DEMONSTRATION OF HIGH-ENERGY EXTRACTION EFFICIENCY IN A LASER-DIODE-PUMPED HIGH-GAIN ND-YAG REGENERATIVE AMPLIFIER

High energy extraction efficiency of 48 +/- 4% for the cavity mode cro ss section (17.5% +/- 1 % for the entire lasant cross section) and hig h energy gain of 71 +/- 1 dB have been demonstrated simultaneously, fo r the first time, in a laser-diode pumped Nd:YAG regenerative amplifie r (RA). The RA was operated at an initial small-signal gain of 3.15 +/ - 0.20, an input pulse energy of 0.5 +/- 0.1 nJ (pulse width of 910 +/ - 12 ps), an amplified output pulse energy of 6.0 +/- 0.3 mJ (pulse wi dth <1 ns), and a repetition rate of 50 Hz. The dependence of energy e xtraction efficiency on initial small-signal gain of the RA was shown to be well fitted with the theory of Lowdermilk and Murray.