This work presents a novel method for achieving controlled polarization-selective enhancement of the Photonic Spin Hall Effect (PSHE) by integrating waveguiding effects with surface plasmonic behavior. The conventional plasmonic wave generation, limited to TM waves, is expanded by introducing waveguiding effects, enabling resonances for TE waves. This dual resonance mechanism contributes to the enhancement of PSHE for both horizontally (H) and vertically (V) polarized waves. Utilizing thin metal layers (Ag and Al) of a few nanometers in conjunction with waveguiding glass layers under 500nm thickness, significant enhancements of PSHE are demonstrated at the submillimeter scale. This integrated approach offers a promising avenue for tailoring and controlling PSHE with applications in advanced photonic devices.
Previously, the enhanced photonic spin Hall effect (PSHE) in plasmonic devices was only possible with horizontal polarization (H-polarized). The wave-guiding surface plasmonic resonance (SPR) effect is used to report enhanced PSHE of reflected light for both horizontal and vertical polarized waves in this work. Further findings suggest the manipulation of active polarization mode and control in PSHE enhancement by simply adjusting the thickness of the wave-guiding layer. A finite element technique simulation study is used to investigate the influence of an additional thin dielectric waveguiding layer on PSHE. This research opens up the possibility of using both horizontal and vertical polarization-based quantum devices and sensors, in which light spin plays an important role.
Nanowires with metallic or dielectric materials have received considerable interest in many research fields for optical and optoelectronic devices. Metal nanowires have been extensively studied due to the high optical and electrical properties and dielectric nanowires are also investigated owing to the multiple scattering of light. In this research, we report optical meta-films of alumina nanowire arrays with nanometer scale diameters by fabrication method of self-aggregate process. The aluminum oxide nanowires are transparent from ultraviolet to near infrared wavelength regions and array structures have strong diffusive light scattering. We integrate those optical properties from the material and structure, and produce efficient an optical haze meta-film which has high transparency and transmission haze at the same time. The film enhances efficiencies of optical devices by applying on complete products, such as organic solar cells and LEDs, because of an expanded optical path length and light trapping in active layers maintaining high transparency. On the other hands, the meta-film also produces solar steam by sputtering metal on the aluminum oxide nanowire arrays. The nanowire array film with metal coating exhibits ultrabroadband light absorption from ultraviolet to mid-infrared range which is caused by nanofocusing of plasmons. The meta-film efficiently produces water steam under the solar light by metal-coated alumina arrays which have high light-to-heat conversion efficiency. The design, fabrication, and evaluation of our light management platforms and their applications of the meta-films will be introduced.
Light emitting diodes (LEDs) are used to very diverse fields because of their high efficiency and long life time. Especially, GaN-based LEDs has good properties such as high power and electrical stability, so it can be used for light source in many devices. However, because of large difference of refractive index between SiC substrate of LEDs and air, Fresnel reflection loss and Total internal reflection loss are occurred. For that reason, light extraction efficiency of LEDs is very low. In this study, we fabricate Alumina based scattering film and show light extraction efficiency of LEDs can be enhanced through attaching scattering film on SiC substrate. Alumina nanowires were fabricated by wet etching process of porous alumina layer. Nanowires were collapsed randomly by capillary force of water during drying process forming microscale ridges. This scattering film has extremely high transmittance and scattering value which is determined by etching time. The effective refractive index of the film lies between the refractive index of SiC and air. So attached scattering film on SiC substrate of LEDs creates gradually varying index distribution reducing Fresnel reflection loss. Microscale ridges of scattering film play as light scatterers, and incidence light scattered in all direction reducing incident angle dependence so they can reduce total internal reflection loss. Light extraction efficiency of scattering film attached LED is about 20% higher than bare LED.
In this work, we investigated the diffraction of inverse-hemisphere shaped polymer grating. We fabricated an inverse-hemisphere- shaped grating structure using soft lithography of close-packed PS nanospheres that is easy and cost-effective method. Then the diffraction wavelength shift induced from lattice change was measured. The periodicity of the grating was tuned by swelling in acetone. The measurement results suggest that the device can be used as a strain gauge or a chemical sensor.
KEYWORDS: Gold, Absorption, Organic photovoltaics, Solar cells, Thin film solar cells, Plasmonics, Metals, Finite-difference time-domain method, Optical properties, Solar energy
The fabrication method of plasmonic nanodots on ITO or nc-ZnO substrate has been developed to improve the efficiency of organic thin film solar cells. Nanoscale metallic nanodots arrays are fabricated by anodic aluminum oxide (AAO) template mask which can have different structural parameters by varying anodization conditions. In this paper, the structural parameters of metallic nanodots, which can be controlled by the diverse structures of AAO template mask, are investigated to enhance the optical properties of organic thin film solar cells. It is found that optical properties of the organic thin film solar cells are improved by finding optimization values of the structural parameters of the metallic nanodot array.
We demonstrate a convenient method to improve the surface Plasmon resonance sensitivity by manipulating the
permittivity of active medium using metal-dielectric (Ag-SiO2) composite monolayer. We demonstrate the successful
permittivity engineering of SPR active medium in both theory and experiments. Based on the basic theory of SPR and
Bruggeman effective medium theory (EMT), we theoretically confirm that the angular sensitivity enhances using
manipulated permittivity of metal-dielectric composite layer.
