Effective medium analysis for optical control of laser tuning in a mixture of azo-nematics and cholesteric liquid crystal

The selective reflection band structure of a mixture composed of azo-nematics and cholesteric liquid crystal (azo-based CLC) is investigated as an effective single optical medium. Berreman's 4×4 matrix method is adopted to analyze the photoisomerization-induced changes in the azo-based CLC by identifying the effective refractive indices as well as the helical pitch. In a laser dye-doped azo-based CLC, a stable reversible tuning of laser wavelengths at each domain of the two-dimensional laser array is demonstrated.