Photonic Crystal Structure Research Articles

A low-threshold single-mode higher-order topological photonic crystal nanowire array laser

A higher-order topological photonic crystal GaAs/AlGaAs/GaAs nanowire array laser based on 0D corner modes is proposed and analyzed. The structure is composed of a nanowire trivial photonic crystal sandwiched by two topological photonic crystals. Compared with the conventional deformed honeycomb lattice photonic crystal structure, an additional mode selection mechanism is introduced by adjusting the coupling strength of topological cavities formed at two topological interfaces. By optimizing the structure parameters, a large side-mode suppression ratio of 24 dB and a high-quality factor of 7935 are obtained. Due to the strong mode confinement, lasing is achievable at an ultrasmall diameter of 86 nm, with a high confinement factor of 7.96 and low threshold gain of 230 cm−1. Moreover, the laser exhibits a small beam divergence of 6.6°. This work may pave a way for the development of low-threshold single-mode miniaturized lasers.

One-dimensional porous silicon photonic crystals for chemosensors: Geometrical factors influencing the sensitivity

One-dimensional photonic crystals with microcavity were prepared to be used as optical chemosensors. The experimental reflectance of the as-etched devices immersed in solvent solutions appear greater than the theoretical one. The fitting procedure of the experimental data using the transfer matrix method together with the Looyenga effective medium approach reveals that the deviation of the experimental data occurs because of the expansion-contraction effect of the high and low porosity layers, respectively, caused by the presence of the solvent into the porous matrix and is proportional to the solvent effective refractive index. Due to this phenomenon, the sensitivity of the as-etched photonic crystals increases about two times but is not stable because of the aging effect. To avoid this effect, the photonic crystal structures were passivated by thermally silicon oxide growing, gold thin film and titanium oxide deposition. After thermal treatment in an air environment, the optical response achieves its stabilization even after long storage times, thus showing the importance of the passivation procedure. Among them, the passivation by TiO2 shows better performance and lower loss in sensitivity in comparison to the as-etched devices.

Ultra-sensitive pressure sensing capabilities of defective one-dimensional photonic crystal

Present research work deals with the extremely sensitive pressure-sensing capabilities of defective one-dimensional photonic crystal structure (GaP/SiO2)N/Al2O3/(GaP/SiO2)N. The proposed structure is realized by putting a defective layer of material Al2O3 in the middle of a structure consisting of alternating layers of GaP and SiO2. The transfer matrix method has been employed to examine the transmission characteristics of the proposed defective one-dimensional photonic crystal in addition to MATLAB software. An external application of the hydrostatic pressure on the proposed structure is responsible for the change in the position and intensity of defect mode inside the photonic band gap of the structure due to pressure-dependent refractive index properties of the materials being used in the design of the sructure. Additionally, the dependence of the transmission properties of the structure on other parameters like incident angle and defect layer thickness has also studied. The theoretical obtained numeric values of the quality factor and sensitivity are 17,870 and 72 nm/GPa respectively. These results are enough to support our claim that the present design can be used as an ultra-sensitive pressure sensor.

Investigation of graphene flake and photonic crystal structure enhancement effect by Raman spectroscopy of thymine

Raman spectroscopy is widely used for studying bioorganic materials. However, dealing with biological samples presents challenges such as limited quantities, tight timelines, complex preparation, and the need for improved precision. Hence, efforts are needed to enhance sensitivity and visualization for specific molecules or cells. This study explored using periodic waveguide structures (PWS) to amplify Raman signals of biological molecules, focusing on thymine. We found that composite nanostructures significantly boosted thymine’s Raman signal, further enhanced by injecting graphene nanoflakes. This research highlights the potential of enhanced Raman techniques in bioanalysis and paves the way for future advancements in this field.

