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We propose a simple optical model, which consists of two Kerr nonlinear parallel planar waveguides sandwiching a one-dimensional photonic crystal for demonstrating the phenomenon of spontaneous symmetry breaking in optics. We study the shape and stability of soliton pairs propagating in two planar waveguides and the spontaneous symmetry breaking of the power distribution of solitons in the two waveguides. The results of numerical simulation show that there is supercritical type of spontaneous symmetry breaking in this system. More optical power P and smaller refractive index of photonic crystals C 0 make soliton solutions more prone to spontaneous symmetry breaking bifurcation. Asymmetric soliton solutions and symmetric soliton solutions correspond to different dispersion relations. Under the given total power P, for the symmetric soliton solutions, the propagation constant k increases linearly with C 0 , and for asymmetric soliton solutions, the propagation constant k decreases nonlinearly with C 0 . The minimum point of k (C 0) is just the demarkation between the symmetric soliton solutions and the asymmetric soliton solutions. If C 0 is fixed, the minimum point of the Hamiltonian of the system, E (P) , is also the critical point of the two different kinds of soliton solutions. We also study stable and unstable distributions of two kinds of soliton solutions. [ABSTRACT FROM AUTHOR]

Real‐world resonances face surface‐scaling radiation leakage, hindering light confinement in optically large systems. Conventional bound states in continuum (BICs) challenge this by enabling states with theoretically infinite lifetimes in 2D periodic structures. However, when fabricated, the truncation of these systems to finite sizes inevitably re‐introduces leakage, uncontrollably downgrading their quality factors. Here, a novel form of finite‐size 3D quasi‐BICs (QBICs) is demonstrated that leverage a skyrmion field topology of Bloch modes in 3D cubic photonic crystals. The associated finite systems exhibit highly suppressed radiation in all three spatial directions, with a remarkable exponential volume‐scaling of quality factors. With an unprecedentedly large 3D prototype of 24 cm3 and great scalability, the existence of skyrmion QBICs is experimentally proven through unique far‐field polarization wrapping and spectral singularity. These demonstrations enable to have omnidirectional topological radiation suppression, 3D vortex generation, and access to arbitrarily large volume and volumetric interfaces. 3D QBIC may empower extreme 3D light‐trapping, enhanced volumetric sensing, and topological skyrmion emitters. [ABSTRACT FROM AUTHOR]

Photonic crystals (PC) with structural colors have been used in various sensors or indicators given that they change the colors upon mechanical deformation. However, the color also changes according to the incident or viewing angle, presenting a challenge when the structural color serves as the practical sensor or indicator. Therefore, it is necessary to compensate for this color variation caused by the incident or viewing angle. This study presents devices in which strain-sensitive photonic crystals (SSPCs) and strain-insensitive crystals are fabricated together. The photonic crystals were fabricated by the self-assembly of nanoparticles and the deposition of a thin metallic film, after which they were transferred onto flexible and adhesive tape so that the devices, i.e., the sensors and indicators, could be fabricated. When the nanoparticles were in a close-packed arrangement, the thin film formed into a continuous layer upon a monolayer of the nanoparticles. Accordingly, the lattice constant of the PC did not change while the device were deformed, resulting in strain-insensitive photonic crystals (SIPCs). Meanwhile, when the nanoparticles were not in a close-packed arrangement, as realized by deep reactive ion etching, the thin film formed into separate layers on the individual nanoparticles. The lattice constant of the PC varied in this case when the device were deformed, resulting in strain-sensitive photonic crystals. The devices consist of both types of photonic crystals such that the colors from each PC could be compared to each other, enabling angle-compensating characteristics. In this way, the colors can be used as effective signals of mechanical strain or as chemical liquids at arbitrary angles. They can also be used as an anticounterfeiting stamp. This study thus introduces a fabrication method that therefore enables a choice between strain-sensitive and strain-insensitive photonic crystals. [ABSTRACT FROM AUTHOR]

We propose a photonic crystal (PC) nanostructure that combines bound states In the continuum (BIC) with a high-quality factor up to 107 for emitting circularly polarized beams. We break the in-plane inversion symmetry of the unit cell by tilting the triangular hole of the hexagonal lattice, resulting in the conversion of a symmetrically protected BIC to a quasi-BIC. High-quality circularly polarized light is obtained efficiently by adjusting the tilt angles of the hole and the thickness of the PC layer. By changing the hole's geometry in the unit cell, the Q-factor of circularly polarized light is further improved. The quality factor can be adjusted from 6.0 × 103 to 1.7 × 107 by deliberately changing the shape of the holes. Notably, the proposed nanostructure exhibits a large bandgap, which significantly facilitates the generation of stable single-mode resonance. The proposed structure is anticipated to have practical applications in the field of laser technology, particularly in the advancement of low-threshold PC surface emitting lasers (PCSELs). [ABSTRACT FROM AUTHOR]

In this paper, an attempt has been made to investigate a one-dimensional photonic crystal containing N-doped germanium semiconductor as a nonlinear defect layer with an intensity-dependent refractive index, silica (SiO2) and zinc selenide (ZnSe) as crystal cells. Bistability of the TE polarization of the transmission spectrum due to the nonlinear property of the defect layer is investigated by the transfer matrix method (TMM). The refractive index of the germanium nonlinear semiconductor layer is simultaneously depending on the doping density and the intensity of the irradiated light. The changes in both factors are investigated. The impact on the transmission spectrum of the bistability threshold due to the change in the thickness of the defect layer, the thickness of other layers of crystal cells, and the angle of incident light are investigated. The nonlinear effect caused by light intensity as well as doped density effect on the germanium nonlinear semiconductor medium is used simultaneously. As a result, the nonlinear effect caused by the light intensity to create bistability is more than the doping density. [ABSTRACT FROM AUTHOR]

