TY - CHAP A1 - Poulikakos, Lisa A1 - Gutsche, Philipp A1 - McPeak, Kevin A1 - Burger, Sven A1 - Niegemann, Jens A1 - Hafner, Christian A1 - Norris, David T1 - A Far-Field Interpretation of Optical Chirality in Analogy to Poynting’s Theorem T2 - META '15 Proceedings N2 - The optical chirality density is a valuable tool in locally characterizing chiral electromagnetic near-fields. However, how this quantity could translate into the far-field is not well understood. Here, we formulate a far-field interpretation of optical chirality by investigating its conservation law in isotropic media in analogy to Poynting’s Theorem. We define the global chirality and find that lossy materials, in particular plasmonic nanostructures, can act as chirality generators. This can enable chiral sensing applications at the single molecule level. Y1 - 2015 SP - 1215 EP - 1216 ER - TY - GEN A1 - Poulikakos, Lisa A1 - Gutsche, Philipp A1 - McPeak, Kevin A1 - Burger, Sven A1 - Niegemann, Jens A1 - Hafner, Christian A1 - Norris, David T1 - A Far-Field Interpretation of the Optical Chirality T2 - Frontiers in Nanophotonics (Congressi Stefano Franscini) N2 - A chiral structure is not super-imposable with its mirror image. Most commonly found in organic molecules, chirality can also occur in other systems, such as electromagnetic fields, where circularly polarized light is the most widespread example. Chiral electromagnetic fields can be a useful tool for biosensing applications. In particular, it has been shown that chiral plasmonic nanostructures have the ability to produce strongly enhanced chiral near-fields. Recently, our group has developed chiral plasmonic nanopyramids, which have the ability to focus chiral near-fields at their tip. This could enable chiral sensing at the single-molecule level. Chiral near-fields can be characterized in terms of the “optical chirality density”. This time-even and parity-odd pseudoscalar was first derived by Lipkin and was found to follow a conservation law analogous to the energy conservation of electromagnetic fields. More recently, Tang and Cohen identified the physical meaning of the “optical chirality density” as the degree of asymmetry in the excitation rate of a chiral molecule. However, how this near-field interpretation of the optical chirality could translate into the far-field is not well understood. Here, we formulate a far-field interpretation by investigating the conservation law for optical chirality in matter, and performing time-averaging in analogy to Poynting’s Theorem. In parallel to extinction energy, we define the “global chirality” as the sum of chirality dissipation within a material and the chirality flux leaving the system. With finite-element simulations, we place a dipole source at locations of enhanced local chirality and investigate the global chirality and ellipticity of emitted light in the far-field. Interestingly, we find that lossy materials with a complex dielectric function have the ability to generate global chirality when excited by achiral light. In particular, chiral plasmonic nanostructures are found to act as effective global chirality generators. The global interpretation of optical chirality provides a useful tool for biosensing applications with chiral plasmonic nanostructures, where the detection is routinely performed in the far-field. Y1 - 2015 ER - TY - JOUR A1 - McPeak, Kevin A1 - van Engers, Christian D. A1 - Bianchi, Sarah A1 - Rossinelli, Aurelio A1 - Poulikakos, Lisa A1 - Bernard, Laetitia A1 - Herrmann, Sven A1 - Kim, David K. A1 - Burger, Sven A1 - Blome, Mark A1 - Jayanti, Sriharsha V. A1 - Norris, David T1 - Ultraviolet Plasmonic Chirality from Colloidal Aluminum Nanoparticles Exhibiting Charge-Selective Protein Detection JF - Adv. Mater. Y1 - 2015 U6 - https://doi.org/10.1002/adma.201503493 VL - 27 SP - 6244 ER - TY - JOUR A1 - Poulikakos, Lisa A1 - Gutsche, Philipp A1 - McPeak, Kevin A1 - Burger, Sven A1 - Niegemann, Jens A1 - Hafner, Christian A1 - Norris, David T1 - The Optical Chirality Flux as a Useful Far-Field Probe of Chiral Near Fields JF - ACS Photonics Y1 - 2016 U6 - https://doi.org/10.1021/acsphotonics.6b00201 VL - 3 SP - 1619 ER - TY - GEN A1 - Gutsche, Philipp A1 - Poulikakos, Lisa A1 - Burger, Sven A1 - Hammerschmidt, Martin A1 - Schmidt, Frank T1 - Optical chirality: conservation law in arbitrary space T2 - 606. WE-Heraeus-Seminar on Nanophotonics and Complex Spatial Modes of Light N2 - The introduction of the near-field quantity of optical chirality has emerged in various numerical and few experimental studies of local chirality enhancement due to its relation to the excitation rate of chiral molecules. This time-even pseudoscalar has been dismissed as being a higher-order version of helicity. Nevertheless, we revisit the derivation of the underlying conservation law and define optical chirality in media similar to. We identify the mechanism of chirality conversion by either inhomogeneous or anisotropic space to complement the conservation of optical chirality. The conservation law of optical chirality in arbitrary space enables the extension of the concept of polarization to the near-field where no distiniguished propagation direction of light is present. We show that the connection of electromagnetic energy and optical chirality provide the ability to define a circular polarization basis in time-harmonic near-field analysis. In order to illustrate our theory, we present electromagnetic field simulations of simple as well as more complex nanostructures. Results using the well-known far-field polarization concept are readily reproduced and extended from the point of view of chirality conversion. Y1 - 2016 ER - TY - JOUR A1 - Gutsche, Philipp A1 - Poulikakos, Lisa A1 - Hammerschmidt, Martin A1 - Burger, Sven A1 - Schmidt, Frank T1 - Time-harmonic optical chirality in inhomogeneous space JF - Proc. SPIE Y1 - 2016 U6 - https://doi.org/10.1117/12.2209551 VL - 9756 SP - 97560X ER -