Genetic Optimization of the Y-Shaped Photonic Crystal NOT Logic Gate

The present paper is devoted to the actual problem of photonic crystal (PhC) logic gate design. The development of components for photonic digital computing systems will provide opportunities for high-efficient information processing. The use of 2D photonic crystals is one of the most promising approaches to designing interference logic gates. Photonic crystal band gap and use of lattice defects are giving opportunities for flexible control of waveguiding light. Interference logic gates of NOT, OR, AND, and XOR types based on the Y-shaped structure are well known. However, known realizations have limited energy efficiency. Earlier, a method for minimizing energy losses at the PhC waveguide bending based on genetic optimization of the PhC waveguide topology was proposed and investigated. In this paper, the genetic algorithm for optimization of the PhC interference logic gate of the NOT type was used. Optimization of the Y-shaped topology allowed for an increase in the energy efficiency of the logic gate to 95%. A description of the developed numerical procedure as well as computer simulation results are presented. The developed procedure includes the possibility of taking into account the limitations of the technology to be used for the realization of a designed 2D PhC structure.

Photonic crystal fiber sensor structure with vertical and horizontal cladding for the detection of hazardous gases

Photonic crystal fiber sensor structure with vertical and horizontal cladding for the detection of hazardous gases

Preparation and formation mechanism of colorful photonic crystals on rough yarns

The environmentally friendly dyeing of textiles combining regular photonic crystals (PCs) has shown remarkable promise for application. However, the surface is rough and undulating and contains many harnesses due to full-curved structure of yarns. All these factors increase the difficulty of assembling colloidal microspheres into regular PCs on yarns. Therefore, relevant studies on the preparation methods and fundamental theories for constructing bionic structural colors on conventional flexible yarns are few. This study contains two main parts: first, regular PC-based yarns were produced by the dip coating method with poly (styrene–butyl acrylate–methacrylate) (P(St–BA–MAA)) as building block. Specifically, the softness and surface flatness of acrylic yarns were improved using silicone-modified polymer solution and cationic acrylate solution. The results indicated that assembling of PC with vivid structural color was easier when the base color of yarns was black and the concentration of P(St–BA–MAA) colloidal microspheres was about 60 wt%. Second, the self-assembling mechanism of microspheres on acrylic yarns was further studied by untwisting and slicing. The results showed that colloidal microspheres would fill the surfaces and voids of the outer fibers of acrylic yarns to form regular PCs, and they would also enter the inner fibers of yarns by capillary forces. However, the structure of yarns was tight inside and loose outside due to twisting and other reasons. Therefore, the colloidal microspheres had more difficulty entering the fibers on the inner side of the yarn to form an ordered PC structure when the fibers were closer to the yarn axis. The PC-based colored yarn also remained bright after the rubbing test. The color phase of the structured colored yarns based on PC could be adjusted as well by regulating the particle size and the observation angle. The prepared structured colored yarns were woven into fabrics, which were named yarn-structure colored fabrics. This research provides theoretical support and technical guidance for the preparation and practical application of flexible structured colored yarns based on PC.

Chemical sensors based on photonic colloidal crystals

Objectives. The paper analyzes the results of research into the formation of photonic crystal structures from polymer microspheres and the mechanisms of spectral shifts during selective reflection of non-monochromatic incident radiation from them in the visible and infrared light, as well as the use of polymer microspheres as sensors for detecting chemical substances having similar structures.Results. Research carried out at the Ya.K. Syrkin Department of Physical Chemistry in the Institute of Fine Chemical Technologies of the RTU MIREA is presented. Issues related to the detection of substances with similar chemical structure using sensors based on photonic crystals made of polystyrene microspheres 160–300 nm in size, are considered. Spectral shifts of the reflected radiation from the crystal surface are registered in the visible spectrum when substances in the liquid or gas phase are detected by the crystal surface.Conclusions. The method of electrophoretic deposition of colloidal particles in the form of polymeric microspheres on conducting surfaces can be used to create ordered structures over large areas. However, the detection of individual compounds by the optical method is impossible without controlling the kinetics of spectral shifts of reflected radiation from the surface of photonic colloidal crystals. The spectral characteristics of such radiation are directly related to the particle sizes that determine the period of the crystal lattice. The diffusion of chemical substances into a photonic crystal, which results in a swelling of the particles forming it and a shift in the spectrum of reflected radiation, is determined by a change in the period of the crystal lattice due to a change in the size of these particles A kinetic model of swelling polymer microspheres, which describes the diffusion of substances into porous polymer particles, is proposed. An excess amount of substance deposited on the surface of a photonic crystal above the limit is shown to lead to its degradation, which is manifested in the “fading” of the crystal surface and the concomitant disappearance of narrow peaks of reflected radiation.

