Optical Field Research Articles

Mode-folded thin-film lithium niobate phase shifter for channel scalable optical interconnect with high switching efficiency

Paralleled optical interconnection has been widely used in optical transceivers. Reconfigurable photonic integration with scalable channel numbers is thus highly useful in timely adjusting the link capacity to the changing traffic patterns in data centers or high-performance computing (HPC) systems. In this paper, a 1×8 Mach–Zehnder switch (MZS) over thin-film lithium niobate is proposed and experimentally demonstrated for 1-to-8 channel scalable optical interconnects, with high switching efficiency through utilizing the mode-folded phase shifter. The three-mode phase shifter recirculates the light three times, undergoing phase changing with different waveguide modes. Simultaneously, the multimode waveguiding within the phase shifter results in a pronounced enhancement of the optical field confinement, further improving the Pockels effect for all modes. A 3.5-time improvement of the switching efficiency is experimentally demonstrated, exhibiting a low Vπ·L of 0.6 V⋅cm. The proposed MZS also features low channel crosstalk (below -20 dB over 1530-1565 nm) and nanosecond-order switching time, paving the way towards channel scalable and versatile MSA-compatible optical interconnect.

Thermal Vacuum State Corresponding to Displaced Thermal Optical Fields Density Operator and Its Applications

Thermal Vacuum State Corresponding to Displaced Thermal Optical Fields Density Operator and Its Applications

Pyro-Phototronic Effect Induced Circularly Polarized Light Detection with a Broadband Response.

Photopyroelectric-based circularly polarized light (CPL) detection, coupling the pyro-phototronic effect and chiroptical phenomena, has provided a promising platform for high-performance CPL detectors. However, as a novel detection strategy, photopyroelectric-based CPL detection is currently restricted by the short-wave optical response, underscoring the urgent need to extend its response range. Herein, visible-to-near-infrared CPL detection induced by the pyro-phototronic effect is first realized in chiral-polar perovskites. Specifically, chiral-polar multilayered perovskites (S-BPEA)2FAPb2I7 (1-S, S-BPEA = (S)-1-4-Bromophenylethylammonium, FA = formamidinium) with spontaneous polarization shows intrinsic pyroelectric and photopyroelectric performance. Strikingly, combining its merits of the pyro-phototronic effect and intrinsic wide-spectrum spin-selective effect, chiral multilayered 1-S presents efficient photopyroelectric-based broadband CPL detection performance spanning 405-785nm. This research first realizes photopyroelectric-based infrared CPL detection and also sheds light on developing high-performance broadband CPL detectors based on the pyro-phototronic effect in the fields of optics, optoelectronics, and spintronics.

Structural and optical characterizations of zircon and zirconia nanopowders derived from zircon sands

This study explores the structural and optical properties of zircon (ZrSiO4) and zirconia (ZrO2) nanopowders using two types of natural Indonesian zircon sands. The former powders were synthesized through dissolution and non-dissolution methods, while the latter powders were synthesized using alkali fusion and co-precipitation techniques. x-ray fluorescence (XRF) analysis revealed a reduction in impurities post-synthesis. X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM) analyses indicated that the dissolution process yielded pure zircon, whereas the non-dissolution method resulted in the presence of minor additional phases. For zirconia, all samples exhibited a tetragonal phase, albeit with varying structures. Optical properties were investigated using UV–vis spectroscopy, which showed that both materials exhibit high absorption in the ultraviolet region, with slight differences in wavelengths peak. Consequently, zircon and zirconia demonstrated similar band gap energies ranging from 3.76 to 3.95 eV and 3.99 to 4.06 eV, respectively. Photoluminescence testing further revealed identical emission peaks 350 nm for both materials, highlighting their comparable optical characteristics. This study provides valuable understandings into the synthesis and optical properties of zircon and zirconia nanopowders derived from Indonesian zircon sands, emphasizing their potential applications in various optical and electronic fields.

