Angle Of Incident Light Research Articles

Effect of incidence angle on PV soiling loss

The effect of light incidence angle is crucial for accurate interpretation of soiling sensor readings and soiling loss data. In this study, the effect of incidence angle on soiling loss is investigated under a solar simulator using artificially and naturally produced soiling samples on different types of glass substrates. It was found that the incidence angle dependence of soiling loss can be described satisfactorily using a two-parameter model, which has one power-law parameter associated with dust morphology and a fraction parameter dependent on the substrate’s angular transmittance. These results are applicable to beam radiation; further research is needed to apply them to field conditions in which diffuse solar radiation is significant. Findings from this study may provide an approach for more accurately calculating PV soiling loss based on optical sensor readings and for more meaningful soiling loss comparison across different locations.

IGT/LAZY genes are differentially influenced by light and required for light-induced change to organ angle

BackgroundPlants adjust their growth orientations primarily in response to light and gravity signals. Considering that the gravity vector is fixed and the angle of light incidence is constantly changing, plants must somehow integrate these signals to establish organ orientation, commonly referred to as gravitropic set-point angle (GSA). The IGT gene family contains known regulators of GSA, including the gene clades LAZY, DEEPER ROOTING (DRO), and TILLER ANGLE CONTROL (TAC).ResultsHere, we investigated the influence of light on different aspects of GSA phenotypes in LAZY and DRO mutants, as well as the influence of known light signaling pathways on IGT gene expression. Phenotypic analysis revealed that LAZY and DRO genes are collectively required for changes in the angle of shoot branch tip and root growth in response to light. Single lazy1 mutant branch tips turn upward in the absence of light and in low light, similar to wild-type, and mimic triple and quadruple IGT mutants in constant light and high-light conditions, while triple and quadruple IGT/LAZY mutants show little to no response to changing light regimes. Further, the expression of IGT/LAZY genes is differentially influenced by daylength, circadian clock, and light signaling.ConclusionsCollectively, the data show that differential expression of LAZY and DRO genes are required to enable plants to alter organ angles in response to light-mediated signals.

Sensorless Iterative Solar Tracking In Multiple On-Grid Photovoltaic Generators With Improved Tracking Strategy

The efficiency of the energy conversion in photovoltaic panels varies according to the angle of light incidence. A new method of iterative repositioning of the panels at maximum-efficiency direction has been proposed. This method frees up the use of sun position sensors and uses the instantaneous power delivered to the power line by each panel, among a series of photovoltaic panels, as a feedback in determination of the best position in a closed-loop operation. The proposed repositioning method, as well as the repositioning dynamic of a series of photovoltaic panels, has been modeled. The system has been simulated in a single parallel-rays light source scenario. In simulations, the convergence of panels to the best energy conversion position was observed.

Coupled effect of light incidence angle and deformation on the light-induced bending of liquid crystal elastomers plates

In this paper, the light-induced bending of a liquid crystal elastomers (LCEs) plate with the coupled effect of light incidence angle and deformation is studied for the first time. Based on the Reissner-Mindlin plate theory, a finite element model incorporating the coupled effect is developed to investigate the bending behavior of the LCEs plate. Deflections of the LCEs plate subjected to the light illumination with different light incidence angles are given. It is found that the coupled effect will significantly affect the bending deformation of the LCEs plate such as the location of the peak and the bending shape. Comparisons of the spontaneous bending of the LCEs plate with and without the coupled effect demonstrate the necessity of this study, especially for the LCEs plate subjected to the non-normal incidence light.

Spin-Selective Angular Dispersion Control in Dielectric Metasurfaces for Multichannel Meta-Holographic Displays.

