Ultra-high sensitive dual-parameter sensor based on double-hole fiber for simultaneous detection of magnetic field and temperature.

An ultra-high sensitive dual-parameter sensor based on double-hole fiber (DHF) is proposed for simultaneous detection of magnetic fields and temperatures. The sensor utilizes the DHF containing a Ge-doped core with two large air holes symmetrically arranged at its two sides. To enhance the sensitivity to both a magnetic field and temperature, Al wires with different diameters are embedded on the inner walls of the air holes in the DHF, creating a magnetic field sensing channel filled with magnetic fluid and a temperature sensing channel filled with thermo-sensitive liquid. Structural parameters and metal materials of the sensor are optimized by using the finite element method. Numerical results demonstrate that this DHF-based dual-parameter sensor can detect magnetic fields ranging from 40 Oe to 130 Oe and temperatures ranging from 24.3 °C to 49.3 °C simultaneously. The maximum magnetic field sensitivity reaches up to 64000 pm/mT, while the maximum temperature sensitivity is approximately 44.6 nm/°C, both exceeding current reports by more than one order of magnitude for simultaneous detection of magnetic field and temperature. With its high sensitivity, low fabrication difficulty, and simple structure, this DHF-based dual-parameter sensor has potential applications in the fields of material characterization analysis, geological environmental monitoring, and aeronautical engineering.

Ultra-high sensitivity weak magnetic field detecting magnetic fluid surface plasmon resonance sensor based on a single-hole fiber.

An ultra-high sensitivity weak magnetic field detecting magnetic fluid surface plasmon resonance (SPR) sensor based on a single-hole fiber (SHF) is proposed for detecting weak magnetic fields. The sensor is constructed with a single-hole fiber in which an exclusive air hole in the cladding is embedded with a metal wire and filled with a magnetic fluid (MF) to enhance the magnetic field sensitivity. The effects of the structural parameters, embedded metals, and refractive index difference between the core and cladding on the magnetic field sensitivity and peak loss are investigated and optimized. The sensitivity, resolution, figure of merit (FOM), and other characteristics of the sensor are analyzed systematically. The numerical results reveal a maximum magnetic field sensitivity of 451,000 pm/mT and FOM of 15.03 mT-1. The ultra-high magnetic field sensitivity renders the sensor capable of detecting weak magnetic fields at the pT level for the first time, in addition to a detection range from 3.5 mT to 17 mT. The SHF-SPR magnetic field sensor featuring high accuracy, simple structure, and ease of filling has immense potential in applications such as mineral resource exploration as well as geological and environmental assessment.

Surface plasmon resonance sensor composed of micro-nano optical fibers for high-sensitivity refractive index detection.

Spurred by the continuous development of surface plasmon resonance (SPR) technology, optical fiber sensors based on SPR have become a research hotspot. Although single-mode fibers (SMFs) are simple and easy to manufacture, the sensitivity is quite poor. On the other hand, even though photonic crystal fibers (PCFs) and anti-resonant fibers (ARFs) can achieve high-sensitivity detection and the wavelength sensitivity is tens of times that of SMFs, they are complex and difficult to produce. Herein, an SPR refractive index sensor composed of micro-nano optical fibers (MNFs) is designed to detect analytes in the refractive index range between 1.33 and 1.43. Analysis by the finite element method (FEM) reveals that the maximum wavelength sensitivity is 49,000 nm/RIU. The SPR sensor boasting a simple structure, low cost, and high wavelength sensitivity has enormous potential in applications such as chemical analysis, environmental monitoring, and other fields.

Effects of different cladding materials on orbital angular momentum modes propagating in photonic crystal fibers.

With the development of orbital angular momentum (OAM) photonic crystal fibers (PCFs) for more efficient communication, fiber claddings are important to the performance. In this paper, the influence of S i O 2 and four new optical materials, which are amethyst, SSK2, SF11, and LaSF09, as cladding materials, on the OAM mode characteristics is studied based on a common PCF for OAM transmission. In addition, the effective index difference, dispersion, confinement loss, and other properties of OAM modes transmitted in the five materials are derived by the finite element method. After in-depth analysis, universal rules can be obtained as guidelines for optimization of PCF in the future for improving the efficiency of optical fiber communication. Through chart analysis, it can be concluded that when materials of high effective refractive indices are used as cladding materials for PCF, the dispersion, nonlinear coefficient, confinement loss, mode purity, and other properties are significantly improved. Lower dispersion and confinement loss are more conducive to long-distance communication transmission. The decrease in nonlinear coefficient represents a better effect in suppressing nonlinear effects, and the increase in numerical aperture and mode purity respectively improves the transmission efficiency and stability of OAM communication. These conclusions provide universal rules for high-quality communication in the future.

HE1,1 mode excited surface plasmon resonance for high-sensitivity sensing by photonic crystal fibers.

Surface plasmon resonance (SPR) is widely used in photonic crystal fiber sensors. In this work, a photonic crystal fiber sensor based on HE1,1 mode excited SPR is designed and analyzed by the finite element method. The maximum wavelength sensitivity, optimal resolution, and amplitude sensitivity of the optical fiber sensor are 24,600 nm/RIU, 4.07×10-6RIU, and 1164.13RIU-1, respectively, for the refractive index range between 1.29 and 1.39. The sensor has excellent properties and wide application prospects in bimolecular and biochemical sensing, environmental monitoring, food safety, and other fields.