Quantitative Determination of Enhanced and Suppressed Transmission through Subwavelength Slit Arrays in Silver Films

TL;DR

This study measures how subwavelength slit arrays in silver films can significantly enhance or suppress light transmission, revealing interference effects with surface plasmon polaritons that depend on array parameters.

Contribution

It provides experimental data and a model explaining the modulation of light transmission through slit arrays due to SPP interference, highlighting the effects of array pitch and slit number.

Findings

Transmission can be enhanced by up to 6 times or suppressed by up to 9 times compared to an isolated slit.

Pronounced minima occur at specific array pitches related to SPP wavelengths.

Increasing the number of slits beyond four does not significantly increase per-slit transmission.

Abstract

Measurement of the transmitted intensity from a coherent monomode light source through a series of subwavelength slit arrays in Ag films, with varying array pitch and number of slits, demonstrate enhancement (suppression) by as much as a factor of 6 (9) when normalized to that of an isolated slit. Pronounced minima in the transmitted intensity were observed at array pitches corresponding to lambda_SPP, 2lambda_SPP, and 3lambda_SPP where lambda_SPP is the wavelength of the surface plasmon polariton (SPP). Increasing the number of slits to more than four does not increase appreciably the per-slit transmission intensity. These results are consistent with a model for interference between SPPs and the incident wave that fits well the measured transmitted intensity profile.