Electromagnetically induced transparency mediated by phonons in strongly coupled exciton–phonon systems

It is shown theoretically that electromagnetically induced transparency (EIT) due to strong exciton–phonon coupling can occur in strongly coupled exciton–phonon systems such as polymers and organic semiconductors and lead to ultra-slow light effects. The results indicate that the strong coupling of excitons and phonons is important, but the exciton– exciton interaction plays a small role in the generation of the EIT. Numerical results for polydiacetylene–toluene sulfonate are also presented. This EIT in a solid-state medium might be utilized for efficient multiwave mixing and quantum nondemolition measurements, as well as for novel acousto-optical devices.