Dual-band and ultra-broadband photonic
spin-orbit interaction for electromagnetic shaping
based on single-layer silicon metasurfaces
XIN XIE,
1,2
MINGBO PU,
1,2
XIONG LI,
1,2
KAIPENG LIU,
1,2,3
JINJIN JIN,
1,2
XIAOLIANG MA,
1,2
AND
XIANGANG LUO
1,2,
*
1
State Key Laboratory of Optical Technologies on Nano-Fabrication and Micro-Engineering, Institute of Optics and Electronics,
Chinese Academy of Sciences, Chengdu 610209, China
2
School of Optoelectronics, University of Chinese Academy of Sciences, Beijing 100049, China
3
School of Optoelectronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China
*Corresponding author: lxg@ioe.ac.cn
Received 15 January 2019; revised 11 March 2019; accepted 13 March 2019; posted 14 March 2019 (Doc. ID 357743); published 30 April 2019
Achieving electromagnetic wave scattering manipulation in the multispectral and broad operation band has been
a long pursuit in stealth applications. Here, we present an approach by using single-layer metasurfaces composed
of space-variant amorphous silicon ridges tiled on a metallic mirror, to generate high-efficiency dual-band and
ultra-wideband photonic spin-orbit interaction and geometric phase. Two scattering engineered metasurfaces
have been designed to reduce specular reflection; the first one can suppress both specular reflectances at
1.05–1.08 μm and 5–12 μm below 10%. The second one is designed for an ultra-broadband of 4.6–14 μm, which
is actually implemented by cleverly connecting two bands of 4.6–6.1 μm and 6.1–14 μm. Furthermore, the
presented structures exhibit low thermal emission at the same time due to the low absorption loss of silicon
in the infrared spectrum, which can be regarded as an achievement of laser– infrared compatible camouflage.
We believe the proposed strategy may open a new route to implement multispectral electromagnetic modulation
and multiphysical engineering applications.
© 2019 Chinese Laser Press
https://doi.org/10.1364/PRJ.7.000586
1. INTRODUCTION
In recent years, artificial metasurfaces have enabled rapid devel-
opment of ultrathin optical devices that can modify the light
wavefront by altering its phase and amplitude [1–6]. A variety
of functional devices based on metasurfaces have been proposed
and demonstrated, including vortex beam generators [7,8],
polarization modulators[9–11], flat lenses [12–14], perfect
absorbers [15], and optical holograms [16–18]. Since metasur-
faces open a new route to redirect reflected wave around the
object, numerous structures have been put forward and exper-
imentally characterized to reduce the reflection and scattering of
objects, resulting in desired camouflage or invisibility [19–24].
Utilizing the phase discontinuity of metasurface, the electro-
magnetic shape of the objects can be arbitrarily manipulated
with no influence on their geometric properties. However, most
current phase-gradient metasurfaces are designed in only a single
spectrum with narrow bandwith. Though some dual-band and
wideband approaches are achieved by vertical stacking of meta-
surfaces [21,25], the volume and fabrication difficulty are inevi-
tably increased. In addition, these low-reflection metasurfaces
generally cannot achieve therm al invisibility at the same time
due to their high infrared absorption/emission arising from
the complex metal–dielectric compo sites. Recently, by combin-
ing the low thermal emission nature of metal and geometric
phase, all-metallic metasurfaces have been proposed to reduce
both the specular reflectance and infrared emissivity [26].
Nevertheless, the operating bandwidth is significantly limited.
In this paper, we present two metasurfaces to simultaneously
implement low infrared specular reflection and emission in
dual-band and ultra-broadband ranges, respectively. Both meta-
surfaces comprise a monolayer of amorpho us silicon (α-Si) gra-
tings with the same geometry but diverse spatial orientations
deposited on a metal mirror, which can be utilized to generate
dual-band and wideband high-efficiency photonic spin-orbit
interaction (PSOI) and geometric phase. Theoretically, low
thermal emission results from silicon, which is nearly free of
loss in the infrared spectrum, and low specular reflection can
be achieved by tailoring the wavefront and redirecting the
reflected energy to other angles.
2. DESIGN AND METHODS
The reflected wavefront can be modified by modulating the
phase of scattered wave upon structured surfaces. According to
the generalized Snell’s law [27,28], by properly designing
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Vol. 7, No. 5 / May 2019 / Photonics Research
Research Article
2327-9125/19/050586-08 Journal © 2019 Chinese Laser Press