EXPERIMENTAL-OBSERVATION OF THE INTERFERENCE OF 3-WAVE AND 5-WAVE MIXING PROCESSES INTO THE SIGNAL OF 2ND-HARMONIC GENERATION IN BACTERIORHODOPSIN SOLUTION

The second harmonic (SH) generation with a Ti:sapphire femtosecond las er system in a randomly oriented suspension of finely fragmented purpl e membranes of Halobacterium halobium has been studied experimentally. The existence of two interfering contributions to the SH signal due t o second-and fourth-order nonlinear processes has been established. Th e phase and the value of the fourth-order electronic susceptibility (h yperpolarizability) relative to the second-order ones have been determ ined. The analysis of the experimental data shows the existence of a c oherent contribution into the SH signal. (C) 1997 Elsevier Science B.V .