Partial loss compensation in dielectric-loaded plasmonic waveguides at near infra-red wavelengths.

We report on the fabrication and characterization of straight dielectric-loaded surface plasmon polaritons waveguides doped with lead-sulfide quantum dots as a near infra-red gain medium. A loss compensation of ~33% (an optical gain of ~143 cm⁻¹) was observed in the guided mode. The mode propagation, coupling efficiency and stimulated emission were characterized using leakage radiation microscopy. The guided mode signature was separated using spatial filters in the Fourier plane of the microscope for quantitative measurements of stimulated emission.