Phys. Rev. Lett. 90, 083902 (2003)

Defect Mode Emission of a Dye Doped Cholesteric Polymer Network

J. Schmidtke1, W. Stille1, H. Finkelmann2

1Physikalisches Institut, Universität Freiburg, D-79104 Freiburg, Germany

2Institut für Makromolekulare Chemie, Universität Freiburg, D-79104 Freiburg, Germany


We have observed enhanced fluorescence and laser emission due to a photonic defect mode in a dye doped cholesteric polymer network. The defect is caused by a phase jump of the cholesteric helix at the interface of two stacked layers of a cholesteric polymer film. Fluorescence spectra show an additional resonant mode inside the photonic stop band. Pulsed excitation gives rise to laser emission of the defect mode, with an exceptionally low lasing threshold. The defect mode emission has a circular polarization whose sense of rotation is opposite to that of the cholesteric helix.