Measurement of the large optical nonlinearity of nickel dithiolene doped polymers

Abstract The nonlinear refractive indices and the two-photon absorption coefficients of films of three nickel dithiolene complexes dissolved at various concentrations in a polymethylmethacrylate (PMMA) host were measured using the Z-scan technique. Nonlinear refractive indices up to 10 −8 cm 2 /kW were observed. The device-based figure of merit, Δ n sat /αλ, was found to be greater than 2. At high doping concentrations two-photon absorption increased more rapidly with concentration than the nonlinear refractive index, reducing the ratio of the Re χ (3) to Im χ (3) below that acceptable for devices, thus limiting the maximum usable concentration of the guest in a PMMA host.