Bound states in the continuum (BICs) emerge throughout Physics as leaky/resonant modes that remain, however, highly localized. They have attracted much attention in Photonics, and especially in metasurfaces[2,3]. One of their most outstanding features is their divergent Q-factors, indeed arbitrarily large upon approaching the BIC condition (quasi-BICs) [4,5]. Here we investigate how to tune quasi-BICs in magneto-optic (MO) all-dielectric metasurfaces. The impact of the applied magnetic field in the BIC parameter space is revealed for a metasurface consisting of Si spheres with MO response. Through our coupled electric/magnetic dipole formulation, the MO activity is found to manifest itself through the interference of the (MO-induced) out-of-plane electric/magnetic dipole resonances with the in-plane magnetic/electric (directly induced) dipole, leading to a rich, magnetically-tuned quasi-BIC phenomenology, resembling the behavior of Brewster quasi-BICs for tilted vertical-dipole resonant metasurfaces. Such resemblance underlies our proposed design for a fast MO switch of a Brewster quasi-BIC by simply reversing the driving magnetic field. This MO-active BIC behavior is further confirmed in the optical regime for a realistic YIG nanodisk metasurface through numerical calculations. Our results present various mechanisms to magneto-optically manipulate BICs and quasi-BICs, which could be exploited throughout the electromagnetic spectrum with applications in lasing, filtering, and sensing .
 Chia Wei Hsu, et al., Nat. Rev. Mater. 1 16048, (2016)
 D.C. Marinica, et al., Phys. Rev. Lett., 100, 183902 (2008)
 Chia Wei Hsu, et al., Nature 499, 188 (2013)
 Kirill Koshelev, et al., Phys. Rev. Lett. 121, 193903 (2018)
 Diego R. Abujetas, et al., Sci. Rep. 9, 16048 (2019)
 Diego.R. Abujetas, et al., Nanophotonics 10, 4223 (2021)
Here, we show that magneto-optically resonant particles present a large anisotropic thermal magnetoresistance (ATMR) in the near-field radiative heat transfer when the direction of an external magnetic field is changed with respect to the heat current direction. We illustrate this effect with the case of two InSb particles where we find that the ATMR amplitude can reach values of up to 800% for a magnetic field of 5 T, orders of magnitude larger than its spintronic analogue.
We also show that this two InSb particles experience non-reciprocal forces leading to a Stern-Gerlach like effect and permanent non-reciprocal torque.
In this work we show that the insertion of a dielectric layer in Au/Co/Au magnetoplasmonic nanodisks fabricated by hole
mask colloidal lithography makes it possible to obtain systems that simultaneously exhibit large magneto-optical (MO)
activity and low optical extinction. The physical mechanism underlying this effect is the internal EM field redistribution,
in such a way to concentrate it in the MO active layer (Co) and, at the same time, reduce it in the non MO active
elements. We have performed a systematic study of the optical and MO response upon the variation of the Co layer
thickness within the nanodisk, finding an increase of the MO response with the increment of thickness, accompanied
with a blue shift and broadening of the peaks associated with the plasmon excitations.
Surface plasmon excitation using a variation of Kretschmann method based on light guiding through an optical fiber has
been extensively studied in the literature. But, due to its particularly bad propagation conditions, plastic optical fiber was
not taken into account in documented experiments. We propose a low cost sensor using this type of fiber, in which we
try to avoid the problems both through careful design and signal processing. First of all we discuss the sample fabrication
and measurement in section 2; then the results obtained are discussed in section 3, including the problems faced because
of the multimode character of the fiber, for which we propose alternative sample shapes as a mean of reducing them. As
a conclusion we propose a roadmap to design a low cost sensor based in the structures studied in this paper.
The coupling between waveguides via cavities fabricated in 2D
photonic crystals is investigated within a numerical framework.
We demonstrate that the symmetry of the modes plays an important
role in light propagation through waveguides coupled by cavities.
Two different situations are addressed: the structures are defined
varying the geometrical parameters and varying the dielectric
constant ε. In both situations we show that if the
symmetry of the waveguide mode does not correspond to that of the
localized mode of the cavity the coupling is negligible.
The conductance of nano-sized, surface disordered wires is theoretically analyzed all the way during an elongation process. Even though wire cross-section is kept constant during the whole process, the statistical analysis of the conductance reveals clear preference to take values close to integer multiples of the conductance quantum. We show that this is a consequence of having a very small number of channels and surface disorder only.