Ultra-short light pulses

After an introduction of ways of increasing laser power the authors briefly discuss the mechanism and evaluation of u.s.p. generation by self mode-locking. They describe their own work (in relation to that of others) in the U.S.S.R., on u.s.p. generation in a laser with a non-linear absorber. Their experiments yield on explanation of generation of u.s.p. as radiation pulse passes through a 2-component medium. The pulses can be amplified but the increase in power is limited by atomic processes in the active medium. Possible ways of overcoming the problems are indicated, such as using one pulse passing several times through an amplification rod. It is then possible to obtain pulses having controlled durations with energies of several joules.