Applications Of Photonic Crystals Research Articles

Crystalline Assemblies of DNA Nanostructures and their Functional Properties.

Self-assembly presents a remarkable approach for creating intricate structures by positioning nanomaterials in precise locations, with control over molecular interactions. For example, material arrays with interplanar distances similar to the wavelength of light can generate structural color through complex interactions like scattering, diffraction, and interference. Moreover, enzymes, plasmonic nanoparticles, and luminescent materials organized in periodic lattices are envisioned to create functional materials with various applications. Focusing on structural DNA nanotechnology, here, we summarized the recent developments of two- and three-dimensional lattices made purely from DNA nanostructures. We review DNA-based monomer design for different lattices, guest molecule assembly, and inorganic material coating techniques and discuss their functional properties and potential applications in photonic crystals, nanoelectronics, and bioengineering as well as future challenges and perspectives.

Giant lateral shift in single mode cavity containing four-level sodium atomic medium

Abstract In this paper, a four-level sodium atomic medium coupled to a single-mode cavity is used to investigate the Goos-Ha¨nchen (GH) shift. Using the collective phase of the control fields and intensity of Rabi oscillation, the positive as well as negative GH-shift in transmission and reflection beams are examined. In the transmission beam, a maximum GH-shift of ±6λ is observed. Furthermore, GH-shift in both reflection and transmission beams in a four-level sodium atomic medium is significantly enhanced by photon number density as well as by the cavity coupling strength. By varying the collective phase of the control fields and the probe field frequency, GH-shift in reflection exhibits a maximum value of ±2λ. Our findings may open up significant applications in micro-optics, sensors, photonic crystals and nano-processor technology.

Infrared Stealth Coating with Tunable Structural Color Based on ZnO Spheres.

It is important to develop low infrared (IR) emissive coating with tunable structure color to improve the infrared-visible stealth performance of military equipment. In this work, uniform ZnO spheres are used as building units to construct photonic structures with both bright adjustable structure color and low IR emissivity due to the relatively high refractive index and low IR emissivity of ZnO. The vivid tunable structural colors are provided by the photonic bandgap of ZnO photonic crystals (PCs) or the quasi-bandgap of amorphous photonic crystals (APCs), respectively. Both ZnO PCs and APCs exhibited low IR emissivity in 3-5µm. The IR emissivity of 255nm ZnO PCis 0.483 and the IR emissivity of 255nm ZnO APC is 0.492 at 25°C. With the increase of temperature, the IR emissivity offurther decreased to 0.295 and 0.312 at 300°C. These structures can be applied to a variety of surfaces, and all these structures have good thermal and light stability as well. This work may open a simple and effective way to fabricate materials with good infrared-visible stealth performance, expanding the application of ZnO PCs and APCs coatings in the camouflage area.

Photonic defect modes in cholesteric liquid crystal resonators with embedded isotropic layers

Photonic defect modes are explored as a viable alternative to standard photonic band edge modes in photonic crystal applications, especially due to their typically high Q-factors and local density of states. For example, they can be used in nonlinearity enhancement, lasing, and cavity quantum electrodynamics. However, they are strongly dependent on any structural change and need to be well-controlled to ensure the desired resonance frequency. Here, we present a study of the photonic defect modes that appear in a structure where a layer of isotropic material is embedded between two layers of cholesteric liquid crystal (CLC), using full electrodynamics numerical simulations. We present typical transmission spectra and electric field profiles of selected defect modes and then analyze the influence of geometrical and material parameters on the eigenfrequencies and Q-factors of the modes within and around the photonic bandgap, including refractive indices and thicknesses of isotropic and liquid crystal layers, and different anchoring orientations at the boundaries of the isotropic defect layer. Additionally, a connection of such defect modes to previously extensively analyzed twist defect modes is given. Eigenmodes in asymmetric resonators are also presented, where CLC layers surrounding the intermediate isotropic layer are not equally thick, enabling biasing of specific directional light emission. More generally, this work aims to contribute to the understanding and design capability in topological soft matter photonics where defect mode lasing could be realized in CLC geometries with different singular and solitonic topological defect structures.

Prediction of Electric Load Neural Network Prediction Model for Big Data

In this study, the two-dimensional hexagonal Photonic crystal energy band structure was simulated using COMSOL Multiphysics field simulation software. The 2D hexagonal Photonic crystal structure was constructed by setting parameters such as periodic boundary conditions and air hole radius. Using the frequency domain solver of COMSOL software, the transmission and reflection spectra of the structure were calculated, and the energy band structure diagram was obtained. The effects of different parameters on the energy band structure were analyzed by adjusting the structure parameters. The results show that the fine tuning of the energy band structure of 2D hexagonal Photonic crystals can be realized by adjusting the radius of air holes and the periodic boundary conditions. This study provides a useful reference for further research on the properties and applications of 2D photonic crystals.

