DETERMINATION OF 3RD-ORDER NONLINEAR OPTICAL SUSCEPTIBILITIES OF POLYSILANE THIN-FILMS

Third-order nonlinear optical susceptibilities chi(3)(-3-omega; omega, omega, omega) have been measured by third-harmonic generation for thin films of a series of polysilane polymers and copolymers and polycarbosilanes with different alkyl and aryl side groups. Chi(3)(-3-omega; omega, omega, omega) values for all the polymers studied were found to be in the range 0.3 x 10(-12)-4.5 x 10(-12) esu. Factors affecting the magnitude of chi(3), including the nature of the substituents, Si sequence length, polymer conformation, and film preparation, are discussed.