A subwavelength slit as a quarter-wave retarder

Abstract

Abstract:We have experimentally studied the polarization-dependent transmission properties of a nanoslit in a gold film as a function of its width. The slit exhibits strong birefringence and dichroism. We find, surprisingly, that the transmission of the polarization parallel to the slit only disappears when the slit is much narrower than half a wavelength, while the transmission of the perpendicular component is reduced by the excitation of surface plasmons. We exploit the slit's dichroism and birefringence to realize a quarter-wave retarder.

Optical angular momentum conversion in a nanoslit

“…This interaction between spin and orbital angular momentum of light by way of a Berry-Pancharatnam phase has also been studied in space-variant gratings [6] and plasmonic nanostructures in the context of selection rules [7], and also outside the domain of optics, in electron beams [8]. We present here a novel method for this conversion using a subwavelength slit in a metal film that acts like a quarter-wave plate [9]. We show how this method relaxes the requirement of circular symmetry, allowing greater versatility in the form of the vortex created.…”

“…© 2012 Optical Society of America OCIS codes: 310.6628, 230.7370, 260.1440, 050.1930 The curious phenomenon of optical vortices arising from axial symmetry in birefringent materials has been studied in uniaxial crystals of variable length [1,2] and birefringent plates with a spatially varying optical axis and half-wave retardation ("q-plates") [3][4][5]. This interaction between spin and orbital angular momentum of light by way of a Berry-Pancharatnam phase has also been studied in space-variant gratings [6] and plasmonic nanostructures in the context of selection rules [7], and also outside the domain of optics, in electron beams [8].We present here a novel method for this conversion using a subwavelength slit in a metal film that acts like a quarter-wave plate [9]. We show how this method relaxes the requirement of circular symmetry, allowing greater versatility in the form of the vortex created.…”

“…The expectation value of the orbital angular momentum per photon is Qℏ [10]. The difference between the two forms of angular momentum is beautifully apparent in the interaction of a beam with small particles: interaction with the spin angular momentum in the absence of absorption requires particles that are birefringent; they will start to rotate about their own axis, whereas interaction with a beam carrying orbital angular momentum causes particles, whether birefringent or not, to rotate about the beam's optical axis [11].Recently, we reported on how a subwavelength slit in a metal film can act as an optical retarder [9]. A slit that is subwavelength in one direction and extended in the other has two eigenpolarizations: parallel and perpendicular to the slit.…”

“…We present here a novel method for this conversion using a subwavelength slit in a metal film that acts like a quarter-wave plate [9]. We show how this method relaxes the requirement of circular symmetry, allowing greater versatility in the form of the vortex created.…”

“…Recently, we reported on how a subwavelength slit in a metal film can act as an optical retarder [9]. A slit that is subwavelength in one direction and extended in the other has two eigenpolarizations: parallel and perpendicular to the slit.…”