Spectroscopy and radiation trapping of Yb3+ ions in lead phosphate glasses

Abstract

This paper reports ytterbium-doped lead phosphate (PbPhYb) glasses made by melt-quenching technique and their linear and nonlinear refractive indices. Raman and FTIR spectral analysis has been carried out to investigate the functional groups that constitute the host matrix. The oscillator strength of the absorption transition, (2F7/2→2F5/2) has been evaluated by using the Smakula model for various concentrations. The near infra-red emission and excitation spectra have been investigated and observed that the profile of the emission spectra changes as a function of Yb2O3 concentration, temperature, optical path length and thickness of the sample. From the optical absorption spectra, the spectroscopic and laser performance parameters have been evaluated and in turn used to estimate the gain cross-section of the Yb3+ ions. On the other hand, the lifetime for the 2F5/2 level of Yb3+ ion decreases with increase in Yb2O3 concentration up to 6mol% after an initial increase due to energy migration among the Yb3+ ions. The increase in lifetime could be due to radiation trapping but when the concentration is enlarged the energy migration processes are more predominant. The emission profile and lifetime change when the temperature is reduced to cryogenic temperature (11K). The results reveal that the prepared glasses could be considered for high energy and high power laser as well as solid state cryocooler applications.