Comparative analysis of diode-pumped 3-μm Er:YLF lasers at cryogenic and room temperatures.

The performances of the diode-pumped CW and free running pulsed (Q-CW) 3-μm Er:YLF lasers, operating at room and cryogenic temperatures (RT and LNT), were compared theoretically and experimentally. It is shown that cryogenic cooling considerably enhances laser output power and efficiency in both modes of operation. On the other hand, our prediction for a Q-switched mode is that cryogenic performance can be so severely limited by amplified spontaneous emission (for some gain element designs) that the RT Q-switching may result in substantially higher pulse energies, albeit at lower efficiency.