Limitations in design and applications of ultra-small mode volume photonic crystals

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.

Three-Dimensional Photonic Crystals Based on Porous Anodic Aluminum Oxide.

Photonic crystals (PCs) consisting of a periodic arrangement of holes in dielectric media have found success in light manipulation and sensing. Among them, three-dimensional (3D) PCs are in high demand due to their unique properties originating from multiple photonic band gaps (PBGs) and even full ones. Here, 3D PCs based on porous anodic aluminum oxide (AAO) were fabricated for the first time. Our approach involves prepatterning of the aluminum surface by a focused ion beam to form a hexagonal array of pore nuclei. Subsequent anodization in 1 M H3PO3 using a sine wave profile of voltage provides AAO with a defect-free in-plane porous structure and out-of-plane porosity modulation. The ability to tune the position, width, and depth of the PBGs is demonstrated. The combination of the flexibility of the proposed approach with the unique properties of AAO extends the range of practical applications of 3D PCs far beyond the current achievements.

Photonic crystal-coupled enhanced steering emission: A prism-free, objective-free, and metal-free loss-less approach for biosensing

Diagnostic assays utilizing fluorescent reporters in the context of low abundance biomarkers for cancer and infectious disease can reach lower limits of detection through efficient collection of emitted photons into an optical sensor. In this work, we present the rational design, fabrication, and application of one-dimensional photonic crystal (PC) grating interfaces to accomplish a cost-effective prism-free, metal-free, and objective-free platform for augmentation of fluorescence emission collection efficiency. Guided mode resonance (GMR) of the PC is engineered to match the laser excitation (532 nm) and emission maximum (580 nm) of the radiating dipoles to arrive at optimized conditions. The photo-plasmonic hybrid nano-engineering using silver nanoparticles presented >110-fold steering fluorescence enhancement enabling placement of the sample between the excitation source and detector that are in a straight line. From the experimental and simulation inferences, we propose a radiating GMR model by scrutinizing the polarized emission properties of the hybrid substrate, in accordance with the radiating plasmon model. The augmented fluorescence intensity realized here with a simple detection instrument provides sub-nanomolar sensitivity to provide a path toward point-of-care scenarios.

Regulating two-dimensional colloidal crystal assembly through contactless acoustic annealing

Two-dimensional colloidal crystals assembled from polystyrene nanospheres have emerged as a pivotal foundation for fabricating large-area nano-functional surfaces. These assemblies, defined by their hexagonal close-packed configuration and interlaced with grain boundaries, have garnered significant attention for applications in plasmonic structures, catalysts, photonic crystals, and inverse opals. Nonetheless, achieving consistent large-scale regularity has proven challenging due to unpredictable crystal growth and the introduction of defects. Utilizing acoustic waves excited from the airside, our experiments demonstrate the significant effects of such waves on the self-assembly process, leading to larger crystal domains and reduced defects. In comparison to the extensively studied water-end excitation techniques, our air-end excitation method introduces a novel dynamic in regulating colloidal monolayer crystallization and presents a comprehensive analysis of varying acoustic parameters, frequency, amplitude, and waveform. These findings reveal the potential of airside acoustic annealing in refining the structure of two-dimensional colloidal arrays. To elucidate our experimental observations, we delve into the theoretical underpinnings of particle dynamics, driven by classical hydromechanical constraints like surface tension and gravity. Using a qualitative estimate, we shed light on the resonant excitations and their potential role in optimizing the self-assembly process, especially focusing on resonances pertinent for enhancing cluster enlargements. Conclusively, our research, steeped in robust theoretical frameworks and groundbreaking experimental techniques, offers a multifaceted solution for perfecting two-dimensional colloidal arrays. This combined approach not only broadens the scope of acoustically induced crystallization but also charts a path for its adoption across diverse environments, signaling transformative prospects for nanomanufacturing and optical research.

Photonic crystal and Ti nanoparticles enhanced high-absorption GaAs thin-film solar cell

The research aims to investigate the application of photonic crystals and metal nanoparticles in the design of thin-film solar cell (TFSC). The propagation of electromagnetic waves in the vicinity of the cell and the light absorption process were simulated to analyze the performance variations of GaAs TFSC combining GaAs photonic crystals and Ti nanoparticles. By optimizing the cell model structure and doping concentration, we achieved high absorption across a broader wavelength spectrum. The research indicates that the incorporation of photonic crystals effectively extends the optical path length within the solar cell, while the integration of metal nanoparticles further enhances the cell's light absorption efficiency. Ultimately, the cell model proposed in this article achieves efficient light absorption in the wavelength range of 400–860 nm, with the absorption rates of the cell consistently exceeding 90% across all spectral bands. And nearly perfect absorption is realized in the wavelength range of 728–860 nm. Simultaneously, the performance of the cell exhibits significant improvements, culminating in a photoelectric conversion efficiency (PCE) of 34.48%. This research provides useful guidance for the development of solar cell technology and makes a positive contribution to the sustainable utilization of clean energy.