Effect of Ti3C2-MXene size on cell viability of human carcinoma cells

MXene nanoflakes, a new type of transition metal carbides, nitrides, and carbonitrides (named as MXene) have emerged as biocompatible transition metal structures, which illustrate desirable performance for various applications due to their unique physicochemical, and compositional virtues. MXenes are currently expanding their application from optical, chemical, electronic, and mechanical fields towards biomedical areas. In terms of biomedical applications, the biological toxicity of MXenes materials in different forms must be considered inevitably. In this paper, Ti3C2-MXene nanoflakes with different sizes have been prepared by means of wet etching method combined with powerful ultrasonication for exploring the effect in human breast carcinoma cells (MDA-MB-231 Cells) and human thyroid carcinoma cells (GLAG-66 Cells). Clinically representative MDA-MB-231 Cells and GLAG-66 Cells are selected as experimental subjects and their biotoxicities are characterized when exposed to Ti3C2-MXene nanoflakes with different sizes and concentrations. The results show that Ti3C2-MXene nanoflakes with sizes below 200 nm is almost non-toxic to MDA-MB-231 Cells and GLAG-66 Cells at low concentrations, and enhance their bioactivity and proliferation. When the nanoflake size is above 200 nm, Ti3C2-MXene has a significant inhibitory effect on the proliferation of the cells. This phenomenon may be due to the different roles of Ti3C2-MXene materials at different scales in cell proliferation as well as in complex physiological processes. This result is of great significance for material screening and design before biological experiments using Ti3C2-MXene.

Optical switching with high-Q Fano resonance of all-dielectric metasurface governed by bound states in the continuum

The discovery of bound states in the continuum (BIC) of optical nanostructures has garnered significant research interest and found widespread application in the field of optics, leading to an attractive approach to achieve high-Q (Quality factor) Fano resonance. Herein, an all-dielectric metasurface consisting of four gallium phosphide (Gap) cylinders on the MgF2 substrate is designed and analyzed by the finite element method (FEM). By breaking the symmetry of the plane, specifically by moving the two cylinders to one side, it is possible to achieve a transition from the symmetry-protected BIC to quasi-BIC. This transition enables the excitation of sharp dual-band Fano resonance at wavelengths of 1,045.4 nm and 1,139.6 nm, with the maximum Q factors reaching 1.47 × 104 and 1.28 × 104, respectively. The multipole decomposition and near-field distributions show that these two QBICs are dominated by the electric quadrupole (EQ) and magnetic quadrupole (MQ). Furthermore, bidirectional optical switching can be accomplished by changing the polarization direction of the incident light. As a result, the maximum sensitivity and figure of merit (FOM) are 488.9 nm/RIU and 2.51 × 105 RIU-1, respectively. The results enrich our knowledge about BIC and reveal a platform for the development of high-performance photonics devices such as optical switches and sensors.

Optical axis-driven field enhancement in a hyperbolic medium.

Field enhancement of applied electric field is the foundation for the variety of applied domains at a nanoscale level. Traditionally, efforts to achieve field enhancement have required the use of complicated metamaterial-based structures with a transition behavior. Here, the electromagnetic field solution of the TM-polarized wave that interacts with an optical-axis-driven hyperbolic medium with a transition behavior is established. Detailed calculations reveal that such field enhancement can be achieved over a broad range of incident angles (i.e., near critical angle). Definitely, such flexibility of the incident angle for achieving the field enhancement enriches the understanding and provides novel prospective toward its practical realization.

Efficient spatial separation for chiral molecules via optically induced forces.

We investigate an efficient spatial enantioseparation method of chiral molecules in cyclic three-level systems coupled with three optical fields using optically induced forces. When the overall phase differs by π between two enantiomers, significant variations in the magnitude and direction of the optically induced forces are observed. The manipulation of the center of mass of chiral molecules in optical fields can be achieved through the induced gauge force, primarily generated from the variations in the chirality-dependent scalar potentials created by the three inhomogeneous laser fields. By appropriately configuring the system, we can completely separate the slow spatial and fast inner dynamics, making instantaneous eigenstates of the inner Hamiltonian independent of the transverse profiles of the laser beams. Compared to previous methods, which required adiabatic conditions to be satisfied, the proposed method overcomes the limitations of the adiabatic approximation by utilizing a specific system configuration. This allows for increased flexibility in the transverse profiles of the laser beams and relaxes the constraints on the velocity of chiral molecules, leading to significantly greater spatial separations achievable across a broader range of parameters.

