Chirality in Optical Trapping and Optical Binding

Abstract

Optical trapping is a well-established technique that is increasingly used on biological substances and nanostructures. Chirality, the property of objects that differ from their mirror image, is also of significance in such fields, and a subject of much current interest. This review offers insight into the intertwining of these topics with a focus on the latest theory. Optical trapping of nanoscale objects involves forward Rayleigh scattering of light involving transition dipole moments; usually these dipoles are assumed to be electric although, in chiral studies, magnetic dipoles must also be considered. It is shown that a system combining optical trapping and chirality could be used to separate enantiomers. Attention is also given to optical binding, which involves light induced interactions between trapped particles. Interesting effects also arise when binding is combined with chirality.

Quantum formulation for nanoscale optical and material chirality: symmetry issues, space and time parity, and observables

“…One of the main or implicit motivations for several of the recent studies in this area is the prospect of achieving, by optical means, a separation of particles-especially chiral molecules-of opposite handedness [7,10,43,[98][99][100][101][102][103][104][105][106][107][108][133][134][135][136][137][138][139][140][141][142][143][144][145]. Certainly such a capacity might have important commercial applications-notably in the pharmaceutical industry, where oppositely handed compounds can deliver drastically different effects.…”

Quantum delocalization in photon-pair generation

“…Arguably the most well-known application of the theory is the formulation of the Casimir-Polder potential [47]-which takes due account of retardation effects. Contemporary examples of the spheres of application include optical trapping [48][49][50][51][52] optical binding [53][54][55][56][57][58], and optical vortices [59][60][61][62], to name but a few.…”

Quantum localization issues in nonlinear frequency conversion and harmonic generation

“…The leading terms in the multipolar expansion of H int are: (2) provides for calculations within the well-known electric-dipole approximation -a constraint adopted in the primary determination of non-local features in nonlinear optics. Higher order couplings become significant when studying chiral discriminatory effects in optical processes including forces [31][32][33] and non-linear optics. [34][35] A quantum field description that gives the correct results for condensed phase materials requires account to be taken of the modification of the fields experienced (and produced) by any specific optical centre(s), due to its surroundings by the other atoms and molecules in the material.…”