2D Photonic Structures Research Articles

Frequency Division Multiple Access with High Performance Based on Several Defect Resonators According to the Fibonacci Sequence in 1D Photonic Star Waveguide Structure

Frequency Division Multiple Access with High Performance Based on Several Defect Resonators According to the Fibonacci Sequence in 1D Photonic Star Waveguide Structure

2D Photonic Colloidal Liquid Crystals Composed of Self-Assembled Rod-Shaped Particles.

Photonic crystals, characterized by their periodic structures, have been extensively studied for their ability to manipulate light. Typically, the development of 2D photonic crystals requires either sophisticated equipment or precise orientation of spherical nanoparticles. However, liquid-crystalline (LC) materials offer a promising alternative, facilitating the formation of periodic structures without the need for complex manipulation. Despite this advantage, the development of 2D photonic periodic structures using LC materials is limited to a few colloidal nanodisk liquid crystals. Herein, 2D photonic colloidal liquid crystals composed of biomineral-based nanorods and water is reported. The soft photonic materials with 2D structure by self-assembled LC colloidal nanorods are unique and a new class of photonic materials different from conventional solid 2D photonic materials. These colloids exhibit bright structural colors with high reflectance (>50%) and significant angular dependency. The structural colors are adjusted by controlling the concentration and size of the LC colloidal nanorods. Furthermore, mechanochromic hydrogel thin films with 2D photonic structure are developed. The hydrogels exhibit reversible mechanochromic properties with angular dependency, which can be used for an advanced stimuli responsible sensor.

Understanding of bandgap engineering in a 2D photonic structure for the realization of narrow white light

Understanding of bandgap engineering in a 2D photonic structure for the realization of narrow white light

Double-pulse-laser volumetric modification of fused silica: the effect of pulse delay on light propagation and energy deposition.

Volumetric modification of dielectrics by ultrashort laser pulses is a complex dynamic phenomenon involving material photoexcitation and associated nonlinear processes. To achieve control over modification, it is necessary to gain a deep insight into the dynamics of laser-excited processes that can be realized using double-laser-pulse experiments with different time separations supported by numerical simulations. In this paper, we apply this approach to investigate fused silica modification with femtosecond laser pulses that provides time-resolved information about the dynamic behavior of the laser-excited bandgap material. It is shown that the laser-generated free-electron plasma causes a shielding effect for the following pulse with a characteristic duration of ∼600 fs after the pulse action. Within this time interval, the second pulse produces a reduced modification as compared to a longer time separation between pulses. For double pulses with different energies, it was found that the volumetric modification is stronger when a lower-energy pulse couples with material first. This is explained by the combination of the effects of the re-excitation of self-trapped excitons, which are generated as a result of free electron recombination and associated light shielding. Experimental results are supported by numerical simulations of double laser pulse propagation in nonlinear media based on Maxwell's equations. Our findings offer a route for better controlling the inscription of 3D photonic structures in bulk optical materials.

Recent Advances in 1D Photonic Crystals: Diverse Morphologies and Distinctive Structural Colors for Multifaceted Applications

Abstract1D photonic crystals (1DPCs) with hierarchically structured lamellar periodic frameworks that enable precise control of light‐matter interactions and contribute robust structural colors represent a groundbreaking advancement in optical materials. The microstructural characteristics and the constituent material properties of these photonic materials play pivotal roles in determining their optical performance and functionality. In recent years, a diverse array of novel 1D photonic structures crafted from various materials emerged, showcasing their tremendous potential in advanced applications. This article provides an in‐depth review of the recent developments in 1DPCs, emphasizing their morphological designs, fabrication strategies, and optical applications. In detail, 1DPCs featuring distinct geometrical morphologies, including lamellar, helical, fibrous, spherical, and nanochained structures are systematically introduced, highlighting the unique optical properties arising from their periodic microstructures. Then, various fabrication methods, involving some innovative techniques utilizing standing‐wave optics, UV dual photopolymerization, and inkjet printing, are succinctly summarized for constructing different photonic structures by using diverse building materials. Subsequently, some typical application examples of 1D photonic materials are listed and discussed involving visual sensing, intelligent displays, anti‐counterfeiting technology, photonic pigments, and optical devices. Finally, the passage addresses the current challenges and presents a forward‐looking perspective on the future fabrication and application of 1DPCs.

