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[Display omitted] Manipulating the chirality at nanoscale has drawn great attention among scientists, considering its pivotal role in various applications of current interest, including nano-optics, biomedicine, and photocatalysis. In this work, we delve into this arena by fabricating chiral Swiss roll nanoarray (SRNA) continuous films employing colloidal lithography. The technique permits the dimension of Swiss roll metamaterials to reduce to nanoscale, thus achieving chiroptical response (circular dichroism (CD)) in the visible region. The interplay between the CD signals and plasmon resonance modes is revealed through theoretical simulations, enabling a deep understanding of chiral plasmonic metamaterials. The polarization-sensitive photocatalytic activity of chiral SRNAs is investigated, noting a marked increase in the reaction rate when the chirality of SRNAs matches with the handedness of circularly polarized light (CPL). Notably, the SRNA continuous films based on substrate possess integration and reusability without complex recycling process, enhancing their practicality in applications like sensing and plasmonic nanochemistry, particularly toward polarization-dependent photocatalysis. [ABSTRACT FROM AUTHOR]

Multiplexing multiple yet distinct functionalities in one single device is highly desired for modern integration optics, but conventional devices are usually of bulky sizes and/or low efficiencies. While recently proposed metasurfaces can be ultra-thin and highly efficient, functionalities multiplexed by metadevices so far are typically restricted to two, dictated by the number of independent polarization states of the incident light. Here, we propose a generic approach to design metadevices exhibiting wave-control functionalities far exceeding two, based on coherent wave interferences continuously tuned by varying the incident polarization. After designing a series of building-block metaatoms with optical properties experimentally characterized, we construct two metadevices based on the proposed strategy and experimentally demonstrate their polarization-tuned multifunctionalities at the wavelength of 1550 nm. Specifically, upon continuously modulating the incident polarization along different paths on the Poincare’s sphere, we show that the first device can generate two spatially non-overlapping vortex beams with strengths continuously tuned, while the second device can generate a vectorial vortex beam carrying continuously-tuned polarization distribution and/or orbital angular momentum. Our proposed strategy significantly expands the wave-control functionalities equipped with a single optical device, which may stimulate numerous applications in integration optics.

As a natural biaxial hyperbolic material, α-phase molybdenum trioxide (α-MoO3) exhibits dielectric and metallic properties in the plane, rendering it an exceptional candidate for polarization-dependent devices. In this work, we design a lithography-free polarization-dependent absorber consisting of an α-MoO3 film, a germanium layer, and a silver substrate. The results show that a narrowband absorption of up to 0.99 is achieved at a wavelength of 12.2 µm for transverse magnetic polarization. In contrast, the absorption is only 0.06 at this wavelength for transverse electric polarization. This remarkable polarization-dependent absorption performance is attributed to the coupling of epsilon-near-zero modes and Fabry-Perot resonances, which is confirmed by the electric field and power dissipation density distributions. Furthermore, strong polarization-dependent performance could also be achieved when the crystal axis of α-MoO3 is rotated in the out-of-plane. This work demonstrates that in-plane anisotropic α-MoO3 has the potential for designing high polarization-dependent devices. [ABSTRACT FROM AUTHOR]

Metasurfaces can arbitrarily manipulate the amplitude, phase, and polarization of optical fields on subwavelength scales. Due to their arbitrary manipulation and compact size, the metasurface can be well integrated with optical fibers. Herein, we demonstrate a polarization-dependent metasurface using birefringent meta-atoms, which can independently control X- and Y-polarization incident light. Each meta-atom allows for the division of phase into 16 steps ranging from 0 to 2π for both X- and Y-polarization, resulting in 256 nanopillars selected from the meta-atom library to satisfy the required phase. With the different effective refractive indices of the cuboid meta-atoms along the X- and Y-axis, we can achieve collimation of the X-polarization emitted beam from an optical fiber while deflecting orthogonally polarized light. As a result, the proposed metasurface collimates an X-polarized beam with a beam radius of 20 μm at z = 1 mm and 43.9 μm at z = 2 mm. Additionally, the metasurface can effectively deflect the Y-polarized beam to 36.01°, consistent with the results of the theoretical computation. The proposed metasurface exhibits a deflection efficiency of 55.6% for Y-polarized beams with a relative polarization efficiency of 82.2%, while the efficiency for the X-polarization is 71.4%. Our work is considered a promising application for optical communication, sensing, and quantum measurement. [ABSTRACT FROM AUTHOR]

