Harmonic strain-optical response revealed in the isotropic (liquid) phase of liquid crystals
Abstract
A strong optical birefringence is observed when applying a small amplitude oscillatory strain to the
liquid phase of a liquid crystal. This unpredicted birefringence is found to oscillate at the same
frequency as the driving frequency, with frequencies down to 0.01 Hz. This birefringence is visible
up to 15 C above the liquid crystal transition. This opto-dynamic property is interpreted as a result
of a coupling of the orientational pretransitional fluctuations existing in the isotropic phase and
long range elastic interactions recently identified in liquids. The conversion of the mechanical
wave in an optical response is shapeable. Two examples of synchronized periodic signals are
shown: the sine and the square waves. The optimization of the signal is analyzed using a
Heaviside-step shear test. This optical property is immediately exploitable to design low energy
on/off switching materials
Origin : Files produced by the author(s)
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