Twisted light seminar by Prof Eugene Kaminetskii
Many thanks to Eugene for the interesting seminar (here is the recorded version):
Twisted fields in waveguides with subwavelength resonant particles
Microwave Magnetic Laboratory
Ben Gurion University of the Negev, Israel
Circularly polarized light, carrying spin angular momentum (SAM), is a chiral light. Light carrying SAM can interact with chiral and magnetoelectric materials. There are different light configurations with SAMs: (a) Light with transverse and longitudinal SAM. (b) Complex fields having circular polarizations of opposite directions or the same directions. Another thing concerns generation of light beams with orbital angular momentum (OAM). In this case, we are talking about twisted light. OAM is dependent on the field spatial distribution, and not on the polarization. In OAM light, azimuthal dependence of beam phase results in a helical wavefront. Orientation of the local momentum of the beam has a vortex pattern. It means that the optical vortices carry quantized OAM states.
In increasing the capabilities of the optical and microwave techniques further into the subwavelength regime, dipole-carrying resonant structures have attracted considerable interest. The examples are exciton polaritons, surface-plasmon polaritons, and magnon polaritons. Currently, one of the topical problems is interaction of material structural elements with SAM and OAM light in subwavelength regions. But the question arises: Is it possible at all to observe electromagnetic radiation with the SAM and OAM in the subwavelength regions? In the near-field regions of subwavelength particles one can measure only either the electric or magnetic field with accuracy. Moreover, separation of the total angular momentum of the field into the SAM and OAM parts is normally considered to be not observable.
In this seminar, we will refer to new and important aspects of chiral and twisted subwavelength fields. We show that this presumes the existence of specific near ﬁelds with unique symmetry properties. Recently, such field structures, called ME ﬁelds, were found as the near fields of a quasi-2D subwavelength-size ferrite disk resonator with magnetic-dipolar-mode magnon oscillations. The near fields of these oscillations are characterized by subwavelength power-flow vortices with strong enhancing the field intensity. We discuss unique applications of the ME-ﬁeld structures in microwaves and optics.
E. O. Kamenetskii, “Quantization of magnetoelectric fields”, J. Modern Opt. 66, 909 (2019).
E. O. Kamenetskii, “Quasistatic oscillations in subwavelength particles: Can one observe energy eigenstates?”, Ann. Phys. (Berlin) 531, 1800496 (2019).
E. O. Kamenetskii,,”Electrodynamics of magnetoelectric media and magnetoelectric fields”, Ann. Phys. (Berlin) 532, 1900423 (2020).
E. O. Kamenetskii, “Magnetoelectric near fields”, arXiv:2009.08084; A book chapter in "Chirality, magnetism, and magnetoelectricity: Separate phenomena and joint effects in metamaterial structures", SPRINGER (2021).