We investigated a three-channel reflective grating beam splitter with double-groove which eliminated ± 1st orders under TE and TM polarization. The grating has a polarization-dependent structure with different ridge thicknesses under TE and TM polarizations. Inhibitions of ± 1st orders are rarely reported from the previous work. The diffraction efficiency of the 0th order and ± 2nd orders for TE polarization orders can reach 32.7% and 33.3%, respectively. And the diffraction efficiency of 0th order and ± 2nd orders for TM polarization can reach 32.9% and 31.9%, respectively. It indicates that the uniformity of diffraction efficiency under the two polarizations also reaches more than 95%. The excellent bandwidth and tolerance make this grating suitable for a wide range of applications in the optical field. Compared conventional three-channel splitting, inhibitions of ± 1st orders are presented by double-groove microstructure. [ABSTRACT FROM AUTHOR]

Phonon polaritons (PhPs) in two-dimensional van der Waals crystals, such as hexagonal boron nitride (hBN) and α-phase molybdenum trioxide (α-MoO3), exhibit remarkable spatial confinement and extremely low optical losses, offering possibilities for the development of novel micro and nanophotonic devices at mid-infrared wavelengths. Here, we demonstrate the potential of the proposed Tamm structure to achieve dual-band high quality-factor perfect absorption within the mid-infrared range. This structure utilizes upper and lower spacer layers to isolate the anisotropic materials hBN and α-MoO3 from one-dimensional photonic crystals, where the Tamm phonon polaritons (TPhPs) are respectively excited at the interfaces, facilitating strong coupling with incident light and leading to significant dual-band perfect absorption phenomena. The results demonstrate that due to polariton resonances, the absorption peaks exhibit extremely narrow absorption bandwidths, with the maximum quality-factor reaching up to 297. In addition, tunable resonant wavelengths and polarization-dependent absorption properties are also demonstrated in the proposed Tamm structure. This study provides an alternative and straightforward approach for constructing dynamic and multifunctional optical devices such as optical modulators, tunable multi-band filters and biosensors.

Metasurfaces can arbitrarily manipulate the amplitude, phase, and polarization of optical fields on subwavelength scales. Due to their arbitrary manipulation and compact size, the metasurface can be well integrated with optical fibers. Herein, we demonstrate a polarization-dependent metasurface using birefringent meta-atoms, which can independently control X- and Y-polarization incident light. Each meta-atom allows for the division of phase into 16 steps ranging from 0 to 2π for both X- and Y-polarization, resulting in 256 nanopillars selected from the meta-atom library to satisfy the required phase. With the different effective refractive indices of the cuboid meta-atoms along the X- and Y-axis, we can achieve collimation of the X-polarization emitted beam from an optical fiber while deflecting orthogonally polarized light. As a result, the proposed metasurface collimates an X-polarized beam with a beam radius of 20 μm at z = 1 mm and 43.9 μm at z = 2 mm. Additionally, the metasurface can effectively deflect the Y-polarized beam to 36.01°, consistent with the results of the theoretical computation. The proposed metasurface exhibits a deflection efficiency of 55.6% for Y-polarized beams with a relative polarization efficiency of 82.2%, while the efficiency for the X-polarization is 71.4%. Our work is considered a promising application for optical communication, sensing, and quantum measurement.

This paper presents the design and optimization of a dual-band polarization-dependent metasurface capable of dynamically switching transmission and reflection characteristics. The metasurface is composed of three metallic patterns, with the bottom layer governing the reflection and transmission phase for both TE-polarization and TM-polarization states. The middle and top layers are strategically employed to ensure optimal transmission and reflection performance. The results confirm that the metasurface enables the transformation of the transmission band into a complete reflection band, and vice versa, through variations in the incident wave polarization. Remarkable transmission and reflection characteristics are achieved within the frequency ranges of 6.1–6.55 GHz and 8.9–9.3 GHz, respectively. The proposed metasurface offers promising applications in advanced communication systems and radar technology, enabling dynamic manipulation of electromagnetic waves. [ABSTRACT FROM AUTHOR]

Polarization detection is an important part of many polarization applications such as polarization imaging, wireless communication, and circular dichroism spectroscopy. In this paper, two polarization-dependent terahertz wave absorption and transmission metasurface for linearly and circularly polarized light are proposed and proved by numerical simulations. Polarization filtering and polarization absorption are integrated on a single cell, and the orthogonal polarization component is transmitted and absorbed, respectively. The linearly polarization-dependent transmission and absorption structure can obtain a transmission extinction ratio of 11.5 dB and an absorption extinction ratio of over 270 dB at 3 THz. Moreover, the circularly polarization-dependent structure can obtain a transmission extinction ratio of 8.1 dB and an absorption extinction ratio of 4.66 dB at 2.8 THz. Our design facilitates the acquisition of full Stokes parameters and the high-resolution imaging. [ABSTRACT FROM AUTHOR]

