Narrowing the oscillation spectra of a cholesteric liquid crystal laser

Abstract

The possibility of a single-mode laser generation on the basis of cholesteric liquid crystals (CLC) at the creation of a defect in a spiral structure is studied. To create a defect in CLC on a viscous 3-component mixture of esters of cholesterol, we use the orthogonal orientation of directors on focusing substrates with an additional turn of one of the substrates. As a result, the small ’’dip of transparency’’, which was predicted by the theory of a photon crystal at the infringement of its spiral structure, arose in the selective reflection (SR) band. The appearance of such a dip in the SR-band was just possible at its spectral shift from the dye absorption band about 100 nm. The formation of this defect in the structure was accompanied by narrowing the oscillation spectrum to the only longitudinal mode in a wide range of the above-threshold pumping. The nature of the phenomenon is discussed.

Keywords:

• cholesteric liquid crystal
• planar texture
• lasing spectra
• defect in a spiral structure

Notes on contributor

Igor P. Ilchishin - Institute of Physics, National Academy of Sciences, Nauky prosp., 46, 03680, Kyiv, Ukraine. E-mail: [email protected]; phone: [phone]; fax: [phone].

Eugene A. Tikhonov - Institute of Physics, National Academy of Sciences, Nauky prosp., 46, 03680, Kyiv, Ukraine. E-mail: [email protected]; [phone]; fax: [phone].

Taras V. Mykytiuk - Institute of Physics, National Academy of Sciences, Nauky prosp., 46, 03680, Kyiv,Ukraine. E-mail: [email protected]; phone:[phone]; fax:[phone]