Performance Of Optical Fiber Sensors Research Articles

Utilizing magneto-optical short-range surface plasmon resonance to enhance the performance of optical fiber sensor

Although the short-range surface plasmon resonance (SRSPR) has larger sensitivity than the long-range surface plasmon resonance (LRSPR) excited simultaneously, SRSPR is usually ignored in previous studies of the LRSPR sensors due to its much larger peak width. However, since the resonance peaks of both SRSPR and LRSPR narrow vastly when combined with the magneto-optical (MO) effect, SRSPR has the potential to reach much higher figure-of-merit (FOM) than LRSPR due to its higher sensitivity. In this work, the feasibility of utilizing magneto-optical short-range surface plasmon resonance (MOSRSPR), which is the combination of SRSPR and MO effect, to enhance FOM was verified first by analyzing the prism-based structure sensor with the transfer matrix method (TMM). Then a novel optical fiber sensor based on MOSRSPR was proposed. The structure of the proposed sensor is a D-shaped optical fiber coated with an MgF2 film, a thin silver film, and a MO material film of cerium-doped yttrium-iron garnet (CeYIG). The influence of the structural parameters including the MgF2, silver, and CeYIG film thicknesses was analyzed theoretically by the finite element method (FEM). With the optimal parameters, the FOM of the optical fiber MOSRSPR sensor is greatly enhanced to 10,750 RIU−1 in maximum and 2888 RIU−1 in average, which surpasses all reported optical fiber LRSPR sensors vastly. The miniaturized and simple design of the D-shaped fiber MOSRSPR sensor, coupled with its high performance, offers a significant reference for the study of optical fiber sensors with ultra-high FOM.

High-Quality Fiber Bragg Gratings Inscribed by Femtosecond Laser Point-by-Point Technology.

We experimentally studied the inscription of fiber Bragg gratings by using femtosecond (fs) laser point-by-point (PbP) technology. The effects of the focusing geometry, grating order, laser energy and grating length on the spectral characteristics of the PbP FBG were investigated. After optimizing these parameters, a high-quality first-order PbP FBG with a reflectivity > 99.9% (i.e., Bragg resonance attenuation of 37.7 dB) and insertion loss (IL) of 0.03 dB was successfully created. Moreover, taking advantage of the excellent flexibility of the fs laser PbP technology, high-quality FBGs with various Bragg wavelengths ranging from 856 to 1902.6 nm were inscribed. Furthermore, wavelength-division-multiplexed (WDM) FBG arrays consisting of 10 FBGs were rapidly constructed. Additionally, a Fabry-Perot cavity was realized by using two high-quality FBGs, and its birefringence could be reduced from 3.04 × 10-5 to 1.77 × 10-6 by using a slit beam shaping-assisted femtosecond laser PbP technology. Therefore, such high-quality FBGs are promising to improve the performance of optical fiber sensors, lasers and communication devices.

Machine learning boosts performance of optical fiber sensors: a case study for vector bending sensing.

The spectral response produced when a high-sensitivity optical fiber sensor (OFS) is subject to an external perturbation has recently been shown to contain rich information that can be potentially exploited for multi-dimensional sensing. In this article, we propose the use of machine learning to directly and statistically learn the relation between the complex spectral response from an OFS and a measurand of interest, without knowing if there are distinct and tractable features in the spectrum. As a proof-of-concept demonstration, it is shown that a simple heterostructure-based device with a capillary tube sandwiched between two single-mode fibers without any fiber modification and complicated fabrication steps, is able to achieve directional bending sensing in a broad dynamic range with machine learning as a tool for signal analysis. It is also demonstrated that stringent requirements of the sensor interrogator, such as the wavelength and bandwidth of the light source, can be greatly relaxed due to the direct spectral mapping between the sensor and the measurand of interest, and importantly, without sacrificing the performance of the sensor. The proposed technique is highly generalizable and can be extended to any OFSs with regular or irregular characteristic spectra for sensing any measurands.

