We report new observations of optical spatio-temporal structures formed in
terbium gallium garnet when it is excited at resonance by a strong laser be
am. We also present a theoretical description of this pattern formation, wh
ich accounts well for our observations. We finally discuss useful applicati
ons of both time and power dependence of these structures. (C) 1999 Elsevie
r Science B.V. All rights reserved.