Properties Of Incident Light Research Articles

Polarization remote sensing of ships in sea haze

ABSTRACT Sea haze reduces the visibility of ships and makes the optical imaging system blind, which increases the difficulty of ship remote sensing. In this paper, we propose a new method for polarization remote sensing of ships in sea haze. The method takes advantage of image haze removal and exposure correction to improve the visibility of ships in sea haze. Different from the existing polarization-based image haze removal methods, the proposed method does not depend on any assumptions about the polarization properties of incident light. The exposure correction method is proposed based on the Retinex model and Bayes theorem, which can improve the visibility of ships in haze removal images. To evaluate the effectiveness of the proposed method, we implemented an outdoor experiment on polarization remote sensing of ships in sea haze weather. The experimental results indicate that the method can improve the visibility of ships significantly. In addition, the method outperforms the Stokes parameter-based ship remote sensing method in terms of the image quality metric fog aware density evaluator and can be easily generalized to RGB image haze removal.

Optically induced antiferromagnetic order in dielectric metasurfaces with complex supercells

Metasurfaces are 2D planar lattices of nanoparticles that allow the manipulation of incident light properties. Because of that attribute, metasurfaces are promising candidates to replace bulky optical components. Traditionally, metasurfaces are made from a periodic arrangement of identical unit cells. However, more degrees of freedom are accessible if an increasing number of structured unit cells are combined. The present study explores a type of dielectric metasurface with complex supercells composed of Mie-resonant dielectric nanocylinders and nanoscale rings. We numerically and experimentally demonstrate the signature of an optical response that relies on the structures sustaining staggered optically induced magnetic dipole moments. The optical response is associated with an optical antiferromagnetism. The optical antiferromagnetism exploits the presence of pronounced coupling between dissimilar Mie-resonant dielectric nanoparticles. The coupling is manipulated by engineering the geometry and distance between the nanoparticles, which ultimately enhances their effective magnetic response. Our results suggest possible applications in resonant nanophotonics by broadening the modulation capabilities of metasurfaces.

Multicolor sensing of organic-inorganic hybrid heterostructure: From visible to invisible colors

Photodetection of organic-inorganic hybrid heterostructures from visible to invisible ultraviolet and infrared rays is revisited with respect to their material properties aspect, device structure, and emerging applications. The approach of organic-inorganic hybrid heterostructures using two or more varied materials has been extensively attempted as the emergence of broadband photodetection covering multi-colors as well as ultraviolet to infrared rays has ignited considerable interest in new applications. This review provides a timely overview of the scientific relationship between materials engineering and incident light properties, a systematic classification of representative material combinations, and a particular focus on each principle's insights. We also summarize recently-presented applications in organic-inorganic hybrid heterostructure-based photodetectors according to the target light wavelength.

Two-dimensional beam steering with tunable metasurface in infrared regime

Abstract Tunable metasurfaces can change the optical properties of incident light at will such as amplitude, phase, and polarization in a time-dependent fashion. Ultrafast switching speed and the ability for the pixel size reduction of the tunable metasurface can allow various applications such as light detection and ranging, interferometric sensors, and free space optical communications, to name a few. Although there have been successful demonstrations of the wavefront shaping using the tunable metasurface, the implementation of the two-dimensional metasurface pixel array that can be individually addressed in the optical frequency regime still remains challenging. Here, we present the experimental demonstration of the two-dimensional beam steering with the metasurface array by the binary phase grating in the infrared regime. The metasurface unit cell is composed of metal–dielectric–oxide structure with the indium tin oxide as an active layer, which is modulated by using the top fan-out electrodes. The metasurface array is two-dimensionally pixelated and has the phase change above 137° in the infrared regime.

