Kent State University

The University Court of the University of Aberdeen

Jie V Xiang

Oleg D Lavrentovich

John M Storey

Corrie T Imrie

Peter Palffy-Muhoray

Sergij V Shiyanovskii

Andrii Varanytsia

Fred Minkowski

Sergij V Shiyanovsii

Young-Ki Kim

Daniel E Paterson

Daniel A Paterson

A lasing device includes an active layer comprising a cholesteric liquid crystal material and a laser dye, and a liquid crystal cell including spaced apart substrates defining a cell gap in which the active layer is disposed. The substrates include electrodes arranged to bias the active layer into an oblique helicoidal (Ch) state. At least one substrate of the liquid crystal cell is optically transparent for a lasing wavelength range of the device.

Electrically tunable laser with cholesteric liquid crystal heliconical structure

A liquid crystal cell includes substrates defining a gap and electrodes having one of (i) an in-plane geometry generating an electric field parallel with the substrates and (ii) a top-down geometry generating an electric field across the gap between the two spaced apart substrates. A liquid crystal material disposed in the gap between the substrates comprises a chiral nematic material formed by a mixture of: 1-(4-cyanobiphenyl-4'-yl)-6-(4-cyanobiphenyl-4&#x2032;-yloxy)hexane (CB6OCB) or &#x3b1;,&#x3c9;-bis(4,4-cyanobiphenyl)nonane (CB9CB) dimeric liquid crystal material; at least one additional dimeric liquid crystal material; and a chiral dopant. The liquid crystal material within an operational range of electric field applied by the electrodes exhibits a heliconical state with an oblique angle helicoid director whose helicoid axis is oriented parallel with the electric field and whose helicoid pitch is sized to provide diffraction or Bragg reflection of light in a spectral range of interest impinging on one of the substrates of the liquid crystal cell.

Field induced and controlled heliconical structure of cholesteric liquid crystal

A diffraction grating comprises a liquid crystal (LC) cell configured to apply an electric field through a cholesteric LC material that induces the cholesteric LC material into a heliconical state with an oblique helicoid director. The applied electric field produces diffracted light from the cholesteric LC material within the visible, infrared or ultraviolet. The axis of the heliconical state is in the plane of the liquid crystal cell or perpendicular to the plane, depending on the application. A color tuning device operates with a similar heliconical state liquid crystal material but with the heliconical director axis oriented perpendicular to the plane of the cell. A power generator varies the strength of the applied electric field to adjust the wavelength of light reflected from the cholesteric liquid crystal material within the visible, infrared or ultraviolet.

Field induced heliconical structure of cholesteric liquid crystal

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Kent, OH, United States of America

Jie V Xiang