High-efficiency multi-wavelength metasurface
with complete independent phase control
Jing Yan (严 璟)
1,2
, Yinghui Guo (郭迎辉)
1,2
, Mingbo Pu (蒲明博)
1,2
, Xiong Li (李 雄)
1,2
,
Xiaoliang Ma (马晓亮)
1,2
, and Xiangang Luo (罗先刚)
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
University of Chinese Academy of Sciences, Beijing 100049, China
*Corresponding author: lxg@ioe.ac.cn
Received January 12, 2018; accepted February 28, 2018; posted online April 23, 2018
As a consequence of Kramers–Kronig relations, the wavelength-dependent behavior of the metasurface is one of
the critical limitations in existing metasurface structures, which reduces the design freedom among different
wavelengths. Here, we present an approach to construct a high-efficiency multi-wavelength metasurface with
independent phase control by coding different wavelengths into orthogonal polarizations. As proof of the con-
cept, two dual-band metasurfaces have been proposed and numerically demonstrated by multiple vortex beam
generation in near-field and polarization multiplexing achromatic beam deflection. Furthermore, simulated re-
sults show that the proposed metasurface exhibits high transmission efficiency at both wavelengths, which may
find widespread applications in subwavelength electromagnetics.
OCIS codes: 160.3918, 350.4010, 120.7000.
doi: 10.3788/COL201816.050003.
Metamaterials composed of specially designed subwave-
length resonators have attracted much attention. A large
number of revolutionary devices based on the metamate-
rials have been proposed and fabricated to achieve a vari-
ety of novel applications, such as negative refraction
[1,2]
,
high-resolution imaging and lithography
[3–5]
. Unfortu-
nately, the widespread application of metamaterial has
been severely limited due to some insuperable difficulties
in fabrication and material loss. Recently, the emergence
of a two dimensional metasurface has provided an effective
solution to solve the aforementioned restrictions, which
are attributed to their powerful ability to manipulate
the wavefron t of the incident electromagnetic waves over
a subwavelength scale
[6–8]
. When the local phases of unit
cells are appropriately distributed, the properties of
electromagnetic waves could be manipulated at will based
on the generalized Snell’s law and generalized Fresnel’s
equations
[6]
, which promises a number of applications,
such as waveplates
[9,10]
, flat lens
[11]
, metahologram
[12–14]
,
orbital angular momentum (OAM) generations
[15–17]
, and
broadband spin Hall effect
[18]
.
Although the metasurfaces have been widespread inves-
tigated during the past few years, most of the previous
work aimed to obtain the optimized performance within
a single band. Only a few researches were devoted to con-
struct the multiband and broadband devices until re-
cently, including absorbers and a polarization converter
through elaborated dispersion management
[9,19,20]
. In order
to meet the development of optical integration, multifunc-
tional detection, and multispectral analysis, the metasur-
face that could realize different functionalities within
different operation bands are urgently desired
[21–24]
. For
example, by combining the subwavelength unit cells with
different operation frequencies, achromatic deflection
and focusing can be realized at a triple wavelength
andevenanultra-broadfrequencyband
[25–27]
. Recently,
independent amplitude and phase modulations at two
terahertz (THz) wavelengths are realized by varying
the opening angles and rotations of the C-shape split-ring
resonators (CSRRs) and C-slot split-ring resonators
(CSSRRs)
[28,29]
. However, the existing dual-wavelength
modulation structures always suffer from low transmis-
sion efficiency.
In this Letter, by utilizing the unique tunable dispersion
properties of the metasurfaces
[6]
, we proposed a metasur-
face that can realize independent phase modulations at
two microwave wavelengths. The conversion efficiency
was above 92% for b oth wavelengths. In order to verify
the performance of the structure, two OAMs with differ-
ent signs at two microwave bands were generated at the
near-field with the proposed metasurface. In addition, we
designed a high-efficiency dual-wavelength deflector that
can deflect the transmission waves into the same direc-
tion at two different frequencies. The numerical results
demonstrated that the presented structure in this Letter
offers an effective method to realize high-efficiency trans-
mission and simultaneous frequency-independent phase
modulation.
Figure
1 presents the schematic of the unit cell for the
dual-wavelength microwave metasurface, which is com-
posed of three metallic patterns printed on the two sides
of the dielectric substrate of thickness d
1
¼ d
2
¼ 1.6 mm
with a permittivity of 4.6 and a loss tangent of 0.01. The
front and back metallic patterns are two of the same
CSRRs with split directions that are perpendicular to each
other. The middle metallic layer is composed of a CSRR,
COL 16(5), 050003(2018) CHINESE OPTICS LETTERS May 10, 2018
1671-7694/2018/050003(5) 050003-1 © 2018 Chinese Optics Letters