Transition metal dichalcogenides boost the performance of optical fiber SPR sensors

We show the active role that the transition metal dichalcogenide MoS2 plays in enhancing the sensing performance of optical fiber sensors based on surface plasmon resonance (SPR). This is proved experimentally suggesting that the optical fiber SPR sensor with the MoS2 has an about 24 percent increase in the bulk refractive index sensitivity compared to the one without the MoS2. Also, we investigate the surface sensing performance of the sensor using self-assembly monolayers of polyelectrolytes with well-defined thickness and refractive index.

A Review of Coating Materials Used to Improve the Performance of Optical Fiber Sensors.

In order to improve the performance of fiber sensors and fully tap the potential of optical fiber sensors, various optical materials have been selectively coated on optical fiber sensors under the background of the rapid development of various optical materials. On the basis of retaining the original characteristics of the optical fiber sensors, the coated sensors are endowed with new characteristics, such as high sensitivity, strong structure, and specific recognition. Many materials with a large thermal optical coefficient and thermal expansion coefficients are applied to optical fibers, and the temperature sensitivities are improved several times after coating. At the same time, fiber sensors have more intelligent sensing capabilities when coated with specific recognition materials. The same/different kinds of materials combined with the same/different fiber structures can produce different measurements, which is interesting. This paper summarizes and compares the fiber sensors treated by different coating materials.

Sensitivity enhanced D-type large-core fiber SPR sensor based on Gold nanoparticle/Au film co-modification

A D-type large core optical fiber sensor with high sensitivity and good stability based on the coupling of gold nanoparticles and Au film was proposed and demonstrated by simulation and experiments. The proposed sensor is numerically simulated based on the finite element method. The simulation shows that the electric field intensity of the gap coupling between gold nanoparticles and Au film is 4–5 times higher than that of Au film, and the electric field intensity on the surface of gold nanoparticles is twice as strong as that on the surface of Au films. The electric field coupling effect between the Au film surface plasmon resonance (SPR) and the gold nanoparticle localized surface plasmon resonance (LSPR) can improve the refractive index sensitivity of the sensor. Experimental results show that the refractive index sensitivity of D-type optical fiber/Au film/gold nanoparticles sensor reaches 3074 nm/refraction index unit (RIU), which is 1.4 times that of D-type optical fiber/Au film sensor. SPR–LSPR coupling effect is a good method to improve the sensing performance of optical fiber sensors, especially for detecting the refractive index changes of surrounding media. Compared with existing similar biosensors, the designed biosensor has higher sensitivity and the sensor proposed in this paper has great application prospects in the field of biological detection.

辐射对光纤传感器性能影响的研究进展

辐射对光纤传感器性能影响的研究进展

A Critical Evaluation of the Performance of Optical Fiber Sensors for Monitoring Dynamic Strains

Abstract An experimental study is conducted to evaluate the applicability of optical fiber sensors in measuring strains under dynamic loading conditions. Both phase modulated and intensity modulated sensors are studied. The experiments are performed to characterize the high strain rate response of these sensors and test their ability to measure changes in dynamic strain resulting from one-dimensional stress wave propagation. The stress waves are generated using both compressive and tensile gas gun setups. Then, optical fiber sensors are employed to monitor the stress wave pulse as it propagates down the bar. The output from the optical fiber sensors is compared to strain gages mounted at the same location. The results demonstrate that only localized optical fiber sensors that are bonded over the entire sensing region can be used for monitoring dynamic strain fields.

Importance of coatings to optical fiber sensors embedded in 'smart' structures

The importance of coatings to the overall performance of optical fiber sensors embedded in smart host materials is explored with closed-form solutions. Particular attention is paid to the mechanical ramifications of varying the properties and thickness of the coating, when the fiber is embedded in a transversely isotropic host material that is experiencing tensile loading parallel to the optical fiber. Analytical solutions are developed that show that strain concentrations near an embedded optical fiber are highly dependent on the thickness and material properties of the coating. Analytical evidence is presented of the existence of optimum coating material and thickness combinations for a given host material. Depending on the optimizing criterion selected, this optimum choice can minimize or even eliminate stress concentrations either in the host material immediately surrounding the embedded fiber, or in the coating, or in the optical fiber itself.