Development Of Optical Devices Research Articles

Constant Photocurrent Method to Probe the Sub‐Bandgap Absorption in Wide Bandgap Semiconductor Films: The Case of α‐Ga2O3

The optical absorption coefficient is one of the fundamental properties of semiconductors and is critical to the development of optical devices. Herein, a revival of the constant photocurrent method is presented to measure sub‐bandgap absorption in wide bandgap semiconductor films. The method involves maintaining a constant photocurrent by continually adjusting the impinging photon flux across the energy spectrum. Under such conditions, the reciprocal of the photon flux for uniformly absorbed light is proportional to the absorption coefficient. This method is applied to α‐Ga2O3 and reveals that it can access the absorption coefficient from 1 × 105 cm−1 at the band edge (5.3 eV) to 0.8 cm−1 close to mid‐bandgap (2.7 eV). Changes in the steepness of the absorption curve in the sub‐bandgap region are in excellent agreement with defect states of α‐Ga2O3 reported by deep level transient spectroscopy, indicating that the technique shows promise as a probe of energetically distributed defect states in thin film wide bandgap semiconductors.

Green Synthesis of Magnetite Nanoparticles Using <i>Moringa oleifera</i> and their Electro-Optic Surface Plasmon Resonance Properties

The application of an external electric field to the surface plasmon resonance (SPR) system of green-synthesized magnetite (Fe3O4) nanoparticles (MNPs) is very promising for increasing the SPR detection signal. Electro-optic surface plasmon resonance (EOSPR) behavior of MNPs has been successfully carried out. The EOSPR system was investigated using the Kretschmann configuration with the prism/Au thin film/MNPs/air layer arrangement and applying an electric voltage of 0 V, 2 V, 4 V, and 6 V. In this study, we synthesized MNPs using the green synthesis approach from moringa oleifera extract. The benefits of green synthesis include being safe, affordable, clean, and ecologically friendly processes. X-ray diffraction results obtained crystal size of the MNPs is about 9.2 nm with inverse spinel face-centered cubic crystal structure. Fourier transforms infrared characterization showed the presence of Fe-O bonds at wave numbers 569 cm-1 and 629 cm-1, indicating that MNPs were successfully formed. The saturation magnetization of the samples is 55.3 emu/g. The SPR angle of the SPR system Prism/Au thin film/air without the addition of MNPs is 44.66°. After being deposited by MNPs and induced by a voltage of 0 V, 2 V, 4 V, and 6 V, the SPR angles changed to 44.87°, 44.90°, 44.95° and 45.12°. The addition of MNPs and an external electric field causes the SPR angle to increase. The results of this study can provide new insights into the development of optical devices that can be manipulated electrically and have the potential for future biosensor applications.

Effect of Creating Oxygen Deficiency on the Optical Characteristics of CdO: A DFT based theoretical study

This study presents detailed computational research using density functional theory (DFT) with the PBE-GGA functional and Material Studio software to investigate the optical characteristics of pure CdO and oxygen-deficient CdO at the supercellular level. The study optimizes the structures of both CdO configurations with convergence tests which are confirmed result with structural deviations of 4.1% for simple CdO and 4.2% for oxygen-deficient CdO, respectively. The optical characteristics are afterwards examined, including the conductivity, loss function, dielectric function, and refractive index. The dielectric function for both structures exhibits distinct features, with significant absorption peaks in the region of 2.9-10 eV for oxygen-deficient CdO and a band gap at 2.58 eV for simple CdO, according to the research. The refractive index remains constant at lower energies while the conductivity curves show excitonic behavior on inducing oxygen deficiency at the supercellular level. In addition to this, the loss function exhibits peaks indicating various excitations and absorption activities. It is worth mentioning here that understanding these properties contributes to the development of optical devices, and the computational approach offers a powerful tool for atomic-level investigations.

Calamitic Liquid Crystals for Reversible Light-Modulated Phase Regulation Based on Arylazopyrazole Photoswitches.

The design of responsive liquid crystals enables a diversity of technological applications. Especially photochromic liquid crystals gained a lot of interest in recent years due to the excellent spatiotemporal control of their phase transitions. In this work we present calamitic light responsive mesogens based on a library of arylazopyrazole photoswitches. These compounds show liquid-crystalline behavior as shown by differential scanning calorimetry, grazing incidence X-ray diffraction and polarized optical microscopy. UV-vis spectroscopy and NMR analysis confirmed the excellent photophysical properties in solution and thin film. Additionally, polarized optical microscopy studies of the pristine compounds show reversible phase transition upon irradiation with light. Moreover, as a dopant in the commercially available liquid crystal 4-cyano-4'-pentylbiphenyl (5CB), the temperature range was reduced to ambient temperatures while preserving the photophysical properties. Remarkably, this co-assembled system shows reversible liquid-crystalline to isotropic phase transition upon irradiation with light of different wavelengths. The spatiotemporal control of the phase transition of the liquid crystals offers opportunities in the development of optical devices.

