Corner Effect to Enlarge Light Funneling Area Inconsistent to Transmission Through a Plasmonic Slit

This study investigates the phenomenon of light funneling through a subwavelength plasmonic slit, examining the corner effect resulting from the interaction between the incident wave and the round-trip wave within the slit. Our findings reveal an inconsistent relationship between transmittance and the size of the funneling area. Notably, constructive interference of the waves significantly enhances transmittance, leading to the unexpected emergence of a ring-like Poynting vector contour at the entrance corner of the slit. In cases where transmittance remains moderate and constructive interference continues to dominate, the light funneling area expands due to the presence of the ring. Furthermore, the extent of the ring expansion correlates with the enlargement of the funneling area, and the underlying mechanism can be elucidated through an examination of the dynamics of light fields and Poynting vectors.