Optically induced light modulation in an hybrid nanocomposite system of inorganic CdSe/CdS nanorods and nematic liquid crystals

We studied the thermo-optical properties and nonlinearities of new materials prepared in our labs which consisted in a nanocomposite blend of liquid crystals and semiconductor CdSe/CdS nanorods. We found a thermally induced optical bistability when a laser beam travelled across the cell, as the beam was able to cause a reversible switching in the optical properties of the blend from a scattering state to a transmissive state. The optically induced light modulation by a pump beam (Ar+ laser) was probed by a weak He–Ne beam when the two laser beams were incident on the cell simultaneously. The dependence of the hysteresis loop on the modulation frequency of the incident beam was also studied, and the variation in the light intensity was successfully exploited as a mean to switch the system from an opaque state to a transmission state, as it had a strong influence on the thermo-optical behaviour of the blend. Our results indicate a thermally- and optically induced light modulation, and demonstrate that the proposed system is promising for applications in thermo-optical switches.