Optical Enhancement of Indirect Bandgap 2D Transition Metal Dichalcogenides for Multi-Functional Optoelectronic Sensors.

The unique electrical and optical properties of transition metal dichalcogenides (TMDs) make them attractive nanomaterials for optoelectronic applications, especially optical sensors. However, the optical characteristics of these materials are dependent on the number of layers. Monolayer TMDs have a direct bandgap that provides higher photoresponsivity compared to multilayer TMDs with an indirect bandgap. Nevertheless, multilayer TMDs are more appropriate for various photodetection applications due to their high carrier density, broad spectral response from UV to near-infrared, and ease of large-scale synthesis. Therefore, this review focuses on the modification of the optical properties of devices based on indirect bandgap TMDs and their emerging applications. Several successful developments in optical devices are examined, including band structure engineering, device structure optimization, and heterostructures. Furthermore, it introduces cutting-edge techniques and future directions for optoelectronic devices based on multilayer TMDs.

Temperature-dependent optical properties of monocrystalline CaF2, BaF2, and MgF2

CaF2, BaF2, and MgF2 are low-index, infrared-transparent materials that are extensively used in optical systems. Despite their technological importance, a systematic investigation into the temperature dependence of their optical properties is lacking. In this study, spectroscopic ellipsometry was used to obtain the refractive index of monocrystalline CaF2, BaF2, and MgF2 for wavelengths between 220 nm and 1700 nm, and for temperatures between 21 °C and 368 °C. The raw ellipsometric data was fit to a Sellmeier model with temperature-dependent oscillator terms to extract the real part of the refractive index of each material. The refractive index of CaF2 and BaF2 was observed to decrease linearly with increasing temperature, which can be largely attributed to a reduction in the mass density due to thermal expansion. In contrast, the refractive index of MgF2 was found to vary nonlinearly with temperature, which suggests competing effects from the material’s electronic polarizability. The temperature-dependent refractive index data reported here provide a finely-resolved mapping of the thermo-optic coefficient for these three materials, which could inform the development of optical devices operating at elevated or unsteady temperatures.

Probing Families of Optical Soliton Solutions in Fractional Perturbed Radhakrishnan–Kundu–Lakshmanan Model with Improved Versions of Extended Direct Algebraic Method

In this investigation, we utilize advanced versions of the Extended Direct Algebraic Method (EDAM), namely the modified EDAM (mEDAM) and r+ mEDAM, to explore families of optical soliton solutions in the Fractional Perturbed Radhakrishnan–Kundu–Lakshmanan Model (FPRKLM). Our study stands out due to its in-depth investigation and the identification of multiple localized and stable soliton families, illuminating their complex behavior. We offer visual validation via carefully designed 3D graphics that capture the complex behaviors of these solitons. The implications of our research extend to fiber optics, communication systems, and nonlinear optics, with the potential for driving developments in optical devices and information processing technologies. This study conveys an important contribution to the field of nonlinear optics, paving the way for future advancements and a greater comprehension of optical solitons and their applications.

Utilization of Bioactive Silk Protein in the Development of Optical Devices: Recent Advancements and Applications.

Typically, materials used to create optical devices have chemical and physical properties that have been precisely designed for a narrowly defined purpose, allowing for changes in design to account for device variability. There is a growing need for devices built of materials with changeable optical responses, as optical systems are incorporated into platforms with much functionality. Regenerated silk fibroin is described in this article as an enabling gadget with an active optical response as a result of the inherent characteristics of proteins. Silk's capacity for controlled movement, to swell and shrink reversibly, alter conformation and degradation that is customizable, impacts both the shape and the response of the optical structure-representative silk-based gadgets. The diversity of silk material is shown and discussed in this paper, concentrating on architectures that show reconfigurable behavior, an optical waveguide that is physically temporary and provides reversible responses. Finally, innovative research directions for silk-based materials and optical devices are presented in this paper. Since ancient times, silk, a natural biopolymer, has been used as a repair material in medicine. In the past 20 years, it has attracted a lot of interest to be used in several biomedical applications. Various healthcare items with silk as their substrate have been developed thanks to significant advancements in silk biomaterial research. Silk is a fabric created from spider and silkworm cocoons. Hierarchical structures and conventional structural elements are present in them. Different silk types can be produced using certain methods, such as films, fibers, microspheres, sponges, and hydrogels. The structural characteristics of secondary proteins present in silk can also be modified. This paper investigates the use of silk in biomedical and optical applications, and examines the technical trend in electronic fields.

