Time response of plasmonic spatial differentiators

We investigate the time response of plasmonic spatial differentiators based on prism coupling configurations. We show that when the incident light is time-modulated, in addition to the spatial differentiation, the output field is also contributed by the signal derivative with respect to time. To reduce this impact, the incident pulse needs a steady time span, and the shortest steady time span is about 100 fs. We further show that the time modulation does not degrade the resolution of the spatial differentiation. Also, we numerically demonstrate the image processing of edge detection by the plasmonic spatial differentiator, with the time-modulated signal. (C) 2019 Optical Society of America