RESUMEN
A photonic crystal fiber utilizing surface plasmon resonance (PCF-SPR) sensor based on refractive index (RI) control of magnetic fluid (MF) is designed. The air holes of the sensor are arranged in a hexagonal shape, and the optical field transmission channels on both sides of the central air hole can effectively confine the energy of the optical field. We use MF as the sensing medium, and coat the inner wall of the central air hole with gold. It can effectively stimulate the SPR effect to achieve the purpose of magneto-refractive modulation. We study the sensing characteristics of the proposed sensor by finite element analysis. The results show that the highest refractive index sensitivity reaches 19520 nm/RIU in the RI range of 1.42-1.435 and the maximum figure of merit (FOM) is 374.3 RIU-1. In addition, the magnetic field and the temperature response characteristics of the designed sensor are also investigated. In the magnetic field range of 50-130 Oe, the magnetic field sensitivity is 590 pm/Oe. In the temperature range of 24.3-144.3 °C, the temperature sensitivity is only -29.7 pm/â. The proposed sensor has significant advantages such as stable structure, high sensitivity, easy integration, resistance to electromagnetic interference and can be used for weak magnetic magnitude detection. It has wide application prospects in industrial production, military, and medical equipment.
RESUMEN
Based on the polymer encapsulation method, a compact structure and high-sensitivity temperature and pressure dual parametric sensor was developed in this paper by wrapping an optical microfiber coupler (OMC) in polydimethylsiloxane (PDMS). Benefiting from the stable chemical properties and good optical field control ability of PDMS, the sensor showed good stability and repeatability. The dependence of the sensor sensitivity on wavelength, temperature, and pressure was experimentally investigated. The results showed that the temperature and pressure sensitivity could reach -2.283â nm/°C and 3.301â nm/Mpa in the C-band range. To overcome the cross-sensitivity of sensor temperature and pressure, a sensitivity matrix was established to realize dual-parameter simultaneous demodulation. In addition, the pressure repeatability of the sensor was tested. Based on this, the sensitivity matrix was further calibrated to reduce the error and improve the accuracy of demodulation. Finally, we also designed a protective shell for the sensor to meet the requirements of practical marine applications. Compared with other existing types of optical fiber sensors, this sensor has the advantages of simple fabrication, high sensitivity, and environmental adaptability, and has great potential for application in the field of marine environmental monitoring.
RESUMEN
To improve the sensing performance of optical fiber magnetic field sensor based on magneto-refractive effect, a D-shaped photonic crystal fiber-surface plasmon resonance (PCF-SPR) sensor based on magneto-refractive effect is proposed and its magnetic field sensing characteristics are investigated. The designed D-shaped PCF has a core-analyte-gold structure. Within the D-shaped PCF, the side polishing surface is coated with the gold film and the special hole is sandwiched between the core and the gold film. To realize the high magnetic field sensitivity for the fiber SPR magnetic field sensor, the special hole is filled with magnetic fluid (MF). In this paper, we analyze the mode transmission characteristics and magnetic field sensing characteristics of this fiber sensor by finite element method. We also obtain a general rule for the optimization of PCF-SPR sensors by analyzing the dispersion curves, the energy of the surface plasmon polariton mode and the core mode on the sensing performance of the designed fiber sensor. The maximum refractive index sensitivity and magnetic field sensitivity of the optimized fiber are 59714.3 nm/RIU and 21750 pm/mT (50-130 Oe), respectively. Compared with optical fiber magnetic field sensors based on magneto-refractive effect reported previously, the magnetic field sensitivity in this paper is nearly two orders of magnitude higher and it can initially achieve nT magnitude magnetic field resolution and testing capability. The proposed fiber sensor has the advantages of simple structure, easy production, high sensitivity, and strong environmental adaptability. It not only improves the sensing performance of optical fiber magnetic field sensors, but also provides an ideal alternative platform for biosensors like microfluidics because of its high refractive index sensitivity and the special structure.
RESUMEN
In this paper, an optical fiber magnetic field and temperature sensor based on an optical microfiber coupler (OMC), Polydimethylsiloxane (PDMS), and magnetic fluid (MF) is proposed, and its magnetic field and temperature sensing characteristics are analyzed theoretically and verified experimentally. Based on the OMC and using MF as the sensing medium, the sensor can respond to the magnetic field and temperature respectively after encapsulated by PDMS. The experimental results show that the maximum magnetic field sensitivity is 96.8 pm/Oe, and the maximum temperature sensitivity is 919.1 pm/°C. To overcome the cross-sensitivity of the magnetic field and temperature of the sensor, the sensitivity matrix is established and demodulated. In addition, we discuss the optimization of the sensitivity demodulation matrix by the size design of the PDMS package and the OMC structure. The proposed two-parameter sensor in this article has the advantages of high sensitivity, low cost, small volume and high integration, which is of great significance for the multi-parameter sensing of basic physical parameters such as magnetic field and temperature.
RESUMEN
In order to meet the needs of phase generated carrier (PGC) demodulation technology for interferometric fiber optic hydrophones, we proposed an optical microfiber all-optical phase modulator (OMAOPM) based on the photo-induced thermal phase shift effect, which can be used as a phase carrier generation component, so as to make the modulation efficiency and working bandwidth of this type of modulator satisfy the requirements of underwater acoustic signal demodulation applications. We analyzed the modulation principle of this modulator and optimized the structural parameters of the optical microfiber (OM) when the waist length and waist diameter of OM are 15 mm and 1.4 µm, respectively. The modulation amplitude of the modulator can reach 1 rad, which can meet the requirements of sensing applications. On this basis, the fiber optical hydrophone PGC-Atan demodulation system was constructed, and the simulated underwater acoustic signal test demodulation research was carried out. Experimental results showed that the system can demodulate underwater acoustic signals below 1 kHz.