Active control of surface plasmon polaritons by optical isomerization of an azobenzene polymer film

Active control of surface plasmon polaritons (SPPs) by optical isomerization of an azobenzene polymer film is proposed and demonstrated in this letter. A tightly focused 532 nm laser beam was used to change the wave number of the SPPs and a separate unpolarized light source was employed to erase the change, forming one cycle of the control. The largest change of the SPPs wave number obtained in the experiments is about 0.0382K(0) in the case of 54 nm thickness azo-polymer film. Validity of this method is confirmed by consistence between theoretical and experimental results.