Non-degenerate optical parametric amplification analysis of surface plasmon polariton wave in a silver coated PPLN planar waveguide

Optical parametric amplification (OPA) of a SPP wave is investigated theoretically to enhance its propagation length. Excited SPP mode in a silver coated periodically poled lithium niobate (PPLN) planer waveguide interact with a guided mode via χ(2)-based difference frequency generation (DFG). Proper quasi phase matching domain periodicity governs the allowed SPP↔guided mode combination for efficient amplification of desired SPP wave. Although, the acceptance bandwidth of the amplified SPP mode shows its power dependent behavior but the SPP length enhancement up to 11 mm in a wide range of about 18 nm would be feasible. Figure below illustrates the design structure used in the paper for SPP wave amplification. Excited SPP modes and guided modes are shown as well. Schematic presentation of the three layer structure used to model the SPP wave amplification. A 2 μm thick layer with the increased permittivity of ε1 = ε2 + 0.04 in both ordinary and extraordinary directions builds a planer dielectric waveguide which is coated with silver. The SPP modes (red and blue) together with the guided mode (green) can be excited in the structure. The direction of the arrows shows the sign of the χ(2) coefficient in different domains of the PPLN substrate 156