Liquid Crystals Under Two Extremes: (1) High-Power Laser Irradiation, and (2) Single-Photon Level

• Published in: Molecular Crystals and Liquid Crystals Vol. 559; no. 1; pp. 127 - 157
• Main Author: Lukishova, Svetlana G.
• Format: Journal Article
• Language: English
• Published: Philadelphia Taylor & Francis Group 19-07-2012; Taylor & Francis Ltd
• Subjects: Arrays; Atoms & subatomic particles; Crystals; Fluorescence; Helix unwinding; Irradiation; Lasers; Liquid crystals; Microcavities; Microscopy; Molecular chemistry; Nanomaterials; Nanostructure; nonlinear refraction; Quantum physics; single-photon source
• ISSN: 1542-1406; 1563-5287; 1527-1943
• DOI: 10.1080/15421406.2012.658703

This paper describes some of my results on liquid crystal investigations under unconventional, incident light powers: (1) under high-power laser irradiation both in free space and inside laser resonators, and (2) in single-photon source applications for quantum information technology. Several effects under high-power, nanosecond laser irradiation are outlined: athermal helical pitch dilation and unwinding of cholesteric mirrors, showing the limits for using them in laser physics; some pitfalls in measurements of thermal-density refractive nonlinearity and the first observation of thermal lens effects in liquid crystals under several nanosecond, low-pulse-repetition rate (2-10 Hz) laser irradiation in the presence of two-photon absorption; feedback-free kaleidoscope of patterns (hexagons, stripes, etc.) in dye-doped liquid crystals. At the single-photon level, definite linear and circular polarizations of single (antibunched) photons for quantum communications were obtained using single-emitter fluorescence in planar-aligned nematic and cholesteric hosts. Circular polarized cholesteric microcavity resonances were also observed under cw-excitation. In addition, using near-field optical microscopy and AFM, 2D-hexagonal arrays made of cholesteric oligomers were investigated. With progress of this technology, similar arrays can be used for fluorescence control of single emitters.