2D Photonic Crystals Research Articles

Conventional Biophotonic Sensing Approach for Sensing and Detection of Normal and Infected Samples Containing Different Blood Components

The present research work focused on the biosensing capabilities of one-dimensional (1D) defected photonic crystal (PC). This proposed structure is capable of simultaneously discriminating between normal and infected samples containing the platelet, plasma, and hemoglobin components of blood. The proposed biosensor was designed by creating a defect layer D of air in the middle of 1D PC (PQ)N to form modified 1D PC with a defect as (PQ)N/2D(PQ)N/2. The period number (N) of 1D PC (PQ)N was chosen to be 10. The cavity region of air was used to investigate only one of the five samples, at each time, that are part of this study. The theoretical findings of the proposed work were obtained using the well-known transfer matrix method in addition to MATLAB software. The results were computed corresponding to defect layer thicknesses of 200 and 700 nm under normal incidence to overcome the difficulties associated under oblique incidence corresponding to TE and TM polarized waves. We examined the performance of the proposed design by calculating the sensitivity, figure of merit, and quality factor values of the biophotonic sensor loaded with different samples. It was found that the sensitivity of our design reaches to a maximum of 428.6 nm/RIU corresponding to the defect layer thickness of 700 nm, when the cavity is loaded with an infected blood sample containing plasma only. This study successfully simultaneously examined the normal and infected blood samples containing the platelet, plasma, and hemoglobin components of blood.

Improving the efficiency counting of Cherenkov detector by using high transmittance photonic crystal materials

In this study, a new type of photonic crystal (PC) designed as a transmitter. The transmittance spectra of the one-dimensional (1D) photonic crystal which are consist of silicon dioxide/magnesium fluoride (SiO2/MgF2). We are simulated the results using different incident angles, and the results showed a high transmittance (99.5%) within the wavelength range of (200–700 nm). Simulations of two-dimensional (2D) photonic crystals were studied, as well as the transmittance values were investigated. As a transmitter, photonic crystals in a one-dimensional array of SiO2 and MgF2 with periodicities N = 5 were employed around the wall of the Cherenkov counter vial. The high transmittance of the SiO2/MgF2 PC allows Cherenkov light to pass without any losing in its initial incident intensity which improves the Cherenkov counting efficiency, which is utilized in a wide range of applications. By replacing the traditional polyethylene (generally used to fabricate the walls of the counter vial) with the high transmittance photonic crystal SiO2/MgF2 which is allow to the most of the emitted Cherenkov radiation to reach the photomultiplier tube without any losing in its way to the tube. Subsequently, the efficiency of the Cherenkov counter was improved. Comparing the counting efficiency for both the polyethylene and the SiO2/MgF2 photonic crystal, it was found that the counting efficiency will be increased by 15% in one-dimension and 9.5% in two-dimensions if the polyethylene walls of the vial were replaced by SiO2/MgF2.

A high-performance, metallodielectric 2D photonic crystal for thermophotovoltaics

Fuel-combustion-based thermophotovoltaic (TPV) systems are emerging as a viable power source for small, portable generators for a spectrum of applications such as UAVs, robotic platforms, and sensors. In TPV systems, an emitter heated to above 1000 K emits radiation that is then converted to electricity by a low bandgap photovoltaic cell. One promising class of TPV emitters are two-dimensional photonic crystals (PhCs) made of tantalum, which have shown high-temperature stability at 1150–1250K over hundreds of hours [1] , [2] and have been implemented in a prototype system with 4.4% fuel-to-electricity efficiency [1] . Tantalum PhCs filled and capped with hafnium oxide can enable even higher optical performance with in-band emissivities of 0.8–0.9. However, two key features are difficult to realize simultaneously: a uniformly filled cavity and a thin capping layer of hafnium oxide [3] , [4] . Here, we present a process that results in reduced roughness and better thickness control of the capping layer. We use room temperature reflectance measurements and full system simulations to estimate system performance gains. This selective emitter paves the way toward efficient, practical, and portable mesoscale generators. • A broadband selective emitter for TPV has been fabricated and measured. • Emitter consists of tantalum photonic crystal, filled and capped with hafnium oxide. • Up to 37.5% increase in power output is estimated over previous system prototype.

Resonant dielectric multilayer with controlled absorption for enhanced total internal reflection fluorescence microscopy.

