Absorption and pitch relationships in dichroic guest–host liquid crystal systems

The absorption of a dichroic dye dissolved in chiral nematic hosts in the Grandjean texture increased with decreasing pitch of the host. Absorption was higher for hosts of low birefringence and high order parameter. Boundary condition, homeotropic or parallel (homogeneous), had no appreciable effect on absorption, but threshold voltage was higher for the parallel than homeotropic boundary. The results agreed with theoretical plots relating absorption to pitch.