Showing papers on "Photonic crystal published in 2023"

Highly Sensitive Bilirubin Biosensor Based on Photonic Crystal Fiber in Terahertz Region

Abstract: An unstable bilirubin level in the human blood causes many dangerous health problems, such as jaundice, coronary artery disease, ulcerative colitis, and brain lesions. Therefore, the accurate and early detection of bilirubin concentrations in the blood is mandatory. In this work, a highly sensitive biosensor based on photonic crystal fiber (PCF) for monitoring bilirubin levels is proposed and analyzed. The sensor parameters, including relative sensitivity, effective mode area, confinement loss, and effective material loss, are calculated. The geometrical parameters are studied, and a modal analysis of the suggested sensor is carried out using the full-vectorial finite element method (FEM). The fabrication tolerance of the geometrical parameters is also studied to ensure the fabrication feasibility of the reported design. High sensitivities of 95% and 98% are obtained for the x-polarized and y-polarized modes, respectively. Furthermore, a small material loss of 0.00193 cm−1, a small confinement loss of 2.03 × 10−14 dB/cm, and a large effective mode area of 0.046 mm2 are achieved for the y-polarized mode. It is believed that the presented sensor will be helpful in health care and in the early detection of bilirubin levels in the blood.

Multiplication of photonic band gaps in one-dimensional photonic crystals by using hyperbolic metamaterial in IR range

Abstract: Abstract The light-slowing effect near band endpoints is frequently exploited in photonic crystals to enhance the optical transmittance. In a one-dimensional binary photonic crystal (1DPC) made of hyperbolic metamaterials (HMMs), we theoretically examined the angle-dependent omnidirectional photonic bandgap (PBG) for TM polarization. Using the transfer matrix approach, the optical characteristics of the 1DPC structure having dielectric and HMM layers were examined at the infrared range (IR). As such, we observed the existing of numerous PBGs in this operating wavelength range (IR). Meanwhile, the HMM layer is engineered by the subwavelength dielectric- nanocomposite multilayers. The filling fraction of nanoparticles have been explored to show how they affect the effective permittivity of the HMM layer. Furthermore, the transmittance properties of the suggested structure are investigated at various incident angles for transverse magnetic (TM) and transverse electric polarizations. Other parameters such as, the permittivity of the host material, the filling fraction of nanoparticles, and the thickness of the second layer (HMM) are also taken into account. Finally, we investigated the effect of these parameters on the number and the width of the (PBGs). With the optimum values of the optical parameters of the nanocomposite (NC) layer, this research could open the way for better multi-channel filter photonic crystals.

Butterfly‐Inspired Tri‐State Photonic Crystal Composite Film for Multilevel Information Encryption and Anti‐Counterfeiting

Abstract: Counterfeiting is a worldwide issue and has long troubled legitimate businesses, while nowadays anti‐counterfeiting materials and technology are still insufficient to combat the escalating counterfeit behaviors. Inspired by hindwing structure of Troides magellanus, a new kind of anti‐counterfeiting material taking advantage of both physical and chemical structures to display multiple optical states is prepared. The chemical units (luminescent lanthanide) are blended with physical units (monodispersed colloidal particles) and mediating molecules, which are then assembled into a photonic crystal structure at room temperature in less than 10 s through a new assembly technique called molecule‐mediated shear‐induced assembly technique (MSAT). The as‐prepared photonic crystal films feature three unique optical states, each displaying structural, fluorescent, and phosphorescent color under different lighting conditions, which integrates colors from both physical and chemical origins. Furthermore, by incorporating different luminescent materials into different parts of the photonic crystal pattern, a high‐level information encryption system is designed to be capable of carrying three distinct types of information. Thanks to this powerful tool of MSAT, it is now possible to assemble different‐sized, even irregular non‐spherical units with monodispersed spherical units into high‐quality photonic crystal films, which provides easy access to incorporating new features into photonic crystal systems.

Photonic time crystals: a materials perspective [Invited].

Abstract: Recent advances in ultrafast, large-modulation photonic materials have opened the door to many new areas of research. One specific example is the exciting prospect of photonic time crystals. In this perspective, we outline the most recent material advances that are promising candidates for photonic time crystals. We discuss their merit in terms of modulation speed and depth. We also investigate the challenges yet to be faced and provide our estimation on possible roads to success.

