Radius Of Air Holes Research Articles

Prediction of Electric Load Neural Network Prediction Model for Big Data

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

The impact of incident wave angle and air hole radius parameter on the optical responses of a GaAs-based 2D photonic crystal, using the FDFD method

The impact of incident wave angle and air hole radius parameter on the optical responses of a GaAs-based 2D photonic crystal, using the FDFD method

Dual core photonic crystal fiber based plasmonic refractive index sensor with ultra-wide detection range.

In this study, an ultra-wide range plasmonic refractive index sensor based on dual core photonic crystal fiber is suggested and analyzed numerically. The proposed design achieves fabrication feasibility by employing external sensing mechanism in which silver is deposited onto the flat outer surface of the fiber as plasmonic material. A thin layer of titanium oxide (TiO2) is considered on top of the silver layer for preventing its oxidation problem. The sensor attains identification of a vast array of analytes consisting a wide range of refractive indices of 1.10 - 1.45. It achieves a maximum spectral sensitivity of 24300 nm/RIU along with its corresponding resolution of 4.12 × 10-6 RIU. The maximum figure of merit of the sensor is 120 RIU-1. The sensor also supports amplitude interrogation approach and exhibits a maximum amplitude sensitivity of 172 RIU-1. The impact of the design parameters such as radius of air holes, polishing distance, thickness of silver and titanium oxide layers are investigated thoroughly. An ultra-wide detection range with high sensitivity, fabrication feasibility, and easy application make the sensor a potential candidate for detection of a wide array of bio-originated materials, chemicals, and other analytes.

Suppressing the sample-to-sample variation of photonic crystal nanocavity Q-factors by air-hole patterns with broken mirror symmetry.

It is known that the quality factors (Q) of photonic crystal nanocavities vary from sample to sample due to air-hole fabrication fluctuations. In other words, for the mass production of a cavity with a given design, we need to consider that the Q can vary significantly. So far, we have studied the sample-to-sample variation in Q for symmetric nanocavity designs, that is, nanocavity designs where the positions of the holes maintain mirror symmetry with respect to both symmetry axes of the nanocavity. Here we investigate the variation of Q for a nanocavity design in which the air-hole pattern has no mirror symmetry (a so-called asymmetric cavity design). First, an asymmetric cavity design with a Q of about 250,000 was developed by machine learning using neural networks, and then we fabricated fifty cavities with the same design. We also fabricated fifty symmetric cavities with a design Q of about 250,000 for comparison. The variation of the measured Q values of the asymmetric cavities was 39% smaller than that of the symmetric cavities. This result is consistent with simulations in which the air-hole positions and radii are randomly varied. Asymmetric nanocavity designs may be useful for mass production since the variation in Q is suppressed.

Photonic Crystal-Based Water Concentration Estimation in Blood Using Machine Learning for Identification of the Haematological Disorder

Human blood is made up primarily of water. Water is significantly involved in balancing the human body. It affects the component of blood like mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), and mean platelets volume (MPV). The water concentration varies from 80 to 90% in blood. The change in water concentration changes the refractive index of plasma, and the change in the refractive index of plasma also changes the refractive index of blood. The proposed structure is designed to analyze the water concentration in human blood by analyzing the shifting in resonant peak and this shifting is processed by machine learning algorithm to estimate the concentration of water in human blood. Nanocavity ring structures in the waveguide region are designed as sensing nodes in this proposed structure. The air hole radius of these Nanocavity ring structures is 80 and 50 nm, whereas the proposed structure’s dimension is 12.15 by 8.45 μm2. The sensitivity of the design structure is 570 nm/RIU, and the quality factor is 650. The structure is simulated through the Finite Difference Time Domain (FDTD) method.

Quad core gold coated photonic crystal fiber temperature sensor based on surface plasmon resonance

This paper shows a simple quad core Photonic Crystal Fiber (PCF) temperature sensor based on Surface Plasmon Resonance (SPR) which has very high sensitivity and sensor resolution. For evaluating the sensing performance Finite Element Method (FEM) is used. In this design, gold is used as plasmonic material and the outer layer of the designed PCF has to be filled by it for making the fabrication easier than any other model. Besides, the Chloroform is used as the temperature sensitive liquid (analyte). The designed temperature sensor has the maximum wavelength sensitivities which are 7.5 nm/°C and 10.5 nm/°C for x and y-polarization respectively. The sensor shows the resolution of 13.33 × 10−3 RIU for x-polarization and 9.52 × 10−3 RIU for y-polarization. Core diameter, radius of air hole, thickness of gold and pitch are the structural parameters which are adjusted to their optimized value for getting higher sensitivity. Easy fabrication and simplicity are the major aspects of this proposed model which makes it applicable to various applications such as medical science, power plant, engineering sector, environment monitoring etc.

