Eur. Phys. J. B 31, 179
(2003)
Fluorescence of a dye-doped cholesteric liquid crystal
film in the region of the stop band: theory and experiment
J. Schmidtke and W. Stille
Physikalisches Institut, Universität Freiburg,
D-79104 Freiburg, Germany
Abstract
Due to the sinusoidal modulation of the
dielectric properties along the helical axis, cholesteric liquid crystals
exhibit a photonic stop band for circularly polarized light, which strongly
affects the emission of fluorescent guest molecules. In this paper, we
discuss the resulting changes in the emission spectrum. In an analytical
treatment, we first derive the photonic densities of states of the two normal
light modes for propagation parallel to the helical axis, taking into account
multiple reflections due to the finite film thickness. Then we discuss the
influence of the degree of order of the dye's transition dipole moment on the
emission characteristics. Finally, we present experimental results, which
show excellent quantitative agreement with our theoretical description.