Intensity dependence of picosecond nonlinear response time of polydiacetylene

Abstract
The relaxation time of the transient degenerate four-wave mixing grating in 4-butoxycarbonylmethylurethane polydiacetylene in polymethylmethacrylate matrix films has been found to be laser energy fluence dependent. This phenomenon is attributed to a transient reversible light-induced structure change in polydiacetylene films, involving a cooperative effect originating from side-chain intramolecular hydrogen bonding.