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Soil moisture (SM) and vegetation optical depth (VOD) estimates using passive microwave remote sensing at L-band (1.4 GHz) are essential for attaining a better understanding of water exchanges at the land-atmosphere interface. However, current retrieval algorithms often ignore the polarization dependence of vegetation effects. This study proposed a parameter self-calibrating framework for the multi-channel collaborative algorithm (MCCA) and presented a new SM and the first polarization-dependent VOD product based on the dual-polarized L-band observations at a fixed angle (40°) from the NASA Soil Moisture Active Passive (SMAP) mission. The parameter self-calibrating framework utilizes an information theory-based approach to obtain surface roughness and effective scattering albedo globally. Furthermore, the MCCA does not require auxiliary data for vegetation or soil moisture to constrain the retrieval process. Comparison with other SM and VOD products, such as MT-DCA version 5, DCA, SCA-H, SCA-V from SMAP Level-3 products version 8, and SMAP-IB, demonstrate analogous spatial patterns. The MCCA-derived SM exhibits the lowest unbiased root mean square deviation (ubRMSD, about 0.055 m3/m3), followed by SMAP-IB and DCA (0.061 m3/m3), with an overall Pearson's correlation coefficient of 0.744 (SMAP-IB performed best with R = 0.764) when evaluated against in-situ observations from 18 dense soil moisture networks. The MCCA generates VOD values for both vertical and horizontal polarization, demonstrating a slight polarization difference of vegetation effect at the satellite scale. Both VODs exhibit a strong linear relationship with above-ground biomass and canopy height. The polarization difference of VODs is primarily observed in densely vegetated and arid areas. • No ancillary data are used to calibrate parameters or constrain the cost function. • MCCA SM shows lower uncertainty and similar correlation compared to SMAP products. • The first SMAP VOD product that takes account of its polarization dependence. • VOD at H-polarization is greater than VOD at V-polarization over dense vegetation. [ABSTRACT FROM AUTHOR]

• The polarization dependence of the fiber Bragg grating is proved. • Multi-wavelength operation and switchable transverse mode are realized. • Azimuthally and radially polarized beams can be easily generated. We have proved the polarization dependence of the fiber Bragg grating (FBG), and demonstrated an all few-mode fiber laser that can realize multi-wavelength oscillation and switchable transverse modes simultaneously based on the polarization dependence of FBG. In this fiber laser, single-, dual- and triple-wavelength oscillation can be realized by merely adjusting the polarization controller inside the cavity. Three output transverse modes including fundamental mode, second-order mode, and hybrid modes can be switched as the laser operates at three different single-wavelengths correspondingly. In addition, azimuthally and radially polarized beams can be easily generated. This all few-mode fiber laser scheme may play a more significant role in wavelength division multiplexed (WDM) systems, mode division multiplexed (MDM) systems, sensing, and so on. [ABSTRACT FROM AUTHOR]

The polarization dependence plays a great impact on the SERS intensities for the surface plasmon coupling between nanoparticle aggregating. In this work, the SERS intensities collected from nanorice heterogeneous dimer or homogeneous dimer on Au, ITO and glass substrates exhibit strong polarization dependence. This result is further analyzed by the simulated surface charge distribution and electromagnetic enhancement distribution. Our data illustrate that SERS polarization dependence exhibits in all gaps in whole system, not only the gaps between nanorices but also gaps between nanorices and film, which could be important for the application of SERS as an ultrasensitive sensing technique. [ABSTRACT FROM AUTHOR]

