Optical Bistability in Cholesteric Liquid Crystals
Cholesteric liquid crystals possess an intrinsic helical structure which leads to some rather striking linear optical properties.1 These properties include a very strong rotatory power and the Bragg reflection of circularly polarized light of the appropriate helicity and wavelength. In this paper we consider nonlinear optical propagation in cholesterics. For wavelengths in the Bragg regime, we find that the intense light can change the pitch of the helix and thus yield a bistable reflection characteristic. 2 In the regime of wavelengths much shorter than the helix pitch (the so-called Mauguin limit) where there are no Bragg reflections, we show that the polarization state of the transmitted light exhibits bistability as the incident intensity is varied. In this limit one may place the cholesteric liquid crystal between crossed polarizers and observe an intensity bistability which does not rely on either Bragg reflections or mirror feedback.
KeywordsBragg Reflection Optical BISTABILITY Cholesteric Liquid Crystal Incident Intensity Liquid Crystal Molecule
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