With the development of micro/nano-optics, metasurfaces are gaining increasing attention working as novel electromagnetic wave control devices. Among which, metalenses have been developed and applied as a typical application of metasurfaces owing to their unique optical properties. However, most of those previous metalenses can only produce one focal point, which severely limits their applications. Inspired by the fly compound eye, we propose a special kind of spatial multifocal metalens. Our metalenses can reverse the polarization state of the incident circularly polarized light, which is then focused. In addition, a horizontally aligned multifocal metalens can be achieved by designing reasonable phase and region distributions, which is similar to a vertically aligned one. Most significantly, a spatially 3D-arrayed multifocal metalens with low crosstalk is well achieved by combining these two distribution methods. The proposed bionic 3D-arrayed multifocal metalens with amazing focusing effect promises applications in imaging, nanoparticle manipulation, optical communication, and other fields. [ABSTRACT FROM AUTHOR]

In this letter, a novel broadband compact circularly polarized antenna is proposed, which consists of a novel 4 × 4 cross‐layer metasurface (MS) structure and a slanted slot fed through microstrip line. The cross‐layer MS structure is formed by loading several cross‐layer stacked patches along one dimension of traditional square MS structure, and these stacked patches are located below the gaps of the original square patches directly. Compared with traditional square MS structure, the proposed cross‐layer MS structure can be viewed as one polarization‐dependent MS, exhibiting different reflection features in two orthogonal dimensions. Then, by properly tailoring the phase difference of the polarization‐dependent MS structure between the two orthogonal dimensions and combining it with a slanted coupling slot, two degenerate modes can be generated and then a wideband circular polarization radiation can be realized. Furthermore, the proposed antenna has a much compact aperture size of 0.41λ0 × 0.41λ0 due to the cross‐layer stacked patches, which can also enlarge the total capacitance by introducing extra cross‐layer capacitances. Finally, measured results show that the −10 dB impedance bandwidth of the proposed antenna is 39.6% (5.82 ~ 8.69 GHz), and 3‐dB axial ratio bandwidth is 26.3% (6.51 ~ 8.48 GHz) with a peak gain of 5.81 dBi. The simulated and measured results are in good agreement to verify the good performance of the proposed antenna. [ABSTRACT FROM AUTHOR]

This paper presents the design and optimization of a dual-band polarization-dependent metasurface capable of dynamically switching transmission and reflection characteristics. The metasurface is composed of three metallic patterns, with the bottom layer governing the reflection and transmission phase for both TE-polarization and TM-polarization states. The middle and top layers are strategically employed to ensure optimal transmission and reflection performance. The results confirm that the metasurface enables the transformation of the transmission band into a complete reflection band, and vice versa, through variations in the incident wave polarization. Remarkable transmission and reflection characteristics are achieved within the frequency ranges of 6.1–6.55 GHz and 8.9–9.3 GHz, respectively. The proposed metasurface offers promising applications in advanced communication systems and radar technology, enabling dynamic manipulation of electromagnetic waves.

Coupling free‐space light into surface plasmons (SPs) has traditionally faced challenges in arbitrarily controlling the directionality of the SPs with respect to the incident polarization. Recently reported polarization‐dependent directional coupling of SPs using metasurfaces has attracted enormous attention for its promise in developing innovative and on‐demand plasmonic devices. However, further progress has been hampered by the limitation in designating the directional coupling with tailorable polarization‐dependent feature and compatible ability to incidence of complex polarization distribution. Here, a directional coupling strategy is introduced to overcome these limits. It is demonstrated that, by utilizing the interference between two pairs of slit resonators with different resonance responses, the directional SP coupling can be expanded to arbitrary group of polarized incidence by simply varying their relative distance, and the SP coupling direction will reverse under the corresponding orthogonally polarized incidence without affecting the efficiency. To exhibit the versatile design capability of the strategy, it is further utilized to construct several polarization‐dependent plasmonic devices for controlling SP propagations, including two SP metalenses and a plasmonic Airy beam launcher, in which it is shown that the device can even be designed to work for non‐uniformly polarized incidence. The strategy paves a reliable route towards many practical on‐chip applications. [ABSTRACT FROM AUTHOR]

The transfer of large-area and clean graphene to arbitrary substrates, especially to those with raised nanostructures, represents a great challenge. Polymer-based supporting layers generally lead to organic residues, while graphene transfer using alternative supporting materials like paraffin suffers from breaking and thus limits the transfer area. We demonstrated an improved poly-(methyl methacrylate) (PMMA)/paraffin double layer, enabling the large-area transfer of graphene with high cleanliness and high coverage (81%) onto gold nanopyramid (AuNP)-structured substrates. The impact of supporting layers including single PMMA or paraffin and mixed PMMA/paraffin was clarified. The properties of graphene on AuNPs were theoretically and experimentally examined in detail. Raman spectra show a polarization-dependent D peak due to the folding of large-curvature graphene. The graphene on AuNPs shows a slightly tensile strain and provides extra surface-enhanced Raman scattering (SERS) with an enhancement factor of ~20 times. These findings open a pathway to extend the applications of transferred graphene on raised nanostructures in many fields, such as SERS detection, catalysis, biosensors, light-emitting diodes, solar cells, and advanced transparent conductors. [ABSTRACT FROM AUTHOR]

