The dynamics of the optical synthesis of a waveguide channel in a weakly ab
sorbing photopolymerizable composition, representing a nonlinear focusing m
edium with memory, was studied by experimental and numerical modeling metho
ds. A qualitative model is proposed that describes the formation of a nondi
vergent light guide. It is shown that an extended (greater than or equal to
1 cm) light guide can form only in a medium possessing a sufficiently high
contrast factor (gamma greater than or equal to 2). (C) 2001 MAIK "Nauka/In
terperiodica".