We present evidence of photoselection by polarized multiphoton absorption (MPA) in an azo dye, i.e., Disperse Red 1 (DR1), dispersed in films of poly(methyl-methacrylate). MPA of DR1 at a fundamental of 785 nm, from a pulsed, regeneratively amplified, Ti:sapphire laser, results in photobleaching of the dye, and linearly polarized MPA of DR1 creates anisotropy, a feature that is indicative of orientational hole burning by MPA. The slopes of the early-time evolution of the isotropic absorbance and anisotropy show a dependence on the 3.65±0.15 power of the excitation laser intensity, and the dynamics of MPA-induced orientation are described by a theoretical model for MPA selective bleaching.
© 2006 Optical Society of America
Original Manuscript: August 12, 2005
Revised Manuscript: November 21, 2005
Manuscript Accepted: November 23, 2005
Hidekazu Ishitobi, Zouheir Sekkat, and Satoshi Kawata, "Photo-orientation by multiphoton photoselection," J. Opt. Soc. Am. B 23, 868-873 (2006)