Creating and moving nanoantenna cold spots anywhere

Cold spots are sub-wavelength regions which might emerge near a nanoantenna when components of a far-field illumination cancel with scattered light. The authors show that by changing only the polarization, amplitude, and phase of two plane waves, a unique, zero-magnitude and highly sub-wavelength cold spot can be created and moved anywhere in space around a nanoantenna of arbitrary shape. This can be achieved using ultra-fast modulated pulses, or within a time-harmonic approximation. Such manufactured cold spots are fragile—easily disturbed by changes in the nanoantenna’s material or position—suggesting applications in nanoscale sensing. Exploiting linearity of Maxwell’s equations, the technique can extend to any system governed by the linear wave equation, including acoustic scattering, enabling potentially ultra-fast sub-wavelength electric field manipulation.

Alex J. Vernon, Francisco J. Rodríguez-Fortuño