We report realizations of nanoscale integrated all-optical XNOR, XOR, NOT, and OR logic gates using plasmonics slot waveguides based on linear interference between surface plasmon polariton modes. The miniature device size with.. lateral dimensions smaller than 5 mu m,. precisely controlled optical phase difference, and quasi-monochromatic surface plasmon. polariton modes excited by a continuous wave 830 nm laser beam ensure a high intensity contrast ratio of 24 dB between the output logic states "1" and "0". Compared with previous reported results, the. intensity contrast ratio is enhanced 4-fold, whereas the lateral dimension is reduced 4-fold. These compact. logic devices are stable, robust, free from environmental impact, and much suitable for practical on chip applications These also provide a means to construct all-optical devices and nanophotonic processors