Conventional colored radiative cooling (ColPRC) has a single color and limited reflection of visible light bands, which affects its radiative cooling effect, and the introduction of multiple photonic crystal structures can improve its radiative cooling performance. Therefore, in this study, a composite film was established by cross‐linking cellulose nanocrystals (CNC) with CO2‐based waterborne polyurethane (WPU) to obtain multistage structural colors. X‐ray diffraction pattern, thermogravimetric analysis, scanning electron microscopy, spectral analysis, and so on were used to examine the structure and properties of the films. The results showed that with the increase of CNC content, the color shifted blue, the crystallinity increased, the flame retardancy increased, but the thermal stability decreased; the addition of WPU assists in resisting moisture; the reflectivity of the multistage structured films is improved in the VIS–NIR range compared with the monochromatic films (an average increase of 5%), which helps to reduce solar irradiation in the visible wavelengths; high emissivity (≈90%) in the atmospheric window, which facilitates deep‐space heat exchange. The maximum temperature difference of the multistage structural color film can reach 6°C under strong solar irradiation. This research can be applied in photovoltaic devices or outdoor thermal management to provide new ways to address human energy efficiency. [ABSTRACT FROM AUTHOR]

Topological photonics is revolutionizing the integrated electromagnetic devices, on account of the robust mode propagations immune to structural defects and sharp bends. Such robust modes have spawned attractive devices known as photonic topological waveguides (PTW), especially implemented on compact photonic‐crystal platforms. However, these exotic waveguides are challenging to be high‐efficiently interconnected with conventional integrated photonic devices. To tackle this challenge, a general energy‐efficient strategy for topological photonic structures is proposed. Such strategy is implemented onto three types of typical PTWs, which extract electromagnetic energy high efficiently from standard single‐mode rectangular waveguides. Moreover, the results of dual‐polarization valley PTW proves the polarization‐independence of their strategy. The measured near‐perfect excitation efficiencies are stable across the whole operational band of topological waveguides, thus verifying the frequency independence of this strategy. By utilizing this energy‐efficient strategy, an integrated topological high‐gain antenna, which achieves the peak directive gain of 20.25 dBi and half power beam width of 5.23° at 60 GHz, is realized. This strategy on energy‐efficient design is general to be applicable on other types of topological photonic platforms and paves the way for applications of topological electromagnetic devices. [ABSTRACT FROM AUTHOR]

A method of sequential spraying of polyvinyl alcohol with carbon quantum dots (PVA@CDs) aqueous suspension and SiO2 aqueous suspension is proposed to rapidly prepare multicolor dual-mode anti-counterfeiting labels. With the optimization of the concentration (15%) of colloidal microspheres in the SiO2 aqueous suspension as well as the spraying process parameters (spray distance of 10 cm, spray duration of 3 s, and assembly temperature of 20 °C), different-sized SiO2 microspheres (168 nm, 228 nm, and 263 nm) were utilized to rapidly assemble red, green, and blue photonic crystals. Furthermore, the tunable fluorescence emission of carbon quantum dots endows the labels with yellow, green, and blue fluorescence. The constructed dual-mode labeling was used to develop an anti-counterfeiting code with dual-channel information storage capabilities and also to create dual-mode multicolor anti-counterfeiting labels on various packaging substrates. This work provides a novel solution for anti-counterfeiting packaging and information storage. [ABSTRACT FROM AUTHOR]

With the development of virtual reality, the projection design of the head-mounted display (HMD) requires improvement as well. The surface relief grating (SRG) is one of the popular diffraction elements to achieve light guiding through the waveguide. Using the SRG as the coupler, incoming information light can be coupled into the waveguide by the 1-order diffraction. To increase possible design options for the HMD, SRG with complex geometry has been designed to fit more diffraction conditions. In this paper, a 2D SRG is proposed to form by periodically arranging slanted glass pillars on the surface of a glass waveguide, just like a photonic crystal. The structure can suppress all the other diffraction orders except the 0-order and the [1, 0] order. The best diffraction efficiency of the [1, 0] order can be obtained when the incident light is incident with not only an incident angle but also an azimuth angle. The geometric parameters of the pillars are investigated and optimized with the diffraction efficiency by the finite element method, and the relationship between the incident angles and the diffraction efficiency will also be discussed. The proposed structure has the potential in both the in-coupler and the out-coupler, respectively, for integrating light coming from different azimuth angles or for outputting light to different azimuth angles. [ABSTRACT FROM AUTHOR]

Uranyl ion (UO22+) is both radiotoxic and chemically toxic, which has harmful effects on the ecological environment and human health. This work presents a novel material called two-dimensional photonic crystal polyacrylic acid hydrogel (2D-PCPAAH), which contains massive carboxyl groups that can bind to UO22+ by strong coordination interaction. UO22+ can be combined with multiple ligand groups, causing the shrinkage of the 2D-PCPAAH which results in a reduction in particle spacing and a color change. Via measuring the Debye diffraction ring diameter using a ruler, the particle spacing can be easily obtained and the UO22+ concentration can be determined. [ABSTRACT FROM AUTHOR]

