Mid-infrared direct injection and sub-wavelength focusing of designer's surface plasmons polaritons

A surface plasmon polariton (SPP) mode is directly excited on a metal/air interface using an integrated mid-infrared (MIR) quantum cascade laser. We demonstrate the SPP generation and propagation via far-field and near-field MIR imaging. We also demonstrate bending and focusing of MIR surface-plasmons using a sub-wavelength metal patterning.