Eight-pass neodymium glass slab amplifier with a waveguide and with phase conjugation

An eight-pass amplifier was constructed from an active element of rectangular cross section and 74×24×4 cm dimensions. Its output energy was 170 J with an input energy of 5×10^–4 J and a pulse duration of 20 nsec. The use of phase conjugation made it possible to compensate considerable distortions of the wavefront introduced by the active element. Over 50% of all the energy was concentrated in an angle of 7×10^–5 rad.