Achieving high-speed and efficient data processing in optical processors is a key goal for researchers in integrated photonics. Photonic crystals, with their ability to control light propagation through periodic variations in refractive index, offer a promising platform for realizing compact and high-performance optical components. This work presents a novel low-power 4 × 2 all-optical encoder design based on a two-dimensional photonic crystal structure. The proposed encoder makes use of waveguides and ring resonators inside the photonic crystal to create AND, OR, and NOT gates in combination. The design incorporates four input ports, two output ports, two ring resonators, five optical waveguides, and two power dividers. By strategically introducing defects and optimizing the coupling between waveguides and resonators, the desired logical operations are achieved. The encoder exhibits a low input power requirement of 15 mW and a maximum delay time of 1.33 ps. Additionally, the compact footprint of 522 μm2 makes the design well-suited for integration into photonic integrated circuits. Simulation results, obtained through plane-wave expansion and finite-difference time-domain methods, validate the functionality of the proposed encoder, with output powers of 55% and 10% for logic 1 and logic 0, respectively. This work demonstrates the potential of photonic crystal-based architectures for realizing efficient, high-speed, and compact optical signal processing components with applications in data communication and optical computing. [ABSTRACT FROM AUTHOR]

We propose a photonic crystal-based cascaded micro ring resonator to increase the quality factor using the concept of two-dimensional constrained topological edge states. The topological features of the photonic crystal are used to acquire the increased quality factor by finite-difference time-domain (FDTD) numerical simulation. Two micro ring resonators with different band topologies that come together at an interface and are confined inside a slab of dielectric material give rise to a topological edge state. The transmission dropout issue arises whenever the quality factor is enhanced in a conventional photonic system, which can be improved remarkably by employing the present approach. As an application, the proposed topological edge state structure is used to increase the sensitivity and quality factor of the pressure sensor. In FDTD simulation, resonance wavelength shifts are employed to calculate the pressure of a system, while structural deformation and refractive index change are used as input parameters. The proposed structure is incredibly small and suitable for photonic integrated circuits. [ABSTRACT FROM AUTHOR]

In this communication, the design of broad band optical reflector and selective polarization filter using a one-dimensional photonic crystal (1D-PC) containing superconductor and semiconductor layer has been proposed and investigated theoretically. The proposed design consists of alternate layers of yttrium barium copper oxide YBa2Cu3O7 (YBCO) and silicon (Si), respectively. The refractive indices of YBCO and Si layers are modulated as the function of temperature and wavelength both. This characteristic brings this study closer to actual physical implementation. To obtain the reflectance and transmittance properties of the proposed structure and to analyze the propagation characteristics of electromagnetic waves, the transfer matrix method (TMM) has been employed. The analysis of the reflectance spectra shows that near the critical temperature of YBCO layers no broad band reflection (from 0 to 85°) is observed. On the other hand, when the temperature is lowered below the critical temperature, ODR arises. The proposed YBCO/Si structure gives a broad band reflection band (from 1394 to 1621 nm (bandwidth 227 nm)) for both TE and TM modes of polarizations at 85 K. Also, at higher incident angles, the proposed structure acts as a selective polarization-based filter without introducing any defect in the geometry. [ABSTRACT FROM AUTHOR]

Polyvinyl alcohol (PVA)/TiO2/colloidal photonic crystal (CPC) films with photocatalytic properties are presented, where TiO2 nanoparticles were introduced into the PVA gel network. Such PVA/TiO2/CPC films possess three-dimensional periodic structures that are supported with a PVA/TiO2 composite gel. The unique structural color of CPCs can indicate the process of material preparation, adsorption, and desorption. The shift of diffraction peaks of CPCs can be more accurately determined using fiber-optic spectroscopy. The effect of the PVA/TiO2/CPC catalyst films showed better properties as the degradation of methylene blue (MB) by the PVA/TiO2/CPC film catalyst in 4 h was 77~90%, while the degradation of MB by the PVA/TiO2 film was 33% in 4 h, indicating that the photonic crystal structure was 2.3~2.7 times more effective than that of the bulk structure. [ABSTRACT FROM AUTHOR]

Disordered and correlated disordered photonic materials have emerged in the past few decades and have been rapidly proposed as a complementary alternative to ordered photonics. These materials have thrived in the field of photonics, revealing the considerable impact of disorder with and without structural correlations on the scattering, transport, and localization of light in matter. Scanning near-field optical microscopy (SNOM) has proven to be a fundamental tool for the study of the interaction between light and matter at the nanoscale in such systems, allowing for the investigation of optical properties and local electromagnetic fields with extremely high spatial resolution, surpassing the diffraction limit of conventional optical microscopy. In this review, the most important and recent advances obtained for disordered and correlated disordered luminescent structures by means of the aperture SNOM technique are addressed, showing how it allows the tailoring of local density of states (LDOS), as well as providing access to statistical analysis for multi-resonance disordered and hyperuniform disordered structures at telecom wavelengths. [ABSTRACT FROM AUTHOR]

In‐plane Hyperbolic Phonon polaritons (HPhPs) are quasiparticles formed via coupling of photons and optical phonons in in‐plane hyperbolic materials and offer unique applications in sensing, thermal emitters and high‐resolution imaging. However, the large momentum mismatch between photons and these in‐plane HPhPs has restricted their technological potential as most experimental demonstrations rely on sophisticated and expensive near‐field detection schemes. In this work, using the example of α‐MoO3, it is demonstrated that by constructing photonic hypercrystals of this material, one can not only excite these in‐plane HPhPs in the far field but also tune the far field response via twisting the hypercrystal lattice with respect the lattice of α‐MoO3. The findings will pave the way for the development of practical in‐plane HPhP devices as well as provide access to new fundamental physics of such materials via conventional and well developed far‐field measurement techniques. [ABSTRACT FROM AUTHOR]