A Metasurface Beam Combiner Based on the Control of Angular Response

Beam combiners are widely used in various optical applications including optical communication and smart detection, which spatially overlap multiple input beams and integrate a output beam with higher intensity, multiple wavelengths, coherent phase, etc. Since conventional beam combiners consist of various optical components with different working principles depending on the properties of incident light, they are usually bulky and have certain restrictions on the incident light. In recent years, metasurfaces have received much attention and become a rapidly developing research field. Their novel mechanisms and flexible structural design provide a promising way to realize miniaturized and integrated components in optical systems. In this paper, we start from studying the ability of metasurfaces to manipulate the incident wavefront, and then propose a metasurface beam combiner in theory that generates an extraordinary refracted beam based on the principle of phase gradient metasurface. This metasurface combines two monochromatic light incidents at different angles with identical polarization but arbitrary amplitudes and initial phases. The combining efficiency, which is defined as the ratio of the power in the combining direction to the total incident power, is 42.4% at the working wavelength of 980 nm. The simulated results indicate that this proposed method is able to simplify the design of optical combiners, making them miniaturized and integrated for smart optical systems.

Light intensity and spectral composition drive reproductive success in the marine benthic diatom Seminavis robusta

The properties of incident light play a crucial role in the mating process of diatoms, a group of ecologically important microalgae. While species-specific requirements for light intensity and photoperiod have been observed in several diatom species, little is known about the light spectrum that allows sexual reproduction. Here, we study the effects of spectral properties and light intensity on the initiation and progression of sexual reproduction in the model benthic diatom Seminavis robusta. We found that distinct stages of the mating process have different requirements for light. Vigorous mating pair formation occurred under a broad range of light intensities, ranging from 10 to 81 µE m−2 s−1, while gametogenesis and subsequent stages were strongly affected by moderate light intensities of 27 µE m−2 s−1 and up. In addition, light of blue or blue–green wavelengths was required for the formation of mating pairs. Combining flow cytometric analysis with expression profiling of the diatom-specific cyclin dsCyc2 suggests that progression through a blue light-dependent checkpoint in the G1 cell cycle phase is essential for induction of sexual reproduction. Taken together, we expand the current model of mating in benthic pennate diatoms, which relies on the interplay between light, cell cycle and sex pheromone signaling.

Multiplexing meta-hologram with separate control of amplitude and phase.

Metasurfaces have shown their unique capabilities to manipulate the phase and/or amplitude properties of incident light at the subwavelength scale, which provides an effective approach for constructing amplitude-only, phase-only or even complexed amplitude meta-devices with high resolution. Most of meta-devices control the amplitude and/or phase of the incident light with the same polarization state; however, separately controlling of amplitude and phase of the incident light with different polarization states can provide a new degree of freedom for improving the information capacity of metasurfaces and designing multifunctional meta-devices. Herein, we combine the amplitude manipulation and geometric phase manipulation by only reconfiguring the orientation angle of the nanostructure and present a single-sized design strategy for a multiplexing meta-hologram which plays the dual roles: a continuous amplitude-only meta-device and a two-step phase-only meta-device. Two different modulation types can be readily switched merely by polarization controls. Our approach opens up the possibilities for separately and independently controlling of amplitude and phase of light to construct a multiplexing meta-hologram with a single-sized metasurface, which can contribute to the advanced research and applications in multi-folded optical anti-counterfeiting, optical information hiding and optical information encoding.

Highly sensitive refractive index sensing by epsilon near zero metamaterials

We designed a highly sensitive refractive index sensor (RIS) with a simple and compact structure. In this regard, a metal-dielectric-metal (MDM) nanostructured thin film was considered to achieve a highly sensitive and tunable refractive index sensor in the near-infrared region. The MDM nanostructured thin film was used to determine the optical properties of incident light with transverse electric (TE) polarization at different angles. The effective relative permittivity obtained via numerical simulation confirms that the MDM thin film can be considered as an ENZ metamaterial. This is also verified by the results of group delay and group velocity in the structure. According to the results, the proposed RIS has a sensitivity of 1462 nm per refractive index unit, which is high enough compared to the state of the art. The significant advantage of our RIS is its small footprint, which is extensively used in electronic and photonic integrated devices. We think the proposed sensor can be used for future nanosensing applications, such as plasmonic metamaterial sensors.

