Amplified spontaneous edge‐ emissions from π‐conjugated polymer ultrathin films: Discrete or continuous energy detuning

Abstract

Abstractπ‐conjugated polymer film waveguides, with sufficient thickness to accept multiple waveguided modes, showed amplified spontaneous emissions (ASE's) detuned by as much as 240 meV, showing that the detuning was made on the basis of evanescent field leak into the substrate, consistent with our previous report on the detuning using a photonic crystal substrate, that should be strongest at the critical reflection angle of guided ASE field within the polymer waveguide. Still the ASE energy was selected as one of the discrete series of accompanying molecular vibrational transitions of the constituent polymer, indicating that the coupling is stronger between the vibrational transition and the photoexcited molecular polarization oscillating at the optical frequency than the coupling between this polarization and the waveguide mode. It is the extended π‐conjugation along the polymer backbone that connects the molecular vibrations with the molecular polarization. With higher photoexcitation, continuous detuning was also observed due to filling of the excited state. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)