Angle-dependent next-generation displays have potential applications in 3D stereoscopic and head-mounted displays, image combiners, and encryption for augmented reality (AR) and security. Metasurfaces enable such exceptional functionalities with groundbreaking achievements in efficient displays over the past decades. However, limitations in angular dispersion control make them unfit for numerous nanophotonic applications. Here, we propose a spin-selective angle-dependent all-dielectric metasurface with a unique design strategy to manifest distinct phase information at different incident angles of light. As a proof of concept, the phase masks of two images are encoded into the metasurface and projected at the desired focal plane under different angles of left circularly polarized (LCP) light. Specifically, the proposed multifunctional metasurface generates two distinct holographic images under LCP illumination at angles of +35 and -35°. The presented holographic displays may provide a feasible route toward multifunctional meta-devices for potential AR displays, encrypted imaging, and information storage applications.

Electric power from shadows and indoors: solar cells under diffuse light conditions

There is diffuse light in urban areas, so we need to utilize the angle of incident light for urban solar cells. In this paper, we propose a model to deal with complex diffuse light and predict the performance of solar cells in urban environments.

Angle-tunable polymeric photonic diode with 1D-photonic crystal for enhanced light control

This work introduces an angle-tunable polymeric photonic diode with enhanced light control by integrating it with a 1D photonic crystal. The diode's non-reciprocity can be controlled by changing the incident light angle.

Modeling and admittance recursive simulation of anti-reflective coatings for photothermal conversion: synergy between subwavelength structures and gradient refractive index layers.

In the field of photothermal conversion, light-absorbing layers show limitations such as low solar energy utilization and excessive surface reflection. This paper proposes a new anti-reflective coating consisting of a gradient-doped fluorescent glass film covering a subwavelength structural layer for photothermal conversion. Its transmittance was simulated using equivalent medium theory and the admittance recursion method. The subwavelength structure provides a refractive index gradient, and its shape solves the problem of the sharp decrease in transmittance at high angles of incidence. Subsequently, we adjust the material parameters of the gradient refractive layers and control the thickness of each layer to minimize interlayer Fresnel reflections. Finally, the efficient light-trapping ability of the model was verified by calculating and comparing the transmittances of the optimized model and bare glass. Notably, within the visible spectrum, our model achieves an average transmittance of over 95% across wavelength and angle ranges, effectively suppressing surface reflections. At a larger light incident angle, the transmittance increases by 29.7%, and the minimum angle transmittance reaches 92.7%. This study proposes an innovative method to enhance the performance of transmission layers in photothermal conversion devices.

Performance Analysis of a Single Light Source Bidirectional Visible Light Communication Reverse Reflection Link

Visible light communication has the advantages of large bandwidth, high security, and no RF interference, among which LED light sources are an important light source for indoor visible light communication. The use of LED as a light source for visible full-duplex communication is both to meet the lighting requirements and to ensure high-speed transmission of information. The uplink using the “cat’s eye” reverse modulation system can greatly reduce the system complexity of the reverse reflector. In order to analyze the factors affecting the optical power at the receiving end of the uplink of the indoor single light source visible light communication, this paper establishes the indoor visible light full-duplex communication system model and deduces the calculation method of the effective incidence angle of the uplink transmission light and the movable range of the reverse reflection end according to the model. The results show that when the link distance of the BK7 lens is 3 m, the lens aperture is increased from 100 mm to 150 mm, the lens focal length is increased from 100 mm to 150 mm, the travel distance of the reverse reflector is increased by 60%, and the effective range of the incidence angle is increased by about twice. In the absence of link loss, each 1 m increase in link distance increases the maximum travel distance of the reverse reflector by 0.8 m. Increasing the lens aperture, decreasing the focal length, and increasing the link distance can improve the movable range of the reverse reflector, and the effective incidence angle changes more gently with the position of the reverse reflector.