Symmetry-protected bound states in the continuum (BICs) allow for high-efficiency light-matter interactions. Multi-channel BICs supported by a single nanophotonic-based device capable of further enriching the trapping and manipulation of light. It is well established that by breaking the in-plane geometrically symmetry, BICs can be transformed into quasi-BICs (qBICs). In this work, we propose and theoretically demonstrate that such optical states can also be accessed in metasurfaces with symmetric geometric parameters by breaking the in-plane symmetry in the permittivity of the comprising materials. We show that multiband qBICs with exquisitely high quality (Q) factors are excited under different polarization light incidence at near-infrared range, where a strong modulation of the optical response can be obtained by a small perturbation of the permittivity symmetry of the system. The group-theoretical methods and the representation theory are used to uncover the physical mechanism of qBICs and their polarization dependence. The full-wave and eigenfrequency simulations confirm the theoretical analysis.The results of near-field distributions and detailed multipole decompositions reveal that these qBICs present different optical characteristics. The polarization-multiplexed all-dielectric metasurfaces with high Q factors have great potential for applications in integrated multi-channel optical devices. • We demonstrate that SP-qBICs can be excited by introducing permittivity asymmetries in an all-dielectric metasurface. • Based on group-theoretical methods, we reveal the polarization dependence of the permittivity-asymmetric metasurface. • This multi-channel polarization-multiplexed metasurface enables unique extensibility and flexibility in photonic devices. [ABSTRACT FROM AUTHOR]

Due to its inherent exceptional mechanical flexibility and strength, graphene provides an ideal platform for strain engineering, enabling versatile modulation and significant enhancement of their optical properties. Both uniaxial and biaxial strain have been achieved by transferring monolayer graphene onto monodispersed Au nanoparticles with negligible charge doping. We present a study on the phonon frequency and crystallographic orientation in graphene monolayer wrinkles under uniaxial and biaxial strain. The G and 2D peaks of graphene exhibit significant red shifts under tensile strain. The doubly degenerate G peak splits in two sub-peaks G− and G+ under larger uniaxial strain because of symmetry breaking, while this phenomenon does not occur in the 2D peak. But the 2D peak is much more sensitive to strain. Further, Raman spectra of the unsplit G and 2D peaks have been proved to show a distinctive polarization dependence. We proposed polarized Raman spectroscopy to determine the crystallographic orientation with respect to the strain of graphene by the unsplit G mode. The polarization dependence of 2D mode offers a unique opportunity to examine the anisotropic modifications of the phonon dispersion and changes in electronic structures. This result is of significant in strain engineering of graphene and other two-dimensional materials. • The method is a facile approach for introducing uniaxial and biaxial strain with negligible doping in graphene. • G and 2D modes exhibit significant redshift due to tensile strain, with G mode splitting under larger uniaxial strain. • Raman spectra of the unsplit G and 2D peaks show a distinctive polarization dependence. • Polarization dependence of the unsplit Raman G mode is proposed to determine the crystallographic orientation. [Display omitted] [ABSTRACT FROM AUTHOR]

The femtosecond fiber-based optical frequency combs have been proved to be powerful tools for investigating the energy levels of atoms and molecules. In this paper, an Er-doped fiber femtosecond optical frequency comb has been implemented for studying the polarization dependence of 5 S –5 D two-photon transitions in thermal gas of atomic rubidium 87 using an entirely symmetrical optical configuration. By changing the polarization states of the counter-propagating light beams, the polarization dependence of direct two photon transition spectrum is demonstrated, and a dramatic variation (up to 5.5 times) of the two-photon transitions strength has been observed. The theory for the polarization dependence of two photon transition based on the second-order perturbation was established, which is in good agreement with the experimental results. The measurement results indicate that the polarization state manipulation with the existing frequency comb is used for femtosecond optical frequency comb based two photon transition spectroscopic purposes, which will improve the precision measurement of the absolute transition frequency and related applications. [ABSTRACT FROM AUTHOR]

Optical anisotropy of self-assembled elliptical InP quantum dots has been investigated in terms of the polarization dependence of excitons. Although large size inhomogeneity is present, two kinds of characteristic quantum dots, which are classified into large and small quantum dots, were found in terms of the polarization anisotropy. We have confirmed that the large quantum dots are more pronounced in the polarization anisotropy, where the degree of linear polarization for the large quantum dots is significantly larger (∼60%) than that for the small ones (∼36%). The effective shape of quantum dots is also estimated by using the size dependence of oscillator strength, which is in agreement with the AFM image. We also suggest that the anisotropy of exciton oscillator strength can be modified via the dipole–dipole interaction between nearest exciton dipoles. [ABSTRACT FROM AUTHOR]

