculated using Judd-Ofelt(JO)theory.6)The non-polarized and polarized fluorescence spectra of Nd:CNAGS crystals were analyzed;The fluorescence lifetime results show that partially replacing Ga3+with A13+ can prolong the fluorescence lifetime and reduce the fluorescence quenching phenomenon.7)A 1066 nm wavelength laser output was achieved using Nd:CNAGS crystals.8)As a local structure regulator ion,A13+ions can regulate the spectrum and laser performance of Nd3+ions doped CNAGS crystals through local structure regulation.