Development of optical devices learning media using webtoon for high school class XI students

Successful education will determine the development of a country towards independence in all fields. Learning media is an important part because learning media is a tool used to deliver learning materials. Physical learning cannot be separated from the media and teaching materials used. Media and teaching materials are often used in the form of books or modules that contain explanations with sentences and only a few pictures and make students bored and lacking in experience. The complexity of the material presented makes students less interested in reading textbooks including physics books. Students tend to be interested in reading picture story books (such as comics) rather than ordinary textbooks, or they can also use webtoons. The development of science. and technology, gave birth to online learning and using internet facilities as a learning method that solves problems to reduce difficulties in understanding learning. In this case, students will understand the material of optical instruments that are packaged more easily. The story presented is plotted so that students can imagine and easily recall the optical instrument material. The problem in this research is how to develop Webtoon-based learning media for the material of optical devices for class XI high school students. This research method uses research and development methods. Research and development (RD) in education is to develop and validate educational products. While the type of development is carried out using a 4D model (Define, Design, Develop, and Disseminate). The results of this study. Based on the results of the analysis and discussion, it can be concluded that the learning media using webtoons for optical instrument material in class XI high school students is very feasible with several improvements.

Near ultraviolet excitable cyan-green phosphors of Ba6La2Al3ScO15:Ce3+ and Ba6La2Al3ScO15:Ce3+,Tb3+: investigations on the crystal structure, site assignment of Ce3+ and Tb3+ ions, and an energy transfer process from Ce3+ to Tb3.

An energy transfer from Ce3+ to Tb3+ is feasible in energy transition processes for the development of optical devices, especially phosphor-converted white LEDs (pc-wLEDs). Most of the energy transfer phosphors co-doped with Ce3+ and Tb3+, unfortunately, have weak absorption under a near-ultraviolet light of around 405 nm and blue light excitation, making them incapable for use as near ultraviolet or blue LEDs. In this study, novel energy transfer luminescent materials, Ba6La2Al3ScO15:Ce3+,Tb3+, isostructural with existing Ba6La2(Al,Fe)4O15, were successfully synthesized through a conventional solid-state reaction as a single phase. The phosphors showed a broad cyan emission of Ce3+ and narrow green emissions of Tb3+ under a near-ultraviolet light of 405 nm, which was nearly located at an emission wavelength of near-ultraviolet LEDs. The occurrence of energy transfer from Ce3+ to Tb3+ was evidenced by emission lifetime measurements. The lifetime analysis based on formulated energy transfer models, such as Inokuti-Hirayama, Yokota-Tanimota and Martin models, revealed that an energy transfer process from Ce3+ to Tb3+ took place dominantly by a dipole-dipole interaction with low migration among the donors of Ce3+.

Spin‐Orbit Modal Optical Vortex Beam Shaping from Dielectric Metasurfaces

AbstractOptical information and communication technologies are essentially based on the ability to shape the light field, either at the transmission or at the reception of the optical signal. Nowadays, wavelength and polarization state are already implemented in current telecom architectures and adding the spatial structuring of the light field as a novel degree of freedom to enhance data rate is desirable. In this context, the development of optical devices to shape optical modes belonging to orthogonal basis remains challenging. Here, in the context of singular optics, this work reports on the design, fabrication, and characterization of modal optical vortex beam shaping of paraxial light in the visible domain, in the framework of the Laguerre–Gauss basis. Both the azimuthal and radial degrees of freedom are univocally shaped via optical spin‐orbit interaction mediated by dielectric metasurfaces by combining the spatial modulation of amplitude, geometric phase, and dynamic phase. These results not only demonstrate the realization of new optical components, but also highlight how metasurface‐based technologies can contribute to optical information processing in the classical or quantum regime.

Terahertz Biosensor Based on Mode Coupling between Defect Mode and Optical Tamm State with Dirac Semimetal.