Silicon thin films were deposited on a sapphire and a highly oriented pyrolytic graphite (HOPG), which have atomically flat and chemically inert surfaces. The electronic and geometrical structures of the films were analyzed by X-ray photoelectron spectroscopy (XPS) and polarization-dependent X-ray absorption fine structure (XAFS). It was found that the silicon K- edge XAFS spectra for ultra-thin silicon films thinner than 0.2 monolayer exhibited two distinct resonance peaks which were not observed for bulk silicon. The peaks were assigned to the resonance excitations from the Si 1 s into the valence unoccupied orbitals with π ∗ and σ ∗ characters. The average tilted angle of the π ∗ orbitals was determined by the polarization dependencies of the peak intensities. It was demonstrated that direction of a part of the π ∗ orbitals in silicon film is perpendicular to the surface. These results support the existence of quasi-freestanding single-layered silicon films with sp 2 configuration. [ABSTRACT FROM AUTHOR]

Abstract: We theoretically and experimentally investigate the effect of the incidence angle and polarization of sunlight on the optimized layer structure of organic solar cells (OSCs) to obtain the best absorption efficiency in a realistic deployment situation. We use the generalized transfer matrix method with respect to the incidence angle and polarization, which can calculate the spatial distribution of the optical power dissipation in both the incoherent glass substrate and the coherent multilayer without using any indirect correction factor. The angular dependence of the short-circuit current, the open-circuit voltage, and the output electric power is calculated and compared with the experimental results. Using the simulation parameters matched with the experimental results, we calculate the generation energy density per day by considering the variation of the incidence angle during daytime and determine the optimized thickness of the active region for maximum absorption efficiency. We show that the optimized active-region thickness based on the generation energy density per day is different from that determined from the variation of the short-circuit current density in only normal incidence, which is generally used for optimizing device structure of OSCs. [Copyright &y& Elsevier]

Abstract: Theoretical and practical aspects of resonant magnetic and charge scattering in the soft X-ray and extreme ultraviolet spectral ranges are reviewed. Intensity-only measurements are considered because they are more efficient than polarization-resolving measurements. Two very different approaches are discussed and compared; transmission small-angle scattering described by a simple kinematical scattering model and specular reflection described by more complex yet standard magneto-optical formalisms. In both cases the scattered intensity is seen to contain distinct terms resulting from pure-charge scattering, pure-magnetic scattering, and charge-magnetic cross-terms, and emphasis is placed on distinguishing these contributions via their energy spectra and its dependence on incident polarization. Combined with measurements vs. scattering vector q, both approaches provide significant capability to resolve magnetic and chemical structure down to nanometer length scales. The role of and need for modeling to obtain reliable information from data is discussed, as are current directions and opportunities. [Copyright &y& Elsevier]

Abstract: The mode coupling in the tilted long period fiber grating (TLPG) is analyzed by using the full vector complex coupled mode theory (FV-CCMT). Compared with the non-tilted LPG, new resonance bands corresponding to the LP1m cladding modes are observed in the transmission spectrum of the TLPG. The coupling to LP1m cladding modes is the combination of the coupling to degenerate vector modes TE0m , TM0m and HE2m with different propagation constants. The maximum coupling between LP01 and LP1m modes occurs at a tilt angle of ∼87°. Numerical results show that the state of polarization (SOP) of the input light would induce the shift of the new resonance wavelength. Also, the RI sensitivity of the new resonance wavelength is much higher than that of the normal resonance wavelength corresponding to the LP0m cladding modes. Such TLPG would find application in chemical and biological sensing fields. [Copyright &y& Elsevier]

Abstract: We fabricated a superconducting single-photon detector (SSPD) with bilayer structure. The detector consists of two meanders which are superposed face-to-face using optical adhesive. When the two nanowires are superposed perpendicularly, the degree of linear polarization dependence is reduced from 0.16 to 0.000617. This means that the polarization dependence, which has been a drawback in SSPDs, is suppressed almost completely using the present structure. [Copyright &y& Elsevier]