Three-dimensional perovskite-based photonic structures made by two-step crystallization

Three-dimensional (3D) photonic structure made of light-emitting materials is a prospective platform for designing lasers and 3D displays, where directivity and efficiency of the emission are highly demanded. While the fabrication of two-dimensional (2D) light-emitting photonic structures is a well-developed technology, the extension of dimensionality up to 3D requires complex and multistep approaches. In this regard, solution-processible halide perovskites are promising materials, which can be easily integrated with various scaffolds supporting optical modes. Here we demonstrate a novel simple two-step technique for fabrication of halide perovskite-based light-emitting 2D and 3D photonic structures based on femtosecond laser photopolymerization and further perovskite growth inside the structures. High defect tolerance of halide perovskites supports synthesis of high-quality material inside the photonic structures, which demonstrate amplified spontaneous emission and stable laser generation. Moreover, we show that the developed method is rather universal and allows for the successful fabrication of photonic structures filled by the various halide perovskites like all-inorganic, organic–inorganic, bromide, and chlorine ones.

High-power and high-beam-quality photonic-crystal surface-emitting lasers: a tutorial

Realization of single-mode, high-power and high-beam-quality (namely, high-brightness) semiconductor lasers, which can rival or even replace bulky lasers such as gas, solid, and fiber lasers, is one of the ultimate goals of laser physics and photonics. The demand for such ultimate single-mode high-brightness semiconductor lasers is increasing for a wide variety of emerging applications including next-generation remote sensing for smart mobility and high-precision laser processing for smart manufacturing. Photonic-crystal surface-emitting lasers (PCSELs) show promise to meet these demands, based on their broad-area coherent two-dimensional (2D) resonance at a singularity (Γ) point of their 2D photonic band structure. In this tutorial paper, the lasing principle, theoretical analysis, and experimental demonstration of PCSELs are described. Recent progress in PCSEL development, including the formulation of a design guideline for realizing 100-W-to-kW-class single-mode operation, the experimental demonstration of a brightness of 1 GW cm–2 sr–1, and an extension of the lasing wavelengths to telecommunication and mid-infrared wavelengths are also covered.

Understanding the coupling between MIM cavities due to single and double Tamm plasmon polaritons

The interplay between light and matter plays a crucial role in various applications, ranging from sensor technologies to integrated optoelectronic architectures. In this contribution, a systematic numerical study is made over the symmetry role of the 1D photonic structures (PhSs) containing a low number of slabs embedded in thin metal layers, in order to find the adequate conditions to enhance the quality factor of resonances and energy confinement in the subwavelength scale. We show the existence of single and double Tamm plasmon polaritons (TPPs) states according to the symmetry of the PhS, which allow to tune weak and strong coupling regimes with Metal–Insulator–Metal (MIM) platforms combined in a unique MIM-PhS-MIM structure. We found that while weak coupling is observable between MIM and PhS states at the PhS cavity mode wavelengths, strong coupling among the 2 MIMs and the PhS is obtained only at the TPP resonance wavelengths, exhibited by anti-crossing splittings at adequate insulator thicknesses. We found that for the double Tamm plasmon polaritons, the energy splitting can reach up to 134 meV, unlike the single TPPs where the maximum energy splitting is on the order of 50 meV. The degree of coupling was explained by the implementation of a variational method that exploits the analogy the optical superlattice herein proposed and an analogous superlattice quantum well. This article shows that TPP resonances are responsible for the coherent coupling between the two MIMs placed at a long distance given by the PhSs. Thus, these platforms provide an interesting and experimentally accessible route for the coupling of emitters in optoelectronic devices.

High Performance Biosensor for Detection of the Normal and Cancerous Liver Tissues Based on 1D Photonic Band Gap Material Structures

High Performance Biosensor for Detection of the Normal and Cancerous Liver Tissues Based on 1D Photonic Band Gap Material Structures

Self-adaptive IR emitter with a solution-processed VO2 active layer for tunable radiative cooling

Controlling the infrared (IR) emissivity of a photonic structure as a function of temperature is essential for regulating thermal emission. However, such self-adaptive radiative control often requires sophisticated fabrication processes to achieve the desired emissivity modulation, making large-scale implementation challenging. Here, we demonstrated a simple 1D photonic structure consisting of spin-coated VO2/ZnS/Al that does not require a costly vacuum deposition and/or lithography process for forming the active layer. Based on the phase change in VO2, over 50% modulation depth of peak emissivity was achieved in the atmospheric window. We also unraveled the optical constants of the solution-processed VO2 films using IR ellipsometry under temperature control, enabling realistic prediction of the emissive performance.

