RELATIVE CONTRIBUTION OF THE ELECTRIC-FIELD-INDUCED 3RD-ORDER EFFECT TO 2ND-HARMONIC GENERATION IN POLED, DOPED, AMORPHOUS POLYMERS

A novel approach involving a delay-trigger method and doped, glassy polymers has been developed to determine the contribution of the electric-field-induced third-order effect to the second-order macroscopic susceptibility chi(2) of nonlinear optical dyes. A submillisecond, variable time delay is employed for switching on or off the electric poling field with respect to the laser pulse. For the several dyes tested at 30-degrees-C the contribution of the electric-field-induced third-order effect (second-harmonic wavelength = 532 nm) ranges from (6 +/- 2)% of chi(2) 4-(dimethylamino)benzylidenemalononitrile to (20 +/- 3)% of chi(2) for 4-(dimethylamino)-4'-nitrostilbene.