A polarization-dependent transmissive and reflective phase-gradient metasurface (PGMS) is investigated and experimentally verified in the $Ku$ -band. The PGMS is based on a single-layer substrate-integrated element, which consists of a cross-shaped dielectric unit and a couple of metallic strips/patches that are printed on the dielectric unit. Taking advantage of both the dielectric and the metallic components, the proposed element can transmit or reflect the linearly polarized (LP) incident wave depending on its polarization. Moreover, the phase of the transmitted or reflected wave can be independently controlled by different phase-control parameters. As a result, two independent foci can be obtained on the transmission and reflection sides of the PGMS for two orthogonal LP waves. For demonstration, a prototype of the PGMS is fabricated and tested. Both the transmissive and reflective foci are observed at the target positions. Also, the PGMS is shown to be able to manipulate the wavefronts independently on its two sides by adjusting the phase distributions. These features make the proposed PGMS a great choice for use in polarization identification, near-field energy transfer, or far-field wireless communication. [ABSTRACT FROM AUTHOR]

Polarization detection is an important part of many polarization applications such as polarization imaging, wireless communication, and circular dichroism spectroscopy. In this paper, two polarization-dependent terahertz wave absorption and transmission metasurface for linearly and circularly polarized light are proposed and proved by numerical simulations. Polarization filtering and polarization absorption are integrated on a single cell, and the orthogonal polarization component is transmitted and absorbed, respectively. The linearly polarization-dependent transmission and absorption structure can obtain a transmission extinction ratio of 11.5 dB and an absorption extinction ratio of over 270 dB at 3 THz. Moreover, the circularly polarization-dependent structure can obtain a transmission extinction ratio of 8.1 dB and an absorption extinction ratio of 4.66 dB at 2.8 THz. Our design facilitates the acquisition of full Stokes parameters and the high-resolution imaging.

• We demonstrate that the Tamm structure achieves dual-band, high Q-factor perfect absorption within the mid-infrared range. • Tamm phonon polaritons (TPhPs) are effectively excited at hBN/α-MoO 3 interfaces with a photonic crystal, enhancing light absorption. • Due to α-MoO 3 's in-plane anisotropy, TPhPs excited in the 12–18 μm range exhibit excellent polarization-dependent absorption. • Introducing this dual-band perfect absorber offers a streamlined method to develop versatile and dynamic optical devices. Phonon polaritons (PhPs) in two-dimensional van der Waals crystals, such as hexagonal boron nitride (hBN) and α-phase molybdenum trioxide (α-MoO 3), exhibit remarkable spatial confinement and extremely low optical losses, offering possibilities for the development of novel micro and nanophotonic devices at mid-infrared wavelengths. Here, we demonstrate the potential of the proposed Tamm structure to achieve dual-band high quality-factor perfect absorption within the mid-infrared range. This structure utilizes upper and lower spacer layers to isolate the anisotropic materials hBN and α-MoO 3 from one-dimensional photonic crystals, where the Tamm phonon polaritons (TPhPs) are respectively excited at the interfaces, facilitating strong coupling with incident light and leading to significant dual-band perfect absorption phenomena. The results demonstrate that due to polariton resonances, the absorption peaks exhibit extremely narrow absorption bandwidths, with the maximum quality-factor reaching up to 297. In addition, tunable resonant wavelengths and polarization-dependent absorption properties are also demonstrated in the proposed Tamm structure. This study provides an alternative and straightforward approach for constructing dynamic and multifunctional optical devices such as optical modulators, tunable multi-band filters and biosensors. [ABSTRACT FROM AUTHOR]

Recently, ultrathin metalenses have attracted dramatically growing interest in optical imaging systems due to the flexible control of light at the nanoscale. In this paper, we propose a dual-wavelength achromatic metalens that will generate one or two foci according to the polarization of the incident. Based on geometric phase modulation, two unit cells are attentively selected for efficient operation at distinct wavelengths. By patterning them to two divided sections of the metalens structure plane, the dual-wavelength achromatic focusing effect with the same focal length is realized. In addition, the holographic concept is adopted for polarization-dependent bifocal generation, in which the objective wave is originated from two foci that are respectively formed by two orthogonal polarization states of circularly polarized light, namely Left-handed circularly polarized (LCP) light and Right-handed circularly polarized (RCP) light. The incident light is considered as the reference light. The achromatic focusing and polarization-dependent bifocusing are numerically verified through simulations. The proposed design opens the path for the combination of multi-wavelength imaging and chiral imaging, which may find potential applications, such as achromatic optical devices and polarization-controlled biomedical molecular imaging systems.

