Fundamental symmetry origins in the chiral interactions of optical vortices

Abstract

Recently, a variety of mechanisms have been discovered that extend the range of optical techniques for identifying and characterizing molecular chirality, beyond those associated with optical polarization. It is now evident that beams of light with a twisted wavefront, known as optical vortices, can also interact with chiral matter with a specificity determined by relative handedness. Exploring this chiral sensitivity of vortex light in its interactions with matter requires careful consideration of the symmetry properties that engage in such processes. Most of the familiar measures of chirality are directly applicable to either matter, or to light itself—but only to one or the other. To elicit the principles that determine the viability of distinctly optical vortex‐based forms of chiral discrimination invites a more universal approach to symmetry analysis, as is afforded by the common, fundamental physics of symmetry. Taking this approach supports a comprehensive and straightforward analysis to identify the mechanistic origins of vortex chiroptical interactions. Careful inspection of selection rules for absorption also elicits the principles governing any identifiable engagement with vortex structures, providing a reliable basis to ascertain the viability of other forms of enantioselective vortex interaction.

Observation of Magnetic Quadrupole Endowed Helical Dichroism in Artificial Propeller Meta‐Molecules

“…Light field with orbital angular momentum (OAM) is also known as vortex beam which has been well applied in optical tweezers, [12] communication, [13] manufacturing, [14] etc. [15,16] The helical wavefront also gives vortex beam a chiral degree of freedom and its handedness is determined by the sign of the OAM munber l. [17][18][19] Interestingly, recent theoretical and experimental studies have demonstrated that the interaction between vortex beam and chiral matters depends on the sign of l. [20][21][22][23][24][25][26][27][28][29][30] This suggests that photonic OAM can provide another promising approach to investigate chiral physics. The giant helical dichroism (HD) has been achieved for a single helix, [25,29] planar-chiral nanostructure, [26] twisted stereometamaterial, [27] and chiral oligomer.…”

Optical Spin Waves

“…Chirality is a universal symmetry property of matter and waves that is important in biology, medicine, physics, , and materials science . In optics, chiral effects usually involve chiral light, characterized by helical waves carrying angular momentum. − The helical phase structure or field pattern rotation produces orbital angular momentum (OAM), while the rotation of the light polarization vector introduces spin angular momentum (SAM) . Analogies between electron and optical spin effects have recently led to the investigation of novel chiral states of light, such as photonic skyrmions. , Similar to their magnetic skyrmion counterparts, these spin-optical textures are topologically protected against external perturbations.…”