Abstract: Surface plasmon polaritons (SPPs), the electromagnetic fields propagating along the metal-dielectric interface, are regard as the promising candidate of the next photonic integrated circuits. Several metal slit structures based on the SPPs are summarized. By using the Fabry–Perot resonator effect, Fano resonance, and multimode interference, the SPP propagation could be controlled and modulated by these metal slit structures. As a result, a subwavelength unidirectional SPP generator, a submicron broad unidirectional SPP generator, submicron SPP splitters, nano-focusing devices, and submicron all-optical switches were realized in the metal slit structures. These nano-plasmonic devices have important applications in highly integrated photonics.

Key words: Fiber and waveguide optics; surface plasmon polaritons; unidirectional generator; splitter; nano-focusing; all-optical switch