Relative contribution of the electric-field-induced third-order effect to second-harmonic generation in poled, doped, amorphous polymersr

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 χ⁽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°C the contribution of the electric-field-induced third-order effect (second-harmonic wavelength = 532 nm) ranges from (6 ± 2)% of (2) 4-(dimethylamino)benzylidenemalononitrile to (20 ± 3)% of χ⁽²⁾ for 4-(dimethylamino)-4¹-nitrostilbene.