Wavelength-Selective Transmittance in Nano Structure

Purpose : In order to investigate the cause of the change in light transmittance according to the diameter, the optical properties of incident light and transmitted light were analyzed. The change in transmittance of the central wavelength according to the collagen fiber diameter was analyzed. Methods : In order to analyze the characteristics of transmitted light, a 3D simulator of the FDTD method was used. The incident light was set to a Gaussian Modulated Continuous Wave with the center wavelength of 589 nm and the wavelength range of 300 to 900 nm.Results : Even when the radius of the collagen fiber was changed, there was no significant difference in the ratio of the area occupied by the collagen fiber to the simulation space. However, as the diameter of collagen fibers increased, the sum of the transmittance intensity decreased. It increased at 20 to 30 nm of the diameter and rapidly decreased at 30 nm again. Analyzing the optical characteristics according to the change of the central wavelength, it was found that the wavelength at which the transmittance became lowered was not constant depending on the collagen fiber diameter.Conclusion : In the simulation of a real collagen-like structure, selective transmission or absorption occurs at a specific wavelength regardless of the range of central wavelength. It is expected that there will be applied to the selective light beam that runs high-efficiency optical devices.

Spectral Modulation through the Hybridization of Mie-Scatterers and Quasi-Guided Mode Resonances: Realizing Full and Gradients of Structural Color.

Metasurfaces made up of subwavelength arrays of Mie scatterers can be engineered to control the optical properties of incident light. The hybridization of the fundamental Mie resonances with lattice resonances greatly enhances the scattering cross-section of individual Mie scatterers. Through careful design of the locations of these hybridized modes using two differently engineered hydrogenated amorphous silicon nanorods, we numerically calculate and experimentally fabricate two examples of full color printing; one with spectral colors comparable to the Adobe RGB gamut, and another with gradients of color. We identify and characterize the mechanisms behind each and provide a framework that can be used to design any all-dielectric metasurfaces of subwavelength Mie scatterers for spectral modulation.

Interpreting Intensity Speckle as the Coherency Matrix of Classical Light

We show that an intensity speckle can be directly interpreted as the properties of incident light - amplitude, phase, polarization, and coherency over spatial positions. Revisiting the speckle-correlation scattering matrix (SSM) method [Lee and Park, Nat. Comm. 7, 13359 (2016)], we successfully extract the intact information of incident light from an intensity speckle snapshot as the form of coherency matrix. The idea is verified experimentally by introducing the peculiar states of light that exhibit uneven amplitude, phase, polarization, and coherency features. We also find substantial practical advantage of the proposed method compared to the conventional coherency matrix measuring techniques such as Stokes polarimetry. We believe this physical interpretation of an intensity speckle could open a new avenue to study and to utilize the speckle phenomenon in vast subfields of wave physics.

Incoherent control of optical bistability and multistability in a hybrid system: Metallic nanoparticle-quantum dot nanostructure

We discuss the optical bistability and multistability properties of incident light on a unidirectional ring cavity consisting of a hybrid semiconductor quantum dot-metal nanoparticle system driven by coupling and incoherent pumping fields. We consider the quantum dot system as a three-level V-type configuration which is placed near the metallic nanoparticle. We realize that the threshold of optical bistability and optical multistability can be controlled by tuning the center-to-center distance between quantum dots and metallic nanoparticles. Moreover, the effect of incoherent pumping field on optical bistability and optical multistability has been discussed for different distances between quantum dots and metallic nanoparticles.

Color Perception: Objects, Constancy, and Categories.