Total internal reflection fluorescence microscopy (TIRF-M) is widely used in biological imaging. Evanescent waves, generated at the glass-sample interface, theoretically strongly improve the axial resolution down to a hundred of nanometers. However, objective based TIRF-M suffers from different limitations such as interference fringes and uneven illumination, mixing both propagating and evanescent waves, which degrade the image quality. In principle, uneven illumination could be avoided by increasing the excitation angle, but this results in a drastic loss of excitation power. We designed dedicated 1D photonic crystals in order to circumvent this power loss by directly acting on the intensity of the evanescent field at controlled incident angles. In this framework, we used dedicated resonant multi-dielectric stacks, supporting Bloch surface waves and resulting in large field enhancement when illuminated under the conditions of total internal reflection. Here, we present a numerical optimization of such resonant stacks by adapting the resulting resonance to the angular illumination conditions in TIRF-M and to the fluorescence collection constraints. We thus propose a dedicated resonant structure with a control of the absorption during thin film deposition. A first experimental demonstration illustrates the concept with a 3-fold fluorescence enhancement in agreement with the numerical predictions.

Wide-angle polarization selectivity based on anomalous defect mode in photonic crystal containing hyperbolic metamaterials.

Conventional defect modes in all-dielectric 1D photonic crystals (PCs) are polarization-insensitive. This poses a great challenge in achieving high-performance polarization selectivity. In this Letter, we introduce a defect layer into a 1D PC containing hyperbolic metamaterials to achieve an anomalous defect mode with polarization-sensitive characteristics. As the incident angle increases, such a defect mode remains almost unshifted under transverse magnetic polarization, while strongly shifting toward shorter wavelengths under transverse electric polarization. The polarization-sensitive characteristics of the defect mode can be well explained by the Fabry-Perot resonance condition. Assisted by the polarization-sensitive defect mode, wide-angle polarization selectivity with an operating angle width up to 54.8° can be realized. Our work provides a route to designing wide-angle linear polarizers using simple 1D structures, which would be useful in liquid crystal display and Q-switched lasers.

Design and optimization of 1 × 2 and 1 × 4 Y-shaped beam splitters in GaSb-based 2D photonic crystals

In this paper, we investigate the structural design of beam splitters with high total transmission efficiency in the two-dimensional (2D) GaSb (Gallium Antimonide)-based photonic crystals, and several optimal structures for [Formula: see text] and [Formula: see text] Y-shaped beam splitters have been provided. Using our proposed alternating iteration algorithm, by introducing several microstructures in the bend and Y-shaped junction areas to achieve topology optimization, the design of Y-shaped beam splitters with high total transmission efficiency at 1550 nm makes great progress. The splitter structures are designed on 2D GaSb-based photonic crystals with a triangular lattice of air holes immersed in the GaSb. All designs are simulated numerically and analyzed by using the finite element method. The optimized structures of [Formula: see text] Y-shaped beam splitters show that our optimization technique is efficient and simple. And the total transmission efficiencies both over [Formula: see text] at output ports are obtained, which indicates that our method is relatively efficient to other methods in some related reports.

Smart and Rapid Design of Nanophotonic Structures by an Adaptive and Regularized Deep Neural Network.

The design of nanophotonic structures based on deep learning is emerging rapidly in the research community. Design methods using Deep Neural Networks (DNN) are outperforming conventional physics-based simulations performed iteratively by human experts. Here, a self-adaptive and regularized DNN based on Convolutional Neural Networks (CNNs) for the smart and fast characterization of nanophotonic structures in high-dimensional design parameter space is presented. This proposed CNN model, named LRS-RCNN, utilizes dynamic learning rate scheduling and L2 regularization techniques to overcome overfitting and speed up training convergence and is shown to surpass the performance of all previous algorithms, with the exception of two metrics where it achieves a comparable level relative to prior works. We applied the model to two challenging types of photonic structures: 2D photonic crystals (e.g., L3 nanocavity) and 1D photonic crystals (e.g., nanobeam) and results show that LRS-RCNN achieves record-high prediction accuracies, strong generalizibility, and substantially faster convergence speed compared to prior works. Although still a proof-of-concept model, the proposed smart LRS-RCNN has been proven to greatly accelerate the design of photonic crystal structures as a state-of-the-art predictor for both Q-factor and V. It can also be modified and generalized to predict any type of optical properties for designing a wide range of different nanophotonic structures. The complete dataset and code will be released to aid the development of related research endeavors.

Pachyrhynchus Weevils Use 3D Photonic Crystals with Varying Degrees of Order to Create Diverse and Brilliant Displays.