Quantitative Evaluation of the Relationship between Strain and Color Change in Opal Photonic Crystal Films and Application into Complex Specimen Geometries

The color change of opal photonic crystal films (OPCFs) due to deformation was quantitatively evaluated using digital image correlation (DIC) analysis. OPCFs were pasted on specimens of three different gauge geometries, and random patterns were formed on the opposite side of each specimen for DIC analysis. To assess the applicability of using OPCFs-based strain characterization for analyzing steel structural components and associated metallurgical analyses, smooth, width-gradient, and holed specimens were prepared in this study. As deformation increased in the smooth specimen, the color of the OPCFs changed significantly. The color change in the OPCFs could be quantitatively converted into strain values through Hue value analysis. Heterogeneous strain distributions could also be quantitatively analyzed using OPCFs-based analysis at the submillimeter or millimeter scale. When the strain gradient is too high, for example, near a stress concentration site such as a hole, local peeling of the OPCFs away from the specimen surface can occur. Consequently, for quantitative characterization, we must take proper care when measuring this upper limit of the “strain gradient” as well as strain, which would depend on the adhesion and surface condition of the specimen.

Spontaneous formation of liquid-crystalline nuclei in blue-phase liquid crystals based on different chirality

The self-assembly of three-dimensional nanostructures of blue-phase liquid crystals is becoming the spotlight of soft matter research and has potential applications in photonic crystals, sensors, electro-optic devices, and others.

Dual-band semi-Dirac cones in two-dimensional photonic crystal and zero-index material

<sec>Semi-Dirac cones, a type of unique dispersion relation, always exhibit a series of interesting transport properties, such as electromagnetic topological transitions and anisotropic electromagnetic transmission. Recently, dual-band semi-Dirac cones have been found in three-dimensional photonic crystals, presenting great potential in electromagnetic wave regulation. However, to the best of our knowledge, there has been no report on dual-band semi-Dirac cones and their applications in two-dimensional photonic crystals, and most of two-dimensional systems have only realized semi-Dirac cones at a single frequency. Therefore, we are to realize dual-band semi-Dirac cones in two-dimensional photonic crystals.</sec><sec>In this work, a type of two-dimensional photonic crystal that comprises a square lattice of elliptical cylinders embedded in air is proposed. By rotating the elliptical cylinders and adjusting their sizes appropriately, accidental degeneracy at two different frequencies is achieved simultaneously in the center of the Brillouin zone. Using <inline-formula><tex-math id="M2">\begin{document}${\boldsymbol{k}} \cdot {\boldsymbol{p}}$\end{document}</tex-math><alternatives><graphic specific-use="online" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="18-20240800_M2.jpg"/><graphic specific-use="print" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="18-20240800_M2.png"/></alternatives></inline-formula> perturbation theory, the dispersion relations near the two degenerate points are proved to be nonlinear in one direction, and linear in other directions. These results indicate that the double accidental degenerate points are two semi-Dirac points with different frequencies, and two different semi-Dirac cones, i.e. dual-band semi-Dirac cones, are realized simultaneously in our designed photonic crystal. More interestingly, the dual-band semi-Dirac cones exhibit opposite linear and nonlinear dispersion relation along the major axis and the minor axis of the ellipse, respectively. And our photonic crystal can be equivalent to an impedance-matched double-zero index material in the direction of linear dispersion and a single-zero index material in the direction of nonlinear dispersion, which is demonstrated by the perfect transmission in the straight waveguide and wavefront shaping capabilities of electromagnetic waves. Based on the different properties of the equivalent zero-refractive-indices near the frequencies of two semi-Dirac point, the designed Y-type waveguide can be used to realize frequency separation by leading out the plane waves of different frequencies along different ports. We believe that our work is meaningful in broadening the exploration of the band structures of two-dimensional photonic crystals and providing greater convenience for regulating electromagnetic waves.</sec>

Terahertz gas sensor and its application in gas detection of power pipe gallery

During the operation of a power cable duct, the content of flammable gas is an important element in the safety of the cable duct. The accurate detection and location of gas in the pipeline corridor are important to improve the safety and stability of the power system. In view of the change of the refractive index of the gas in the power cable tube gallery, this paper presents the important application of terahertz one-dimensional photonic crystals with high-quality factors in gas sensing, change of the gas refractive index in the tube gallery simulated, and the gas refractive index change in the tube gallery can be obtained accurately by analyzing the change of transmission peak at terahertz range, the potential of terahertz sensor in gas detection in power tube gallery is verified.

