Influence of higher modes on plasmonic force in a narrow slit

The plasmonic force due to electromagnetic waves between two metallic walls has been studied earlier for a subwavelength slit taking into consideration only zero mode. In the present paper, the effects of the second mode are analyzed. The higher modes are shown to decrease the attractive force. The magnetic field of the p-wave is compared with the model of a perfect conductor. The difference occurs maximal at the threshold, where the second mode changes its behavior from evanescent to propagating. The effect of possibly changing the attractive force to the repulsive force for a relatively wide slit is found.