Parametric optimization of hollow core photonic crystal fiber and its comparison with conventional single mode fiber

Photonic Crystal Fibers (PCF) are flexible in its structural dimensions such as core radius, cladding hole radii and pitch. This flexibility permits the researcher to optimize the fiber to its best performance for desirable applications. Therefore, the objective of this paper is to propose an optimized Hollow Core Photonic Crystal Fiber (HCPCF) by investigating the optical parameters of the fiber. In addition to this, the manuscript intends to provide a brief comparative analysis of conventional Single Mode Fiber (SMF) and proposed HCPCF. Major parameters for study are taken as confinement factor, confinement loss, dispersion and birefringence. Based on these optical parameters, efficiency of the design is judged, where all the structural entities are chosen and investigated sequentially. The optimized value for pitch, radius of air-holes of core and cladding region of HCPCF are calculated as 3.8 µm, 18.01 µm and 1.2 µm, respectively. On comparison of HCPCF and conventional SMF, it is observed that the CF for the proposed HCPCF is higher than conventional SMF. On the other hand, confinement loss is lower for the conventional SMF. Thus, it is inferred that this optimized HCPCF can be used for high power small distance communication or sensing based optical applications.

Photonic crystal fiber supporting 394 orbital angular momentum modes with flat dispersion, low nonlinear coefficient, and high mode quality

A photonic crystal fiber (PCF) with an SSK2 dense crown glass ring is designed and analyzed. After optimization of the radius of the central air hole and thickness of the annular region, 394 orbital angular momentum (OAM) modes in the range of 1.48 to 1.62 μm can be transmitted stably. The effective refractive index, effective index difference, dispersion, effective mode area, nonlinear coefficient, numerical aperture (NA), mode quality, and confinement loss are analyzed numerically by the finite element method. The results show that the effective index difference of all the OAM modes is greater than 1 × 10 − 4 and they can propagate stably in the PCF. Besides, the fiber shows flat dispersion with a minimum variation of 8.55 ps / ( km · nm ) , very small nonlinear coefficient of less than 0.232 W − 1 · km − 1, as well as high mode quality bigger than 94.57%. This high-performance PCF has immense application potential in optical fiber communication.

The Light Extraction Efficiency of GaN-based LED with Air-Hole Photonic Crystal Structures

In order to improve the light extraction efficiency (LEE) of GaN-based light-emitting diodes (LEDs), a layer of cylindrical air-hole photonic crystal (PC) structure inserted into P-GaN is proposed and investigated numerically. Finite difference time domain (FDTD) method is used to make a series of simulations in the LEE of GaN-based LED with air-hole photonic crystal structure. According to the variable-controlling approach, the PC structure is simulated and optimized. The results of the simulations show that the LEE depends on the PC’s position and relevant structural parameters. When PC is etched in the active layer, and its dielectric constant [Formula: see text][Formula: see text][Formula: see text]m, etching [Formula: see text][Formula: see text][Formula: see text]m and air-hole radius [Formula: see text][Formula: see text][Formula: see text]m, higher LEE is obtained as 44.5%, translated into a 13.6-fold enhancement for the case of a planar LED. The remarkable enhancement is of particular interest for improving LEE of LED and provides a theoretical reference for future LED structure design efforts.

Tailoring anisotropic absorption in a borophene-based structure via critical coupling.

The research of two-dimensional (2D) materials with atomic-scale thicknesses and unique optical properties has become a frontier in photonics and electronics. Borophene, a newly reported 2D material, provides a novel building block for nanoscale materials and devices. We present a simple borophene-based absorption structure to boost the light-borophene interaction via critical coupling in the visible wavelengths. The proposed structure consists of borophene monolayer deposited on a photonic crystal slab backed with a metallic mirror. The numerical simulations and theoretical analysis show that the light absorption of the structure can be remarkably enhanced as high as 99.80% via critical coupling mechanism with guided resonance, and the polarization-dependent absorption behaviors are demonstrated due to the strong anisotropy of borophene. We also examine the tunability of the absorption behaviors by adjusting carrier density and lifetime of borophene, air hole radius in the slab, the incident angle and polarization angle. The proposed absorption structure provides novel access to the flexible and effective manipulation of light-borophene interactions in the visible and shows a good prospect for the future borophene-based electronic and photonic devices.

Mechanism and characteristics of a tunable dispersion-compensating dual-ring microstructure fiber for different orbital angular momentum modes.