Abstract: We calculate the Fe 2p X-ray absorption spectrum (XAS) of RbMn[Fe(CN)6] in the ferromagnetic (FM) and photo-induced (PI) phases based on the calculation for the low-temperature (LT) and high-temperature (HT) phases. We use a configuration-interaction full-multiplet theory for a Fe(CN)6 cluster model and take account of the influence of adjacent Mn spins on the Fe(CN)6 cluster as an exchange field acting on the N 2p level. We predict that the Fe component of the magnetic moment can be decided by the Fe 2p XAS in the FM phase. In the PI phase, we predict a remarkable incident photon polarization dependence of the Fe 2p XAS. We examine the effect of a uniaxial crystal field on the Fe 2p XAS because RbMn[Fe(CN)6] in the LT phase takes the tetragonal structure which is one of factors for the temperature-induced valence transition. We also calculate the Mn 2p XAS of RbMn[Fe(CN)6] in the HT phase using a Mn(CN)6 cluster model. The average Mn 3d electron count is somewhat larger than the formal Mn valence (Mn2+) because of ligand-to-metal charge transfer. [Copyright &y& Elsevier]

Abstract: The vertically and horizontally polarized second harmonic responses from arrays of gold metallic nanocylinders with different two-dimensional spatial organization, namely square, hexagonal and random arrangements, have been determined in transmission as a function of the input fundamental polarization angle. The results demonstrate that the second harmonic response is incoherent, resulting from the breaking of the centrosymmetry of the shape of the nanocylinders by surface defects. As a result, no effect from the geometrical arrangement of the nanocylinders on the substrate is observed. [Copyright &y& Elsevier]

Abstract: The ordering and molecular orientation of polydimethylsilane (PDMS) films grown on indium tin oxide (ITO) surface has been assigned. The film has been synthesized by vacuum evaporation heated by electron bombardment. The orientation of the samples as well as that of the annealed sample was studied by Si K-edge near-edge X-ray absorption fine structure (NEXAFS) and X-ray photoelectron spectroscopy using linearly polarized synchrotron radiation. The Si K-edge NEXAFS spectra for the thick film have at least four resonance peaks of which two peaks are found to be strongly polarization dependent. The lower-energy resonance peak at 1842.0eV has short-axis polarization corresponding to the resonance excitation from Si 1s→σ* pyz orbital of Si–C bond and the higher-energy resonance peak at 1843.2eV has long-axis polarization due to the excitation of Si 1s→σ* px orbital of Si–Si bond. On the basis of the polarization dependences, it is revealed that the backbones of the PDMS films are perpendicularly oriented to the ITO surface. The angle between surface and the Si–Si bonds for multilayered film calculated from the helical structure of PDMS molecule was found to be 41.5° which was almost coincided with the experimentally obtained angle of 40°. The polarization dependency disappeared for the annealed sample at about 80°C which suggests that the PDMS was almost parallel and/or randomly oriented to the ITO surface after annealing. [ABSTRACT FROM AUTHOR]

Abstract: In the present work, we have investigated the molecular orientation of phthalocyanine films deposited on polycrystalline gold. Three films built from the following molecules are investigated: phthalocyanine (H2Pc), cobalt phthalocyanine (CoPc) and copper phthalocyanine (CuPc). The films are prepared by spin coating and drop casting methods. Orientation analysis has been performed using polarization dependent Fourier transform infrared (FTIR) spectroscopy using transmission and grazing angle reflectance mode. The FTIR study suggests that each phthalocyanine film contains both α- and β-phases. H2Pc based films demonstrate deposition method dependence on the molecular orientation, while the CuPc and CoPc films preserve their molecular orientation independent of deposition method. Grazing angle analysis also suggests that CoPc films show negligible preferred orientation irrespective of film deposition methods. In literature, the band at 878cm−1 in CuPc has been assigned to out-of-plane bending of C–H. Our grazing angle experiments suggest that this band cannot be assigned to out-of-plane bending vibrations of C–H. Accurate band assignments are also described here for the phthalocyanine system. [Copyright &y& Elsevier]

