Polarization dependence of light transmission through individual nanoapertures in metal films

Abstract

We present a systematic study of light transmission through individual nanoscale apertures (rectangular slits and circular holes) etched in a 300-nm-thick silver film. Transmission spectra were obtained as functions of aperture shape and size, as well as the wavelength and polarization state of the normally incident light beam. By varying the wavelength of the incident light in the 550-750 nm range and the characteristic dimensions of the apertures from ∼100 nm to 10 μm, a universal behavior of light transmission is revealed. The role of incident polarization and aperture dimensions is investigated in detail, and a clear transition from the geometric regime of light transmission (large apertures) to the subwavelength regime is demonstrated experimentally. A quantitative analysis of the extinction coefficient is reported for rectangular slits, demonstrating that they can act as efficient linear polarizers with extinction ratios >100∶1. Finally, a method to convert far-field to near-field data is developed for circular apertures, revealing the contribution of surface plasmon polaritons to the decrease in light transmission for apertures below the cutoff condition.

Circular slit-groove plasmonic interferometers: a generalized approach to high-throughput biochemical sensing [Invited]

“…It is also important to note that the device sensitivity can be higher for smaller changes of the refractive index, as shown for example in Ref [19]. It is well known that linear nano-slits on a metal film can be efficient polarizers [29]: light can be transmitted through the slits without cutoff under transverse magnetic (TM) illumination condition, i.e. when the electric field of the incident electromagnetic wave is perpendicular to the long slit axis; instead, a transverse electric (TE) incident field is highly attenuated [29].…”

“…It is well known that linear nano-slits on a metal film can be efficient polarizers [29]: light can be transmitted through the slits without cutoff under transverse magnetic (TM) illumination condition, i.e. when the electric field of the incident electromagnetic wave is perpendicular to the long slit axis; instead, a transverse electric (TE) incident field is highly attenuated [29]. Due to its circular symmetry, randomly polarized light can be transmitted through a circular slit without a significant loss.…”

“…7(c), a circular plasmonic interferometer shows a polarization insensitive light transmission. In contrast, the linear SG plasmonic interferometer shows more than two orders of magnitude higher transmission under TM illumination compared to TE polarization, since the linear slit is characterized by an extinction ratio > 100: 1 [29]. Devices with high light throughput are important for potential biochemical sensors.…”

Plasmonic control of extraordinary optical transmission in the infrared regime

“…In elongated elliptical and rectangular holes, this dependence is stronger than in circular or square ones. The rich phenomenology of both single rectangular apertures [10][11][12][13][14][15][16][17][18] and rectangular hole arrays [12,[19][20][21][22][23] have been applied to develop single molecule fluorescence [24], spectral and polarization sensing [25][26][27][28], perfect absorption [29], and probing the optical magnetic field [30,31].…”