The Judd-Ofelt theoretic transition intensity parameters A_(tp)~k of luminescence of rare-earth ions in solids are important for the quantitative analysis of luminescence.It is very difficult to determine them with em...The Judd-Ofelt theoretic transition intensity parameters A_(tp)~k of luminescence of rare-earth ions in solids are important for the quantitative analysis of luminescence.It is very difficult to determine them with emission or absorption spectra for a long time.A "full profile fitting" method to obtain A_(tp)~k in solids with its emission spectrum is proposed,in which the contribution of a radiative transition to the emission spectrum is expressed as the product of transition probability,line profile function,instrument measurement constant and transition center frequency or wavelength,and the whole experimental emission spectrum is the sum of all transitions.In this way,the emission spectrum is expressed as a function with the independent variables intensity parameters A_(tp)~k,full width at half maximum(FWHM) of profile functions,instrument measurement constant,wavelength,and the Huang-Rhys factor S if the lattice vibronic peaks in the emission spectrum should be considered.The ratios of the experimental to the calculated energy lifetimes are incorporated into the fitting function to remove the arbitrariness during fitting A_(tp)~k and other parameters.Employing this method obviates measurement of the absolute emission spectrum intensity.It also eliminates dependence upon the number of emission transition peaks.Every experiment point in emission spectra,which usually have at least hundreds of data points,is the function with variables A_(tp)~k and other parameters,so it is usually viable to determine A_(tp)~k and other parameters using a large number of experimental values.We applied this method to determine twenty-five A_(tp)~k of Yb^(3+) in GdTaO_4.The calculated and experiment energy lifetimes,experimental and calculated emission spectrum are very consistent,indicating that it is viable to obtain the transition intensity parameters of rare-earth ions in solids by a full profile fitting to the ions' emission spectrum.The calculated emission cross sections of Yb^(3+):GdTaO_4 also indicate that the F-L formula gives larger values in the wavelength range with reabsorption.展开更多
The Yb:YAG is an excellent high-average power and ultra-short pulse laser crystal. Transition intensity parameters A_(tp)~k and Huang–Rhys factors are fitted to its emission spectrum by the full-profile fitting metho...The Yb:YAG is an excellent high-average power and ultra-short pulse laser crystal. Transition intensity parameters A_(tp)~k and Huang–Rhys factors are fitted to its emission spectrum by the full-profile fitting method. Calculated results indicate that the emission spectrum of Yb:YAG at cryogenic temperature consists of three pure electron state transitions and two phononassisted transitions, one vibronic transition releases one-phonon of 3 cm^(-1), and the other vibronic transition absorbs onephonon of 22 cm^(-1). At 300 K, the phonon assisted transition of 3 cm^(-1) turns into two-or more-phonon assisted transitions.The procedure absorbing phonon can reduce the thermal load of Yb:YAG and improve the laser efficiency, which may be one of the reasons why Yb:YAG has excellent performance. The emission bands of Yb:YAG are broadened thermally, and the peak values decrease by several times. The emission cross sections of Yb:YAG determined by Fuchtbauer–Ladenburg(F–L) formula are remarkably different from those calculated with A_(tp)~k, which indicates that it is necessary for a laser material to determine its transition intensity parameters A_(tp)~kin order to reasonably evaluate the laser performance.展开更多
Profile function properties with different variables are discussed, the formulae of stimulated absorption, spontaneous and stimulated emission, absorption and emission coefficients, and cross sections are deduced, and...Profile function properties with different variables are discussed, the formulae of stimulated absorption, spontaneous and stimulated emission, absorption and emission coefficients, and cross sections are deduced, and some confusing issues are clarified.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51172236,51502292,51272254,51102239,61205173,and 61405206)
文摘The Judd-Ofelt theoretic transition intensity parameters A_(tp)~k of luminescence of rare-earth ions in solids are important for the quantitative analysis of luminescence.It is very difficult to determine them with emission or absorption spectra for a long time.A "full profile fitting" method to obtain A_(tp)~k in solids with its emission spectrum is proposed,in which the contribution of a radiative transition to the emission spectrum is expressed as the product of transition probability,line profile function,instrument measurement constant and transition center frequency or wavelength,and the whole experimental emission spectrum is the sum of all transitions.In this way,the emission spectrum is expressed as a function with the independent variables intensity parameters A_(tp)~k,full width at half maximum(FWHM) of profile functions,instrument measurement constant,wavelength,and the Huang-Rhys factor S if the lattice vibronic peaks in the emission spectrum should be considered.The ratios of the experimental to the calculated energy lifetimes are incorporated into the fitting function to remove the arbitrariness during fitting A_(tp)~k and other parameters.Employing this method obviates measurement of the absolute emission spectrum intensity.It also eliminates dependence upon the number of emission transition peaks.Every experiment point in emission spectra,which usually have at least hundreds of data points,is the function with variables A_(tp)~k and other parameters,so it is usually viable to determine A_(tp)~k and other parameters using a large number of experimental values.We applied this method to determine twenty-five A_(tp)~k of Yb^(3+) in GdTaO_4.The calculated and experiment energy lifetimes,experimental and calculated emission spectrum are very consistent,indicating that it is viable to obtain the transition intensity parameters of rare-earth ions in solids by a full profile fitting to the ions' emission spectrum.The calculated emission cross sections of Yb^(3+):GdTaO_4 also indicate that the F-L formula gives larger values in the wavelength range with reabsorption.
基金supported by the National Natural Science Foundation of China(Grant Nos.61405206,51502292,and 51702322)the Knowledge Innovation Program of the Chinese Academy of Sciences(Grant Nos.CXJJ-16M251 and CXJJ-15M055)the National Key Research and Development Program of China(Grant No.2016YFB0402101)
文摘The Yb:YAG is an excellent high-average power and ultra-short pulse laser crystal. Transition intensity parameters A_(tp)~k and Huang–Rhys factors are fitted to its emission spectrum by the full-profile fitting method. Calculated results indicate that the emission spectrum of Yb:YAG at cryogenic temperature consists of three pure electron state transitions and two phononassisted transitions, one vibronic transition releases one-phonon of 3 cm^(-1), and the other vibronic transition absorbs onephonon of 22 cm^(-1). At 300 K, the phonon assisted transition of 3 cm^(-1) turns into two-or more-phonon assisted transitions.The procedure absorbing phonon can reduce the thermal load of Yb:YAG and improve the laser efficiency, which may be one of the reasons why Yb:YAG has excellent performance. The emission bands of Yb:YAG are broadened thermally, and the peak values decrease by several times. The emission cross sections of Yb:YAG determined by Fuchtbauer–Ladenburg(F–L) formula are remarkably different from those calculated with A_(tp)~k, which indicates that it is necessary for a laser material to determine its transition intensity parameters A_(tp)~kin order to reasonably evaluate the laser performance.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51172236,51272254,51102239,61205173,and 61405206)
文摘Profile function properties with different variables are discussed, the formulae of stimulated absorption, spontaneous and stimulated emission, absorption and emission coefficients, and cross sections are deduced, and some confusing issues are clarified.
