Manipulating surface plasmon polaritons with M-shaped nanoslit array via polarized incident waves

Surface plasmonic bending beams (SPBs), which preserve their spatial shapes while propagating along the desired curved trajectories in a metal-dielectric interface, offer important applications in the fields of fiber sensors, optical trapping, and micro-nano fabrication. In this work, the straight-lined, single-curved and double mirror-symmetric curved distributions of M-shaped nanoslit arrays are designed on a metal film to generate SPBs. These SPBs include unidirectional coupling of SPPs, single arbitrary bending beams, and double arbitrary bending beams. The electric-field intensity and the propagation directions of these SPBs are controlled by the polarization angle of input light waves. Especially, the reverse propagation of unidirectional coupling of arbitrary SPBs is generated by the polarization angles 45° and 135°. These findings provide guidance in the design and optimization of plasmonic bending beam generators.