Exponentially index modulated nanophotonic resonator for high-performance sensing applications

Abstract: In this manuscript, a novel photonic crystal resonator (PhCR) structure having an exponentially graded refractive index profile is proposed to regulate and alter the dispersion characteristics for the first time. The structure comprises silicon material, where porosity is deliberately introduced to modulate the refractive index profile locally. The structural parameters are optimized to have a resonant wavelength of 1550 nm. Further, the impact of various parameters like incidence angle, defect layer thickness, and analyte infiltration on device performance is evaluated. Finally, the sensing capability of the proposed structure is compared with the conventional step index-based devices. The proposed structure exhibits an average sensitivity of 54.16 nm/RIU and 500.12 nm/RIU for step index and exponentially graded index structures. This exhibits the generation of a lower energy resonating mode having 825% higher sensitivity than conventional resonator structures. Moreover, the graded index structures show a 45% higher field confinement than the conventional PhCR structure.

Sensing and Detection Capabilities of One-Dimensional Defective Photonic Crystal Suitable for Malaria Infection Diagnosis from Preliminary to Advanced Stage: Theoretical Study

Abstract: In the present research work we have examined the biosensing capabilities of one-dimensional photonic crystals with defects for the detection and sensing of malaria infection in humans by investigating blood samples containing red blood cells. This theoretical scheme utilizes a transfer matrix formulation in addition to MATLAB software under normal incidence conditions. The purpose of considering normal incidence is to rule out the difficulties associated with oblique incidence. We have examined the performance of various structures of cavity layer thicknesses 1000 nm, 2200 nm, 3000 nm and 5000 nm. The comparison between the performances of various structures of different cavity thickness helps us to select the structure of particular cavity thicknesses giving optimum biosensing performance. Thus, the proper selection of cavity thickness is one of the most necessary requirements because it also decides how much volume of the blood sample has to be poured into the cavity to produce results of high accuracy. Moreover, the sensing and detection capabilities of the proposed design have been evaluated by examining the sensitivity, figure of merit and quality factor values of the design, corresponding to optimum cavity thickness.

One-Dimensional Photonic Crystal with a Defect Layer Utilized as an Optical Filter in Narrow Linewidth LED-Based Sources

Abstract: A one-dimensional photonic crystal (1DPhC) with a defect layer is utilized as an optical filter in a simple realization of narrow linewidth LED-based sources. The 1DPhC comprising TiO2 and SiO2 layers is characterized by two narrow defect mode resonances within the 1DPhC band gap, or equivalently, by two peaks in the normal incidence transmittance spectrum at wavelengths of 625.4 nm and 697.7 nm, respectively. By combining the optical filter with LEDs, the optical sources are employed in interferometry experiments, and the defect mode resonances of a Lorentzian profile with linewidths of 1.72 nm and 1.29 nm, respectively, are resolved. In addition, a simple way to tune the resonances by changing the angle of incidence of light on the optical filter is demonstrated. All-dielectric optical filters based on 1DPhCs with a defect layer and combined with LEDs thus represent an effective alternative to standard coherent sources, with advantages including narrow spectral linewidths and variable output power, with an extension to tunable sources.

Effective pressure sensor using the parity-time symmetric photonic crystal

Abstract: Monitoring the variations in pressure, distribution, and the magnitude of the emitted gases at the ground surface is very important in different applications. Because of the parity-time symmetric mechanism, a novel one-dimensional photonic crystal as a pressure sensor is proposed. The transmittance spectra are calculated and analyzed using the transfer matrix method. The parity-time symmetric property amplifies the transmittance of the defect mode and gives an additional hand to enhance the magnification and performance of the sensor. The optimum conditions are the normal angle of incidence, defect layer thickness of 1400 nm, the porosity of the porous silicon layer of 80%, and macroscopic Lorentz oscillation intensity of 5 × 10-4. The results show that the position and amplitude sensitivities are 4.9 nm GPa−1 and 1844%/GPa. That means in such sensors, by altering pressure, the desired value of magnified transmittance and sensitivity can be achieved as required according to the optical communication devices. Therefore, the proposed device performs better with high precision and accuracy. Consequently, it is much more helpful in optical communication and optoelectronic devices.

