Wj. Firth et Ma. Vorontsov, ADAPTIVE PHASE-DISTORTION SUPPRESSION IN A NONLINEAR-SYSTEM WITH FEEDBACK MIRROR, J. mod. opt., 40(10), 1993, pp. 1841-1846
Kerr nonlinearity, combined with feedback and diffraction, can be used
to suppress phase distortions of laser beams and improve their collim
ation. No reference beam is required, nor need the beam re-traverse th
e distorting medium.