Nonlinear optical properties of thin films of polysilane

Abstract

Optical third harmonic generation measurements by transmission have been performed on thin films of polysilane deposited by a spinning technique with a thickness varying between 0.15 and 0.45 μm. The films have a good optical quality and support large laser power (∼200 MW/cm² at 1.064 μm). They are transparent in visible and near infrared. The measured average value of cubic susceptibility 〈χ⁽³⁾_xxxx (−3ω; ω,ω,ω)〉 is equal to (1.5±0.1)×10⁻¹² esu at 1.064 μm. The technique used for the third harmonic generation measurements allows determination of both modulus and phase of χ⁽³⁾. It is argued that the large value of χ⁽³⁾ is due to a three‐photon resonance at 1.064 μm.