The brilliant appearance of Easter Egg weevils, genus Pachyrhynchus (Coleoptera, Curculionidae), originates from complex dielectric nanostructures within their elytral scales and elytra. Previous work, investigating singular members of the Pachyrhynchus showed the presence of either quasi-ordered or ordered 3D photonic crystals based on the single diamond ( ) symmetry in their scales. However, little is known about the diversity of the structural coloration mechanisms within the family. Here, the optical properties within Pachyrhynchus are investigated by systematically identifying their spectral and structural characteristics. Four principal traits that vary their appearance are identified and the evolutionary history of these traits to identify ecological trends are reconstructed. The results indicate that the coloration mechanisms across the Easter Egg weevils are diverse and highly plastic across closely related species with features appearing at multiple independent times across their phylogeny. This work lays a foundation for a better understanding of the various forms of quasi-ordered and ordered diamond photonic crystal withinarthropods.

Lithography-free tunable absorber at visible region via one-dimensional photonic crystals consisting of an α-MoO3 layer.

Flexible control of light absorption within the lithography-free nanostructure is crucial for many polarization-dependent optical devices. Herein, we demonstrated that the lithography-free tunable absorber (LTA) can be realized by using two one-dimensional (1D) photonic crystals (PCs) consisting of an α-MoO3 layer at visible region. The two 1D PCs have different bulk band properties, and the topological interface state-induced light absorption enhancement of α-MoO3 can be realized as the α-MoO3 thin film is inserted at the interface between the two 1D PCs. The resonant cavity model is proposed to evaluate the anisotropic absorption performances of the LTA, and the results are in good agreement with those of the transfer matrix method (TMM). The absorption efficiency of the LTA can be tailored by the number of the period of the two PCs, and the larger peak absorption is the direct consequence of the larger field enhancement factor (FEF) within the α-MoO3 layer. In addition, near-perfect absorption can be achieved as the LTA is operated at the over-coupled resonance. By varying the polarization angle, the absorption channels can be selected and the reflection response can be effectively modulated due to the excellent in-plane anisotropy of α-MoO3.

Intensity and phase encoding for realization of integrated Pauli X, Y and Z gates using 2D photonic crystal

Nano-scale all-optical logic gates systems are desirable for the all-optical computing and signal processing applications. All-optical Quantum computing offers excellent computational abilities and lossless operations. The Pauli X, Y and Z gates are vital quantum logic gates for all-optical systems. In this paper, the integrated all-optical Pauli X, Y, Z gate is realized using a square lattice 2D photonic crystal of silicon rods. The phase encoding and intensity encoding techniques have been used simultaneously for the integrated operation. Pauli X, Y, Z logic gate truth table has been verified at the operating wavelength of 1.55 µm.The system offers a linear operation, compact size, low power requirement, and high contrast ratio of 10.4 dB. The footprint of the proposed structure is about 70µm x 70µm and demonstrates a fast response time of 2 ps, bit rate of 0.25 Tbps, which makes it suitable for photonic integrated circuits (PICs).

Photonic-crystals-based GAGG:Ce scintillator with high light output and fast decay time for soft X-ray detection

Gd2O2S:Tb (P43) powder was widely used in soft X-ray detection due to its high light yield. Compared with P43, GAGG:Ce scintillator has high light transmittance, fast decay time and strong radiation resistance. Photonic crystals (PhCs) can be used to enhance the light output of scintillator. In this paper, two-dimensional (2D) photonic crystals that consist of square arrays of air holes etched into TiO2 layer were fabricated on the exit surface of GAGG:Ce scintillator to enhance its light output. The luminescence spectra and the light output of GAGG:Ce scintillator with/without PhCs were measured at the BL08U1A beamline of Shanghai Synchrotron Radiation Facility. The results showed that the light output of GAGG:Ce scintillator with PhCs can be enhanced by a factor of 1.43 times compared with the reference GAGG:Ce scintillator, 2.35 times compared with YAG:Ce scintillator, 1.24 times compared with Gd2O2S:Tb scintillation ceramic and 0.76 times compared with P43 powder layer with the mass thickness of about 1.3mg/cm 2 with optical grease coupling. No significant change was observed in luminescence decay time between GAGG:Ce scintillator with and without PhCs. It makes GAGG:Ce scintillator with PhCs a promising material instead of P43 powder and YAG:Ce scintillator in soft X-ray detector.

