Phase matched SHG of surface polariton along a silver layer on a slab‐type optical waveguide

Abstract

The existence is found for coupled guidedand surface polariton‐modes, in a slab‐type waveguide with a silver thin layer on top of it. The phase‐matched condition for the second harmonic generation (SHG), due to the fundamental and surface polariton modes, is determined. In waveguides of this structure, the realization of long propagation‐length (i.e., long interaction‐length) is possible in a waveguide with energy storage (Corning glass 7059), to compensate for the losses due to excitation of plasma polaritons. The generation of the phase matched second harmonics due to the surface polaritons is experimentally observed. The waveguide is tapered perpendicular to the direction of propagation. The theoretical phase matched condition between the fundamental and second harmonic waves is determined for a specific silver thickness on top of the slab waveguide. This phase‐matched condition is confirmed experimentally. The output of a Q switched Nd: YAG laser is used as the fundamental wave.