Structural color is an optical phenomenon resulting from light interacting with nanostructured materials. Although structural color (SC) is widespread in the tree of life, the underlying genetics and genomics are not well understood. Here, we collected and sequenced a set of 87 structurally colored bacterial isolates and 30 related strains lacking SC. Optical analysis of colonies indicated that diverse bacteria from at least two different phyla (Bacteroidetes and Proteobacteria) can create two-dimensional packing of cells capable of producing SC. A pan-genome-wide association approach was used to identify genes associated with SC. The biosynthesis of uroporphyrin and pterins, as well as carbohydrate utilization and metabolism, was found to be involved. Using this information, we constructed a classifier to predict SC directly from bacterial genome sequences and validated it by cultivating and scoring 100 strains that were not part of the training set. We predicted that SCr is widely distributed within gram-negative bacteria. Analysis of over 13,000 assembled metagenomes suggested that SC is nearly absent from most habitats associated with multicellular organisms except macroalgae and is abundant in marine waters and surface/air interfaces. This work provides a large-scale ecogenomics view of SC in bacteria and identifies microbial pathways and evolutionary relationships that underlie this optical phenomenon. [ABSTRACT FROM AUTHOR]

Mechanochromic photonic materials present promising prospects for enhancing diverse facets of human life. Cholesteric liquid crystal elastomers (CLCEs) present immediate mechanochromic properties, allowing their utility in various fields, including camouflages, textiles, and anticounterfeiting. Nonetheless, it is essential to provide differentiated color information corresponding to diverse types and degrees of deformation for practical use in real life. Herein, the mechanochromic responses of CLCEs are investigated using their optical rotation under compression and uniaxial stretching. The CLCEs exhibit the same reflection colors indistinguishable for compression and uniaxial stretching due to their contracted pitches. In contrast, the linearly polarized light passing through deformed CLCEs can be modulated by optical rotation, resulting in distinct transmission colors that can be discerned through mechanical deformations. A visual signaling system with color information derived from optical rotation is demonstrated. By comprehending and manipulating the mechanoresponsive behavior of CLCEs, these materials can be advanced into innovative solutions with enhanced functionality and performance, thereby broadening their applications for human life enhancement. [ABSTRACT FROM AUTHOR]

Structural-colored fabrics have been attracting much attention due to their eco-friendliness, dyelessness, and anti-fading properties. Monodisperse microspheres of metal, metal oxide, and semiconductors are promising materials for creating photonic crystals and structural colors owing to their high refractive indices. Herein, Cu2O microspheres were prepared by a two-step reduction method at room temperature; the size of Cu2O microspheres was controlled by changing the molar ratio of citrate to Cu2+; and the size of Cu2O microspheres was tuned from 275 nm to 190 nm. The Cu2O microsphere dispersions were prepared with the monodispersity of Cu2O microspheres. Furthermore, the effect of the concentration of Cu2O microsphere and poly(butyl acrylate) on the structural color was also evaluated. Finally, the stability of the structural color against friction and bending was also tested. The results demonstrated that the different structural colors of fabrics were achieved by adjusting the size of the Cu2O microsphere, and the color fastness of the structural color was improved by using poly(butyl acrylate) as the adhesive. [ABSTRACT FROM AUTHOR]

In this paper, a novel approach to design a photonic crystal exclusive-OR (XOR) gate with high performance using recurrent neural network (RNN) is proposed, integrating the principles of symmetry and asymmetry inherent in photonic structures. The proposed model realizes the nonlinearities and dispersion properties in photonic systems, optimizing the waveguide paths and interference patterns to improve the performance of the logic gate. Simulation results demonstrate that the presented RNN design not only achieves high fidelity in the logical operation but also significantly enhances the functionality of the all-optical gate. This integration of machine learning with photonic crystal technology opens a new era for developing compact, energy-efficient photonic circuits for high-speed optical computing. Finally, the performance of the designed all-optical gate is compared with other related methods, which shows that the proposed gate outperforms other works. The results show that the obtained output power of the proposed all-optical XOR gate is 0, 0.813, 0.82, and 1 × 10−7 in the logical states. [ABSTRACT FROM AUTHOR]

Localization of light spots in a given image is a common task in digital processing but is challenging in analog. Herein, a periodic nonlocal metasurface that has an optical transfer function defined in reciprocal space is proposed to resolve this issue. Assuming an ideal optical transfer function that encodes that of a local lens, the selective spot size reduction of incident Gaussian beams and sharpening of a patterned incidence with a Gaussian line shape are demonstrated. A realistic nonlocal metasurface comprising a trilayer structure with air grating on top that operates as a 2D analog light localizer under unpolarized incidence is presented. Nonlocal metasurfaces, combined with conventional optics, are expected to improve the resolution by sharpening the spatial features and find applications in diverse scientific fields such as medical, materials, and life science. [ABSTRACT FROM AUTHOR]

An optical biosensor designed using a Nanocomposite/Defect/Nanocomposite multilayer 1D photonic crystal is proposed for malaria diagnosis. The defect layer represents blood samples corresponding to various stages of malaria. Employing the Transmission Matrix Method (TMM), we analyse the impact of two kind of nanocomposite (NC) layers: silver-doped TiO2 and silver-doped SiO2. Comparative analyses involving varying thickness and fill factor of NC layers indicate increased sensitivity with higher fill factors and thickness, albeit with a decrease in transmission. Further, we explore the influence of incident angle (TM & TE mode) on sensing performance, revealing enhanced sensitivity at higher angles. The maximum sensitivity peaks are reported to be 1074 nm/RIU and 1064 nm/RIU for the mentioned NC layer cases. This biosensor promises enhanced sensitivity and potential for advanced malaria diagnostics. [ABSTRACT FROM AUTHOR]

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An all optical Gray to BCD converters will be proposed and designed based on photonic crystals. The proposed structure is composed of one XOR gate and a buffer. The final structure consists of 6 optical waveguides and two nonlinear ring resonators. The nonlinear defects are made of doped glass with the Kerr coefficient of 10−14 m2/W. The rest of the structure was made of Si rods with the refractive index of 3.46. The maximum rise time for the proposed structure is 1 ps. [ABSTRACT FROM AUTHOR]

