Electrically tunable laser based on oblique heliconical cholesteric liquid crystal.

A cholesteric liquid crystal (CLC) formed by chiral molecules represents a self-assembled one-dimensionally periodic helical structure with pitch [Formula: see text] in the submicrometer and micrometer range. Because of the spatial periodicity of the dielectric permittivity, a CLC doped with a fluorescent dye and pumped optically is capable of mirrorless lasing. An attractive feature of a CLC laser is that the pitch [Formula: see text] and thus the wavelength of lasing [Formula: see text] can be tuned, for example, by chemical composition.

Cavity modes and their excitations in elliptical plasmonic patch nanoantennas.

We present experimental and theoretical studies of two dimensional periodic arrays of elliptical plasmonic patch nanoantennas. Experimental and simulation results demonstrate that the azimuthal symmetry breaking of the metal patches leads to the occurrence of even and odd resonant cavity modes and the excitation geometries dependent on their modal symmetries. We show that the cavity modes can be described by the product of radial and angular Mathieu functions with excellent agreements with both simulations and experiments.