(Invited) Tuning and Transferring Slow Photons for Unprecedented Visible Light Photocatalysis

Periodic structures with alternating refractive indices such as inverse opal photonic crystals are capable of reducing the group velocity of light such that this slowed light can be more efficiently harvested for highly enhanced solar energy conversion. However, the generation, the manipulation and, in particular, the practical applications of these slow photons remain highly challenging. Here, we report the first proof of concept on the ability to control, in an inverse opal TiO2-BiVO4 hetero-composite, the transfer of slow photons generated from the inverse opal photonic structure to the photocatalytically active BiVO4 nanoparticles for highly enhanced visible light photoconversion. Tuning the slow photon frequencies, in order to accommodate the electronic band gap of BiVO4 for slow photon transfer and for significantly improved light harvesting, was successfully achieved by varying the structural periodicity (pore size) of inverse opal and the light incidence angle. The photocatalytic activity of BiVO4 in all inverse opal structures, promoted by slow photon effect, reached up to 7 times higher than those in the non-structured compact films. This work opens new avenues for the practical utilization of slow photon effect under visible light in photocatalytic energy-related applications like water splitting and carbon dioxide reduction and in photovoltaics.

Design of tunable photothermal porous thermal emitter based on nonreciprocal effect

Tunable thermal emitters have become a research hotspot for high-efficiency, low-loss novel thermal radiation devices. It has been found that the tunability of thermal radiation devices can be greatly strengthened and the efficiency of photothermal conversion enhanced through the tuning of the radiation temperature by magneto-optical microstructures. In this paper, a novel porous thermal emitter for the mid-infrared band is designed and the interconnection between nonreciprocal radiation and photothermal conversion is investigated for the first time. The three-hole column (THC) porous structure is optimized from the traditional one-hole column (OHC) porous structure. Through detailed analysis of the light incident angle, external magnetic field strength, and hole diameter, it is shown that the strong nonreciprocal radiation is due to the variation of the cavity structure parameters, which enhances the microcavity resonance effect, thereby enhancing the surface plasmon resonance (SPR) on the porous surface. The electric field contours at different positions also visualize the enhancement mechanism of SPR for nonreciprocal radiation. It has been investigated that different magnetic field strengths and porous structures have significant impact on nonreciprocal thermal tuning. The nonreciprocal system can be used to tune the local heat around the hole, and the temperature difference increase as nonreciprocal effects is greater as the magnetic field strength and input power increases. This work also provides new ideas for the application of thermal emitters and the design of energy conversion devices.

Information multiplexing from optical holography to multi-channel metaholography

Abstract Holography offers a vital platform for optical information storage and processing, which has a profound impact on many photonic applications, including 3D displays, LiDAR, optical encryption, and artificial intelligence. In this review, we provide a comprehensive overview of optical holography, moving from volume holography based on optically thick holograms to digital holography using ultrathin metasurface holograms in nanophotonics. We review the use of volume holograms for holographic multiplexing through the linear momentum selectivity and other approaches and highlight the emerging use of digital holograms that can be implemented by ultrathin metasurfaces. We will summarize the fabrication of different holographic recording media and digital holograms based on recent advances in flat meta-optics and nanotechnology. We highlight the rapidly developing field of metasurface holography, presenting the use of multi-functional metasurfaces for multiplexing holography in the use of polarization, wavelength, and incident angle of light. In the scope of holographic applications, we will focus on high bandwidth metasurface holograms that offer the strong sensitivity to the orbital angular momentum of light. At the end, we will provide a short summary of this review article and our perspectives on the future development of the vivid holography field.

Prediction of radiation characteristics of solar collectors with multiple geometrical configurations based on Monte Carlo considering absorption element

This paper presents a study on the optical properties of direct absorption solar collector (DASC) modules with different geometrical configurations considering absorption elements. Three DASC module models, namely flat plates, circular tubes, and tri-prisms, were established and solved using the Monte Carlo method and Mie theory. The accuracy of the results was well verified with the reference data. The results show that the DASC with Si absorption elements exhibited higher absorbance than the DASC with TiO2 absorption elements. It is observed that SiO2@Ni nanofluid exhibited the highest absorbance and lowest reflectance, while TiO2 nanofluid displayed the lowest absorbance and highest reflectance. The absorbance of the nanofluids decreases and the reflectance of systems increases with the increasing particle size of the nanofluid. At incident light angles of 0° and 15°, tri-prism collectors outperform other geometric configurations of collectors. At 30° and 45°, circular tube collectors perform best. At 60° and 75°, flat plate collectors show superior performance. Overall, the tri-prism collector using SiO2@Ni nanofluid coupled with Si absorption elements can improve the efficiency of solar energy utilization compared to the other types of solar collectors.