Bulk Dirac semimetal (BDS) has emerged as a "3D graphene" material for the development of optical devices in the past few years. In this study, a BDS-based tunable highly sensitive terahertz (THz) biosensor is proposed by using a Dirac semimetal/Bragg reflector multilayer structure. The high sensitivity of the biosensor originates from the sharp Fano resonance peak caused by coupling the Optical Tamm State (OTS) mode and defect mode. Besides, the sensitivity of the proposed structure is sensitive to the Fermi energy of Dirac semimetal and the refractive index of the sensing medium. The maximum sensitivity of 1022°/RIU is obtained by selecting structural and material parameter appropriately, which has certain competitiveness compared to conventional surface plasmon resonance (SPR) sensors. From the standpoint of the fabrication facility and integration, we judged that the BDS-based layered structure has the potential application in biosensor field.

Sensitivity and spectral control of network lasers

Recently, random lasing in complex networks has shown efficient lasing over more than 50 localised modes, promoted by multiple scattering over the underlying graph. If controlled, these network lasers can lead to fast-switching multifunctional light sources with synthesised spectrum. Here, we observe both in experiment and theory high sensitivity of the network laser spectrum to the spatial shape of the pump profile, with some modes for example increasing in intensity by 280% when switching off 7% of the pump beam. We solve the nonlinear equations within the steady state ab-initio laser theory (SALT) approximation over a graph and we show selective lasing of around 90% of the strongest intensity modes, effectively programming the spectrum of the lasing networks. In our experiments with polymer networks, this high sensitivity enables control of the lasing spectrum through non-uniform pump patterns. We propose the underlying complexity of the network modes as the key element behind efficient spectral control opening the way for the development of optical devices with wide impact for on-chip photonics for communication, sensing, and computation.

Enhanced optical emission at MoS2-WS2 heterostructure interface with n-N junction

Atomically thin transition metal dichalcogenide based heterostructures are of significant interest for the electronic and optoelectronic device applications. Growth of atomically thin heterostructures have gained remarkable importance due to the unusual electrical response and optical emission at the interface. Here, facile chemical vapour deposition growth of n-N type MoS2-WS2 heterostructure is demonstrated. Multifold enhancement in photoluminescence emission at the interface of MoS2-WS2 heterostructure with local excitonic amplifications arising at the interface is observed. The atomic level structure of interface has been investigated with the aid of aberration corrected scanning transmission electron microscopy. Electrical properties of MoS2-WS2 heterostructure with n-N semiconductor junction are systematically probed using micromanipulators interfaced with scanning electron microscope. Our microscopic and spectroscopic investigations along with electrical and optical responses at the interface contribute to the fundamental knowledge to empower the development of optical devices based on two dimensional heterostructures with enhanced emissions.

Transcending the Trade-off in Refractive Index and Abbe Number for Highly Refractive Polymers: Synergistic Effect of Polarizable Skeletons and Robust Hydrogen Bonds.

High-refractive-index polymers (HRIPs) are attractive materials for the development of optical devices with high performances. However, because practical components and structures for HRIPs are limited from the viewpoint of synthetic techniques, it has proved difficult using traditional strategies to enhance the refractive index (RI) of HRIPs to more than a certain degree (over 1.8) while maintaining their visible transparency. Here, we found that poly(phenylene sulfide) (PPS) derivatives featuring both methylthio and hydroxy groups can simultaneously exhibit balanced properties of an ultrahigh RI of n D = 1.85 and Abbe number of νD = 20 owing to the synergistic effect of high molar refraction and dense intermolecular hydrogen bonds (H-bonds). This brand new strategy is anticipated to contribute to the development of HRIPs displaying ultrahigh RI with adequate Abbe numbers beyond the empirical n D-νD threshold, which has not been achieved to date.

A critical review and future prospects of Dy3+-doped glasses for white light emission applications

Rare-earth (RE)-doped glassy systems gained much interest because of its wide variety of applications in numerous potential fields that include optical fibers, solid state lasers, optical amplifiers, optical thermometry sensors, waveguides, infrared detectors, spectral converters, display devices, and so on. Within RE ions, the trivalent dysprosium (Dy3+) ion is the most unique and characteristic ion to examine emission properties for white light and visible display emitting devices. Because, Dy3+ ion emits two intense emissions in the blue (~480 nm) and yellow (~575 nm) regions that are assigned to the 4F9/2→6H15/2 and 4F9/2→6H13/2 transition energies, respectively. Under the excitation of blue laser, Dy3+ ions exhibit attractive yellowish white fluorescence emission with higher quantum efficiency. In view of the importance of identifying efficient luminescent emitting materials for the development of optical devices, the present work is to investigate white light emission in new glass composition of B2O3 +TeO2 +SrCO3 +ZnO+ZnF2 +Dy2O3 glass and in turn to compare and discuss these results with reported Dy3+:glasses. The tabulated reported data bank for 68 Dy3+:glasses at one place should prove valuable information for future work on rationalization of theoretical and practical point of view to enrich white light emission quantification, simulation and systemization.