Study of radiation power spectra in the 1-D photonic periodic dielectric structure

We explored the thermal power radiation spectrum ρ (ω, T) of electromagnetic radiation in a 1D photonic periodic structure combining Si and Sio2 with truncated Sio2 media and an absorbing substrate. A theoretical model based on a transfer matrix for both normal and oblique incidence angles together with Kirchhoff’s second rule is used to predict the thermal radiation power spectrum. In order to study the radiation spectra, we used the TE and TM modes with truncation parameters and incidence angles in the mid, left, and right gap frequencies, which correspond to the mid, left, and right mid-gap temperatures. Layers nA&nB are A and B’s indices are considered to be constant and controlled in these modes.

Observation of Weyl Interface States in Non-Hermitian Synthetic Photonic Systems.

Weyl medium has triggered remarkable interest owing to its nontrivial topological edge states in 3D photonic band structures that were mainly revealed as surface modes yet. It is undoubted that the connection of two different Weyl media will give rise to more fruitful physics at their interface, while they face extreme difficulty in high-dimensional lattice matching. Here, we successfully demonstrate the non-Hermitian Weyl interface physics in complex synthetic parameter space, which is implemented in a loss-controlled silicon waveguide array. By establishing non-Hermitian Hamiltonian in the parameter space, new Weyl interfaces with distinct topological origins are predicted and experimentally observed in silicon waveguides. Significantly, our Letter exploits the non-Hermitian parameter to create the synthetic dimension by manipulating the non-Hermitian order, which successfully circumvents the difficulty in lattice matching for high-dimensional interfaces. The revealed rich topological Weyl interface states and their phase transitions in silicon waveguide platform further imply potentials in chip-scale photonics integrations.

Responsive Spiral Photonic Structures for Visible Vapor Sensing, Pattern Transformation and Encryption

AbstractTwo photon polymerisation using direct laser writing is a burgeoning field of research, with recent focus being placed on bringing added value to microstructures, by incorporating soft, responsive polymers. Moving to the micron‐scale can have a profound impact on such stimuli‐responsive materials, whose speed of actuation can be increased many‐fold compared to their mm‐scale counterparts. Here, the fabrication of submicron 2D photonic structures, based on a vapor‐responsive photoresist with a refractive index <1.55, in the visible wavelength range. The fabricated concentric spiral arrays are evaluated for their feasibility as vapor sensors by testing spectral and structural color reproducibility and reversibility under water, ethanol, isopropanol, and acetone vapors. This approach allows for the realization of predictable uniform color displays that can be modulated upon stimuli response. The transmitted colour in the dry and hydrated states can be accurately modelled. This knowledge is used to design and demonstrate structures for cloaking and image transformation. Such capability can be used for encryption and anti‐counterfeiting applications.

Photopolymerization of 1D photonic structures induced by nematic-isotropic phase transition in liquid crystal.

In this paper, two types of polymer-stabilized periodic structures created by photopolymerization of a nematic liquid crystal confined in a cylindrical structure are presented. Both types of structures were induced by nematic-isotropic phase transition in liquid crystal doped with gold nanoparticles. The first type of structure was created by stabilizing periodic phase separation at the nematic-isotropic phase transition temperature. As a result, a periodic structure with two distinct molecular orientations of nematic liquid crystal was achieved. The period of this structure was equal to the period induced by nematic-isotropic phase separation. The second type of structure, also related to the phase transition, was created due to an induced periodic density change of gold nanoparticles in the sample volume. Through photopolymerization it was possible to preclude the dispersion of gold nanoparticles while preserving the periodicity. An increased concentration of gold nanoparticles caused periodic defects in molecular orientation of the liquid crystal. Both types of structures were stable at room temperature. Consequently, two types of 1D photonic structures stabilized by photopolymerization are presented.

Investigation on Enamel and Dentine of Tooth through 1D Photonic Structure to Identify the Caries in Human Teeth.

In this research, a one-dimensional (1D) photonic structure was employed to study the nature of both enamel and dentine teeth at the signal of 1.8 THz. A simple three layer one-dimensional crystal is chosen to avoid fabrication intricacy. The materials and methods for sample preparations are discussed. The principle of investigation of caries in the teeth relies on the amount of reflected signal from the structure. Similarly, reflectance is a function of refractive indices and thickness of each layer, the nature of both substrate and infiltrated materials, and the configuration of the structure. Apart from this, the fabrication process of one-dimensional structure and experimental set-up was proposed in this article. The numerical treatment is explained here to obtain reflectance, and subsequently, the output potential. Comparison studies on output potential between enamel and dentine are also shown through graphical representation. The output result in terms of milli-Volt (mV) were obtained at the output end and collected at the photodiode. Interesting results were also observed at the photodetector. For example; the output potential of the reflected signal is around 0.18 mV for both enamel and dentine teeth whereas the potential is more than 0.26 mV and 0.31 mV for caries in dentine and enamel, respectively. Finally, it was inferred that the nature of teeth pertaining to the caries in the enamel and dentine teeth can be investigated by identifying the amount of potential at the output end.