Self-Rolled-Up Ultrathin Single-Crystalline Silicon Nanomembranes for On-Chip Tubular Polarization Photodetectors.

Freestanding single-crystalline nanomembranes and their assembly have broad application potential in photodetectors for integrated chips. However, the release and self-assembly process of single-crystalline semiconductor nanomembranes still remains a great challenge in on-chip processing and functional integration, and photodetectors based on nanomembrane always suffer from limited absorption of nanoscale thickness. Here, a non-destructive releasing and rolling process is employed to prepare tubular photodetectors based on freestanding single-crystalline Si nanomembranes. Spontaneous release and self-assembly are achieved by residual strain introduced by lattice mismatch at the epitaxial interface of Si and Ge, and the intrinsic stress and strain distributions in self-rolled-up Si nanomembranes are analyzed experimentally and computationally. The advantages of light trapping and wide-angle optical coupling are realized by tubular geometry. This Si microtube device achieves reliable Ohmic contact and exhibits a photoresponsivity of over 330mA W-1 , a response time of 370 µs, and a light incident detection angle range of over 120°. Furthermore, the microtubular structure shows a distinct polarization angle-dependent light absorption, with a dichroic ratio of 1.24 achieved at 940nm. The proposed Si-based microtubes provide new possibilities for the construction of multifunctional chips for integrated circuit ecosystems in the More than Moore era.

Maskless fabrication of quasi-omnidirectional V-groove solar cells using an alkaline solution-based method

Silicon passivated emitter and rear contact (PERC) solar cells with V-groove texture were fabricated using maskless alkaline solution etching with in-house developed additive. Compared with the traditional pyramid texture, the V-groove texture possesses superior effective minority carrier lifetime, enhanced p–n junction quality and better applied filling factor (FF). In addition, a V-groove texture can greatly reduce the shading area and edge damage of front Ag electrodes when the V-groove direction is parallel to the gridline electrodes. Due to these factors, the V-groove solar cells have a higher efficiency (21.78%) than pyramid solar cells (21.62%). Interestingly, external quantum efficiency (EQE) and reflectance of the V-groove solar cells exhibit a slight decrease when the incident light angle (θ) is increased from 0° to 75°, which confirms the excellent quasi omnidirectionality of the V-groove solar cells. The proposed V-groove solar cell design shows a 2.84% relative enhancement of energy output over traditional pyramid solar cells.

Investigation of the Efficacy of Horizontal Hollow Light Tubes for Energy Conservation in Illuminating Buildings

This study investigates the properties of light transmission and distribution, examining how incident light angles impact illuminance distribution and daylight factor. Light tubes are acknowledged as promising tools to enhance lighting conditions and reduce energy consumption in building design. The study involved installing horizontal hollow light tubes, each measuring 0.5 m in length and 0.30 m in diameter, on a wooden test model. A 20-watt LED lamp was employed as the light source, and an illuminance meter recorded the values at various horizontal and elevation angles. The study’s assessment included calculating the average illuminance and daylight factor to obtain light transmission efficiency and energy-saving potential. The findings revealed that both aluminum alloy and zinc alloy tubes experienced a decrease in illuminance as incident elevation angles increased, with the most effective light transmission occurring at a horizontal angle of 90°. Notably, the aluminum alloy tube outperformed the zinc alloy tube, demonstrating more than a 15% increase in light transmission efficiency. Furthermore, the daylight factor values from both types of tubes aligned with established standards for residential and office activities, underscoring their potential as energy-efficient lighting solutions for spaces lacking natural light or with limited illumination.