On-chip multiple beam splitting assisted by bound states in the continuum.

Usually, on-chip beam splitting can be achieved by manipulating the in-plane iso-frequency curves (IFCs) of the structure, where the confinement of light along the out-of-plane direction is governed by total internal reflection. In this Letter, without needing a high-index dielectric background material for total internal reflection, we achieve on-chip beam splitting in a linear-crossing metamaterial (LCMM) mimicked by a two-dimensional photonic crystal (PhC) slab where the vertical confinement is enabled by a bound state in the continuum (BIC) and totally beyond the light cone. Particularly, the light propagating inside the LCMM can be flexibly controlled by the rotation angle of the rectangular silicon pillars in the PhC slab. On-chip triple beam splitting can further be designed by combining two kinds of LCMM with opposite rotation angles. Such light beam splitting beyond the light cone originates from the combined manipulation of the BIC and the spatial dispersion of LCMMs. Our work promotes the development of optical devices in integrated optics, such as on-chip focusing, switching, and (de)multiplexing.

Electric field analysis in chiral liquid crystals by Berreman’s 4 × 4 matrix method

Berreman’s 4 × 4 matrix method is a standard method for the analysis of the optical properties of chiral liquid crystals such as cholesteric and ferroelectric liquid crystals. This method has been widely used to calculate transmission and reflection spectra and the density of states of chiral liquid crystals. A spatial profile of the electric field in a propagation medium is also important for fundamental research and development of optical devices, but electric field analysis by the 4 × 4 matrix method has not yet been established. We describe the calculation method of internal electric fields in liquid crystals by the 4 × 4 matrix method.

Cucurbit[n]uril Supramolecular Assemblies-Regulated Charge Transfer for Luminescence Switching of Gold Nanoclusters.

Host-guest molecular assemblies are highly desirable for precisely controlling the luminescence properties of nanomaterials. Unfortunately, the design of high-quality luminescent nanoswitches is still very challenging due to the low affinity of traditional macrocyclic molecules (e.g., cyclodextrin) and inherently sophisticated electronic structures of nanoemitters. The current work represents the first to fabricate a luminescent nanoswitch using cucurbit[n]uril supramolecular assemblies-regulated luminescence of gold nanoclusters (AuNCs). It is found that, similar to a small-molecule fluorophore-based system, the luminescence of fabricated AuNC-cationic quencher nanohybrids can be reversibly manipulated by cucurbit[7]uril through altering the key parameters of the charge transfer process including the reorganization energy and electronic coupling between charge-transfer reactants. This study demonstrates the crucial role of cucurbit[n]uril host-guest assemblies in modulating the luminescence of AuNCs and their application in luminescence switching, thus offering new avenues for the fabrication and development of optical devices and smart materials.

Fabrication of nanoporous alumina in 0.3 M oxalic acid and study on mechanical properties using micro indentation test

Anodic nanoporous alumina is becoming increasingly used as a material for the fabrication of nano and micro devices in a biomedical equipment, drug delivery system, corrosion resistive coatings, and range of industries. Because of its ease of production and low manufacturing cost, nanoporous alumina is becoming a more essential nanomaterial templet for a variety of applications such as micro filtration, sensors, optical device development, and tissue engineering. In this research, the fabrication of nanoporous alumina was fabricated using 0.3 M oxalic acid (C2H2O4) at constant voltage DC 60 V using a two-step electro chemical anodization process. Scanning electron microscopic (SEM) images revealed the regular honeycomb structure was formed, having an average pore diameter (Dp) of 48 nm, an interpore distance (Dc) of 125 nm, and a thickness of 98.5 µm with 26.7%. Energy dispersive x-ray spectroscopy (EDS) analysis was performed right after fabrication for chemical component analysis, and it confirms that the fabricated nanoporous membrane has a dominance of aluminum oxide (Al2O3). Finally, the mechanical properties (hardness and elastic modulus) of alumina were analyzed using micro indentation using the Micro Combi Tester (CMS 300) using the Oliver and Pharr method for two loading conditions: 0.05 N and 0.5 N.