New designs of 4 × 2 photonic crystal encoders using ring resonators

Abstract: Abstract Optical encoders are pivotal elements in optical communication applications. There is much need for ultra-compact and high-speed novel designs. This work proposes two new designs of fast, compact 4 × 2 optical encoders using two dimensional photonic crystals. The proposed structures consist of square lattice silicon rods embedded in an air background. The operation of these encoders is based on the wave interference technique. The encoders are designed to help in achieving better performance through increasing the contrast ratio and decreasing the power loss and the return loss. The PWE method is used to analyze the photonic band gap. We used FDTD simulation to obtain the electric field distribution inside each structure and the normalized output power. We prove that the scattering rods improve the directivity of the light toward the desired paths and decrease the backward reflection. The proposed encoders have small footprint areas of 204.8 and 160.4 μm 2 and operate at wavelength 1550 nm. They achieve low response time (254 and 163 fs) and high contrast ratio (6.69 and 12.9 dB). Simplicity and compactness of the designs make them suitable for optical signal processors and photonic integrated circuits. Another advantage of these designs is that low input power is enough for the encoders’ operation, because there is no non-linear materials included. Our designs compete with the published works in the last few years especially in their footprint and response time.

Temperature Sensing Based on Defect Mode of One-Dimensional Superconductor-Semiconductor Photonic Crystals

Abstract: Based on the transfer-matrix method, we theoretically explore the transmission and reflection properties of light waves in a one-dimensional defective photonic crystal composed of superconductor (HgBa2Ca2Cu3O8+δ) and semiconductor (GaAs) layers. The whole system is centrosymmetric and can generate a defect transmission peak in the photonic band gap. We study the effect of the temperature on the defect mode. Results obtained show that the defect mode shifts to the lower frequency regions as the value of the environmental temperature increases, and the resonance of the defect mode can be strengthened further as the number of periods increases. In addition, our findings reveal that the central wavelength of the defect mode increases with the increase in the environmental temperature and it presents a nearly linear relationship between the central wavelength of the defect mode and the temperature in cryogenic environments. Therefore, we can use the temperature response of the defect mode to detect the temperature. It is hoped that this study has potential applications for the development of cryogenic sensors with high sensitivity.

Design of a 2⨯1 Multiplexer with a Ring Resonator Based on 2D Photonic Crystals

Abstract: Multiplexers are widely used logic circuits that connect a number of inputs to an output. These circuits are used to create logic functions. This article designs and simulates a 2 × 1 multiplexer based on 2D photonic crystals. The structure of this multiplexer includes dielectric rods in an air background. At the input, there is a ring resonator between two waveguides. This multiplexer’s structure is relatively small, with 14 × 15 rods. The operating wavelength of this logic circuit is 1.55 μm, which falls within the photonic band gap. The PWE method was used to simulate the band structure, and the FDTD numerical calculation method was used to calculate time.

Continuously tunable topological defects and topological edge states in dielectric photonic crystals

Abstract: Topological defects in solid-state materials are crystallographic imperfections that local perturbations cannot remove. Owing to their nontrivial real-space topology, topological defects such as dislocations and disclinations could trap anomalous states associated with nontrivial momentum-space topology. The real-space topology of dislocations and disclinations can be characterized by the Burgers vector $\mathbf{B}$, which is usually a fixed fraction and integer of the lattice constant in solid-state materials. Here we show that in a dielectric photonic crystal---an artificial crystalline structure---it is possible to tune $\mathbf{B}$ continuously as a function of the dielectric constant of dislocations. Through this unprecedented tunability of $\mathbf{B}$, we achieve proper controls of topological interfacial states, i.e., reversal of their helicities. Based on this fact, we propose a topological optical switch controlled by the dielectric constant of the tunable dislocation. Our results shed light on the interplay of real and reciprocal space topologies and offer a scheme to implement scalable and tunable robust topological waveguides in dielectric photonic crystals.

