  Optical Airy beam, as a novel non-diffracting and self-accelerating wave
packet, has generated great enthusiasm since its first realization in 2007,
owing to its unique physics and exciting applications. Here, we report a new
form of this intriguing wave packet - plasmonic Airy beam, which is
experimentally realized on a silver surface for the first time. By particular
diffraction processes in a carefully designed nano-array structure, a novel
planar Airy beam of surface plasmon polariton (SPP) is directly generated and a
structural dependent phase tuning method is proposed to modulate the beam
properties. This SPP Airy beam is regarded as a two-dimensional (2D)
subwavelength counterpart of the 3D optical Airy beam in free space, allowing
for on-chip photonic manipulations. Moreover, it possibly suggests a
breakthrough in recognition of this unique wave packet in a polariton regime
after its previous evolution from free particle to pure optical wave.