Independent-regulated double-edge Janus angular absorber for terahertz waves based on photonic edge band gaps and graphene wide-angle absorption

In this paper, three categories of Janus angle absorption structures for terahertz (THz) waves are realized by operating the edge hopping property of the photonic band gaps (PBGs) and the wide-angle absorption of graphene heterostructure. The left and right edges of the angle window are determined by the PBGs generated by photonic crystals 1 (PC1) and photonic crystals 2 (PC2), respectively. The appropriate combination of the two can obtain a transmission angle window (TAW), and the edges can be independently manipulated, which makes it possible to construct arbitrary angle filtering structures, making up for the shortage of rigid angle windows in traditional research. Graphene material has absorption potential, and when it is introduced into ternary photonic crystals 3 (PC3), high absorption at large angles will occur. The combination of PC3 and TAW will produce an absorption angle window (AAW) by using the energy cascade transmission features of photonic crystals (PCs). Contributing to the strong absorption properties, the energy transfer on both sides of PC3 is isolated. Consequently, the Janus angle absorption phenomenon will be remarkable by mirroring the PCs structures with different TAWs on both sides of PC3. Through the unique parameter design, the three relationships between the forward AAW and the backward one are investigated, that is inclusion, partial coincidence, and incoherence.

Study transmission characteristics of graded photonic crystal as low pass filter

Here, we investigate propagation characteristics of graded thickness one-dimensional photonic crystal structure made of silicon and air. The optical transmission is obtained by transfer matrix method (TMM) and studied impact of graded index and refractive index variation on the transmission spectra. The optical transmission of suggested structure drops as frequency increases and falls to zero more rapidly as graded index increases. The graded index variable can be used to tune the suggested structure’s cut off frequency, which corresponds to half of the transmission value. So, such device has useful application as tunable optical low-pass filter.

Silicon-Based Zipper Photonic Crystal Cavity Optomechanical System for Accelerometers.

The cavity optomechanical accelerometer based on photonic crystal microcavities combines mechanical resonators with high-quality factor photonic crystal cavities. The mechanical vibrator is sensitive to weak force/displacement in mechanical resonance modes, which can achieve extremely low noise levels and theoretically reach the standard qillatum noise limit. It is an important development direction for high-precision accelerometers. This article analyzes the principle and structural characteristics of a zipper type photonic crystal cavity optomechanical accelerometer, and designs a silicon-based zipper type photonic crystal cavity and mechanical vibrator structure applied to the accelerometer. The influence of the structural parameters of the zipper cavity on the optical Q factor was analyzed in detail. The resonant frequency of the optical cavity was controlled around 195 THz by adjusting the structural parameters, and the mechanical resonance characteristics of the mechanical vibrator and the optical cavity were analyzed. The effective mass of the optical cavity was 30 pg, and, with the addition of the mechanical vibrator, the effective mass was 3.1 ng. The optical mechanical coupling rate reached the GHz/nm level, providing guidance for the manufacturing and characterization of silicon-based zipper cavity accelerometers.

Photonic Crystal Flip-Flops: Recent Developments in All Optical Memory Components.

