Large third-order optical nonlinearities of nickel-dithiolene-doped polymethylmethacrylate

The third‐order optical nonlinearity χ(3) of two novel guest‐host polymers has been measured. The polymers consisted of nickel dithiolene guest molecules in a polymethylmethacrylate host and were prepared as cast or spun films. The optical nonlinearity was measured by degenerate four‐wave‐mixing experiments at a wavelength of 1.06 μm using 100‐ps laser pulses. χ(3) coefficients of up to 10−17 m2/V2 were observed, corresponding to nonlinear refractive index n2 of up to 10−8 cm2/kW with a damage threshold ≳1 GW/cm2.