A phase shift gate deals with the change in phase of light signals passing through it. In this paper, authors propose the tristate form of the phase shift gate and its implementation using frequency and phase encoding techniques simultaneously. Tristate system is capable to process more information simultaneously than that of a two-state system. Three different gate matrices are obtained for the phase shift gate operation. Then, the equivalent quantum optical circuits are developed corresponding to those gate matrices. The optical switching operation is established by using electro-optic Pockels material. One of the tristate phase shift gates is designed on a photonic crystal layout with a footprint area of 189 µm2 to achieve a better response time and higher bit rate of the operation. The circuit operation is simulated by FDTD method to check the operation of the circuit. The response time of the system is obtained to be 0.283 picoseconds. [ABSTRACT FROM AUTHOR]

In this paper, wavelength demultiplexing is demonstrated by using double defect layered 1D ternary photonic band gap (PBG) structures. It is shown that, a wavelength demultiplexer based on double defect layered 1D ternary PBG structure can be used to separate two different wavelengths of light. To separate more number of light wavelengths, more number of double defect layered 1D ternary PBG structures can be used. This idea finds application in WDM based optical networks. [ABSTRACT FROM AUTHOR]

The article proposes the simulation of a 2D photonic crystal structure for the diagnosis of different cancerous and tumour cell detection. The race-track microring resonator (RT-MRR)-based structure has been modelled using FDTD simulation platform. The variation in the index of refraction of the normal and the infected cells has been observed. This difference primes to the alteration in the strength of the light intensity and aids to notice for the detection of cells. The model is sensitive, reliable, simple, and compact and may be included in different sensing applications. [ABSTRACT FROM AUTHOR]

A crucial part of the FTTH (fibre to the home) network, the photonic crystal optical diplexer and triplexer, is investigated. Three optical filters—implemented by the internal cavities put into the waveguides as well as two PhC waveguides with a single line defect make up the proposed optical diplexer and triplexer. Each optical filter's resonant behaviour is tuned by adjusting the size or index of the cavity's central point defect in order to divide three wavelength signals. Three distinct micro pillars make up the resonant ring, which makes it easier to tune the resonant wavelength and improved power coupling effectiveness. In Proposed diplexer wavelengths obtained for Port 1 and Port 2 are 0.16 µm for 1550 nm and 0.122 µm for 1310 nm respectively same way in triplexer for 3 ports the values are 0.122 µm for 1310 nm, 0.145 µm for 1490 nm and 0.16 µm for 1550 nm. [ABSTRACT FROM AUTHOR]

The measurement of patients' dosages of radiation caused by medical diagnostics continues to be challenging. A Cantor sequence photonic crystal structure using porous silicon doped with a polymer of polyvinyl alcohol, carbol fuchsin and crystal violet (DPV) is proposed. The influence rules of geometrical and optical parameters such as the radiation doses, number of periods, porosity of porous layers, incident angle and thickness of layers are investigated using MATLAB based on the transfer matrix method. The transmittance of the Cantor sequence of a defective photonic crystal sensor under different conditions is investigated to select the optimum conditions. The proposed system recorded the accepted sensitivity of 0.265 nm/Gy, FoM of 6.5 Gy − 1 , Q of 12,701, RS of 6 × 1 0 − 3 and LoD of 8 × 1 0 − 3 for gamma radiation. The suggested detector has simple design, accurate monitoring efficiency and immense potential for gamma radiation sensing. [ABSTRACT FROM AUTHOR]

Abstract Graphene Quantum Dots (GQDs) are crucial in biomedicine for sensitive biosensing and high-resolution bioimaging and in photonics for their nonlinear optical properties. Integrating GQDs with photonic structures enhances optical properties by optimizing light-matter interactions and enabling precise control over their emission wavelengths. In this work, we explore a facile synthesis method for GQDs by pulsed laser irradiation in chlorobenzene and highlight the transformative potential of Tamm Plasmon Cavity (TPC) structures for tuning and amplifying the photoluminescence and nonlinear optical properties of GQDs. The characterization of GQDs revealed their exceptional properties, including efficient optical limiting and stable photoluminescence. The study demonstrated that the TPC structure significantly amplifies nonlinear optical effects due to the high light-matter interaction, indicating the potential for advanced optical systems, including optical limiters and nonlinear optical devices. Furthermore, introducing GQDs into the TPC structure leads to a significant enhancement and tuning of fluorescence emission. The Purcell effect, in combination with the confined electromagnetic fields within the TPC, increases the spontaneous emission rate of GQDs and subsequently enhances the fluorescence intensity. This enhanced and tunable fluorescence has exciting implications for high-sensitivity applications such as biosensing and single-molecule detection.

