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K. Huang
which can be realized easily by using one-step top-down lithography that is a
matured technology of manufacturing mass-product integrated circuits in semiconductor industry. Since it could realize full control of light arbitrarily in a compact
volume, metasurface-based devices are drawing the increasing attention in integrated
opto-electronics and portable devices. Therefore, optical metasurfaces are the main
topic that we will focus in this chapter.
From the viewpoint of functionality, the main contribution of optical metasurfaces
to optics community is to introduce arbitrary polarization manipulation of light, in
addition to amplitude and phase modulation. It allows us to manipulate the local states
of polarization at any pixel of interest across an entire meta-device, and simultaneously customize the corresponding amplitude and phase in a high accuracy, which is
not possible for all the previous optical elements. For a polarized light, two commonly
used orthogonal bases such as linear polarization (i.e., e x and e y , where x and y are the
transverse coordinates that are perpendicular to the propagating direction of light)
and circular polarization (i.e., e x ±ie y ) can be used to characterize its polarization
property. The circular polarization is a simple combination of two orthogonal linear
polarizations with an additional phase delay of ±π /2, which leads to the rotating
vector of electric field in circularly polarized light. Determined by the sign of delayed
phase, the rotation is along the clockwise or anti-clockwise direction, which is related
with the chirality of light. Optical geometric metasurfaces could transfer a circularly
polarized light into its cross-polarization, meanwhile imprint an additional phase that
is two times of the rotating angle of the size-fixed rectangle-shape nanorodes. The
rectangle nanorodes operate as a miniaturized half-waveplate that provides a phase
delay of π between two orthogonal components of electric fields. The mechanism
of these half-waveplates depends on the materials: the metal-based plasmonic nanohalfwaveplates hold the physical origin of electric dipole resonances [16], while the
high-refraction-index dielectric nano-halfwaveplates originate from the antiferromagnetic resonances [15]. The interaction between chiral light and geometric metasurfaces increases significantly the full manipulation of circular polarized light, and
therefore results in many intriguing applications such as polarization meta-optics,
spin Hall effects of light [17, 18], beam shaping of chiral light, detection of chirality,
which forms the primary configuration of this chapter.
4.1.2 History of Optical Metasurfaces
Ultrathin metasurfaces could full control of electromagnetic waves by using the
spatially varied subwavelength structures [11, 13, 14, 19–23] that supports the local
responses of well-confined modes, which are commonly used elements at its longwavelength spectrum. For example, the antennas at the radio and microwave frequencies are designed at the scale of subwavelength for sending or receiving the signals.
However, optical metasurfaces have much shorter history because the fabrication
and simulation issue of subwavelength structures at the visible or infrared wavelengths cannot be well-solved until the personal computers with powerful scientific
K. Huang
which can be realized easily by using one-step top-down lithography that is a
matured technology of manufacturing mass-product integrated circuits in semiconductor industry. Since it could realize full control of light arbitrarily in a compact
volume, metasurface-based devices are drawing the increasing attention in integrated
opto-electronics and portable devices. Therefore, optical metasurfaces are the main
topic that we will focus in this chapter.
From the viewpoint of functionality, the main contribution of optical metasurfaces
to optics community is to introduce arbitrary polarization manipulation of light, in
addition to amplitude and phase modulation. It allows us to manipulate the local states
of polarization at any pixel of interest across an entire meta-device, and simultaneously customize the corresponding amplitude and phase in a high accuracy, which is
not possible for all the previous optical elements. For a polarized light, two commonly
used orthogonal bases such as linear polarization (i.e., e x and e y , where x and y are the
transverse coordinates that are perpendicular to the propagating direction of light)
and circular polarization (i.e., e x ±ie y ) can be used to characterize its polarization
property. The circular polarization is a simple combination of two orthogonal linear
polarizations with an additional phase delay of ±π /2, which leads to the rotating
vector of electric field in circularly polarized light. Determined by the sign of delayed
phase, the rotation is along the clockwise or anti-clockwise direction, which is related
with the chirality of light. Optical geometric metasurfaces could transfer a circularly
polarized light into its cross-polarization, meanwhile imprint an additional phase that
is two times of the rotating angle of the size-fixed rectangle-shape nanorodes. The
rectangle nanorodes operate as a miniaturized half-waveplate that provides a phase
delay of π between two orthogonal components of electric fields. The mechanism
of these half-waveplates depends on the materials: the metal-based plasmonic nanohalfwaveplates hold the physical origin of electric dipole resonances [16], while the
high-refraction-index dielectric nano-halfwaveplates originate from the antiferromagnetic resonances [15]. The interaction between chiral light and geometric metasurfaces increases significantly the full manipulation of circular polarized light, and
therefore results in many intriguing applications such as polarization meta-optics,
spin Hall effects of light [17, 18], beam shaping of chiral light, detection of chirality,
which forms the primary configuration of this chapter.
4.1.2 History of Optical Metasurfaces
Ultrathin metasurfaces could full control of electromagnetic waves by using the
spatially varied subwavelength structures [11, 13, 14, 19–23] that supports the local
responses of well-confined modes, which are commonly used elements at its longwavelength spectrum. For example, the antennas at the radio and microwave frequencies are designed at the scale of subwavelength for sending or receiving the signals.
However, optical metasurfaces have much shorter history because the fabrication
and simulation issue of subwavelength structures at the visible or infrared wavelengths cannot be well-solved until the personal computers with powerful scientific