Advances in Plasmonic Photonic Crystal Fiber Biosensors: Exploring Innovative Materials for Bioimaging and Environmental Monitoring

AbstractThis review paper comprehensively analyzes recent advancements in optical fiber‐based biosensors, focusing on conventional fiber and photonic crystal structures. This paper overviews the significant applications of optical fiber biosensors, including bioimaging, quality analysis, food safety, and field environment monitoring, setting the stage for subsequent discussions. The primary objective of the review is to systematically evaluate recent literature concerning optical fiber‐based biosensors, emphasizing their sensitivities and resolutions. The second section explores integrating plasmonic materials such as graphene, TDMC, germanium, black phosphorus, and silicon within optical fiber biosensors, elucidating their roles in enhancing sensitivity and resolution in biosensing applications. A detailed examination of photonic crystal fibers (PCF) follows, categorizing them into internally and externally metal film‐coated biosensors, highlighting their distinct advantages and limitations. Comparative analyses in two tables delineate the performance and sensitivity of optical fiber‐based biosensors, mainly focusing on different coating strategies. The final section of the review discusses emerging trends and applications in optical fiber biosensing technologies, underscoring their potential to transform biomedical and environmental monitoring fields. By synthesizing recent developments and challenges, this review aims to offer researchers and practitioners a comprehensive understanding of optical fiber‐based biosensors, facilitating informed decision‐making and driving further advancements in the field.

TensorFlow Hydrodynamics Analysis for Ly-[formula omitted] Simulations

We introduce the Python program THALAS (TensorFlow Hydrodynamics Analysis for Lyman-Alpha Simulations), which maps baryon fields (baryon density, temperature, and velocity) to Lyα optical depth fields in both real space and redshift space. Unlike previous Lyα codes, THALAS is fully differentiable, enabling a wide variety of potential applications for general analysis of hydrodynamical simulations and cosmological inference. To demonstrate THALAS’s capabilities, we apply it to the Lyα forest inversion problem: given a Lyα optical depth field, we reconstruct the corresponding real-space dark matter density field. Such applications are relevant to both cosmological and three-dimensional tomographic analyses of Lyman Alpha forest data.

Toward High Contrast and Noninvasive Fluorescence Switches via an O-Fused Ring 5,7-Dihydroxy-4-methyl-2,2,3-triphenylbenzofuran-6(2H)-one Strategy.

An unprecedented O-fused ring 5,7-dihydroxy-4-methyl-2,2,3-triphenylbenzofuran-6(2H)-one (3) was first time synthesized. Further, a series of novel dialkyl/fluoroalkyl derivatives of compound 3, 5,7-dialkoxy/fluoroalkoxy-4-methyl-2,2,3-triphenylbenzofuran-6(2H)-one, were obtained with noninvasive fluorescence switching characteristics and aggregation-induced emission properties. Compared with fluoroalkyl derivatives, the alkyl analogs exhibited a significant bathochromic shift in solid-state fluorescence emission. Notably, these noninvasive fluorescent molecular switches could be facilely tuned through light and heat stimulation, which successfully achieved high contrast and reversible fluorescent emission between orange and yellow endowing them with potential applications in data encryption materials. In addition, the single crystal data of compounds 3 and 7-CF3 displayed weak intermolecular interactions in different directions, resulting in twisted conformation and antiparallel slip stacking. Interestingly, the polymer dimethyl silicone film doped with 7-C3F7 also showed an evident light-responsive behavior, meeting the criterion for fluorescent materials in the optical field.

Individual and collective manipulation of multifunctional bimodal droplets in three dimensions.

Spatiotemporally controllable droplet manipulation is vital across numerous applications, particularly in miniature droplet robots known for their exceptional deformability. Despite notable advancements, current droplet control methods are predominantly limited to two-dimensional (2D) deformation and motion of an individual droplet, with minimal exploration of 3D manipulation and collective droplet behaviors. Here, we introduce a bimodal actuation strategy, merging magnetic and optical fields, for remote and programmable 3D guidance of individual ferrofluidic droplets and droplet collectives. The magnetic field induces a magnetic dipole force, prompting the formation of droplet collectives. Simultaneously, the optical field triggers isothermal changes in interfacial tension through Marangoni flows, enhancing buoyancy and facilitating 3D movements of individual and collective droplets. Moreover, these droplets can function autonomously as soft robots, capable of transporting objects. Alternatively, when combined with a hydrogel shell, they assemble into jellyfish-like robots, driven by sunlight. These findings present an efficient strategy for droplet manipulation, broadening the capabilities of droplet-based robotics.