Anisotropic materials provide a new platform for building diverse polarization-dependent optical devices. Two-dimensional α-phase molybdenum trioxides (α-MoO3), as newly emerging natural van der Waals materials, have attracted significant attention due to their unique anisotropy. In this work, we theoretically propose an anisotropic perfect metamaterial absorber in visible frequencies, the unit cell of which consists of a multi-layered α-MoO3 nanoribbon/dielectric structure stacked on a silver substrate. Additionally, the number of perfect absorption bands is closely related to the α-MoO3 nanoribbon/dielectric layers. When the proposed absorber is composed of three α-MoO3 nanoribbon/dielectric layers, electromagnetic simulations show that triple-band perfect absorption can be achieved for polarization along [100], and [001] in the direction of, α-MoO3, respectively. Moreover, the calculation results obtained by the finite-difference time-domain (FDTD) method are consistent with the effective impedance of the designed absorber. The physical mechanism of multi-band perfect absorption can be attributed to resonant grating modes and the interference effect of Fabry–Pérot cavity modes. In addition, the absorption spectra of the proposed structure, as a function of wavelength and the related geometrical parameters, have been calculated and analyzed in detail. Our proposed absorber may have potential applications in spectral imaging, photo-detectors, sensors, etc.

A transmission metasurface with polarization-transforming functionalities is presented. The unit cell is characterized by broadband, low profile and low loss. Due to the asymmetric structure, the proposed metasurface shows different responses to different linear-polarized incidences. For a particular linear-polarized incidence, the polarization direction of transmitted waves will be rotated by 90° in 3.72-8.28 GHz with high polarization conversion ratio (PCR). However, for the orthogonal-polarized ones, the incidence will be reflected totally and the polarization remains. The operating mechanism of proposed metasurface is analyzed both by theoretical investigations and numerical simulations. Measured results of the fabricated samples are in good agreement with the simulated ones.

Plasmonic nanoperiodic Ag nanoparticle arrays with hexagonal close-packed structures and different symmetries were synthesized by localized surface plasmon resonance (LSPR) induced chemical growth. When the plasmonic nanostructure was excited by a laser, the neighboring silver nanoparticles generated high local electric field enhancement for surface-enhanced Raman spectroscopy (SERS), which was used to show the relationship between the axisymmetry of the plasmonic nanostructure and the SERS polarization effect. The experimental results indicate that the optimal axisymmetric structure (six-axis symmetric) exhibited the strongest SERS polarization-dependence, whereas the disordered structure with an arbitrary axis exhibited a relatively weak SERS polarization dependence. To clarify the root cause of SERS polarization dependence, the electric field enhancement distribution for the plasmonic nanostructures was numerically simulated based on S- and P-polarization excitation. Most importantly, the fundamental reasons for the polarization dependence of SERS were obtained by the quantitative numerical simulation of the hotspot distribution for the plasmonic nanostructures. Unlabelled Image • The plasmonic arrays of different axisymmetry were grown by LSPR-induced chemical reaction. • The effect of the axisymmetry on SERS polarization signals was revealed. • SERS polarization dependent mechanism was proven by experimental data and numerical simulation. [ABSTRACT FROM AUTHOR]

We propose polarization‐dependent micro‐lenticular lens arrays (MLAs) based on optical phase modulation by reorientation of nano‐sized LC droplets of the optically isotropic liquid crystals (OILC). On applying gradient in‐plane field, the gradient refractive index is generated between the electrodes, giving rise to the MLAs with the focal length of 22 µm at 50 V rms and switching time of few ms. The OILC can also be applied to switchable microlens. The proposed device has a potential to be applicable to 2D/3D switchable optical lens. [ABSTRACT FROM AUTHOR]

Highlights • SDR exhibits polarization-dependent and angle-dependent characterizations. • SDR can realize THz filter and THz switch on single chip design. • Large transmission shift (0.60 THz) of resonance at TE mode. • SDR exhibits effective resistance to the variation of environmental refraction index. Abstract A terahertz (THz) metamaterial split-disk resonator (SDR) is proposed to possess multifunctionality. This SDR structure is composed of Al disk with a split on Si substrate. It exhibits a large resonance shift in transmission spectrum under reconfiguration of geometrical dimensions. The resonance shift is 0.60 THz. The distinct characteristics at TE and TM modes are investigated and discussed. Such SDR design provides a high-efficiency resonator in THz wave applications and can realize polarization-dependent for THz switch. Furthermore, the design of SDR can resist the variation of ambient refraction index, which provides the capability for the use in various environments. [ABSTRACT FROM AUTHOR]

An optical vortex, which consists of blue phase and isotropic phase, is generated from azobenzene liquid crystal cell with computer generated hologram pattern. This device is optically switchable and can be erased and generated by ultraviolet or green light, respectively. An intensity modulation is formed between blue phase and isotropic phase of liquid crystal cell, where the blue phase liquid crystal selectively reflects circular polarization light due to the Bragg reflection, resulting in a circularly polarization-dependent optical vortex. The proposed method can be applied to any other diffractive optical elements.

