Dynamic manipulation of optical chirality for gammadion nanostructures

We present a method to achieve the dynamic manipulation of optical chirality for a gammadion nanostructure. The gammadion nanostructure is illuminated by two counter-propagating linearly polarized lights (LPLs) with orthogonal polarization directions. By adjusting the phase difference between the two LPLs, the optical chirality enhancement can be adjusted periodically as a function of the phase difference and the optical chirality manipulation range lies between those obtained by single left- and right-handed circularly polarized light excitation. This work provides a convenient and feasible method to achieve the dynamic manipulation of optical chirality for chiral plasmonic nanostructures.