All-dielectric reciprocal bianisotropic nanoparticles

Rasoul Alaee, Mohammad Albooyeh, Aso Rahimzadegan, Mohammad S. Mirmoosa, Yuri S. Kivshar, and Carsten Rockstuhl

Phys. Rev. B 92, 245130 – Published 23 December 2015

Abstract

The study of high-index dielectric nanoparticles currently attracts a lot of attention. They do not suffer from absorption but promise to provide control of the properties of light comparable to plasmonic nanoparticles. To further advance the field, it is important to identify versatile dielectric nanoparticles with unconventional properties. Here, we show that breaking the symmetry of an all-dielectric nanoparticle leads to a geometrically tunable magnetoelectric coupling, i.e., an omega-type bianisotropy. The suggested nanoparticle exhibits different backscatterings and, as an interesting consequence, different optical scattering forces for opposite illumination directions. An array of such nanoparticles provides different reflection phases when illuminated from opposite directions. With a proper geometrical tuning, this bianisotropic nanoparticle is capable of providing a $2 π$ phase change in the reflection spectrum while possessing a rather large and constant amplitude. This allows the creation of reflectarrays with near-perfect transmission out of the resonance band due to the absence of a usually employed metallic screen.

Received 3 September 2015
Revised 18 November 2015

DOI:https://doi.org/10.1103/PhysRevB.92.245130

Authors & Affiliations

Rasoul Alaee^1,*, Mohammad Albooyeh², Aso Rahimzadegan¹, Mohammad S. Mirmoosa², Yuri S. Kivshar³, and Carsten Rockstuhl^1,4

¹Institute of Theoretical Solid State Physics, Karlsruhe Institute of Technology, Karlsruhe 76131, Germany
²Department of Radio Science and Engineering, School of Electrical Engineering, Aalto University, Aalto, Finland
³Nonlinear Physics Centre, Research School of Physics and Engineering, Australian National University, Canberra ACT 0200, Australia
⁴Institute of Nanotechnology, Karlsruhe Institute of Technology, Karlsruhe 76021, Germany

^*Corresponding author: rasoul.khanghah@kit.edu

Article Text (Subscription Required)

Click to Expand

References (Subscription Required)

Click to Expand

Issue

Vol. 92, Iss. 24 — 15 December 2015

Reuse & Permissions

Access Options

Author publication services for translation and copyediting assistance advertisement

Images

Figure 1
(a) Schematic of the proposed bianisotropic high-index dielectric nanoparticle. (b) A cut in the $y z$ -plane of the proposed nanonatenna. The dielectric cylinder has a diameter $D = 300$ nm and height $H = 150$ nm with a cylindrical hole inside it that has a diameter $D_{0} = 150$ nm and height $H_{0} = 10 - 140$ nm. We assumed that the refractive index of the material from which the cylinder is made is $n = 3.5$ . The ambient material shall be air with a refractive index of unity.
Reuse & Permissions
Figure 2
(a) and (c) Total scattering cross sections $C_{sca}^{\pm}$ and contributions from different Cartesian multipole moments as a function of frequency for forward ( $+$ ) and backward ( $-$ ) illumination directions; electric dipole moment $p^{\pm}$ (red dashed line), magnetic dipole moment $m^{\pm}$ (blue dashed line), electric quadrupole moment $Q^{\pm}$ (green dashed line), and magnetic quadrupole moment $Q M^{\pm}$ (purple dashed line). The height of the air hole is $H_{0} = 100$ nm. (b) and (d) normalized magnetic field distributions at $365 THz$ [gray dashed line in (a) and (c)] for both opposite illumination directions.
Reuse & Permissions
Figure 3
(a)–(c) Individual polarizability components of the proposed nanoparticle. The geometrical parameters are: the height of the cylinder $H = 150$ nm, the height of the cylindrical air hole $H_{0} = 100$ nm, and its diameter $D_{0} = 150$ nm. (d) Amplitude of the individual polarizability components at the maximum of the magnetoelectric coupling as a function of $H_{0}$ . The maximum bianisotropy happens when the height of the air hole is approximately half of the height of the dielectric cylinder, i.e., $H_{0} \approx \frac{H}{2} = 75$ nm.
Reuse & Permissions
Figure 4
(a) Normalized backward (blue lines) and forward (red lines) radar cross sections when the nanoparticle is illuminated from backward (dashed lines) and forward (solid lines) directions for $H_{0} = 75$ nm. Note that the forward radar cross sections are identical and hence indistinguishable in the figure. (b) Radiation patterns for forward and (c) backward illumination directions at $445 THz$ , respectively. (d) Normalized forward (solid lines) and backward (dashed lines) optical forces. $F_{p}^{\max} = \frac{3 π}{k^{2}} ε_{0} {| E_{inc} |}^{2}$ is the maximum force applied on a particle which exhibits an electric dipole moment with an incidence plane wave. (e) Schematic view of the different illuminations for forward and (f) backward illumination directions.
Reuse & Permissions
Figure 5
(a) A metasurface composed of an array of bianisotropic nanoparticles with $H_{0} = 75$ nm. (b) Reflection and transmission amplitude for two illumination directions shown in (a). (c) The same plots as in (b) but for the corresponding phases. The reference plane for the phases is considered at the $z = 0$ plane.
Reuse & Permissions
Figure 6
(a) Phase-change curve for the reflection coefficient of an array of nanoparticles versus the diameter of the air hole at resonance frequency $f = 405$ THz for two different illumination directions denoted by $r^{+}$ and $r^{-}$ . $H_{0}$ is fixed to 75 nm. (b) The same plot as in (a) for variation of air hole height. $D_{0}$ is fixed to 150 nm.
Reuse & Permissions

Physical Review B

covering condensed matter and materials physics