This paper reviews recent advancements in all-optical memory components, particularly focusing on various types of all-optical flip-flops (FFs) based on photonic crystal (PC) structures proposed in recent years. PCs, with their unique optical properties and engineered structures, including photonic bandgap control, enhanced light-matter interaction, and compact size, make them especially suitable for optical FFs. The study explores three key materials, silicon, chalcogenide glass, and gallium arsenide, known for their high refractive index contrast, compact size, hybrid integration capability, and easy fabrication processes. Furthermore, these materials exhibit excellent compatibility with different technologies like CMOS and fiber optics, enhancing their versatility in various applications. The structures proposed in the research leverage mechanisms such as waveguides, ring resonators, scattering rods, coupling rods, edge rods, switches, resonant cavities, and multi-mode interference. The paper delves into crucial properties and parameters of all-optical FFs, including response time, contrast ratio, and operating wavelength. Optical FFs possess significant advantages, such as high speed, low power consumption, and potential for integration, making them a promising technology for advancing optical computing and optical memory systems.

A 2D GaAs-Based Photonic Crystal Biosensor for Malaria Detection

Gallium arsenide (GaAs) composite semi-conductive rods with an air background lattice act as the building blocks for the photonic crystal structure used of a biosensor. The study presents a biosensor of a two-rod nano-cavity for identifying distinct stages of plasmodium falciparum in red blood cells (RBCs) in the early detection of malaria. The proposed biosensor enables the creation of a label-free biosensing environment in which optical and dispersion properties are investigated using plane wave expansion (PWE) and finite-difference time-domain (FDTD) techniques. The biosensor, with a sensing region for an analyte, is utilized to detect a change in refractive index to differentiate between normal RBCs and plasmodium falciparum-infected cells. The results show that the biosensor has a high sensitivity of 798.143 nm/RIU, a high Q-factor of 9881.926, a low detection limit (δ) of 222.4 × 10-6 RIU, a high FOM of 4496.079 RIU-1, and a compact area of 46.14 µm2.

Photonic crystal textiles for heat insulation

In this work, we have studied transmission properties of a photonic crystal-like structure that can be woven into fabrics. An interesting possibility emerges when considering the potential energy savings through suppression of radiation. It is a well-established fact that every object at a finite temperature inherently emits electromagnetic waves. Within the specific context of the human body, radiation takes on a crucial role as a fundamental mechanism governing heat dissipation. Thus, exploring ways to manage or mitigate this radiation could offer innovative approaches to optimize energy consumption and enhance heat regulation. It is well known that a photonic crystal can block electromagnetic energy with a specific frequency that is falling into a photonic bandgap. By using the numerical method called a finite-difference time domain, we have shown that this property of a periodic structure can be used to make textiles to save energy that is used to heat a human body environment. Numerical calculations have shown that by using the proposed photonic crystal structure, 53% of electromagnetic energy is reflected. Although we mainly focused on textiles, it is worth highlighting that the same fundamental principle can be extended to diverse fields; for example, this structure can be integrated with construction materials and effectively function as a radiation heat insulator.

A topological gap waveguide based on unidirectional locking of pseudo-spins

Photonic topological insulators have been widely studied due to the robustness of energy transport via supported edge modes immune to structural disorder. In this work, a topological gap waveguide is constructed by introducing line defect into a topological photonic crystal structure and combining it with a gap waveguide structure, the design of which, therefore, combines the advantages of both topological and gap waveguides. Not only does it give high transmission efficiency but it also enables high robustness for energy transmission under structural defects and sharp bends. Our proposed topological waveguide design can be implemented with conventional semiconductor technology and integrated into optical circuits for communication systems.

Circularly Polarized Luminescence from Chiral Photonic Crystals of Caesium Lead Halide Perovskites

AbstractThe generation and detection of circularly polarized light (CPL) are of importance in many modern technologies such as digital communications, machine vision, bio‐imaging, and 3D displays. In this study, inspired by the fact that various species of plants and animals can efficiently produce and/or perceive CPL with chiral photonic crystal structures, efforts are made to fabricate luminescent chiral photonic crystals with caesium lead halide perovskites, a class of solution‐processable semiconductors that have excellent luminescence properties and readily tunable electronic band gaps. Coupling between the emission frequency of the perovskite and the cavity resonance frequency of the photonic crystal structure can be established at any desired point in the visible region, giving rise to CPL output with a dissymmetry factor up to −0.34. These results suggest a new approach to chiral light‐emitting materials and may contribute to the development of semiconductors with ordered microstructures.