Photonic crystal nanostructure as a photodetector for NaCl solution monitoring: theoretical approach

Abstract: In this research, we have a theoretical simple and highly sensitive sodium chloride (NaCl) sensor based on the excitation of Tamm plasmon resonance through a one-dimensional photonic crystal structure. The configuration of the proposed design was, [prism/gold (Au)/water cavity/silicon (Si)/calcium fluoride (CaF2)10/glass substrate]. The estimations are mainly investigated based on both the optical properties of the constituent materials and the transfer matrix method as well. The suggested sensor is designed for monitoring the salinity of water by detecting the concentration of NaCl solution through near-infrared (IR) wavelengths. The reflectance numerical analysis showed the Tamm plasmon resonance. As the water cavity is filled with NaCl of concentrations ranging from 0 g l−1 to 60 g l−1, Tamm resonance is shifted towards longer wavelengths. Furthermore, the suggested sensor provides a relatively high performance compared to its photonic crystal counterparts and photonic crystal fiber designs. Meanwhile, the sensitivity and detection limit of the suggested sensor could reach the values of 24 700 nm per RIU (0.576 nm (g l)−1) and 0.217 g l−1, respectively. Therefore, the suggested design could be of interest as a promising platform for sensing and monitoring NaCl concentrations and water salinity as well.

Novel Photonic Applications of Silicon Carbide

Abstract: Silicon carbide (SiC) is emerging rapidly in novel photonic applications thanks to its unique photonic properties facilitated by the advances of nanotechnologies such as nanofabrication and nanofilm transfer. This review paper will start with the introduction of exceptional optical properties of silicon carbide. Then, a key structure, i.e., silicon carbide on insulator stack (SiCOI), is discussed which lays solid fundament for tight light confinement and strong light-SiC interaction in high quality factor and low volume optical cavities. As examples, microring resonator, microdisk and photonic crystal cavities are summarized in terms of quality (Q) factor, volume and polytypes. A main challenge for SiC photonic application is complementary metal-oxide-semiconductor (CMOS) compatibility and low-loss material growth. The state-of-the-art SiC with different polytypes and growth methods are reviewed and a roadmap for the loss reduction is predicted for photonic applications. Combining the fact that SiC possesses many different color centers with the SiCOI platform, SiC is also deemed to be a very competitive platform for future quantum photonic integrated circuit applications. Its perspectives and potential impacts are included at the end of this review paper.

Growing fields in a temporal photonic (time) crystal with a square profile of the permittivity ε(t)

Abstract: We investigate a band structure [Formula: see text] of a photonic time crystal with periodic square (step) modulation in time of its permittivity [Formula: see text], oscillating between the value [Formula: see text] (sustained for a fraction of time τ of the period) and the value [Formula: see text] [fraction (1 − τ)]. The strength of modulation is [Formula: see text]. We find that [Formula: see text] can be periodic in a wave number k (in addition to the frequency ω), provided that a certain function [Formula: see text] of the parameters m and τ is an irreducible rational number. However, even for arbitrary values of m and τ, [Formula: see text] can be approximated by a fractional number to any desired degree of periodicity. Hence, for square modulation, a photonic band structure is necessarily periodic or quasi-periodic in the wave number. Moreover, for appropriate sets of the parameters m and τ, the modes associated with k values within the band gaps can have identical values of the imaginary part of ω. For simultaneous excitation of these modes, all the fields would grow in time at the same rate, resulting in powerful amplification.

Photonic Band Inversion and Absorption Enhancement in Dirac Semi‐Metal Tamm Plasmon Multilayer System

Abstract: Topological photonics is becoming increasingly important due to its possibility to manipulate light with topological phases. Constrained by tunable material, the concept of the topological phase of light is less employed for the realization of terahertz (THz) devices. Incorporating tunable plasmonic materials with topological photonic structures can promote topological protection at the THz frequency. Here the topological phase transition in the terahertz bands is demonstrated by integrating Dirac semi‐metal with topological photonic crystal. This work proposes photonic band inversion induced frequency splitting and absorption enhancement in bulk Dirac semi‐metal (BDS) based Tamm plasmon multilayer system. The enhancement in absorption is achieved by designing a one‐dimensional topological edge state such that the combination with the Tamm plasmon state provides topological protection to the entire BDS–photonic crystal heterostructure. The proposed structure undergoes band inversion, a topological transition in the photonic band structure. These results may facilitate the realization of terahertz topological effects and contribute to the goal of topological protection in sensing applications.

