THE ROLE OF EXCITED-STATE ABSORPTION IN TUNABLE SOLID-STATE LASERS

The lasing properties of tunable solid state lasers can be strongly influenced by Excited State Absorption (ESA). It is shown that the tuning behaviour of Cr:GSGG and Cr:LLGG is limited at short wavelengths due to the ESA transitions2E →2T2 (b),2T1 (b) and4T2 →4T1 (b), respectively. At long wavelengths the4T2 →4T1 (a) ESA transition narrows the tuning range largely. The reason is that both levels are Jahn-Teller split due to the centric chromium site resulting in a very broad ESA band. In Ti: YAIO3 strong ESA of the pumping wavelength into a charge transfer band occurs, which is caused by a Ti3+/Fe3+ complex centre. By this transition the pumping efficiency is diminished largely. It is believed that the lasing behaviour of Ti: YAIO3 can be improved considerably by growing of highest iron-free crystals. © 1990 Chapman and Hall Ltd.