Lasing Thresholds of Cholesteric Liquid Crystal Lasers

Wenyi Cao ,Antigone Marino ,Giancarlo Abbate ,Peter Palffy-Muhoray ,Bahman Taheri

Liquid Crystal Institute, Kent State University
Dipartimento di Fisica, Universitŕ di Napoli “Federico II”

Cholesteric liquid crystals (CLCs) are one dimensional photonic band-gap materials. Due to distributed feedback, low threshold mirrorless lasing can occur in dye-doped and pure CLCs. In order to optimize the lasing conditions, we have studied the dependence of the lasing threshold on dye concentration and sample thickness. In particular, we have studied dye concentrations in the range of 0.1-3.0wt%, and cell thicknesses are in the range of 5-50ƒÝm. We have found that the system has a shallow lasing threshold minimum and can operate efficiently in the range of dye concentrations of 0.3-2.4wt% and sample thicknesses of 10-50ƒÝm. We discuss the physical processes responsible for the observed behaviour.

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