Amplification of Surface Plasmons

The amplification of surface plasmon polaritons in planar metallic waveguides via propagation through an optically pumped dipolar gain medium incorporated into one of the claddings is discussed theoretically and experimentally. Physically realisable arrangements based on the single-interface and on the thin metal film are described. Experimental results are given, demonstrating amplification of the long-range surface plasmon-polariton along a thin metal stripe at near infrared wavelengths using a dye gain medium. Low amplified spontaneous emission noise into this mode is simultaneously observed.