Microfluidic chips play crucial roles while lack satisfactory controllability and comprehensive functionality. Inspired by biological systems, this study proposes a method utilizing rolling microneedles (RMNs) to generate muti‐structured templates, realizing photonic crystal membrane (PC) based meta microfluidic microneedle chip (MMM) for efficient wound management. This approach offers advantages in terms of speed and cost‐effectiveness, achieving dual‐sided permeation and patterned design by directly RMNs at desired locations, serving as both template tools for microneedle fabrication. The integration of RMNs with a PC membrane results in the design of 3D multilayer microfluidic channels, effectively addressing issues related to spontaneous fluid flow. As fluid reaches the PC membrane, it generates distinctive structural colors and exhibits fluorescence enhancement, enabling the monitoring of inflammatory factors in mouse wounds and facilitating efficient wound management. In summary, this preparation method involving RMNs paves the way for the design and fluid control of microfluidic chips. This bioinspired patch holds significant potential not only for wound management but also for areas such as clinical drug delivery and point‐of‐care testing (POCT). [ABSTRACT FROM AUTHOR]

Dynamically responsive materials with chromotropic properties have received increasing attention in flexible pressure sensing due to their intuitive nature in the information transfer process. Here, inspired by the biological dynamic regulation of structural color in nature, a robust biomimetic mechanochromic photonic ionogel is ingeniously constructed. The photonic ionogel undergoes continuous and regular structural color changes under compression and outputs stable optical signals, possessing excellent linear pressure responsiveness and stability. The photonic ionogel exhibits sensitive changes in structural color and reflection wavelength via adjusting the lattice spacing of the 3D photonic crystal (mechanochromic sensitivity: 2.21 nm per %, Δλ > 150 nm). Furthermore, the good compatibility between ionogel and PC microspheres endows photonic ionogel with good linear pressure responsiveness (R2 ≈ 0.984). Meanwhile, ionic liquid (IL) and the covalent cross-linking network of robust polyurethane elastomer provide photonic ionogel with a wide temperature tolerance range (Tg ≈ −49.5 °C, initial decomposition temperature of 301 °C) and mechanical durability (5000 cycles of compression). This work demonstrates promising applications not only in flexible pressure sensing but also in advanced visual interaction devices. [ABSTRACT FROM AUTHOR]

Polarization is a crucial characteristic of electromagnetic fields, and the ability to fully control it has many useful applications. While novel nanophotonic devices have been designed to achieve unprecedented capability to manipulate light on demand, their usage in the complete control of polarization states for the transmitted light has been relatively limited, and traditional design methods always produce devices with narrow operation bandwidths. In this work, a two‐phase topology optimization strategy is proposed in conjunction with adjoint method to inverse design photonic crystal slabs capable of complete polarization control. It successfully produces devices operating over a broad bandwidth that is significantly larger than the current state‐of‐the‐art designs, and their performances are also robust to material loss. This is also find that the C2v symmetry of the structure can regularize the problem, so that less simulation time and faster convergence can be obtained without compromising performance. This study demonstrates the power of the inverse design method, which can be further applied to achieve more complex polarization control and beyond. [ABSTRACT FROM AUTHOR]

Extensive radiative transfer calculations to fit the more significant average spectral features displayed in measured reflectance spectra by cuticles of Chrysina resplendes scarabs have been carried out. A simulated annealing approach is the starting point to optimize the values of the spatial average uric acid volume fraction, the thickness of the retarder layer located between the two left-handed chiral structures in the cuticle, and the slope of the parameter describing the variation with depth of the uric acid volume fraction through the retarder layer. Both twisted arrangements are characterized in terms of their photonic behaviors to display the variation with depth of the photonic band gaps, effective refractive index and birefringence, wave numbers and relative densities of states. [ABSTRACT FROM AUTHOR]

Researchers have reported two-state quantum Hadamard gate using different optical techniques. In this paper, authors propose a new concept for developing the tristate form of single qubit quantum Hadamard gate using phase encoding technique of light. Phase differences are generated by using electro-optic modulators of appropriate biasing voltages. The circuits are reversible and satisfy the quantum requirements. A similar system is also designed on 2D photonic bandgap crystal-based layout with footprint area 337.5 µm2. The cylindrical rods of refractive index 3.45 are inserted on air substrate to design the layout. The operation of the system is simulated by finite difference time domain (FDTD) method. Desired phase values are obtained by varying the optical path length in the channels. The maximum response time of the system is observed to be 0.125 ps which is very useful in superfast quantum computing and data processing. [ABSTRACT FROM AUTHOR]

A novel terahertz polarization isolator using a two-dimensional square lattice tellurium rod array is numerically investigated at the interesting band of 0.22 THz in this short paper. The isolator is designed by inserting six hexagonal tellurium rods into a fully polarized photonic crystals waveguide with high efficiency of −0.34 dB. The TE and TM photonic band gaps of the 7 × 16 tellurium photonic crystals are computed based on the plane wave expansion method, which happen to coincide at the normalized frequency domain from 0.3859(a/λ) to 0.4033(a/λ), corresponding to the frequency domain from 0.2152 to 0.2249 THz. The operating bandwidth of the tellurium photonic crystals waveguide covers 0.2146 to 0.2247 THz, calculated by the finite element method. The six hexagonal tellurium rods with smaller circumradii of 0.16a serve to isolate transverse electric waves and turn a blind eye to transverse magnetic waves. The polarization isolation function and external characteristic curves of the envisaged structure are numerically simulated, which achieves the highest isolation of −33.49 dB at the central frequency of 0.2104 THz and the maximum reflection efficiency of 98.95 percent at the frequency of 0.2141 THz. The designed isolator with a unique function and high performance provides a promising approach for implementing fully polarized THz devices for future 6G communication systems. [ABSTRACT FROM AUTHOR]

Photonic crystal channel drop filters (CDFs) play a vital role in optical communication owing to their ability to drop the desired channel. However, it remains challenging to achieve high-efficiency CDFs. Here, we demonstrate a highly efficient three-channel CDF with both high transmission and high quality (Q) factor based on a novel ring resonator that is in the middle of two waveguides. A dielectric column with a large radius replaces the homogeneously distributed dielectric columns inside the ring cavity to modulate the coupling ratio with a straight waveguide, thereby enhancing the transmission and Q factor. The transmission and Q factor of the single-cavity filter are 99.7% and 12,798.4, respectively. The mean value of the three-channel filter based on the basic unit can reach up to 94.6% and 10,617, respectively, and a crosstalk between −30.16 and −50.61 dB is obtained. The proposed CDFs provide efficient filter capability, which reveals great potential in integrated optoelectronics and optical communication. [ABSTRACT FROM AUTHOR]