A tunable dual-ring microstructure fiber that can support stable transmission for different orbital angular momentum (OAM) states and possess ultrahigh dispersion coefficients and low confinement losses is proposed and theoretically investigated. The proposed fiber is composed of two high-refractive-index rings and a double-cladding structure. Owing to the central air core and outer cladding, the dual-ring structure can support stable transmission for the OAM states. The mode fields of different OAM states in the inner ring can spread to the outer ring under certain conditions, which leads to high absolute values of dispersion around the coupling wavelengths. By tuning the refractive indices of the dual rings, the proposed fiber can achieve dispersion control for different OAM modes. Moreover, the specially designed two-layer air holes in the inner cladding can affect the mode-coupling coefficients, which are characterized by the effective mode areas and the overlap integral of the electric fields between the resonant ring modes. Therefore, the dispersion curves and operating wavelengths of the OAM modes can be modulated by regulating the physical parameters (the radius of the two-layer air holes or the infiltrated functional materials) of the inner cladding. We built a theoretical model and analyzed the modulation method and mechanism of the dispersion curves based on the coupled mode theory. The theoretical results indicate that the proposed fiber is flexible and has potential dispersion-compensating applications in fiber OAM systems.

Analysis of GaN-based 2D Photonic Crystal Sensor for Real-time Detection of Alcohols

The present research proposes an extensive assay of photonic band gap (PBG) characteristics for transverse electric field polarization in two-dimensional (2D) photonic crystal (PhC) structures, with a vision to sense different groups of alcohol like methanol, ethanol, propanol, butanol and phenol. The plane wave expansion (PWE) technique is implemented for realization of PBG in two types of lattice configurations such as square lattice and triangular lattice with circular air holes. Various structure parameters like radius of the circular air holes, lattice constant, nature of the background material, arrangement of air holes and period of air holes are meticulously optimized for envisaging a complete band gap. A variety of unpredicted trends are observed in the simulation outcomes, which include a substantial shift in band gap width, band gap size, reflected wavelength, reflected light intensity and transmitted light intensity for different types of alcohols. Also, the effect of air filling fraction on the band gap size has been investigated by selecting different radius of circular air holes. Apart from this, high sensitivity of 1645 nm/RIU and resolution of $$6.07\times {10}^{-5}$$ RIU is attained with the proposed structures, which pave the path for different bio-sensing applications.

Design of hollow core step-index antiresonant fiber with stepped refractive indices cladding.

With the benefits of low latency, wide transmission bandwidth, and large mode field area, hollow-core antiresonant fiber (HC-ARF) has been a research hotspot in the past decade. In this paper, a hollow core step-index antiresonant fiber (HC-SARF), with stepped refractive indices cladding, is proposed and numerically demonstrated with the benefits of loss reduction and bending improvement. Glass-based capillaries with both high (n = 1.45) and low (as low as n = 1.36) refractive indices layers are introduced and formatted in the cladding air holes. Using the finite element method to perform numerical analysis of the designed fiber, results show that at the laser wavelengths of 980 and 1064 nm, the confinement loss is favorably reduced by about 6 dB/km compared with the conventional uniform cladding HC-ARF. The bending loss, around 15 cm bending radius of this fiber, is also reduced by 2 dB/km. The cladding air hole radius in this fiber is further investigated to optimize the confinement loss and the mode field diameter with single-mode transmission behavior. This proposed HC-SARF has great potential in optical fiber transmission and high energy delivery.

Design of a microstructure optical fiber supporting 52 vortex beams

We propose a newly designed optical fiber with a microstructure based on SiO2 that supports the transmission of 52 vortex beams. By optimizing the radius of the center air hole and small air holes encircling the center air hole, the effective refractive index difference between adjacent vortex beams is higher than 10−4, which is large enough to support the transmission of vortex beams. Through a numerical analysis, the dispersion of vortex beams is lower than 189.00 ps ⋅ nm−1⋅ km−1 and maintains a flat trend. The confinement loss is as low as 10−9 dB ⋅ m−1 at 1550 nm, and the nonlinear coefficient of the vector modes is on the order of 10−4. The HE31 mode has the longest stable transmission distance among the vector modes, 630.83km at 1550nm. The vortex beams’ purity is analyzed to quantify the spin–orbit coupling (SO coupling) effect. The modes’ purity is higher as the topological charge (L) increases, and the spin–orbit aligned modes’ purity is higher than the spin–orbit anti-aligned mode at the same L. The MOF’s geometric parameters affect vortex beams’ purity.

Investigation of the influence of fluctuation in air hole radii and lattice constant on photonic crystal substrate for terahertz applications

Recently, the use of carrier frequencies in the domain of wireless bearer has been enhanced to fulfill the data transmission need. The research activities are coordinated to wireless communication with high information rates and amended security. An idea of the slotted rectangular patch antenna that depends on the photonic crystal structure is offered for a wireless communication system. The proposed antenna is contrasted with the accustomed slotted antenna. In addition, the investigation of the designed antenna is performed with various radius values and lattice constant. The negligible return loss of −43.79 dB and voltage standing wave ratio of 1.1 are accomplished at 2-μm radius with the lattice constant of a = 5 μm at fr = 2.23 THz.

