Demonstration of wavelength-swept laser using cholesteric liquid-crystal cavity and its application for laser scanning.

A cholesteric liquid-crystal gel (ChLCG) is fabricated by photopolymerizing a ChLC doped with a mesogenic monomer at a high concentration of 38.2 wt%. The reflection band of the ChLCG exhibits a fast, continuous, and time-varying wavelength shift of the order of kilohertz by applying a sine wave voltage. Swept lasing at a swept rate of 100 Hz and with a swept range of 12 nm can be achieved by irradiating a dye-doped ChLCG with a quasi-continuous-wave laser. When the swept laser light is introduced to a diffracting grating, a laser scanning device is demonstrated.