A real-time photonic sampling structure with effective nonlinearity suppression and excellent signal-to-noise ratio (SNR) performance is proposed. The key points of this scheme are the polarization-dependent modulators (P-DMZMs) and the sagnac loop structure. Thanks to the polarization sensitive characteristic of P-DMZMs, the differences between transfer functions of the fundamental signal and the distortion become visible. Meanwhile, the selection of specific biases in P-DMZMs is helpful to achieve a preferable linearized performance with a low noise level for real-time photonic sampling. Compared with the quadrature-biased scheme, the proposed scheme is capable of valid nonlinearity suppression and is able to provide a better SNR performance even in a large frequency range. The proposed scheme is proved to be effective and easily implemented for real time photonic applications. [ABSTRACT FROM AUTHOR]

Epitaxial heterostructures are of particular interest owing to their fascinating properties for wide applications in energy, environment and electronic devices. The understanding of epitaxial growth in solution phase, however, remains a fundamental challenge to realize the rational synthesis of heterostructures. Here we report that anatase TiO 2 can epitaxially grow on the selective polar surface of single-crystal and single-domain ferroelectric PbTiO 3 nanoplates. The interplay of ferroelectric polar surface and corresponding ion adsorptions on them has been revealed experimentally and theoretically to determine the epitaxial growth mode, giving rising to zero-dimensional (0D)/two-dimensional (2D) and 2D/2D heterostructures. A combination of experimental and theoretical calculations indicate that the resulting heterostructures adopt a polarization-dependent photocatalytic performance under visible light irradiation, including hole-based photodegradation and electron-based hydrogen evolution reaction (HER) of water splitting. Such findings allow investigation of the potential of ferroelectric polarization towards tuning epitaxial growth and functionality of heterostructures. [ABSTRACT FROM AUTHOR]

The fluorescence intensities of CdSe/ZnS quantum dots on a silver nanowire and a gold-silver alloy nanotube with different molar ratios of gold and silver are investigated under excitation with different polarization angles. The ratio of the fluorescence intensity of perpendicular and parallel polarization excitations is measured to be 4.05 for a silver nanowire and decreases to 1.30, 1.10 and 1.07 for nanotube with Au:Ag molar ratios of 1:4.0, 1:2.5 and 1:1.5, respectively. The numerical simulation results show that the aforementioned experimental phenomena can be attributed to the variation in the distribution of the surface plasmon electromagnetic field under perpendicular polarized light excitation. The electromagnetic field is primarily distributed on the outer surface of the silver nanowire, while the field partially penetrates the interior of the silver nanotube and becomes completely concentrated at the interior of the gold nanotube. This research also found that the productivity and robustness of the chemical synthesis of the alloy nanotubes can be greatly improved by using a microwave reactor. [ABSTRACT FROM AUTHOR]

A transmission metasurface with polarizationtransforming functionalities is presented. The unit cell is characterized by broad band, low profile and low loss. Due to the asymmetric structure, the proposed metasurface shows different responses to different linear-polarized incidences. For a particular linear-polarized incidence, the polarization direction of transmitted waves will be rotated by 90° in 3.72-8.28 GHz with high polarization conversion ratio (PCR). However, for the orthogonal-polarized ones, the incidence will be reflected totally and the polarization remains. The operating mechanism of the proposed metasurface is analyzed both by theoretical investigations and numerical simulations. Measured results of the fabricated samples are in good agreement with the simulated ones. [ABSTRACT FROM AUTHOR]

A polarization-dependent, frequency-selective metamaterial (MM) absorber based on a single-layer patterned resonant structure intended for F frequency band is proposed. The design, fabrication, and measurement for the proposed absorber are presented. The absorber's absorption properties at resonant frequencies have unique characteristics of a single-band, dual-band, or triple-band absorption for different polarization of the incident wave. The calculated surface current distributions and power loss distribution provide further understanding of physical mechanism of resonance absorption. Moreover, a high absorption for a wide range of TE-polarized oblique incidence was achieved. Hence, the MM structure realized on a highly flexible polyimide film, making the absorber suitable for conformal geometry applications. The proposed absorber has great potential in the development of polarization detectors and polarizers. [ABSTRACT FROM AUTHOR]

