Optical amplification in Ho3+-doped transparent oxyfluoride glass ceramics at 750 nm

Positive transient optical gain has been demonstrated in Ho3+-doped transparent oxyfluoride glass-ceramics. A pump and probe experiment has been designed to show this result. High power laser pulses at 532 nm were used as the pump source to strongly populate the Ho3+ S-5(2):F-5(4) level due to nonresonant ground state absorption. Low power cw laser radiation at 750 nm was used as the probe beam. The signal beam stimulates the emission associated with the Ho3+ S-5(2):F-5(4)-> I-5(7) electronic transition at 750 nm. In addition to this, the high power pump pulses provide population inversion between the S-5(2):F-5(4) and I-5(7), initial and final states of the transition, respectively, giving rise to the optical amplification of the signal beam. A gain coefficient of 3.7 cm(-1) (similar to 16 dB/cm) was obtained for a pump energy density of about 135 mJ/cm(2) and a signal beam power density of 6 mu W/cm(2). (C) 2007 American Institute of Physics.