Electronic nonlinear optical behaviour of a grating coupled polymer (4BCMU) waveguide

The nonlinear optical properties of polydiacetylene (PDA) are of interest both fundamentally and technologically. The nonresonant third order susceptibility χ⁽³⁾ associated with the nonlinear refractive index n₂ has been found to be relatively large (>10^-11 esu) and ultra-fast (<1 ps). Here we show how the reflectivity response of a grating coupled PDA waveguide can be analysed to yield both the real and the imaginary parts of χ⁽³⁾ in a single experiment with the sample in thin film form