Application of Photonic Crystals for the Generation of Broadband Radiation at the LINAC-200 Linear Accelerator

Application of Photonic Crystals for the Generation of Broadband Radiation at the LINAC-200 Linear Accelerator

Coherent perfect absorber and laser induced by directional emissions in the non-Hermitian photonic crystals

In this study, we propose the application of non-Hermitian photonic crystals (PCs) with anisotropic emissions. Unlike the ring of exceptional points (EPs) found in isotropic non-Hermitian PCs, the EPs of anisotropic non-Hermitian PCs appear as symmetrical lines about the Γ point. The formation of EPs is related to the non-Hermitian strength and the real spectrum appears in the ΓY direction. The PCs have been validated as the complex conjugate medium (CCM) by effective medium theory (EMT). Conversely, EMT indicates that the effective refractive index has a large imaginary part along the ΓX direction, which forms an evanescent wave inside the PCs. Consequently, coherent perfect absorption (CPA) and laser can be achieved in the directional emission of the ΓY. The outgoing wave in the ΓX direction is weak, which can significantly reduce the losses and electromagnetic interference. The non-Hermitian PCs enable many fascinating applications such as signal amplification, collimation, and angle sensors.

Realizing the topological rainbow based on cavity-coupled topological edge state

Topological photonic crystals (PCs) can support topologically protected states of light. These states are immune to backscattering and can be used to construct a variety of optical devices. One promising application of topological PCs is the formation of a topological rainbow. We propose a method for realizing a topological rainbow based on cavity-coupled topological edge state (TES) in a topological photonic crystal waveguide (TPCW). This is a new type of cavity coupled TPCW, in which the cavity is located inside the waveguide at the interface between two topologically distinct PCs. We demonstrated that by varying the cavity length in the TPCW, the separation of different frequencies of topological states can be controlled. Moreover, we showed that the topological rainbow is unaffected by the cavity shape inside the TPCW. This method is more robust and versatile than previous methods, as it is unaffected by the cavity shape. This makes it possible to create topological rainbow in a wide variety of high-performance devices. For example, it could be used to build topological rainbow in integrated circuits, which would be very difficult if the cavity shape was precisely controlled. We hope our findings will inspire further research in this area and lead to the development of new and innovative optical devices.

Electrically Tunable Topological Notch Filter for THz Integrated Photonics

AbstractElectromagnetic filtering is essential for emerging integrated photonic technologies and widely adaptable processing of high‐bandwidth signals. The conventional electro‐optic modulator‐based photonic approach for signal filtering at microwave frequencies cannot be implemented at terahertz (THz) frequencies due to the unavailability of the THz signal‐driven optical modulator. Here, an electrically tunable on‐chip THz photonic notch filter based on the topologically protected valley hall waveguide‐cavity platform is demonstrated. The device shows a significantly large notch suppression depth of more than 20 dB with a return loss of 13 dB in the entire tuning range of notch frequency. The feedback control circuit enables precise control of the notch frequency shift with a minimum step size of 7 MHz. This work extends the application of topological photonic crystals in developing THz‐integrated photonic devices for transformative technologies, including sixth‐generation (6G) communication and high‐resolution spectral sensing.

Research on applications of photonic crystals

A photonic crystal is a dielectric structure in which the refractive index varies periodically in space. Due to its special physical properties, it has theoretical research value and wide application prospects. This paper introduces photonic crystals from the aspects of principle, preparation and application, and makes a summary and outlook on them. This paper focuses on the basic principles and applications of photonic crystals, so as to help more people to have a general understanding of photonic crystals.

Bottom-up assembled photonic crystals for label-free sensing: Evaluation between photonic band gap and Fabry−Pérot fringes

The major challenge of the application of photonic crystals (PhCs) biosensors is the test sensitivity, selectivity, and reliability of the target analytes in complex real samples, like bodily fluids. Herein, we introduce the concept of utilizing the optical thickness (OT), which came from Fabry−Pérot fringes (F−P fringes), of bottom-up assembled PhCs to replace the traditional photonic band gap (PBG) as a parameter for biosensing process monitoring and quantification of analytes. The bottom-up assembled silica PhCs films are specialized to own a thickness with good interferometric properties and an ordered porous interconnecting and mechanically stable structure as a scaffold for biological reactions. By selecting a specific diameter (190 nm) of the silica PhCs building block, both PBG and F-P fringes can be observed on the spectrum simultaneously at the range of white light, and during detection, mutual interference between the two can be minimized to a great extent. This study finds that nearly 14 times lower low limit of detection (LLoD) can be achieved with F−P fringes than the PBG in ethanol concentration benchmark test on the same silica PhCs film. The thrombolysis experiment and human immunoglobulin G content evaluation in human plasma also show the sensitivity and reliability of F−P fringes in real samples, which PBG property can not perform well. This is the first systematic comparison study on PBG and F−P fringes in silica PhCs films.