Optical Kerr-like response of dye-doped nematics

When small amounts of suitable dyes are added to a pure nematic liquid crystal, its nonlinear optical response may be enhanced by over two orders of magnitude and even be reversed in sign. This feature may be interesting for applications. We measured the enhancement of the nonlinear optical Kerr coefficient of several dye-nematic mixtures, in order to gain some insight on the molecular mechanism that is supposed to be the basis of the phenomenon.