Recently, the near-field superlens (NFSL) has been used as a suitable material for the super-resolution beyond the
diffraction limits. These NFSL materials in the nature, such as metals and polar dielectric crystals, usually have intrinsic
absorption loss in the Re(ε) < 0 region. In the imaging system, such absorption loss decreases the retardation effects by
softening the singularity of transmission resonances, but it does not remove the phase singularity that severely
deteriorates the ideal image restoration. Because of this problem, TiO2 thin film cannot still have sufficient band of
spatial frequency for the super-resolution in the mid IR regime. In this research, we report the achievement super-resolution
in TiO2 NFSL by elimination of the phase singularity based on the phase correction method.
We design the THz lens made of slit-groove-based metamaterials with tunable far-field focal length as well as
subwavelength resolution, based on surface plasmons(SP) diffraction theory into spoof SP of THz region. In THz
regime, the curved depth profile of grooves from both sides of metal slit produce directional beaming and mimic SP at
the same time. By arranging the depth of grooves in traced profile, it is possible to optimize the focal position in THz
region without changing the size of structure. It is performed numerical simulation of a designed structure through finite-difference
time-domain (FDTD) method and shows the subwavelength imaging of the designed position. In addition, the
change of focal length and the relative Ex phase are observed in the simulation and help to comprehend a subwavelength
1D slit-groove-based metamaterials in THz regime.
In the manufacturing process of stainless steel, it is essential to pickle the oxide layer of steel surface for high corrosion
resistance and fine surface quality. Pickling liquor of stainless steel is commonly composed of mixed hydrofluoric and
nitric acid. Real time monitoring of concentrations of each acid is crucial to optimize pickling process. It also reduces
cost of production and decreases the generation of waste acid. We used non-contact near infrared spectroscopy
technique and rapid analysis method, for the quantification of each acid in an on-line manner. Multivariate calibration
such as partial least square regression method is employed for the better prediction results.
Recently, the near-field superlens (NFSL) based on the negative permittivity (ε < 0) has been much attraction issue
because of its useful application in a near-field imaging system beyond the diffraction limits. Silver in the UV region and
silicon carbide in the mid-IR regime has been reported as suitable materials for the NFSL. However, these materials have
the intrinsic absorption loss, which blurs the near-field image. In this research, we theoretically predict enhancement of
image quality in a lossy NFSL system using the full-wave numerical approach and electrostatic approximation method.
As a result, we recognized that an unmatched NFSL has better image quality compared to the traditional match NFSL.
Mixed acid, which consist of HF and HNO3, is used as a good etchant for silicon dioxide in the wet etching and pickling
process of stainless steel. The optical detection of concentration for such mixed acids is crucial to optimize and cut costs
in the manufacturing process. Optical detection in the IR regime has been utilized to measure the concentration of the
mixed acid for HF and HNO3, because that has several strong absorption peaks, which is contributed by vibrational mode
of each acid molecular in this spectrum. In this research, we observed the concentrations of mixed acid to consist of HF
and HNO3, as we measured the absorption intensity of OH- stretch and NO3
- stretch band by optical spectroscopy. The
concentration range of HF over 1.5-3 wt% and that of HNO3 over 2-10 wt% were studied in room temperature.
Ag slab near-field superlens (NFSL) has been much attractive issue due to their application of nano-imaging by the
resolution beyond the diffraction limits. Although it has the advantages as sub-wavelength imaging tools, Ag NFSL
always suffers from image blurring due to the intrinsic absorption loss, which prevent the ideal reconstruction of nanoimaging.
In this research, through the analysis of focal property using the FDTD, we recognized that the impedance
mismatched Ag NFSL is useful as the phase corrected optical components in the near-field. As a result, the significant
enhanced of visibility, depth of field, and resolving capability is achieved in the mismatched Ag NFSL imaging system.
In the optical lithography technique, the higher aspect ratio is critical as well as small spot size. To achieve higher
aspect ratio with the same nano scale spot size, in this report, we control the confocal parameters of Ag superlens by
changing the position of lens. In our FDTD (Finite Difference Time Domain) calculation, Drude dispersion is
employed to represent the frequency-dependent permittivity of the Ag superlens while the refractive index of Ag
matches with the host material, air and PMMA, at the wavelength of 338nm and 360nm. By changing the wavelength
from 330nm to 340nm, in addition, we investigated the tunable superlensing effects and the amplification of evanescent
wave with Ag slab related to surface plasmon polariton. Consequently, we observed the variation of the confocal
parameters of Ag superlens depending on the position and the tunable wavelength in our results.
Due to the maturity of current laser technology, the limitation of empirical wavelengths of lasers useful for optical
microlithography makes spectrally investigated optimization very important for the design of C-shaped nano apertures;
in order to achieve high optical transmission as well as tight focusing, the resonant transmission of nano apertures
depends on the incident light's wavelength. The optically propagating transmission through the nano aperture,
determined by the effects of the propagating field and evanescent field, is also important in order to achieve deep
patterning. High power throughput and decaying behaviors of propagating light through nano apertures depend on their
resonance condition which is affected by geometric parameters and material properties as well as the wavelength of
incident light. In this report, we analyze the spectral properties of resonant transmission of light through a C-shaped
nano aperture in a metal film using a finite-difference time-domain (FDTD) simulation. These simulations may be
helpful for the design of C-shaped nano apertures for high power throughput with tight focusing. Furthermore, we show
that power dissipation of propagating light through the C-shaped nano aperture depends on metals.
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