Optical power limiting with nonlinear periodic structures

We present observations of optical power limiting using a thermal nonlinearity in a dye-doped colloidal crystal. The transmission of the crystal is studied as a function of the incident intensity for various dye concentrations, lattice spacings, and wavelengths. We have found that optical limiting occurs when the wavelength of the incident light is tuned to the blue edge of the stop gap of these structures. Limiting intensities near 10 kW/cm^2 have been obtained for colloidal solutions with 10^−5 M Kiton Red dye. The experimental results are compared with theoretical models of nonlinear distributive-feedback structures in which the nonlinearity is assumed to be thermal.