Optical near-field and far-field for coupled plasmonic nanosystems are investigated. Gap plasmon-polaritons are
observed and analyzed with Spectral Boundary Integral Equation based approach. The results indicate pronounced
dependence of the field characteristics on the gap size, the particle shape, the orientation and material properties. The gap
optimization process is performed and the configurations which provide powerful enhancement of the field amplitude
inside the gaps are found. The meshfree procedures of numerical simulation algorithm allow essential flexibility of gap
optimization process in comparison with classical boundary element and finite element based tools. Due to fast
convergence of solution numerical algorithm provides superior accuracy to deal with extremely high field gradients. In
addition reduced complexity and calculation time are guaranteed due to extensive use of Fast Fourier Transforms.