Characteristics of Ultrasensitive Hexagonal-Cored Photonic Crystal Fiber for Hazardous Chemical Sensing

A highly sensitive non-complex cored photonic crystal fiber sensor for hazardous chemical sensing with water, ethanol, and benzene analytes has been proposed and is numerically analyzed using a full-vector finite element method. The proposed fiber consists of a hexagonal core hole and two cladding air hole rings, operating in the lower operating wavelength of 0.8 to 2.6 µm. It has been shown that the structure has high relative sensitivity of 94.47% for water, 96.32% for ethanol and 99.63% for benzene, and low confinement losses of 7.31 × 10−9 dB/m for water, 3.70 × 10−10 dB/m ethanol and 1.76 × 10−13 dB/m benzene. It also displays a high power fraction and almost flattened chromatic dispersion. The results demonstrate the applicability of the proposed fiber design for chemical sensing applications.

Simulation of Continuous Tension Stringing Process of Conductor with Bending Stiffness Model

At present, there is no research on the calculation of tension variation of the conductor with bending stiffness model between the continuous span during tension stringing construction. Aiming at the typical terrain with large elevation difference in UHV project, a vector finite element method for calculating the tension of the conductor with bending stiffness model passes through the pulley in the process of tension stringing is proposed. The process of the wire rope under the action of the tractor pulling the conductor passes through the pulley continuously is realized. The variations of tension of tensioner and tractor, reaction force of pulley and envelope angle of the conductor passes through the pulley are obtained by simulation of tension stringing conditions such as 1 pulls 1, 1 pulls 2, etc, which provides reference for equipment selection for the tension stringing construction of mountain terrain with large elevation difference.

Design of a Polarization Splitter for Ultra-broadband Dual-Core Photonic Crystal Fiber

A novel ultra-broadband polarization splitter based on dual-core photonic crystal fiber (DC-PCF) is designed. The full-vector finite element method (FEM) and coupled-mode theory are employed to investigate the characteristics of the polarization splitter. According to the numerical results, graphene-filled layer can not only broaden the working bandwidth but also reduce the size of polarization splitter. Furthermore, the fluorine-doped region and the germanium-doped region could broaden the bandwidth. Apart from that, the 4.78-mm-long polarization splitter can achieve an extinction ratio of -98.6 dB at the wavelength of 1550 nm. When extinction ratio is less than -20 dB, the range of the wavelength is 1027-1723 nm with a bandwidth of 696 nm. Overall, the polarization splitter can be applied to all-optical network communication system in the infrared and near-infrared wavelength range.

Design of broadband single-polarization filter based on simple structure photonic crystal fiber with gold-coated air holes

A polarization filter based on simple structure photonic crystal fiber (PCF) coated with gold air holes is designed in this work. The full vector finite element method (FEM) is used to calculate the characteristic parameters of PCF. In the final numerical simulation results, the loss peak in the [Formula: see text] polarization direction is 2305.72 dB/cm and the [Formula: see text]-polarized loss is as low as 75.86 dB/cm at 1.31 [Formula: see text]m. For the fiber length of 1000 [Formula: see text]m, the CT reaches 1936.83 dB and a wide bandwidth greater than 20 dB can provide above 800 nm. The content of this paper can provide a new idea for filter structure design.

Design of Honeycomb Shaped Spectroscopy based Biosensor for the Detection of Tuberculosis Cells

A novel compact honeycomb spectroscopic-based PCF sensor for the detection of tuberculosis cells is proposed. A circular shape core area and tightly bound hexagonal shape air holes in the cladding area are designed for the suggested structure that exhibits ultra-high sensitivity up to 99.99% and very low loss of order 10-11 dB/m. The optical parameters such as effective area (Aeff), V-parameter or normalized frequency (Veff), spot- size (Weff), numerical aperture, along quality factor of beam have been exhibited and numerically observed. The wavelength operating region is specified as 1.2 μm to 2.5 μm. The guiding properties of this suggested tuberculosis sensor is computed with the full vector finite element method (FV-FEM) in the environment of COMSOL Multiphysics (Version5.3) for the calculation of numerical analysis. Circular shape perfectly matched layer (PML) and hexagonal lattice PCF sensor using silica as a background material is successfully designed to increase the sensitivity response compare to the prior works. Moreover, during the entire operating wavelength presented sensor achieves a single modality. With excellent sensitivity response and very low confinement loss, this proposed sensor doubtfully proves its prominent role to detect tuberculosis cells.

NUMERICAL SOLVING THREE-DIMENSIONAL DIRECT PROBLEM OF PULSED ELECTROMAGNETIC CROSS-WELL EXPLORATION FOR CRYOLITHOZONE MONITORING

The article is devoted to the problem of studying permafrost state and the processes of its geocryological changes using geophysical methods. To monitor the cryolithozone, a method of pulsed electromagnetic cross-well sounding is proposed. On the basis of the vector finite element method, a mathematical model of the cross-well sounding process by a pulsed source in a three-dimensional spatially inhomogeneous medium has been created.

Multi-functional gallium arsenide photonic crystal polarization splitter with a gold core

A multi-functional dual-core photonic crystal fiber (PCF) polarization beam splitter with a central oval hole filled with gold is designed and described. The first layer on the circular holes around the core is filled with the nematic liquid crystal (NLC) to enhance birefringence. The full-vector finite element method is employed to study the characteristics of the polarization beam splitter and derive the optimal parameters. When the fiber length is 14.55 [Formula: see text]m, the polarized light in the [Formula: see text]- and [Formula: see text]-directions can be separated at a wavelength of 1.31 [Formula: see text]m and the bandwidths are 257 and 238 nm, respectively, for extinction ratios bigger than 10 dB. When the fiber length is 10.86 [Formula: see text]m, the polarized light in the [Formula: see text]- and [Formula: see text]-directions can be separated at a wavelength of 1.55 [Formula: see text]m and the bandwidths are 239 and 174 nm, respectively for extinction ratios larger than 10 dB. The multifunctional polarization beam splitter with an ultra-short fiber length and broad bandwidth improves the sensing performance in comparison with single-function devices and our results provide insights into the design of beam splitters with multiple functions.