Abstract: A method based on the combination of finite-difference time-domain (FDTD) algorithm and Fourier transformation was proposed to analyze the Fraunhofer diffraction of gratings. Polarization dependence of the Fraunhofer diffraction of a one-dimensional metallic grating with period less than 8 times the incident wavelength was studied. Some special characteristics were found. The polarization dependence is related to period value, slit width, and thickness of the grating, and the missing orders predicted by scalar analysis appear. Besides, if the period of a grating is larger than 8 times the wavelength but the slit width or the size of the opaque portion of the grating is close to the wavelength, diffraction of the grating also becomes polarization dependent. [Copyright &y& Elsevier]

Abstract: Two-photon absorption (TPA) line strengths for transitions within the configuration of have been successfully calculated with several different time-independent perturbation methods. However, attempts to use similar methods to predict TPA line strengths for transitions within the configuration of have been much less successful, due to the fact that the low-lying excited states make straight-forward application of perturbation theory unreliable. In this work we carry out a direct calculation of TPA line strengths that take into account the major interactions for and configurations nonpertubatively. We also calculate the linewidths of TPA peaks due to nonradiative relaxation to energy levels by considering the odd parity vibrations responsible for nonradiative relaxation. Comparisons of calculated TPA line strengths and linewidths with experimental spectra allow improved energy-level assignments. The calculated TPA spectra give a good reproduction of the experimental line strengths, polarization dependences, and linewidths. [Copyright &y& Elsevier]

Polarization dependence of ion desorption for methyl ester terminated self-assembled monolayer was investigated in carbon and oxygen core-excitations in order to clarify ion desorption mechanism. Site-selective ionic dissociation is induced by the C 1s,O 1s(OCH3)→σ*(O—CH3) and O 1s(OCH3)→σ*(C—OCH3) excitations. Ions site-selectively desorbing in these excitations strongly depend on SR incident angle. On the other hand, ion yields in non-selective excitations indicate almost no dependence. Difference in the polarization dependence is considered due to the dissociation mechanisms characterized as direct and indirect dissociation processes. [Copyright &y& Elsevier]

We investigated the local bonding states of D2 +-irradiated graphite using a photon-stimulated ion-desorption (PSID) technique, which incorporates polarized near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. The carbon K-edge NEXAFS conducted in Auger electron yield mode showed no significant dependence on polarization angles (θ), while H+- and D+-PSID NEXAFS showed polarization-dependent resonances. The σ*(C—H) resonance in H+ ions and σ*(C—D) in D+ ions showed enhanced yields, which were larger at θ =10° than at θ =45° and the σ*(C＝C) peak in D+ ions showed a prominent enhancement which was stronger at θ =10° than at θ =45°. Our results are interpreted assuming that the difference in local structures between C—H and C—D bonds is reflected in the PSID NEXAFS. [Copyright &y& Elsevier]

Abstract: High temperature ion implantation (hot implantation) is used to synthesize carbon nitride (CN x ) films. Three CN x films are compared by near edge X-ray absorption fine structure (NEXAFS) spectroscopy; one is prepared by room temperature implantation, another is prepared by subsequent annealing, and the other is prepared by hot implantation. The former two films show three comparable discrete peaks in N K-edge NEXAFS spectra, which are assigned to different kinds of local structures at N sites. On the other hand, a single peak grows predominantly in the spectra for the film prepared by hot implantation. Through the polarization dependence analysis of NEXAFS, the dominant peak is assigned to the fullerene-like structure of CN x which consists of pentagons and hexagons. The difference between the CN x films which are synthesized by subsequent annealing and hot implantation is also discussed. [Copyright &y& Elsevier]

Abstract: The electronic and geometrical structures of silicon carbide thin films are presented. The films were deposited on graphite by ion-beam deposition using tetramethylsilane (TMS) as an ion source. In the Si K-edge near-edge X-ray absorption fine structure (NEXAFS) spectra for sub-monolayered film, sharp peaks due to the resonance from Si 1s to π*-like orbitals were observed, suggesting the existence of Si=C double bonds. On the basis of the polarization dependencies of the Si 1s → π* peak intensities, it is elucidated that the direction of the π*-like orbitals is just perpendicular to the surface. We conclude that the sub-monolayered SiCx film has a flat-lying hexagonal structure of which configuration is analogous to the single sheet of graphite. [Copyright &y& Elsevier]

