The third‐order optical nonlinearity is estimated to be −10−4 e. s. u. at the exciton resonance in PbI2 evaporated films from the population oscillation effect. Such a large nonlinearity cannot be explained if the system is regarded as independent oscillators. The origin of the third‐order nonlinearity is examined in the density matrix formalism. The observed large nonlinearity is shown to come from the exciton‐exciton interaction.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics