Nonlinear optical spectroscopy on one-dimensional excitons in silicon polymer, polysilane

Abstract

The modulus and phase of the complex third-order nonlinear optical (NLO) susceptibility \ensuremath{\chi}${\mathrm{\ifmmode \tilde{}\else \~{}\fi{}}}^{(3)}$(-3\ensuremath{\omega};\ensuremath{\omega},\ensuremath{\omega},\ensuremath{\omega}) have been measured on an all-trans silicon polymer, poly(dihexylsilane), over a wide photon energy range. Several distinct structures observed in the \ensuremath{\chi}${\mathrm{\ifmmode \tilde{}\else \~{}\fi{}}}^{(3)}$ spectra are in excellent agreement with the theoretical results of a one-dimensional (1D) exciton model. Important aspects of the 1D Wannier-like exciton structure in polysilanes are elucidated in relation to the NLO processes.