Measurement of the nonlinear refractive index of single-crystal polydiacetylene channel waveguides

Abstract

We have measured the nonlinear refractive index (n2) of single crystalline poly(bis(p-toluene sulfonate) of 2,4-hexadiyn-1,6-diol) (PTS) polydiacetylene channel waveguides at 1.06 μm using two different techniques. The first method employs a Mach-Zehnder interferometer to determine the intensity-induced phase shift in the waveguide. In the second case n2 is derived from the intensity-dependent birefringence, which is measured with a Babinet-Soleil compensator. With both measurements the value of n2 in the direction of the PTS polymer chain axis is found to be ∼3×10-11 cm2/W. Such a large value of n2 would allow all-optical device applications of this material at low-power levels.