All-optical encryption by a heterodyne Kerr gate in multilayer reduced graphene oxide decorated with Pt nanoparticles

Herein is reported how the inhibition of the imaginary part of the electrical impedance exhibited by reduced graphene oxide (rGO) yields to stronger conductivity together to an enhancement in its optical nonlinearities. A highly uniform incorporation of plasmonic nanoparticles in the samples was identified to be responsible for the observed effects, while protoplasmatic nanoparticles or random decoration did not promote any important change in the studied parameters. Platinum particles featuring approximately 3 nm in average size were homogeneously decorated on the surfaces of rGO following a two-steps growth procedure. The vectorial nature in the third-order nonlinear optical response exhibited by rGO decorated with platinum nanoparticles (Pt/rGO) was analyzed by a two-wave mixing experiment. Interferometric irradiance and polarization patterns seem to generate different physical mechanisms responsible for the nonlinear refractive index exhibited by the nanostructures. An ablation threshold of 0.35 J/cm² was measured. The contrast in the superposition of two-input binary polarized optical signals was employed to propose an exclusive disjunctive logic gate based on a heterodyne optical Kerr gate. The polarization-selectable multi-photonic properties were explored by nanosecond pulses at 532 nm wavelength and a straightforward XOR encryption function was designed. The optical Kerr effect exhibited by Pt/rGO can be contemplated for developing all-optical switching devices. Immediate applications for encrypting and processing ultrafast functions can be also considered.