Mathematical theory for topological photonic materials in one dimension

This work presents a rigorous theory for topological photonic materials in one dimension. The main focus is on the existence of interface modes that are induced by topological properties of the bulk structure. For a general 1D photonic structure with time-reversal symmetry, we investigate the existence of an interface mode that is induced by a Dirac point upon perturbation. Specifically, we establish conditions on the perturbation which guarantee the opening of a band gap around the Dirac point and the existence of an interface mode. For a periodic photonic structure with both time-reversal and inversion symmetry, the Zak phase is quantized, taking only two values . We show that the Zak phase is determined by the parity (even or odd) of the Bloch modes at the band edges. For a photonic structure consisting of two semi-infinite systems on the two sides of an interface with distinct topological indices, we show the existence of an interface mode inside the common gap. The stability of the mode under perturbations is also investigated. Finally, we study resonances for finite topological structures. Our results are based on the transfer matrix method and the oscillation theory for Sturm–Liouville operators. The methods and results can be extended to general topological Sturm–Liouville systems in one dimension.

Performance Improvement of Thin-Film Solar Cells Using 1D Photonic Structures Optimized by Genetic Algorithm

Performance Improvement of Thin-Film Solar Cells Using 1D Photonic Structures Optimized by Genetic Algorithm

Light dynamics around an exceptional point in a 1D photonic bandgap waveguide

Exceptional points (EP) in a system parameter space at which eigenvalues and corresponding eigenvectors coalesce are ubiquitous in non-Hermitian systems. Many unconventional applications have been proposed while encircling around the EPs. One of the unique application is the direction-dependent mode conversion. Here the appearance of an EP has been investigated in a planar 1D Bragg reflection waveguide(BRW) geometry, which has provided an additional degree of freedom to explore EP-based exotic light dynamics. A planar 1D BRW consists of periodic dielectric arrays and a defect dielectric layer forming the core. An inhomogeneous customized gain-loss profile is incorporated in the core region to couple two quasi-guided transverse electric (TE) modes so that the waveguide hosts an EP of order two. Here, we propose a dynamical EP encirclement scheme and corresponding asymmetric mode conversion phenomenon between two photonic bandgap quasi-guided TE modes in a 1D photonic bandgap-guided structure. Our findings will be potentially important to open up a fertile platform using the paradigm of non-Hermitian coupling to meet a wide range of exotic integrated chip-scale applications in the context of mode selectivity for switching and conversion.

Computational Modelling of Doubly‐Photopolymerized Holographic Biosensors

AbstractHolographic sensors are optical devices capable of tuning reflection wavelength, dependent upon nanostructured variations in refractive index. Computational modelling is utilized to simulate the recording and swelling characteristics of developed doubly photopolymerized (DP) holographic sensors. The holographic devices simplify fabrication processes, reduce financial costs, and improve biocompatibility. A holographic grating is achieved through in situ photopolymerization of a highly crosslinked polymer to produce nanostructured refractive index modulation. The unique swelling characteristics DP holographic sensors possess necessitate the development of system‐specific computational modelling. Hydrogel parameters, including film thickness, refractive index change, layer number, and external medium refractive index are examined for their effect on reflection spectra. Optimized computational models are utilized to study the effect of differential swelling rates of individual layer spacings on sensor response, indicating an idealized reduction in a swelling of 50% for the highly crosslinked region. A 2D photonic crystal geometry with additional periodicity is developed, to inform further sensor design opportunities. Optimized parameters for both 1D and 2D photonic structures will assist the further development of DP holographic sensors.

1D randomized photonic crystals: influence as single- and dual-channel narrowband filter

Nowadays, optical filters with high-level performance are highly demanded. While examining the light transmission properties of both periodic and random one-dimensional (1D) photonic crystals, it is observed that random 1D photonic structures have more favorable properties to meet these demands. With the influence of randomness, novel single- and dual-channel narrowband filters at a 1550 nm wavelength for optical telecommunication are presented in this study. For designing narrowband filters, the central wavelength precision, quality factor and peak transmission are of great importance. Randomness can be attained by permuting the refractive indices of two dielectric materials through the binomial coefficient method, wherein the light transmission properties are calculated using the transfer matrix method. The proposed filters show a minimum full width at half maximum of 0.24 nm in the single-channel narrowband filter and 0.08 and 0.095 nm in the dual-channel narrowband filter at the chosen spectral region. This filters have ultra-narrowband transmission peaks compared with those of existing narrowband filters based on defective 1D photonic structures.