Helicoidal distributed-feedback cavity action in a ferroelectric liquid crystal

Second-Harmonic (SH) generation was observed in homeotropically aligned ferroelectric liquid-crystal cells using fundamental light propagating along the helicoidal axis. Relatively strong SH light was observed in the helicoidal structure when the optical pitch was nearly the same as the SH-light wavelength, though, otherwise, the cancellation of the generated SH light by the helicoid results in negligibly weak SH intensity. Because the observed SH light is independent of the cell thickness, the SH light is attributed to the one generated from the surface region and the SH light generated inside the cell is confined and lost by the helicoid. This phenomenon indicates the helicoidal Distributed-FeedBack (DFB) cavity action and suggests the possibility of the helicoidal DFB laser using dye-doped ferroelectric liquid-crystal cells.