Active mirror amplifiers have been demonstrated to be viable large aperture amplifiers for use in laser fusion systems. In addition to having a large storage efficiency (1.2–1.5%) at the highest pumping level and a thermal recovery time in the 15–30-min range, they are also scalable to large apertures and allow the propagation of circular polarization. An important additional property is that regardless of the angle of incidence, no birefringence occurs in active mirror amplifiers. Based upon a circular polarization scheme that allows passive switching, we have constructed and operated a double-passed active mirror system. For a 50-J input energy and a pulse width of 700 psec (Gaussian FWHM), we have measured a focusable output energy of ≃230 J. Complementary single-pass experiments resulted in an output energy of ≃ 140 J, therefore, using the double-passed arrangement, we have increased the focusable output energy by ~64%. In this paper we describe the short-pulse (B-limited) and long-pulse (damage-limited) staging of double-passed active mirror systems, discuss in detail the passive double-pass system, and describe its experimental verification.
© 1981 Optical Society of America
D. C. Brown, J. A. Abate, L. Lund, and J. Waldbillig, "Passively switched double-pass active mirror system," Appl. Opt. 20, 1588-1594 (1981)