Design and numerical analysis of microstructured-core octagonal photonic crystal fiber for sensing applications

High Sensitivity and Wide Range Refractive Index Sensor Based on Surface Plasmon Resonance Photonic Crystal Fiber

In order to detect the refractive index (RI) of high refractive index materials such as trichlorobenzene and aniline in the near-infrared and mid-infrared spectra and expand the detection range of the refractive index, a surface plasmon resonance (SPR) photonic crystal fiber (PCF) sensor based on an elliptical sensing channel is proposed for high refractive index detection. The fiber core and the analyte channel are surrounded by two types of air holes with different sizes. When the surface plasmon resonance effect appears at the interface between the fiber core and the elliptical sensing layer, obvious resonance peaks appear in the near-infrared and mid-infrared bands. The full vector finite element method (FEM) is used to study the sensing characteristics of the sensor and the influence of structural parameters on the resonance peak. The results demonstrate that the sensor achieves detection in the refractive index range of 1.41-1.58, in the wavelength range of 1600-3200 nm. The average wavelength sensitivity is 9217.22 nm/RIU, and the refractive index resolution is 10.85 × 10^-6 RIU. The proposed sensor realizes high refractive index detection in the near-infrared and mid-infrared bands, and obtains an ultra-wide detection range and higher sensitivity. The sensor has broad application prospects in chemical detection, biomedical sensing and other fields, and provides a theoretical reference for the design of a photonic crystal fiber surface plasmon resonance sensor.

Design and Simulation of Photonic Crystal Fiber for Liquid Sensing

A simple hexagonal lattice photonic crystal fiber model with liquid-infiltrated core for different liquids: water, ethanol and benzene, has been proposed. In the proposed structure, three air hole rings are present in the cladding and three equal sized air holes are present in the core. Numerical investigation of the proposed fiber has been performed using full vector finite element method with anisotropic perfectly match layers, to show that the proposed simple structure exhibits high relative sensitivity, high power fraction, relatively high birefringence, low chromatic dispersion, low confinement loss, small effective area, and high nonlinear coefficient. All these properties have been numerically investigated at a wider wavelength regime 0.6–1.8 μm within mostly the IR region. Relative sensitivities of water, ethanol and benzene are obtained at 62.60%, 65.34% and 74.50%, respectively, and the nonlinear coefficients are 69.4 W−1 km−1 for water, 73.8 W−1 km−1 for ethanol and 95.4 W−1 km−1 for benzene, at 1.3 µm operating wavelength. The simple structure can be easily fabricated for practical use, and assessment of its multiple waveguide properties has justified its usage in real liquid detection.

Construction of photonic crystals with thermally adjustable pseudo-gaps

Photonic crystals (PCs) are periodic dielectric structures with photonic bandgaps and they can be used to control and manipulate photons effectively. Novel photonic crystal materials with tunable bandgaps can be prepared by changing the refractive index of the dielectric or lattice parameters under external stimuli, while using temperature to adjust the photonic band gap is a simple and convenient method. In this paper, silica PCs having different pseudo-gaps in the range of 450-750 nm were prepared with colloidal SiO₂ spheres of different sizes. Thermo-sensitive PNIPAM hydrogel was then infiltrated into the PCs to obtain PNIPAM-PCs, whose pseudo-gap blue-shifted when the temperature was changed from 24 to 34 °C and exhibited good reversibility. The PCs with tunable bandgaps are significant for the development of integrated photonic devices, sensors, and in detection and other technologies.

Ultra-Wide-Bandwidth Tunable Magnetic Fluid-Filled Hybrid Connected Dual-Core Photonic Crystal Fiber Mode Converter

We propose a tunable magnetic fluid-filled hybrid photonic crystal fiber mode converter. Innovative design principles based on the hybrid connected dual-core photonic crystal fiber and magnetically modulated optical properties of magnetic fluid are developed and numerically verified. The mode converter was designed to convert LP11 in the index-guiding core to the LP01 mode in the photonic bandgap-guiding core. By introducing the magnetic fluid into the air-hole located at the center of the photonic bandgap-guiding core, the mode converter can realize a high coupling efficiency and an ultra-wide bandwidth. The coupling efficiency can reach up to 99.9%. At a fixed fiber length, by adjusting the strength of the magnetic field, the coupling efficiency can reach up to 90% and 95% at wavelengths in the ranges of 1.33 µm–1.85 µm and 1.38 µm–1.75 µm, with bandwidth values reaching 0.52 µm and 0.37 µm, respectively. Moreover, it has a good manufacturing flexibility. The mode converter can be used to implement wideband mode-division multiplexing of few-mode optical fiber for high-capacity telecommunications.

Dataset on photonic crystal fiber based chemical sensor

This article represents the data set of micro porous core photonic crystal fiber based chemical sensor. The suggested structure is folded cladding porous shaped with circular air hole. Here is investigated four distinctive parameters including relative sensitivity, confinement loss, numerical aperture (NA), and effective area (Aeff). The numerical outcomes are computed over the E+S+C+L+U communication band. The useable sensed chemicals are methanol, ethanol, propanol, butanol, and pentanol whose are lies in the alcohol series (Paul et al., 2017) [1]. Furthermore, V-parameter (V), Marcuse spot size (MSS), and beam divergence (BD) are also investigated rigorously. All examined results have been obtained using finite element method based simulation software COMSOL Multiphysics 4.2 versions with anisotropic circular perfectly matched layer (A-CPML). The proposed PCF shows the high NA from 0.35 to 0.36; the low CL from ~10^-11 to ~10^-7 dB/m; the high A_eff from 5.50 to 5.66 µm²; the MSS from 1.0 to 1.08 µm; the BD from 0.43 to 0.46 rad at the controlling wavelength λ = 1.55 µm for employing alcohol series respectively.

Ultrahigh birefringence, ultralow material loss porous core single-mode fiber for terahertz wave guidance

In this paper, a novel polarization-maintaining single-mode photonic crystal fiber (PCF) has been suggested for terahertz (THz) transmission applications. The reported PCF has five layers of hexagonal cladding with two layers of porous core. The cladding and core territory of the PCF are constituted by circular and elliptical air cavities, accordingly acting as a dielectric medium. Different geometrical parameters of the proposed PCF including pitches and diameters of circular air holes with the major and minor axes of elliptical air cavities being varied with the optimized structure. Various effects on the proposed PCF such as eccentricity and porosity effects are also carefully investigated. The numerical process is investigated by one of the most popular methods, the finite element method (FEM). All numerical computational results have revealed the ultrahigh birefringence in the order of 1.19×10^-02 as well as the ultralow bulk absorption material loss of 0.0689  cm^-1 at the 1 THz activation frequency. Besides, the V-parameter is also investigated for checking the proposed fiber modality. The proposed single-mode porous core hexagonal PCF is expected to be useful for convenient broadband transmission and numerous applications in the areas of THz technology.