Physical Review Letters
Observation of Superradiance by Nonlocal Wave Coupling of Light and Excitons in CuCl Thin Films
Masayoshi Ichimiya, Masaaki Ashida, Hideki Yasuda, Hajime Ishihara, Tadashi Itoh
Abstract
We report the observation of a remarkably strong coupling between light and a multinode-type exciton. The observed radiative decay time reaches the order of 100 fs, which is much faster than the dephasing process of nonradiative scattering. In this high-speed superradiance, the light wave and the excitonic wave in a high-quality thin film form a harmonized wave-wave coupling over a range of multiple wavelengths. This mechanism contradicts the conventional physical description of light-matter interaction based on the long-wavelength approximation.