Single-longitudinal-mode lasing based on enhanced scattering in eccentric-hole microstructured optical fiber resonators

In this paper, we propose a dual-core eccentric-hole fiber (DCEHF) microresonator to achieve single-longitudinal-mode (SLM) laser emission based on enhanced pump light field induced by scattering effect of the two fiber cores. The directional dependences of the scattered pump field distribution on incident angle as well as overlap integrals between scattered pump light fields and WGMs have been theoretical investigated, and the calculation results show that when the incident angle of the pump light is close to 180°, significant discrepancies would occur in the overlap integrals between WGMs and the scattered field. And consequently, specific mode having the largest overlap integral would outperform through the mode competition process to excite SLM lasing. We have experimentally obtained SLM lasing emission when the DCEHF-based microresonator is rotated by 206°, which is in good accordance with our calculation results. Additionally, experimental observation of the output laser spectrum shows that the proposed fiber microcavity supports highly stable SLM laser emission. The proposed microresonator based on DCEHFs possesses several desirable merits such as compact size, good laser stability, single-mode operation, and good compatibility with existent fiber-optic systems, which make it a good candidate for applications as functional photonic device in future micro-optics systems.

Tuning strong coupling towards the deep ultraviolet region realized through Tamm-plasmon exciton-polaritons

Light-matter interactions at the nanoscale have attracted considerable attention due to its features of high optical-field confinement and large electromagnetic-field enhancement. Herein, we theoretically demonstrate strong coupling between Tamm plasmon (TP) and exciton polaritons towards the deep ultraviolet (DUV) region in metal Al/distributed Bragg reflector (DBR)-molecular structures. By adjusting the thickness of the spacer layer and the angle of incident light, the obvious anti-crossing phenomena can be observed with a Rabi splitting of 38.4 meV. Moreover, through varying the period number of the DBR structure, the coupling strength can be effectively manipulated from weak to strong. These findings may extend the operating wavelength of strong coupling to the DUV region, and benefit the development of new-style optical filters.

Ellipsometry of ultrathin transparent films. Some aspects of optimum experimental conditions choice

Reflection ellipsometry in visible and infrared range, which enables the analysis of isotropic thin films, is one approach that is extremely sensitive and accurate. There are a few restrictions with this technique when analyzing ultra-thin transparent film (UTTF) structures. In our study, the issue of the independent determination of two parameters of a transparent film that is extremely thin (d < 10 nm) is examined from the standpoint of the optimal conditions choosing for an ellipsometric experiment. An original method to calculation the errors in the main parameters of UTTF depending on the experimental conditions is proposed. One analyzed the influence of the substrate optical parameters and the incidence angle of light on the sensitivity of ellipsometric data. The analysis shows that under certain experimental conditions, the sensitivity of ellipsometric measurements allows to independently determine both the refractive index and the thickness of a transparent film down to 3 nm thick.

Numerical investigation of sequential phase-locked optical gating of free electrons

Recent progress in coherent quantum interactions between free-electron pulses and laser-induced near-field light have revolutionized electron wavepacket shaping. Building on these advancements, we numerically explore the potential of sequential interactions between slow electrons and localized dipolar plasmons in a sequential phase-locked interaction scheme. Taking advantage of the prolonged interaction time between slow electrons and optical near-fields, we aim to explore the effect of plasmon dynamics on the free-electron wavepacket modulation. Our results demonstrate that the initial optical phase of the localized dipolar plasmon at the starting point of the interaction, along with the phase offset between the interaction zones, can serve as control parameters in manipulating the transverse and longitudinal recoil of the electron wavefunction. Moreover, it is shown that the incident angle of the laser light is an additional control knop for tailoring the longitudinal and transverse recoils. We show that a sequential phase-locking method can be employed to precisely manipulate the longitudinal and transverse recoil of the electron wavepacket, leading to selective acceleration or deceleration of the electron energy along specific diffraction angles. These findings have important implications for developing novel techniques for ultrafast electron-light interferometry, shaping the electron wavepacket, and quantum information processing.