Small-signal gain measurement in a Ti:Al(2)O(3) amplifier

A small-signal single-pass power gain of < e1 > e < /e1 > (5.2)=180 has been measured for a signal in the pi polarization at 790.7 nm in a longitudinally pumped Ti:Al(2)O (3) amplifier. A double-pass power gain of < e1 > e < /e1 > (5.2 ){approximately equal to}10(4) has been attained for the same polarization at 799.8 nm. The ratio of the gain cross sections at 632.8 and 790.7 nm is 1/25. The gain anisotropy at 632.8 nm is < e1 > g < /e1 > (pi)/ < e1 > g < /e1 > (sigma)=2.3. The lifetime of the upper lasing level decreases with increased pumping, probably as the result of amplified spontaneous emission