Hexagonal boron nitride (h-BN) thin film has been epitaxially formed on Ni(1 1 1) by chemical vapor deposition using borazine gas. The electronic structure of this system is studied by near edge X-ray absorption fine structure (NEXAFS) spectroscopy and X-ray photoelectron spectroscopy (XPS). The thickness of the h-BN is estimated to be about two-layers from XPS. B K-edge NEXAFS spectra show new π* peak which is not observed in the spectrum for bulk h-BN. From a polarization dependence analysis of NEXAFS, we propose this new π* peak originates from the interaction between the h-BN and Ni(1 1 1). This new π* peak clearly proves that conduction band of h-BN/Ni(1 1 1) is different from that of bulk h-BN. [Copyright &y& Elsevier]

We report experimental studies of polarization dependence in resonant soft X-ray emission of 3d transition metal compounds. In metal 2p resonant soft X-ray emission spectra of 3d0 systems, transition to the bonding and antibonding states between 3d0 and 3d1L configurations shows polarization dependence. In TiO2, the polarization dependence is drastic, whereas it is slightly weak in ScF3 and extremely weak in KMnO4. The results are explained by a local symmetry selection rule, strength of hybridization, and phase relation of wave-functions among initial, intermediate, and final states. In oxygen 1s resonant excitation of undoped cuprate, Sr2CuO2Cl2, we demonstrate that Zhang–Rice singlet excitation, dd excitation, as well as two spin-flip excitations can be distinguished according to their symmetry. [Copyright &y& Elsevier]

Low-energy Si+ ions were implanted in highly oriented pyrolitic graphite (HOPG) up to 1% of surface atomic concentration, and the local electronic and geometric structures around the silicon atoms were in situ investigated by means of the Si K-edge X-ray absorption near-edge structure (XANES) and X-ray photoelectron spectroscopy using linearly polarized synchrotron radiation. The resonance peak appeared at 1839.5 eV in the Si K-edge XANES spectra for Si+-implanted HOPG. This energy is lower than those of the Si 1s→σ* resonance peaks in any other Si-containing materials. The intensity of the resonance peak showed strong polarization dependence, which suggests that the final state orbitals around the implanted Si atoms have π*-like character. It is concluded that the σ-type Si–C bonds produced by the Si+-ion implantation are nearly parallel to the graphite plane, and SixC phase forms two-dimensionally spread graphite-like layer with sp2 bonds. [Copyright &y& Elsevier]

• Multi-channel separation from dual-port to seven-port at the 2.5200 THz frequency. • The efficiency of the 0th order suppressed well for the even-port beam splitter. • Good uniformity and moderate tolerance with optimized multi-channel parameters. In this paper, we proposed polarization-dependent terahertz reflective beam splitters under normal incidence, in which resonance-domain diffraction gratings with period comparable to incident wavelength are adopted to achieve multi-channel beam separation, appropriate total diffraction efficiency, and good efficiency uniformity. At the frequency of 2.5200 THz (correspondingly the wavelength λ = 118.83 μm), the beam splitters can implement energy output varying from dual- to seven-port. For transverse electric (TE) polarization, the total efficiency of the beam splitters can reach ~ 95% (assuming the values 96.04%, 96.84%, 94.71%, 96.32%, 96.47%, and 95.08%, respectively, when the splitter's output ports change from two to seven). For transverse magnetic (TM) polarization, under different structural parameters (namely the heights of the grating ridges h 1 and h 2) from TE polarization, the corresponding values are 96.62%, 95.23%, 92.81%, 93.11%, 92.99%, and 93.19%, respectively. Our results (Table 2) demonstrate that all splitters, irrespective of the number of output ports, can provide appropriate total diffraction efficiency and good uniformity. Through rigorous coupled-wave analysis (RCWA), we derived the fabrication tolerance of the incident wavelength and period, which highlights the reliability of the proposed terahertz beam splitters. [ABSTRACT FROM AUTHOR]