Crystal Growth And Spectroscopic Properties Of Tm³⁺-doped Ca₉La?VO₄?₇

With the development of laser diode,the research on the novel solid-state laser crystals which are suitable for LD pumping has attracted more and more researchers'attention.This paper reports the growth,structural characterizations and spectral properties of Tm3+:Ca9La(VO4)7 crystal.A good optical quality Tm3+:Ca9La(VO4)7 crystal with dimensions of ?25x30mm3 was successfully grown by the Czochralski method.The XRD analysis of this crystal was carried out and derived the cell parameters:a = b 10.846 A,c = 37.901 A,V= 3861.2 A3 and Z = 6.The concentration of Tm3+ ions in the grown crystal was measured to be 5.72at%by inductively coupled plasma atomic emission spectrometer,thus the segregation coefficient of Tm3+ ions was calculated to be 0.95,which indicates Tm3+ ions can easily enter the host crystal and substitute the equivalent La3+ ions.The polarized Raman spectra,polarized absorption spectra,fluorescence spectra and fluorescence lifetimes of 5.72at%Tm3+:Ca9La(VO4)7 crystal were measured at room temperature.The Raman bands in the ranges of 200-470 cm-1 and 740-930 cm-1 are assigned to the O-V-O bending modes,the V-O stretching modes and possible vibrations of the V-O-...La/Tm chain,respectively.The maximum absorption cross-sections at 791.3nm and 793nm wavebands are 1.5x10-20cm2 and 0.42xl0-20cm2 with the FWHM of 8.2nm and 19.1nm for a-and ?-polarizations,respectively,which are suitable for commercial?800nm LD pumping.According to Judd-Ofelt theory analysis,the spectral intensity parameters with ?2= 4.682xl0-20cm2,?4 0.659x10-20 cm2 and ?6 ?0.475 xl0-20cm2 were obtained.Meanwhile,the stimulated emission cross sections of 3F4?3H6 transition of Tm3+ ions centered at 1854nm and 1858nm were calculated by reciprocity method to be 1.28x1 O-20 cm2 and 0.38x10-20 cm2 for ?-and ?-polarizations,respectively.The fluorescence lifetime of the 3F4?3H6 transition was fitted to be 1.19 ms.The results show that Tm3+:Ca9La(VO4)7 crystal is a promising new broadband tunable near-infrared laser crystal suitable for LD pumping.