Exfoliated Flexible Photonic Crystal Slabs for Refractive Index and Biomolecular Sensing

Abstract: Using the optical transduction properties of one-dimensional photonic crystal slabs is a promising approach for label-free biosensing in the field of flexible and wearable biosensing. In this work we demonstrate the fabrication of flexible photonic crystal slabs (f-PCS) via an exfoliation method from rigid photonic crystal slabs. We investigate the processing effect on the optical properties and show that the optical resonances are maintained, but affected. The quality factor changes from 50 to 31 for the TE mode and from 187 to 136 for the TM mode after the process. We demonstrate use of f-PCS for refractive index sensing and achieve a limit of detection (LOD) of 3.6 E-4 refractive index units (RIU). Furthermore, we introduce vapor-phase functionalization of the f-PCS and show first results of biosensing of antibodies from diluted feline serum.

Anodic alumina photonic crystals: Structure engineering, optical properties and prospective applications

Abstract: Anodic alumina photonic crystal is a porous periodic dielectric structure and has been extensively studied by researchers due to its straightforward preparation processes, porous features, high chemical, and thermal stability. The photonic structure consists of periodic layers of dielectrics with strong light scattering from the porous feature that allows for versatile tailoring of the optical properties of the anodic alumina photonic crystal. In this review, the related theories, application-oriented structure tailoring, optical properties, and selected applications are summarized. Finally, we forecast future research and applications.

Photonic band-edge assisted enhanced nonlinear absorption of carbon encapsulated gold nanostructures in polymeric multilayers

Abstract: Integration of nonlinear optical materials in nanophotonic structures offers unprecedented opportunities to tailor the light-matter interaction, resulting in tunable optical responses. Periodic dielectric structures are particularly the desired optical platform to incorporate nonlinear materials to enhance their weak nonlinearity for practical applications. In this work, we report the giant enhancement in the nonlinear absorption of a 1-D polymer photonic crystal containing gold-carbon ([email protected]) core–shell structure. The [email protected] nanostructures synthesized by pulsed laser ablation technique were dispersed in spin-coated alternate layers of photonic crystal comprised of polyvinyl carbazole and cellulose acetate. The long-wavelength photonic band-edge of the polymeric Bragg mirror was designed at 532 nm to enhance the non-resonant nonlinear absorption of the core–shell nanostructure. The resultant nonlinearity is ascribed to slow light propagation at the band-edges and consequent local field confinement of optical pulses. Angle-dependent tunability of photonic band-edge effects and nonlinear transmission characteristics were analyzed experimentally and correlated with numerical simulations. These findings open up new ways to implement cost-effective, highly tunable and low input threshold all-optical devices.

High-Sensitivity Early Detection Biomedical Sensor for Tuberculosis With Low Losses in the Terahertz Regime Based on Photonic Crystal Fiber Technology

Abstract: Abstract Tuberculosis is one of the most contagious and lethal illnesses in the world, according to the World Health Organization. Tuberculosis had the leading mortality rate as a result of a single infection, ranking above HIV/AIDS. Early detection is an essential factor in patient treatment and can improve the survival rate. Detection methods should have high mobility, high accuracy, fast detection, and low losses. This work presents a novel biomedical photonic crystal fiber sensor, which can accurately detect and distinguish between the different types of tuberculosis bacteria. The designed sensor detects these types with high relative sensitivity and negligible losses compared to other photonic crystal fiber-based biomedical sensors. The proposed sensor exhibits a relative sensitivity of 90.6%, an effective area of 4.342×10 −8 m 2 , with a negligible confinement loss of 3.13×10 −9 cm −1 , a remarkably low effective material loss of 0.0132cm −1 , and a numerical aperture of 0.3462. The proposed sensor is capable of operating in the terahertz regimes over a wide range (1 THz–2.4THz). An abbreviated review of non-optical detection techniques is also presented. An in-depth comparison between this work and recent related photonic crystal fiber-based literature is drawn to validate the efficacy and authenticity of the proposed design.