All-optical ultrafast logic gates based on saturable to reverse saturable absorption transition in CuPc-doped PMMA thin films

A detailed theoretical analysis of femtosecond transition from saturable (SA) to reverse saturable absorption (RSA) has been carried out in Copper-Phthalocyanine (CuPc)-doped polymethylmethacrylate (PMMA) thin films. The transition due to fifth-order effect of excited-state absorption induced two-photon process has been optimized with respect to intensity, concentration and nonlinear coefficients to design various all-optical logic gates, namely, OR and AND at lower intensities (SA region), XOR at the transition intensity, and the universal NAND and NOR at higher intensities (RSA region). The advantages of ultrafast operation, simplicity, tunability, high contrast, stability of CuPc-doped PMMA thin film, and the possibility to control and realize various logic operations in the same film at the same wavelength by only controlling the pulse intensity, instead of a pump-probe configuration, make them attractive for practical implementation.