We propose a new approach to the use of sensors based on 1D photonic crystals with defect to determine the concentrations of non-binary mixtures. This approach is based on the simultaneous use of several defect modes whose positions are sensitive to differences in the dispersion properties of the different components of the mixture. We also investigate different modes of operation of such a sensor to improve its accuracy, including working with defect modes in different photonic forbidden gaps. The results of this work will extend the applicability of sensors based on defective photonic crystals. [ABSTRACT FROM AUTHOR]

The integration of photonic microstructure into organic microcavities represents an effective strategy for manipulating eigenstates of cavity or polariton modes. However, well‐established fabrication processes for microstructured organic microcavities are still lacking. This study proposes a nanoimprint‐bonding process as a novel fabrication method for microstructured organic microcavities. This process relies on a UV nanoimprint technique utilizing two different photopolymer resins, enabling the independent fabrication of highly reflective reflectors and photonic microstructures without compromising the accuracy of each. The resulting organic microcavities demonstrate spatially localized photonic modes within dot structures and their nonlinear responses on the pumping fluence. Furthermore, a highly precise photonic band is confirmed within a honeycomb lattice structure, which is owing to the high quality factor of the cavity achievable with the nanoimprint‐bonding process. Additionally, a topological edge state is also observable within a zigzag lattice structure. These results highlight the significant potential of the fabrication method for advancing organic‐based photonic devices, including lasers and polariton devices. [ABSTRACT FROM AUTHOR]

Smart thermal emission, which is response to external stimuli, has provided an unparalleled approach to exploiting optical devices that allows for tunable photon radiance. Here, an approach of implementing information encryptions using a smart thermal emission material that exhibits non‐volatile, multifunctional, and on‐chip‐integrable properties is reported. The smart material is a bilayer structure, consisting of a tungsten (W)‐doped vanadium dioxide (VO2) thin film layer and a self‐assembled polystyrene (PS) microsphere layer. Significant differences between the phase transition temperatures of differently doped VO2 films enable reconfigurable thermal emission in response to heat. Levels of information recorded by the patterning of these VO2 films are thus encrypted thermo‐radiatively. Additionally, the structural color of PS layer, as a result of photonic crystal bandgap effect, shades the encoded patterns from visible observation, and provides an anti‐counterfeiting function. Notable observation angle independence and device‐friendly encoding processes are also demonstrated. Based on these thermo‐tunable emission characteristics, the concept of multilevel data encryption via infrared radiation detection, temperature dependence, and visible anti‐counterfeiting, is realized by the smart bilayer material. [ABSTRACT FROM AUTHOR]

In this paper, we design and optimize a single-mode photonic crystal (PhC) nanobeam-grating (NBG) structure with antisymmetric quarter-elliptical walls geometry based on the computational finite element method (FEM). This structure is capable of providing a wide bandwidth spectrum for chemical sensing (ChS) operation due to the 2∆λ ≈ 110 nm wide bandgap (with a Bragg wavelength center of λB ≈ 1550 nm) and filtering out the undesired optical modes. Due to the ChS mode intensification (fundamental mode TE1 wavelength λ = 1550 nm) with a high quality (Q) factor Q = 3.565 × 103 and a very small modal volume (MVol) Vmode = 0.0012(λres/nSi)3 in the cavity area as well as confinement of the evanescent wave mode (EWM) in the air grating near the cavity (where chemical analyte, ChAn, is placed) supporting a very high confinement factor (CFac), Γ ≈ 0.45, the single-mode PhC nanobeam resonator offers a very good platform for ChS operation with very low light dissipation. The proposed nanobeam photonic resonator structure can analyze a very small surface analyte, 0.01199 µm2 of ChAn such as ethanol (C2H5OH) and water (H2O) with extremely high sensitivities SEthanol ≈ 1554.22 nm/RIU and SWater ≈ 1549.49 nm/RIU, respectively. The high sensitivity S and high Q/Vmode ratio, the capability of Label-Free sensing operation as well as being ultra-compact, indicate that the single-mode nanobeam structure as a passive photonic structure is a very practical candidate in the Lab-on-a-Chip (LOC) chemical sensor systems. [ABSTRACT FROM AUTHOR]

Ultra-small mode volume nanophotonic crystal cavities have been proposed as powerful tools for increasing coupling rates in cavity quantum electrodynamics systems. However, their adoption in quantum information applications remains elusive. In this work, we investigate possible reasons why, and analyze the impact of different low mode volume resonator design choices on their utility in quantum optics experiments. We analyze band structure features and loss rates of low mode volume bowtie cavities in diamond and demonstrate independent design control over cavity-emitter coupling strength and loss rates. Further, using silicon vacancy centers in diamond as exemplary emitters, we investigate the influence of placement imprecision. We find that the benefit on photon collection efficiency and indistinguishability is limited, while the fabrication complexity of ultra-small cavity designs increases substantially compared to conventional photonic crystals. We conclude that ultra-small mode volume designs are primarily of interest for dispersive spin-photon interactions, which are of great interest for future quantum networks. [ABSTRACT FROM AUTHOR]