Color has been scientifically investigated by linking color appearance to colorimetric measurements of the light that enters the eye. However, the main purpose of color perception is not to determine the properties of incident light, but to aid the visual perception of objects and materials in our environment. We review the state of the art on object colors, color constancy, and color categories to gain insight into the functional aspects of color perception. The common ground between these areas of research is that color appearance is tightly linked to the identification of objects and materials and the communication across observers. In conclusion, we argue that research should focus on how color processing is adapted to the surface properties of objects in the natural environment in order to bridge the gap between the known early stages of color perception and the subjective appearance of color.

Two-dimensional materials in functional three-dimensional architectures with applications in photodetection and imaging

Efficient and highly functional three-dimensional systems that are ubiquitous in biology suggest that similar design architectures could be useful in electronic and optoelectronic technologies, extending their levels of functionality beyond those achievable with traditional, planar two-dimensional platforms. Complex three-dimensional structures inspired by origami, kirigami have promise as routes for two-dimensional to three-dimensional transformation, but current examples lack the necessary combination of functional materials, mechanics designs, system-level architectures, and integration capabilities for practical devices with unique operational features. Here, we show that two-dimensional semiconductor/semi-metal materials can play critical roles in this context, through demonstrations of complex, mechanically assembled three-dimensional systems for light-imaging capabilities that can encompass measurements of the direction, intensity and angular divergence properties of incident light. Specifically, the mechanics of graphene and MoS2, together with strategically configured supporting polymer films, can yield arrays of photodetectors in distinct, engineered three-dimensional geometries, including octagonal prisms, octagonal prismoids, and hemispherical domes.

Photocatalytic conversion of CO2 into methanol using graphitic carbon nitride under solar, UV laser and broadband radiations

Summary Photocatalytic conversion of carbon dioxide into methanol using highly efficient g-C3N4, in conjunction with three different radiations (solar radiation, broad-band ultraviolet (UV)–visible lamp, and laser beam) is presented. The optical, structural, and morphological properties of the synthesized g-C3N4 were studied using advanced analytical techniques like Fourier transform infrared spectroscopy, UV–visible spectrometer, X-ray diffraction, high-resolution transmission electron microscopy, high-angle annular dark field, and X-ray photoelectron spectroscopy. The relative merits of the three sources of radiation in the presence of g-C3N4 were studied in terms of key figures of merit of the photocatalytic process, namely, methanol production yield and quantum yield. As expected, after 40 min of irradiation, 355-nm laser (40 mJ/pulse, 10 Hz) with g-C3N4 rendered the best methanol production yield (510 μmol g−1 h−1), followed by solar radiation (130 μmol g−1 h−1), and UV broadband lamp. This indicates that the photon flux and the spectral properties of incident light are the key factors for the enhancement of methanol production yield. Although the methanol production yield with 355-nm laser radiation is quite impressive because of the inherent high photon flux and the monochromatic nature of laser, the methanol yield of 130 μmol g−1 h−1 with natural sunlight is quite an important result, as it can be used for the development of large-scale solar fuel generation facilities by harnessing the naturally abundant solar radiation. Copyright © 2017 John Wiley & Sons, Ltd.

Design of a multi-channel polarization-preserving optical system for the KSTAR motional Stark effect diagnostic