Local piezoelectric properties of perforated ferroelectric barium–strontium titanate films

Objectives. Focused ion beam etching remains one of the most common methods for fabricating 2D photonic crystals and structures based on functional materials. This technique is quite well developed for semiconductors. But at the same time, the change in the properties of ferroelectric materials under the action of a focused ion beam, including parameters of distribution and switching of the polarization state under the action of an electric field, remains poorly studied. The purpose of this work is to determine the local piezoelectric parameters in perforated ferroelectric films of barium strontium titanate (Ba0.8Sr0.2TiO3) with ordered vertical air channels fabricated by focused ion beam etching.Methods. Experimental studies were conducted using piezoresponse force microscopy under applied electric field in planar geometry.Results. It is shown that the perforation of a ferroelectric film leads not only to the formation of significant inhomogeneities in the piezoelectric response distribution in the structure, but also to the noticeable increase in the magnitude of both the vertical and lateral components of the piezoresponse near the perforation holes. The calculation results showed that the greatest enhancement is observed for the lateral component of the piezoresponse: from 5 pm/V for a nonperforated film to 65 pm/V in the perforated area.Conclusions. The most probable mechanism for such a change in properties is the influence of a disturbed layer that occurs at the boundary and the inner surface of vertical air channels. The properties of this layer are due to two factors: amorphization of the structure as a result of the focused ion beam etching and the appearance of pinned domain states near the hole, leading to the formation of the complex piezoresponse distribution both at the hole boundary and in the gap between the perforations. The information obtained is important for understanding the peculiarities of the formation of local piezoelectric and ferroelectric responses in photonic crystals fabricated by focused ion beam etching, as well as for finding ways to control their state when an external electric field is applied.

Optimal Design of Surface Relief Grating for High‐Resolution Two‐Photon Interference Lithography

AbstractTwo‐photon interference lithography with an elastomeric phase grating that allows spontaneous conformal contact to the photoresist can be used to fabricate practical‐scale, 3D photonic crystals through a single exposure. In principle, the unit cell symmetry and fill factor of the 3D periodic nanostructures produced using this technique are strongly depend on the structural parameters of the phase grating. However, theoretical approaches to derive the optimal parameters of the phase grating for realizing high‐definition 3D nanostructures are still lacking. Here, the change in the Talbot interference pattern is systematically predicted with the relief height of the phase grating under the conditions in which two‐photon interference lithography is performed through optical simulations. The collective set of results reveals the design error of the relief height of the phase grating, as inferred by the scalar approximation thus far, and presents the optimal condition that satisfies the π‐phase shift inferred by the full‐vectorial numerical solution.

Construction and Research of Multiple Stimuli-Responsive 2D Photonic Crystal DNA Hydrogel Sensing Platform with Double-Network Structure and Signal Self-Expression.

The stimuli-responsive DNA hydrogel has attracted wide attention in the fields of chemical and biological sensing. However, it is still a challenge to integrate characteristics with low-cost, high mechanical strength, and signal self-expression into a DNA hydrogel simultaneously. Herein, a stimuli-responsive 2D photonic crystal double network DNA hydrogel (2D PhC DN-DNA hydrogel) sensing platform is developed via combining the signal self-expression of 2D PhC array with the selective recognition of polyacrylamide (PAM)/DNA DN hydrogel. The change of DNA configuration induced by specific target triggers the change of 2D PhC DN-DNA hydrogel volume, leading to a shift of the Debye diffraction ring diameter. In order to verify the feasibility of this strategy, the 2D PhC DN-DNA hydrogel with C-rich sequences is chosen as a proof-of-concept. The results indicate that the hydrogel has good detection performance for pH and Ag+/Cys. And the Debye diffraction ring diameter of the hydrogel is correlated with the concentration of the Ag+/Cys in the range of 0.5-20 μM. Compared with previously pure DNA hydrogel sensing platform, the 2D PhC DN-DNA hydrogel features low-cost preparation process and label-free determination. Meanwhile, only a laser pointer and a ruler are needed for the determination of targets, which shows that the hydrogel has application prospect in the development of portable response equipment.

Compounding a High-Permittivity Thermoplastic Material and Its Applicability in Manufacturing of Microwave Photonic Crystals.

