Intensity modulation and polarization rotation of visible light by dielectric planar chiral metamaterials

Abstract

We have demonstrated how dielectric planar chiral surfaces can both modulate the intensity and change the polarization state of visible light diffracted from patterned surfaces. These effects are shown to be dependent on the sense of chirality of the surface and the input polarization state of the light. Individual diffracted beams can show variations of over 30% in their intensities for different input polarization states while opposite enantiomeric structures can exhibit differences of over 50%. The size of these effects could make these surfaces particularly promising candidates for the development of solid-state polarization-state detectors. © 2005 American Institute of Physics. ͓DOI: 10.1063/1.1944211͔Metallic planar chiral metamaterials with characteristic length-scales of a few microns have attracted significant interest recently in light of their novel and intriguing polarization properties. 1,2 Most notable of these is their ability to rotate and elliptize the polarization state of light. These effects were first observed for visible light diffracted in reflection from samples consisting of regular arrays of gammadion-shaped holes etched into thin metallic films 3 and were similar in form to effects that had been predicted for somewhat larger structures designed to operate in the microwave regime. 4 The underlying mechanism for these effects has previously been ascribed, at least in part, to the generation of induced currents or surface-plasmon-polaritons ͑SPP͒ in the walls of the metallic gammadions. 1,2 However, we will now demonstrate that similar effects are observable for visible light diffracted from patterned polymer films, suggesting that other mechanisms ͑such as electro-magnetic displacement currents or Fabry-Perot interference effects͒ may also play a significant role. More importantly, these results suggest that most patterned thin films that exhibit twodimensional chirality 5 could be capable of exhibiting polarization sensitive effects, irrespective of the physical properties of the medium in which the chiral pattern is formed.The global significance of these results is that they allude to the possibility of the creation of truly nonreciprocal optical structures from materials that are inherently nonmagnetic. Such effects have been predicted theoretically for a number of idealized physical structures subject to various preliminary assumptions and approximations, 4,6,7 but if they could be demonstrated experimentally for real structures they would undoubtedly prove crucial for the development of entirely new optical devices such as polarization sensitive detectors, manipulators, and other optical elements. Unfortunately, our attempts to realize such a device have so far failed to show any chirality-induced polarization change in the zero-order beam in either reflection or transmission when the sample is illuminated at either normal incidence or glazing incidence. However, other workers studying sub-wavelength structures ͑in which the average separation of the chiral elements, ⌳, is less tha...

A new polarimeter scheme based on solid state semiconductors

“…Beam ( The modulation of the output power over the input azimuth can be observed in Figure 3, attesting the results found in [2,4,7]. It can be noticed that the beams (1,1) and (1,-1) are much weaker than beams (0,1) and (1,0).…”

“…Recently, it has been reported a strong linear dependency on the state of polarization of the incident beam for both the polarization state and the intensity of diffracted beams through two-dimensional (2D) chiral structure [3,4]. In this case 2D chiral feature is defined as "a planar surface that does not possess a line of symmetry within the plane of the patterned surface, and where if the surface pattern is mirror-reflected about any line in the plane of the surface.…”

Golden spiral photonic crystal fiber: polarization and dispersion properties

“…The sense of rotation of the structure changes when viewed from opposite directions unlike a 3D chiral structure such as a helix. Recently experimental and theoretical studies ( [12,13], and references therein) have shown that planar chiral materials can modulate the intensity of light and change the polarization state. The intensity modulation and polarization rotation/elliptization effects change with the direction of the incident light as well as the handedness of the material.…”

Planar chirality of plasmonic multi-split rings

“…Features of planar chiral structures that are of major practical importance include their ability to be fabricated and deposited as layered thin films, their application as magnetic thin films whose properties arise from magnetoelectric coupling, and their potential for generating unusually large optical activity (i.e., relatively large rotary power for the plane of polarization of an impinging wave) compared to that for 3-D chiral structures, as was numerically predicted early on [7] and experimentally verified, cf., e.g., [9]- [14]. This rotary power results from the fact that, like 3-D chiral geometries, 2-D chirality gives rise to a different sensitivity of incident waves exhibiting left-vs. right-hand circular eigenpolarizations (circular birefringence).…”