In this work, we report an optical method for characterizing crystal phases along single-semiconductor III-V nanowires based on the measurement of polarization-dependent second-harmonic generation. This powerful imaging method is based on a per-pixel analysis of the second-harmonic-generated signal on the incoming excitation polarization. The dependence of the second-harmonic generation responses on the nonlinear second-order susceptibility tensor allows the distinguishing of areas of pure wurtzite, zinc blende, and mixed and rotational twins crystal structures in individual nanowires. With a far-field nonlinear optical microscope, we recorded the second-harmonic generation in GaAs nanowires and precisely determined their various crystal structures by analyzing the polar response for each pixel of the images. The predicted crystal phases in GaAs nanowire are confirmed with scanning transmission electron and high-resolution transmission electron measurements. The developed method of analyzing the nonlinear polar response of each pixel can be used for an investigation of nanowire crystal structure that is quick, sensitive to structural transitions, nondestructive, and on-the-spot. It can be applied for the crystal phase characterization of nanowires built into optoelectronic devices in which electron microscopy cannot be performed (for example, in lab-on-a-chip devices). Moreover, this method is not limited to GaAs nanowires but can be used for other nonlinear optical nanostructures. [ABSTRACT FROM AUTHOR]

Polarization-independent plasmonic light absorbers have been widely investigated in the past decades. Nevertheless, the feasibility for artificial manipulation of the optical properties by controlling the polarization state is desirable for numerous applications including the coloring, displaying, filtering, etc. Here, we present a straightforward method to achieve tunable multiple narrowband light absorption by using the polarization-dependent plasmonic cavity resonances in a common metal-dielectric-metal structure consisting of an elliptical disk array. Multiple light absorption bands with the maximal absorption of 98 % are achieved. Moreover, by controlling the illumination polarization state, artificial spectral modulation depth of these light absorption bands can be up to 90 % based on this structure platform. In addition, since this multispectral polarization-manipulated absorber is realized in such a common sub-wavelength plasmonic structure, it will open up a simple and universal approach for multispectral nanophotonic devices including the high-compact polychromatic color filtering, imaging, and detecting. [ABSTRACT FROM AUTHOR]

We fabricated a polarization-dependent terahertz (THz) metamaterial absorber consisted of a metal film, a dielectric spacer and a metal pattern layer. The measured absorptivity for x -polarized wave is about 0.9 at 1.42 THz, and that for y -polarized wave is about 0.87 at 2.15 THz. The full width at half maximum (FWHM) of peaks at 1.42 THz and 2.15 THz are about 0.23 THz and 0.38 THz, respectively. The experimental results are in good agreement with the numerical simulation. In addition, the parameters related to the absorption are presented for deeply understanding the absorption mechanism. Most importantly, these two absorption peaks can be tuned respectively by simply changing the length in x and y directions. Our results suggest potential applications based on metamaterial absorber, such as THz polarization imaging, selective spectral detection, THz sensing and polarization multiplexing. [ABSTRACT FROM AUTHOR]

For the first time, we report remote excitation polarization-dependent surface photochemical reaction by plasmonic waveguide. Remote excitation polarization-dependent surface-enhanced Raman scattering (SERS) spectra indicate a surface photochemical reaction that p-aminothiophenol is converted to p,p′-dimercaptoazobenzene (DMAB) induced by the plasmonic waveguide. Surface plasmon polaritons generated at the end of a silver nanowire can propagate efficiently along the nanowire, and be coupled by nanoparticles near the nanowire as a nanoantenna. Massive electromagnetic enhancement is generated in the nanogap between the nanowire and the nanoparticles. The remote excitation polarization-dependent SERS spectra can be obtained experimentally in the nanogaps; furthermore, the remote excitation polarization-dependent SERS spectra of DMAB reveal the occurrence of this surface catalytic reaction. Theoretical simulations using finite-difference time-domain methods strongly support our experimental results. [ABSTRACT FROM AUTHOR]

Recently, ultrathin metalenses have attracted dramatically growing interest in optical imaging systems due to the flexible control of light at the nanoscale. In this paper, we propose a dual-wavelength achromatic metalens that will generate one or two foci according to the polarization of the incident. Based on geometric phase modulation, two unit cells are attentively selected for efficient operation at distinct wavelengths. By patterning them to two divided sections of the metalens structure plane, the dual-wavelength achromatic focusing effect with the same focal length is realized. In addition, the holographic concept is adopted for polarization-dependent bifocal generation, in which the objective wave is originated from two foci that are respectively formed by two orthogonal polarization states of circularly polarized light, namely Left-handed circularly polarized (LCP) light and Right-handed circularly polarized (RCP) light. The incident light is considered as the reference light. The achromatic focusing and polarization-dependent bifocusing are numerically verified through simulations. The proposed design opens the path for the combination of multi-wavelength imaging and chiral imaging, which may find potential applications, such as achromatic optical devices and polarization-controlled biomedical molecular imaging systems. [ABSTRACT FROM AUTHOR]