In this paper, the implementation of an integrated system of half adder and half subtractor based on 2D Si-air photonic crystal is proposed. The structure includes two input ports, one control port, and two output ports. When light is absent in the control port, the structure operates as a half adder and when light is present in the control port, it functions as a half subtractor. The operation of the structure is based on the phenomenon of constructive and destructive interference of light waves. The novelty of the proposed structure is that using a single control signal, both half adder and half subtractor operations can be realized. Since no nonlinear material has been used to design the structure, the power consumption of the structure is very low. Another advantage of the structure is that same materials have been used for all the rods which makes the fabrication process easier. The structure has been simulated by utilizing PWE and FDTD methods. Different performance parameters such as contrast ratio, rise time, delay time, fall time, response time, and bit rate for the designed structure have been obtained as 14.78 dB, 0.25 ps, 0.3 ps, 0.11 ps, 0.44 ps, and 2.27 Tb/s respectively. Due to its high contrast ratio, fast response time, high bit rate, and smaller dimension, the designed structure can be a promising candidate for realizing high speed optical integrated circuits. [ABSTRACT FROM AUTHOR]

In this study, a novel approach is described for developing an electro-optic decoder utilizing a combination of photonic crystals and a graphene stack. The decoder structure comprises three main components: silicon waveguides, stacks, and one-dimensional photonic crystals. To create favorable interferences similar to reflectors based on Bragg layers, a one-dimensional array of air holes is designed in parallel with a waveguide. Within this array, a graphene-SiO2 stack is incorporated, enabling the creation of a tunable stop-band frequency filter within the wavelength range of 1489 to 1492 nm. This tunability is achieved by altering the graphene refractive index according to the applied chemical potential. By controlling the optical wave transmission through the waveguides, the transmission from the input to the output ports is effectively regulated. Simulation results indicate that decoding operation can be achieved by applying chemical potentials of 0.1 eV and 0.9 eV. The normalized power levels for logic states 1 and 0 are equal to 48% and 6.2%, respectively, resulting in a contrast ratio of 8.89 dB. Additionally, the compact size of the designed structure, occupying only 99 µm2 of space, demonstrates its advantages over previous electro-optic works, particularly in terms of realizing optical circuits. [ABSTRACT FROM AUTHOR]

Breast cancer is the most prevalent cancer in females in a large number of countries around the world. One in every twenty females gets confirmed to have breast cancer during their lifetime, though the number varies significantly by country. There are various conventional methods to spot the breast cancer cells, such as magnetic resonance imaging, X-ray mammography, biopsies, and ultrasound. The early identification of cancer cells helps to save many human lives. This paper investigates tumor detection in a breast phantom using a Photonic crystal (PhC) based hourglass terahertz patch antenna. This paper designed four different antenna structures: conventional hourglass patch antenna (with and without breast phantom) and PhC-based hourglass patch antenna (with and without breast phantom). The proposed PhC antenna models and the breast phantom are designed using the CST studio suite and analyzed the various antenna parameters. The observed S11 parameter for the proposed structures is − 21.50, − 25.34, − 33.78 and − 50.32 dB. The proposed antenna resonated in THz frequency, which does not affect human health and is safer due to non-ionizing characteristics. The suggested PhC structure is tiny, less expensive, lightweight, environmentally benign, and can be utilized as a primary screening technique for people with breast cancer, especially in resource-limited areas. [ABSTRACT FROM AUTHOR]

Urinary kidney injury molecule 1 (uKIM-1) serves as a reliable marker for the early diagnosis of acute kidney injury (AKI). The rapid and facile detection of changes in uKIM-1 is essential for early AKI diagnosis, ultimately improving the prognosis of patients. In this study, we developed a fully printed photonic crystal-integrated microarray with photonic crystal-enhanced fluorescence properties, which can detect uKIM-1 levels at the point-of-care. We confirmed its efficacy in the early diagnosis of AKI using clinical urine specimens. Direct quantitative detection of uKIM-1 was achieved within 10 min. The lowest limit of detection is 8.75 pg·mL−1 with an accuracy of 94.2%. The diagnostic efficacy was validated using 86 clinical urine samples, highlighting the high sensitivity and stability of the photonic crystal microarray. Consequently, a facile and reliable immunoassay was designed and prepared for the rapid quantitative detection of uKIM-1, which is crucial for the early identification and convenient detection of AKI in hospital or community settings. Rapid, convenient, cost-effective, and long-term monitoring of changes in uKIM-1 levels can assist clinicians in making timely adjustments to treatment regimens, preventing the transition from AKI to chronic kidney disease (CKD), improving the quality of life of patients with AKI, and reducing healthcare costs. It highlights the advantages of utilizing urine samples as a noninvasive and easily accessible medium for early detection and monitoring of kidney-related conditions. [ABSTRACT FROM AUTHOR]

Optical cavities play crucial roles in enhanced light-matter interaction, light control, and optical communications, but their dimensions are limited by the material property and operating wavelength. Ultrathin planar cavities are urgently in demand for large-area and integrated optical devices. However, extremely reducing the planar cavity dimension is a critical challenge, especially at telecommunication wavelengths. Herein, we demonstrate a type of ultrathin cavities based on large-area grown Bi2Te3 topological insulator (TI) nanofilms, which present distinct optical resonance in the near-infrared region. The result shows that the Bi2Te3 TI material presents ultrahigh refractive indices of >6 at telecommunication wavelengths. The cavity thickness can approach 1/20 of the resonance wavelength, superior to those of planar cavities based on conventional Si and Ge high refractive index materials. Moreover, we observed an analog of the electromagnetically induced transparency (EIT) effect at telecommunication wavelengths by depositing the cavity on a photonic crystal. The EIT-like behavior is derived from the destructive interference coupling between the nanocavity resonance and Tamm plasmons. The spectral response depends on the nanocavity thickness, whose adjustment enables the generation of obvious Fano resonance. The experiments agree well with the simulations. This work will open a new door for ultrathin cavities and applications of TI materials in light control and devices. [ABSTRACT FROM AUTHOR]