Study On Time-Resolved Spectra Of Nd,Y:SrF₂ Laser Crystals

Nd³⁺ ions formed easily the cluters that are the formation of Nd³⁺-Nd³⁺ pairs of strongly incoherent dipole-dipole interaction,which seriously lead to fluorescence quenching at 1.06 ?m.To avoid the fluorescence quenching effect,emission intensity greatly improved by co-doping Y³⁺ ions.This work researched the change of spectra properties at room temperature for understanding the change of luminescence centers after co-doping Y³⁺ ions.In virtue of excitation spectra,emission spectra,fluorescence lifetime,time resolution spectra at low temperature,we studied change trendy of luminescence centers on Nd,Y:SrF₂ crystals.The 0.5at.%Nd,xat.%Y:SrF₂ crystals have been grown by bridgman and temperature gradient method?TGT?,It is discovered by spectra measurement at room temperature that absorption cross sections increased 3.48 times from 1.17×10-20cm2 to 4.06×10-20cm2,emission cross sections increased 23 times from 0.22×10-20cm2 to 5.12×10-20cm2 and quantum efficiency increased from 11.3% to 92.3%,respectively.Compared with neodymium glass,emission intensity of Nd,Y:SrF₂ laser crystals is 1.02 times than that of neodymium glass.For researching the reason of spectrum properties greatly improved,the time resolution spectra of samples at low temperature also were studied.We discovered that luminescence centers transformed diversification for 0.5at.%Nd:SrF₂? 0.5at.%Nd,1.5at.%Y:SrF₂? 0.5at.%Nd,2.5at.%Y:SrF₂ samples.With co-doping Y³⁺ increasing,luminescence centers decreased from multi-centers to two centers in 0.5at.%Nd,5at.%Y:SrF₂ sample,and again decreased only one when concentration of co-doping Y³⁺ ions got to 10.Luminescence centers of Nd³⁺ ions transformed rise to decline with manipulate Y³⁺ ions increasing when the concentration of Nd³⁺ ions was constant.The evolution of local structure?clusters?of Nd:SrF₂ crystals: typical multi-centers transformed to sole center.When tending to sole center,the spectra properties of Nd,Y:SrF₂ crystals were best.It indicated that co-doping Y³⁺ resulted in breaking the cluters,making luminescence centers sole,greatly reducing fluorescence quenching effects.