An optical system capable of preserving, or minimizing the change of, the polarization properties of incident light has been designed and fabricated for the motional Stark effect diagnostic system which measures internal magnetic field structures inside the tokamak for the Korea Superconducting Tokamak Advanced Research. A dual photoelastic modulator (PEM) with a linear polarizer is included in the optical train with four lenses, a mirror and a dichroic beam splitter. Particular cares have been taken for the polarization properties of the delivered light to be perturbed as little as possible under a strong magnetic field and high vacuum. The lenses are made of STIH-6, a material with low Verdet constant, which minimizes the Faraday rotation. The residual Faraday rotation that takes place in the non-STIH-6 optical elements such as the vacuum window and the optical apertures of the PEM is calibrated out from the in-situ measurements using an in-vessel reference polarizer while energizing the magnetic field coils. In the lens design, the object plane is rotated by 44.8° from the optical axis because of the tilted setup-port. The image surface has a finite curvature to reduce the aberration from the four lenses. The fiber dissector is designed based on the focal plane that aligns the focal points from 25 lines-of-sight, each of which constitutes a bundle of 19 fibers. The fibers run about 35m from the front optics in the tokamak vacuum vessel to the detector in the diagnostic area remote from the tokamak hall. The footprint images at the intersections of the lines-of-sight on the neutral beam trajectory confirms the imaging quality is sufficient to the diagnostic requirement with the designed magnifications.

Simulation-Based Study About the Lifetime and Incident Light Properties Dependence of the Optically Triggered 4H-SiC Thyristors Operation

We investigated a methodology to design light-triggered thyristors thanks to TCAD. The simulation model accuracy, especially the holding current and the minimum incident light intensity to turn-ON, were compared with experimental results. The influence of SiC epitaxial layer lifetime and the incident light properties (wavelength and intensity) on the optically triggered 4H-SiC thyristor characteristics have been studied by simulation. We considered the wavelength dependence of quantum efficiency, penetration depth, and photon energy. The holding current and turn-ON time depends on the lifetime. The minimum intensity to turn-ON the device significantly depends on the wavelength. This intensity becomes less than 0.003 times when the wavelength changed from 380 to 325 nm. In addition, the breakover voltage is affected by the constant incident light even if the intensity is tiny.

Manipulating transmission and reflection properties of a photonic crystal doped with quantum dot nanostructures

The transmission and reflection properties of incident light in a defect dielectric structure is studied theoretically. The defect structure consists of donor and acceptor quantum dot nanostructures embedded in a photonic crystal. It is shown that the transmission and reflection properties of incident light can be controlled by adjusting the corresponding parameters of the system. The role of dipole–dipole interaction is considered as a new parameter in our calculations. It is noted that the features of transmission and reflection curves can be adjusted in the presence of dipole–dipole interaction. It is found that the absorption of weak probe light can be converted to the probe amplification in the presence of dipole–dipole interaction. Moreover, the group velocity of transmitted and reflected probe light is discussed in detail in the absence and presence of dipole–dipole interaction. Our proposed model can be used as a new all-optical devices based on photonic materials doped with nanoparticles.

Controlling of optical bistability and multistability in a defect slab

Optical bistability (OB) and optical multistability (OM) due to wide applications in all-optical switching and transistors is studied in this paper. Here, we study the OB and OM properties of incident light in a defect slab doped by a GaAs quantum well (QW) nanostructure. It is shown that OB and OM features can be manipulated by spin coherence created by circular polarized laser fields in GaAs QWs. The impacts of laser field features, such as intensity, frequency detuning, and relative phase, on OB and OM are simulated. Moreover, the dependence of OB and OM features of a probe light on the thickness of the slab, then, are analyzed. It is found that the thickness of the slab can provide a new way to optimize the intensity threshold of OB and OM. We hope that our proposed model may be useful for developing all-optical devices on nanoscales.

Transmission and reflection properties of propagated pulse through defect slab based biexciton coherence

In this paper, we theoretically investigate transmission and reflection properties of incident light through dielectric medium doped by GaAs/AlGaAs multiple quantum wells with 15 periods of 17.5nm GaAs wells and 15-nm Al0.3 Ga0.7As barriers, grown by metal organic chemical vapor deposition. The destructive quantum interference is set up by a control pulse that couples to a resonance of biexcitons. We found that many-particle interactions such as biexciton binding energy and biexciton decoherence which are inherent in semiconductors can affect the transmission and reflection properties of incident light on the slab. We have also shown that simultaneous subluminal or superluminal transmission, reflection can be achievable at different frequencies of probe field.