Numerical modeling of integrated electro-optic modulators based on mode-gap shifting in photonic crystal slab waveguides containing a phase change material

This paper presents novel designs and simulation results of electro-optic modulators in integrated silicon photonics platforms. The electro-optic modulators described in this paper are based on the modulation of the photonic bandgap in a silicon photonic crystal slab waveguide, consisting of a phase change material (germanium selenide) sandwiched in between silicon layers. Three-dimensional finite difference time domain (FDTD) modeling is employed to simulate two configurations of electro-optic modulators based on mode-gap shifting in photonic crystal slab waveguides—one that is designed for operation with the transverse electric (TE) polarization of light and the other for the transverse magnetic (TM) polarization. When the electric field is applied across the germanium selenide layer surrounded by doped silicon layers, there is a change of phase of the germanium selenide layer. A large refractive index contrast between the two phases of the germanium selenide layer—i.e., between the amorphous phase and the crystalline phase—on application of the electric field is responsible for shifting of the mode gap in the dispersion characteristics of the PhC slab waveguide. Our results show excellent performance of the electro-optic modulators in terms of the high On/Off extinction ratio ( > --> 37 d B in the TE configuration and > --> 28 d B in the TM configuration), broadband switching capability ( ∼ 100 n m ), low insertion loss in the On state ( < 2 d B ), high range of tunability (by changing the lattice constant and radius of air holes), and low operating voltage ( < 4 V ). The proposed devices can be used as electro-optic modulators in future nanoscale photonic integrated circuits.

Hybrid plasmonic–phononic cavity design for enhanced optomechanical coupling in lithium niobate

A hybrid plasmonic–phononic cavity design which enables high vacuum coupling rate has been proposed in lithium niobate (LN) phononic crystals (Phncs) that have been perforated by air holes and coated with thin silver film. By tailoring the geometry, optomechanical interaction between the plasmonic modes (produced by the metal/insulator) and the phononic modes (confined by the phononic bandgap effect) is greatly enhanced. Numerical results based on finite-element method (FEM) reveal that in this hybrid plasmonic–phononic design, high vacuum coupling rate that predominantly contributed by moving boundary effect is on the order of 106 Hz, which is about one to two orders higher than that contributed by photoelastic effect shown in conventional phoxonic crystal designs. Results evidence how the vacuum coupling rate depends on geometrical parameters like the radius of the defect air hole, the thickness of silver layer, and LN layer. The simultaneous confinement and strong coupling, combined with other advantages as lack of constraint to the refractive index, and integration of piezoelectric material and metal in a chip, this hybrid design may be suitable for non-invasive biological sensing, optomechanically tunable plasmonic heater for drug release and lab-on-chip devices.

Micro-structured optical fiber magnetic field sensor based on magnetic fluid filling

A novel micro-structured fiber magnetic field sensor based on magnetic fluid (MF) filling is proposed. The air hole radius in the cladding of fiber is reduced from inner layer to outer layer, and the numerical analysis is performed by the finite element method (FEM). For the [Formula: see text]-pol mode, the proposed sensor has an average sensitivity of 960.61 pm/Oe, and for the [Formula: see text]-pol mode, the average sensitivity can reach 884.85 pm/Oe. The sensor has the advantages of small size and high sensitivity and is competitive in magnetic field sensors.

Analysis and Simulation of Multi Core Modified PCF with Uniformly Polarization High Birefringent and Low Confinement Loss

We are proposing modified design and analysis of the polarization and confinement loss in photonic crystal fiber. We are proposing multi-core fiber having hexagonal geometry having different radius of air holes. The geometry has 37 air holes rings forming the cladding region. The structure is analyzed, simulated and designed by optiFDTD software. Simulation results of proposed design has low dispersion and confinement loss, such as the electric field distribution with polarization.

Refractive index sensor based on photonic quasi-crystal with concentric ring microcavity

In this paper, a refractive index sensor based on Stampfli-type photonic quasi-crystal with concentric ring microcavity is proposed. The variations of resonant wavelength and quality factor with the change of the width of concentric rings and the radius of air holes are researched. The transmission spectra of the sensor filled with analytes with different refractive index are detected, and a high sensitivity of 613 nm per refractive index unit (RIU), as well as a high quality factor of 79423, is obtained. This work will provide guidance for the application of photonic quasi-crystal microcavity in the field of optical sensing.