Abstract: By proper control of underlying templates, lateral InAs quantum dot molecules (QDMs) can be grown with a desired number of quantum dots (QDs) per molecule. We demonstrate that by capping as-grown InAs QDs with lattice-mismatched GaAs layer and by varying the capping temperature between 430 and 470°C, we are able to control the span of nanoholes template to between 150 and 300nm. InAs regrowth on this template result in nanopropellers (0.6ML regrowth) or QDMs (1.2ML), the latter with 4–12 QDs per molecule depending on the span of the underlying nanoholes template. All QDM samples grown share a characteristic feature with a clear preference to orient along the crystallographic direction. Room-temperature photoluminescence measurements show a strong polarization-dependent characteristic, in good agreements with the QDM’s geometry. [Copyright &y& Elsevier]

Anisotropic materials provide a new platform for building diverse polarization-dependent optical devices. Two-dimensional α-phase molybdenum trioxides (α-MoO3), as newly emerging natural van der Waals materials, have attracted significant attention due to their unique anisotropy. In this work, we theoretically propose an anisotropic perfect metamaterial absorber in visible frequencies, the unit cell of which consists of a multi-layered α-MoO3 nanoribbon/dielectric structure stacked on a silver substrate. Additionally, the number of perfect absorption bands is closely related to the α-MoO3 nanoribbon/dielectric layers. When the proposed absorber is composed of three α-MoO3 nanoribbon/dielectric layers, electromagnetic simulations show that triple-band perfect absorption can be achieved for polarization along [100], and [001] in the direction of, α-MoO3, respectively. Moreover, the calculation results obtained by the finite-difference time-domain (FDTD) method are consistent with the effective impedance of the designed absorber. The physical mechanism of multi-band perfect absorption can be attributed to resonant grating modes and the interference effect of Fabry–Pérot cavity modes. In addition, the absorption spectra of the proposed structure, as a function of wavelength and the related geometrical parameters, have been calculated and analyzed in detail. Our proposed absorber may have potential applications in spectral imaging, photo-detectors, sensors, etc. [ABSTRACT FROM AUTHOR]

Abstract: Experimental observation of spatial solitons in azobenzene-doped organic polymer is demonstrated in dye-doped polymer bulk material. Solitons cannot only be formed in this material with linearly polarized light, but also with circularly polarized light. An interesting phenomenon is revealed that the soliton is polarization-dependent. The solitons with the same intensity but with different polarizations have different widths. The experimental results are further theoretically explained with the dynamics model based on a photochemical process, namely photoisomerization. [Copyright &y& Elsevier]

In this letter, a novel compact electromagnetic band-gap (EBG) structure constructed by etching a complementary split ring resonator (CSRR) on the patch of a conventional mushroom-type EBG (CMT-EBG) is proposed. The first bandgap is defined in all directions in the surface structure. Compared to the CMT-EBG structure, the CSRR-based EBG presents a 28% size reduction in the start frequency of the first bandgap. However, asymmetrical frames of the CSRR-based EBG result in different properties at X and Y-directions. Another two tunable bandgaps in Y-direction are observed. Thus, the proposed EBG can be used for multi-band applications, such as dual/triple-band antennas. The EBGs have been constructed and measured. [ABSTRACT FROM PUBLISHER]

Abstract: Recently, metasurfaces made up of dielectric structures have drawn enormous attentions in the optical and infrared regimes due to their high efficiency and designing freedom in manipulating light propagation. Such advantages can also be introduced to terahertz frequencies where efficient functional devices are still lacking. Here, polarization‐dependent all‐silicon terahertz dielectric metasurfaces are proposed and experimentally demonstrated. The metasurfaces are composed of anisotropic rectangular‐shaped silicon pillars on silicon substrate. Each metasurface holds dual different functions depending on the incident polarizations. Furthermore, to suppress the reflection loss and multireflection effect in practical applications, a high‐performance polarization‐independent antireflection silicon pillar array is also proposed, which can be patterned at the other side of the silicon substrate. Such all‐silicon dielectric metasurfaces are easy to fabricate and can be very promising in developing next‐generation efficient, compact, and low‐cost terahertz functional devices. [ABSTRACT FROM AUTHOR]

We report on the systematical study of the second-harmonic generation (SHG) in single zinc sulfide nanowires (ZnS NWs). The high-quality ZnS NWs with round cross-section were fabricated by chemical vapor deposition method. The transmission electron microscopy images show that the actual growth axis has a deviation angle of 0°∼20° with the preferential growth direction [120], which leads to the various polarization-dependent SHG response patterns in different individual ZnS NWs. The SHG response is quite sensitive to the orientations of c axis as well as the (100) and (010) crystal-axis of ZnS NWs; thus, all the three crystal-axis orientations of ZnS NWs are precisely determined by the SHG method. A high SHG conversion efficiency of 7 × 10(-6) is obtained in single ZnS NWs, which shows potential applications in nanoscale ultraviolet light source, nonlinear optical microscopy, and nanophotonic devices.