Unveiling the effect of Ce3+ doping concentration in YAG:Ce single crystals towards high luminance laser lighting

Doping concentration of a phosphor is key parameter, affecting multiple properties such as light absorption, quantum yield, luminescence decay, thermal conductivity, and thermal quenching, etc. These properties could directly influence the luminous efficacy, the saturation threshold, and the emitting area of the phosphor when irradiated by laser, thus determining the peak luminance of a phosphor-converted laser lighting device. But surprisingly no systematic investigation has been done to research the effect of phosphor doping concentration on the luminance performance of laser lighting. Here we report the YAG:Ce single crystal phosphors with different Ce3+-doping concentrations (between 0.05 at% and 0.30 at%) and thicknesses (0.15 mm–0.45 mm). The relationship between Ce3+ concentration, phosphor thickness, and the colorimetric/photometric parameters (luminous efficacy, luminous flux, luminance) are built and elucidated. It is found that the thinner sample with higher doping density tends to be saturated at lower laser power density (314.1 W/mm2) and the device shows lower luminance. This result is also verified by thermal simulation that the corresponding sample shows highest working temperature. Remarkably, the optimal sample with thickness of 0.45 mm and Ce3+ density of 0.30 at% presents a record high luminous exitance of 33414 lm/mm2 and a record high luminance of 10636 Mcd/m2, indicating potential for use in special lighting, projector, and optical communication fields.

Singular dielectricnanolaser with atomic-scale field localization.

Compressing the optical field to the atomic scale opens up possibilities for directly observing individual molecules, offering innovative imaging and research tools for both physical and life sciences. However, the diffraction limit imposes a fundamental constraint on how much the optical field can be compressed, based on the achievable photon momentum1,2. In contrast to dielectric structures, plasmonics offer superior field confinement by coupling the light field with the oscillations of free electrons in metals3-6. Nevertheless, plasmonics suffer from inherent ohmic loss, leading to heat generation, increased power consumption and limitations on the coherence time of plasmonic devices7,8. Here we propose and demonstrate singular dielectric nanolasers showing a mode volume that breaks the optical diffraction limit. Derived from Maxwell's equations, we discover that the electric-field singularity sustained in a dielectric bowtie nanoantenna originates from divergence of momentum. The singular dielectric nanolaser is constructed by integrating a dielectric bowtie nanoantenna into the centre of a twisted lattice nanocavity. The synergistic integration surpasses the diffraction limit, enabling the singular dielectricnanolaser to achieve an ultrasmall mode volume of about 0.0005 λ3 (λ, free-space wavelength), along with an exceptionally small feature size at the 1-nanometre scale. To fabricate the required dielectric bowtie nanoantenna with a single-nanometre gap, we develop a two-step process involving etching and atomic deposition. Our research showcases the ability to achieve atomic-scale field localization in laser devices, paving the way for ultra-precise measurements, super-resolution imaging, ultra-efficient computing and communication, and the exploration of light-matter interactions within the realm of extreme optical field localization.

Bismuth-Doped Fiber Lasers and Amplifiers Operating from O- to U-Band: Current State of the Art and Outlook

The development of unique optical materials that provide amplification and lasing in new wavelength ranges is a major scientific problem, the solution of which is becoming the basis for the emergence of new optical technologies, which are primarily targeting the expanding of operating wavelengths in silica glass. In fact, one of the notable advances in the field of fiber optics over the past two decades has been the production of a new type of laser-active fibers (namely bismuth-doped fibers), which has made it possible to cover previously inaccessible (for rare-earth-doped fibers) spectral ranges, in particular O-, E-, S-, and U-telecom bands. The advance in this direction has led to further growth of the technological capabilities in the telecom industry for amplification and generation of optical radiation in various wavelength bands, which will result in the near future to overcoming the problem known as “capacity crunch” by means of expanding the data transmission range. Recently, bismuth-doped fibers have been actively studying in order to improve their characteristics, which would allow for efficient implementation of optical devices based on bismuth-doped fibers (BDFs) with deployed telecommunications systems. This is one of the dynamically developing areas, where progress has already manifested in form of emergence of new achievements, in particular commercially available various types of BDFs, as well as a series of novel fiber-optic amplifiers for the O- and E-bands. In this review, a number of scientific studies that have already led to a noticeable progress in the field of optical properties of BDFs and the practical implementation of optical devices (lasers and amplifiers) based on them are presented and discussed, with much attention to the achievements of recent years.

All optical 4-bit Galois field adder using 2-D photonic crystals

All optical 4-bit Galois field adder using 2-D photonic crystals

Characterizing Biphoton Spatial Wave Function Dynamics with Quantum Wavefront Sensing.

