Spatial mode control of surface plasmon polariton excitation with gain medium: from spatial differentiator to integrator.

In optical analogue computation, optical differentiator and integrator are the key element devices for ultrafast parallel data processing. Here we demonstrate that a Kretschmann configuration prism can directly perform spatial differentiation for the incident beam profile. Additionally, we realize all-optical reconfiguration from differentiator to integrator by modulating the propagation loss of surface plasmon polariton with optical pump. The feature of reconfiguration opens directions to ultrafast beam transformation, reconfigurable imaging processing, and all-optical analogue computing.