Effect of slit width on surface plasmon resonance

In this paper, a hybrid resonator composed of an all-metal grating made of copper and a dielectric cavity filled with SiO2 between slits is simulated and calculated by the finite-difference time-domain method (FDTD). We study the effect of slit width on surface plasmon resonance by changing the size of the dielectric cavity. In the case of parallel light incident vertically, the resonator can achieve multi-band absorption and have a perfect absorption peak. The dielectric cavity can not only localize the incident light wave, but also enhance the effect of surface plasmon of metal structure. Our results can be widely used in the field of surface plasmon, which is beneficial to the development of surface plasmon resonators in sensing and detection.