Platinum-17-Doped Flexible Nonlinear Distributed Bragg Reflectors for Optical Filtering Applications

Smart filtering of optical radiation involves a combination of advanced materials, optical components, and control methods to accurately tailor the propagation of light. Here, we propose a tunable optical filter by combining the absorptive nonlinearity in platinum nanoclusters and bandgap engineering in Bragg mirrors. Multilayer stacks of polyvinyl carbazole and cellulose acetate, embedded with platinum nanoclusters, are created using the spin-coating method. The improved nonlinear absorption dynamics of these stacks are analyzed using the nanosecond z-scan technique. The resonant excitation of the band edge modes with the 532 nm laser pulse leads to slow photon-mediated redistribution of the optical field. The strong optical confinement enhances the reverse saturable absorption in nanoclusters and in turn, improves the optical power limiting. The structures exhibit lower limiting threshold and onset fluence compared to their monolayers. The proposed design can be used as a frequency filter in the linear optical regime and an attenuator in the nonlinear regime.