Comparative study of tunable room-temperature laser operation in the 900-1100-nm range: LiF:F2+ and Ti3+:sapphire

We report on a comparative evaluation of efficient room-temperature solid-state lasers based on Ti:sapphire and LiF:F(2)(+) operating in the 900-1100-nm range. LiF:F(2)(+) lasers are shown to operate with substantially lower threshold, broader tuning, and higher output pulse energies. The shorter fluorescence lifetime in LiF:F(2)(+) leads to higher peak output powers and a considerable reduction in buildup-time fluctuations. The main limitations on LiF:F(2)(+) laser operation are identified as amplified spontaneous emission (ASE) and long-term thermal degradation of the color centers. ASE restricts the tuning range, slope efficiency, and bandwidth of the LiF:F(2)(+) laser for high pump intensity, but broader tuning is achieved with longer pump pulses. The beam quality of the LiF:F(2)(+) laser is comparable with that of the Ti:sapphire laser.