Third-order optical nonlinearity originating from room-temperature exciton in layered compounds LaCuOS and LaCuOSe

摘要

We have studied the third-order optical nonlinearity (χ~((3))) of epitaxial thin films of layered compounds LaCuOS and LaCuOSe at room temperature by a spectrally resolved degenerative four-wave mixing technique with femtosecond time resolution. The χ~((3)) values in both films are sharply resonant to optical absorption bands in the ultraviolet (UV) light region due to room-temperature exciton. The peak values are evaluated to be as large as 2-4×10~(-9) esu with a fast time response of 250-300 fs. These findings indicate that LaCuOS and LaCuOSe are promising materials for emerging optical nonlinear devices that operate in the UV light region compatible for GaN-based lasers.