Generation and control of optical vortices using left-handed materials

Optical vortices are shown to be generated in the near-field through interference between a propagating wave and the amplified evanescent field in a slab of lossy left-handed material. While small loss adversely impacts the sub-wavelength performance in the lens application, the vortex character shown relies on some degree of imperfection. These vortices can be controlled by means of gain/loss and the incident field.