The optical one-way transmission in helical metal subwavelength slit

• One-way transmission.
• Helical metal aubwavelength slit.
• Surface plasmon polaritons.
• Optical rotation.

A novel line-type optical one-way transmission structure is proposed, which consists of a helical subwavelength metal slit. The simulation results obtained from finite-difference time-domain method show that this structure has excellent one-way transmission properties. When a polarized light propagates forward through the structure, its polarization direction will be rotated 90 degree. The backward propagation is blocked.This helical slit can also be a one-way unit of a plane-type one-way transmission structure, in which the setting angle plays an important role in determination of the transmission properties of the one-way plane via the strong coupling effect between the waves in adjacent slits.