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Laser‐induced gratings are produced in thin films of mixtures of nematic and cholesteric liquid crystals doped with a dye. A transient grating regime is found which decays on the order of seconds; additionally, a ‘‘persistent’’ grating with lifetimes up to 16 h has been found. Mechanisms for creation and decay are discussed.

The dye DCM(4-dicyanomethlene-2-methyl-6-p-dimethyl amino styrl-4H-pyran) is well known as a broadly tunable efficient laser dye and as an active element in luminescent solar concentrators1,2. Our interest has been to study the primary photochemical and photophysical process that are operative in this system.

We have attempted to experimentally detect a nonlinear reflection in mixtures of cholesteric and cholesteric/nematic liquid crystals induced by Nd:YAG laser pulses. At power densities of up to 4 MW/cm2 (532 nm) and 8 MW/cm2 (1064 nm) we have not observed any optically induced pitch dilation or distortion in these media.

The authors designed a course with a laboratory component geared for high school teachers. In this way more students would be reached and inspired to pursue science careers than if high school students were targeted directly.