Design and Optimization of a 3D Pyramidal Nanowaveguide with a Square Cross-section for Plasmonic Field Enhancement for High Harmonic Generation

Surface plasmon polariton wave propagation in a pyramidal 3D nanostructural waveguide carved in silver substrate is numerically studied by using FDTD method. Maximum field enhancement of 97 dB is obtained by using such structure which is enough to initiate high harmonic generation process. Furthermore, three times increase in amplification volume is acquired as compared with other geometries, which make the process of high harmonic generation more feasible. Moreover, effect of the polarization of the incident beam on field enhancement is also numerically investigated.