Determination of Fabry–Perot resonator contribution in light transmission through unsymmetrical nanoslit

The enhanced light transmission through an I-shape aperture is studied by simulation and theory. The transmission profile due to microcavities created in the entrance and exit of the aperture was modified and new peak was observed. By introducing a new formula the refractive index of layers is defined. The Fabry–Perot matrix method is employed to explore the role of Fabry–Perot resonator effect in modified slits, especially I-shape slit in the scope of this work. And the peaks correspond to this effect are determined. The effect of microcavity surface Plasmon polaritons is explored respectively. Both microcavity surface plasmons and Fabry–Perot resonator contribute in transmission enhancement and consider as the origin of extraordinary transmission for unsymmetrical slits.

Research highlights
► Calculation of refractive index in I-shape slits.
► Using Fabry–Perot matrix method to calculate transmission.
► Determination of related peaks to Fabry–Perot resonator.
► Influence of microcavity surface plamson deduced.