Additive Manufacturing (AM) techniques allow the production of complex geometries unattainable through other traditional technologies. This advantage lends itself well to rapidly iterating and improving upon the design of microwave photonic crystals, which are structures with intricate, repeating features. The issue tackled by this work involves compounding a high-permittivity material that can be used to produce 3D microwave photonic structures using polymer extrusion-based AM techniques. This material was acrylonitrile butadiene styrene (ABS)-based and used barium titanate (BaTiO3) ceramic as the high-permittivity component of the composite and involved the use of a surfactant and a plasticizer to facilitate processing. Initial small amounts of the material were compounded using an internal batch mixer and studied using polymer thermal analysis techniques, such as thermogravimetric analysis, rheometry, and differential scanning calorimetry to determine the proper processing conditions. The production of the material was then scaled up using a twin-screw extruder system, producing homogeneous pellets. Finally, the thermoplastic composite was used with a screw-based, material extrusion additive manufacturing technique to produce a slab for measuring the relative permittivity of the material, as well as a preliminary 3D photonic crystal. The real part of the permittivity was measured to be 12.85 (loss tangent = 0.046) in the range of 10 to 12 GHz, representing the highest permittivity ever demonstrated for a thermoplastic AM composite at microwave frequencies.

Centimeter‐Scale Propagation of Optical Surface Waves at Visible Wavelengths

AbstractGuiding and confining light at interfaces is crucial for applications involving light–matter interactions, such as surface spectroscopy, nonlinear optics, and quantum information technology. While dielectric surface waves offer promising perspectives for strong light confinement at non‐absorbing interfaces, their capacity has not yet been widely explored. This article focuses on the propagation properties of optical modes supported at the free surface of a 1D photonic crystal. The contributions of intrinsic and extrinsic loss mechanisms are investigated. Structures optimized to support long propagating optical surface waves are designed and fabricated. This work experimentally demonstrates, for the first time, the existence of optical surface waves capable of propagating over centimeter‐scale distances in the visible spectral range. The results open new perspectives for the use of optical surface waves in integrated optics and enhanced light–matter interactions.

Biomimetic design of functional plasmonic surfaces based on polydopamine

Polydopamine is a bioinspired multifunctional material that is emerging in the last years for applications in the biomedical, energy, environmental and catalytic fields. Whereas the conformal coating of solid objects by polydopamine is a well assessed process, the development of polydopamine thin films is less explored and their potential advantages have still to be fully unveiled. Herein, we describe a green and straightforward fabrication of composite membranes based on polydopamine thin films self-assembled at the air/water interface, and two different biopolymers, bacterial cellulose and silk fibroin. Furthermore, the abundant phenolic hydroxyl groups enable the in situ Au nanoparticle decoration on the polydopamine side, providing the membrane surface with plasmonic features. The surface patterning of polydopamine layers using self-assembled templating structures is also demonstrated, opening up new perspectives for biocompatible functional membranes with tunable optical and spectroscopic properties. Lastly, we demonstrate that the obtained functional surfaces are promising tools for the fabrication of SERS substrates. By bridging dopamine chemistry with natural biopolymers and 2D photonic crystals, the results obtained within this paper establish an excellent platform for designing 2D nanoarchitectures with multiple functions.

3D Photonic Crystals: Synthesis and Drying in Supercritical Ethanol

3D Photonic Crystals: Synthesis and Drying in Supercritical Ethanol

Designing of a Novel Nanophotonic Structure Based on 2D Photonic Crystals for the Detection of Different Materials

Designing of a Novel Nanophotonic Structure Based on 2D Photonic Crystals for the Detection of Different Materials

Targeted Positioning of Quantum Dots Inside 3D Silicon Photonic Crystals Revealed by Synchrotron X-ray Fluorescence Tomography.

It is a major outstanding goal in nanotechnology to precisely position functional nanoparticles, such as quantum dots, inside a three-dimensional (3D) nanostructure in order to realize innovative functions. Once the 3D positioning is performed, the challenge arises how to nondestructively verify where the nanoparticles reside in the 3D nanostructure. Here, we study 3D photonic band gap crystals made of Si that are infiltrated with PbS nanocrystal quantum dots. The nanocrystals are covalently bonded to polymer brush layers that are grafted to the Si–air interfaces inside the 3D nanostructure using surface-initiated atom transfer radical polymerization (SI-ATRP). The functionalized 3D nanostructures are probed by synchrotron X-ray fluorescence (SXRF) tomography that is performed at 17 keV photon energy to obtain large penetration depths and efficient excitation of the elements of interest. Spatial projection maps were obtained followed by tomographic reconstruction to obtain the 3D atom density distribution with 50 nm voxel size for all chemical elements probed: Cl, Cr, Cu, Ga, Br, and Pb. The quantum dots are found to be positioned inside the 3D nanostructure, and their positions correlate with the positions of elements characteristic of the polymer brush layer and the ATRP initiator. We conclude that X-ray fluorescence tomography is very well suited to nondestructively characterize 3D nanomaterials with photonic and other functionalities.