Laser and gain parameters at 2.7 μm of Er3+-doped oxyfluoride transparent glass–ceramics

The room temperature emission spectrum at about 2.7 μm corresponding to the laser transition 4I11/2 → 4I13/2 in Er3+-doped nano-scaled transparent oxyfluoride glass–ceramic has been measured and stimulated emission cross-section for the transition has been calculated. The intensity of the transition has been found to be 40 times stronger and lifetime 50 times longer in the glass–ceramics compared to the precursor glass, which we show to be due to a change of frequency of the phonon involved in non-radiative de-excitation of the 4I11/2 level from 900 cm−1 in the precursor glass to 240 cm−1 in the ensuing glass–ceramics. The absorption cross-section for the excited state absorption 4I13/2 → 4I11/2 has been calculated based on the experimental reciprocal emission spectrum and wavelength dependence of the gain cross-section for the lasing transition 4I11/2 → 4I13/2 vs population inversion has been derived. The lasing/optical amplification gain parameters, such as population inversion, pump saturation intensity and product of emission cross-section and fluorescence lifetime have been obtained at the 2.7 μm wavelength. A noteworthy result is that laser action at 2.7 μm is possible in these Er3+-doped glass–ceramics, already not taking into account energy transfer or up-conversion processes, related to the 4I13/2 level, which favour the population inversion.