With an extremely high dimensionality, the spatial degree of freedom of entangled photons is a key tool for quantum foundation and applied quantum techniques. To fully utilize the feature, the essential task is to experimentally characterize the multiphoton spatial wave function including the entangled amplitude and phase information at different evolutionary stages. However, there is no effective method to measure it. Quantum state tomography is costly, and quantum holography requires additional references. Here, we introduce quantum Shack-Hartmann wavefront sensing to perform efficient and reference-free measurement of the biphoton spatial wave function. The joint probability distribution of photon pairs at the back focal plane of a microlens array is measured and used for amplitude extraction and phase reconstruction. In the experiment, we observe that the biphoton amplitude correlation becomes weak while phase correlation shows up during free-space propagation. Our work is a crucial step in quantum physical and adaptive optics and paves the way for characterizing quantum optical fields with high-order correlations or topological patterns.

Analysis of Stokes singularities using a lateral shear interferometer

Polarization and Poincaré singularities in the optical fields can be studied by analyzing the phase singularities of mathematically constructed Stokes vector fields. The wider applicability of the Stokes construction is found by exploring the generation and detection methods for various types of Stokes singularities and their analysis. Here, we detect and analyze all forms of the Stokes singularities through lateral shear interferometry. Specifically, the projections of a Stokes singularity on three pairs of orthogonal polarization basis states, defined by the eigen polarization states of Pauli’s matrices, are analyzed through unique fork patterns in the shearogram pairs. These interference patterns also provide the topological indices of the singularities. Such a self-referencing interferometric method also helps to remove the degeneracy in the Stokes index and polarization. Through both, simulations and experiments, we have analyzed specific beams represented by higher order Poincaré sphere and hybrid order Poincaré sphere topological constructs.

Analyzing the synergistic effects of hard ceramic TiB2 and rare earth oxide La2O3 on mechanical behaviour, wear resistance, and residual stress of AA6061-T6 hybrid composite fabricated via ultrasonic-assisted stir casting

This investigation involves the fabrication of an aluminium metal matrix composite using AA6061-T6 alloy as the matrix, incorporating 2 wt% of hard ceramic (TiB2, 14 μm particle size) and 0.5 wt% of rare earth oxide (La2O3, 40–50 nm particle size) reinforcement powders through ultrasonic assisted stir casting. The study examines the microstructure, residual stress, and mechanical properties alongside performing pin-on-disk wear tests. Taguchi's optimization and ANOVA are used to optimize the wear rate of the composite using three control parameters: Load, Sliding Distance, and Sliding Speed. Results from optical micrography and field emission scanning electron microscopy (FESEM) with energy-dispersive spectrometer (EDS) analysis confirm the uniform distribution of TiB2 and La2O3 particles within the AA6061-T6 volume when ultrasonic stirring is employed. The composite's microhardness is found to increase by 25.15 %, and its tensile strength by 31.32 % compared to the base alloy due to a higher dislocation density. ANOVA highlights Load as the primary influencer, contributing 69.54 %, followed by Sliding Distance (17.45 %) and Sliding Speed (12.56 %). The optimal parameters for minimizing wear rate are found to be Load (20 N), Sliding Distance (1500 m), and Sliding Speed (2.5 m/s). Scanning Electron Microscope (SEM) images of worn surfaces reveal various mechanisms such as abrasion, delamination, and adhesion, with abrasion being the dominant mechanism. Residual stress increases with the addition of TiB2 and La2O3 particles in the matrix, showing transitions from tensile to compressive stress from the inner to the outer surface of the composite casting.

Localization and Sound Power Estimation of Sound Sources in Industrial Plants using the Sound Field Scanning Method

Reducing sound emissions from industrial plants requires an initial step of localizing key contributing sources. Acoustic cameras are pivotal for quickly identifying these sources, yet challenges persist in low-frequency source localization and presenting results for effective impact assessment. This contribution introduces the Sound Field Scanning technology, utilizing a rotating linear microphone array covering a measurement surface with diameter of 2.5 meters for low-frequency source localization from 125Hz. The underlying sound imaging method compensates for Doppler distortions in the moving microphone signals and evaluates coherence spectra with a non-moving reference microphone to compute an acoustic image. For analysis, a method quantifying sound power contributions from specific regions in the optical image is presented. Comparing sound power metrics of the full optical field of view with metrics of regions of interest enables users to quickly rank source contributions and assess the impact of reducing these contributions on total sound power. In complex scenarios, preliminary investigations can be streamlined with a few measurements from diverse angles, expediting the problem-solving process with confidence. The method is exemplified through the analysis of sound emissions from a production plant.