Ultrahigh sensitivity terahertz refractive index sensor based on four‐inscribed hole defect photonic crystal structure

AbstractWe proposed and investigated an ultrahigh sensitivity terahertz (THz) refractive index sensor based on four‐inscribed hole defect photonic crystal structure. Due to the formation of resonant modes, the sensing properties can be obtained by shifting the sharp resonance in the transmission spectrum as changing of the analyte refractive index. In addition, the influence of structure parameters on the sensing performance is explored and demonstrated numerically. The numerical results illustrate that the Q‐factor and figure of merit reach 323.71 and 167.188 can be obtained under the optimized structural parameters. In particular, an ultrahigh sensitivity of 198.8 μm/RIU can be realized in the frequency range of 0.777–0.779 THz. The proposed sensor may find significant applications in biochemical sensing systems.

Rewritable Structurally Colored Paper Based on Hollow SiO2-Polyurethane Composite Photonic Crystal Film.

Rewritable paper, which can be used multiple times as an effective solution for sustainable development and lessen the heavy environment pollution, has received widespread attention. A photonic crystal with dye-free character and tunable structure color has attracted significant interest in this area. Generally, handwriting on the photonic crystal structure containing a responsive polymer or hydrogel ingredient was based on the change of lattice spacing. It is necessary to enrich the diversities of color adjustment mechanism for further application. Herein, a flexible rewritable photonic crystal structurally colored paper with excellent mechanical strength based on the hollow SiO2 (h-SiO2) particle and polyurethane was developed. Owning to the varied optical response of h-SiO2 photonic crystal film in different solvents, handwriting on this paper was realized by applying polarity solvents such as EG as colorless ink directly, which could also be erased by resoaking the film in water. Writing and erasing on this paper were totally reversible. The color adjustment mechanism and the realization of handwriting on this paper are totally different from those of the previous reported photonic crystal-based rewritable paper. The combination of quick handwriting and flexibility is significant for potential application as rewritable paper.

Simulated annealing algorithm with neural network for designing topological photonic crystals

In this work, we utilize simulated annealing algorithm with neural network, to achieve rapid design of topological photonic crystals. We firstly train a high-accuracy neural network that predicts the band structure of hexagonal lattice photonic crystals. Subsequently, we embed the neural network into the simulated annealing algorithm, and choose the on-demand evaluation functions for optimizing topological band gaps. As examples, designing from the Dirac crystal of hexagonal lattice, two types of valley photonic crystals with the relative bandwidth of bandgap 26.8% and 47.6%, and one type of pseudospin photonic crystal with the relative bandwidth of bandgap 28.8% are obtained. In a further way, domain walls composed of valley photonic crystals (pseudospin photonic crystals) are also proposed, and full-wave simulations are conducted to verify the valley-locked (pseudospin-locked) edge states unidirectionally propagates under the excitation of circularly polarized source. Our proposed method demonstrates the efficiency and flexibility of neural network with simulated annealing algorithm in designing topological photonic crystals.

Transformation one-dimensional photonic crystal omnidirectional reflector

In this paper, a concept of transformation one-dimensional photonic crystal is proposed to design omnidirectional reflector, which has a reduced thickness compared with that of the omnidirectional reflector using conventional one-dimensional photonic crystal structure. At first, the omnidirectional reflection band of an original one-dimensional photonic crystal is simulated using the transfer matrix method for comparison. Next, the transformation one-dimensional photonic crystal is designed based on transformation optics. Simulation results indicate that the transformation one-dimensional photonic crystal structures with arbitrary shrunken thickness can omnidirectionally reflect the incident TM waves that operates in the same omnidirectional reflection band of the original one-dimensional photonic crystal structure. Such a concept of transformation one-dimensional photonic crystal also can be expanded to any omnidirectional reflector designed by using other multilayer dielectric systems.