Polymer-packaged fiber Bragg grating with enhanced thermal sensitivity

1999 ◽  
Author(s):  
Bai-ou Guan
Keyword(s):  
Fiber Bragg Grating ◽  
Thermal Sensitivity ◽  
Bragg Grating

A Needlelike Probe for Temperature Monitoring During Laser Ablation Based on Fiber Bragg Grating: Manufacturing and Characterization

2015 ◽  
Vol 9 (4) ◽  
Author(s):  
Davide Polito ◽  
Michele Arturo Caponero ◽  
Andrea Polimadei ◽  
Paola Saccomandi ◽  
Carlo Massaroni ◽  
...  
Keyword(s):  
Laser Ablation ◽  
Measurement Error ◽  
Response Time ◽  
Fiber Bragg Grating ◽  
Thermal Sensitivity ◽  
Temperature Monitoring ◽  
Respiratory Pattern ◽  
Bragg Grating ◽  
Thermal Paste ◽  
Fbg Sensors

Temperature distribution monitoring in tissue undergoing laser ablation (LA) could be beneficial for improving treatment outcomes. Among several thermometric techniques employed in LA, fiber Bragg grating (FBG) sensors show valuable characteristics, although their sensitivity to strain entails measurement error for patient respiratory movements. Our work describes a solution to overcome this issue by housing an FBG in a surgical needle. The metrological properties of the probes were assessed in terms of thermal sensitivity (0.027 nm °C−1 versus 0.010 nm °C−1 for epoxy liquid encapsulated probe and thermal paste one, respectively) and response time (about 100 ms) and compared with properties of nonencapsulated FBG (sensitivity of 0.010 nm °C−1, response time of 43 ms). The error due to the strain caused by liver movements, simulating a typical respiratory pattern, was assessed: the strain induces a probes output error less than 0.5 °C, which is negligible when compared to the response of nonencapsulated FBG (2.5 °C). The metallic needle entails a measurement error, called artifact, due to direct absorption of the laser radiation. The analysis of the artifact was performed by employing the probes for temperature monitoring on liver undergoing LA. Experiments were performed at two laser powers (i.e., 2 W and 4 W) and at nine distances between the probes and the laser applicator. The artifact decreases with the distance and increases with the power: it exceeds 10 °C at 4 W, when the encapsulated probes are placed at 3.6 mm and 0 deg from the applicator, and it is lower than 1 °C for distance higher than 5 mm and angle higher than 30 deg.

scholarly journals Fiber Bragg Grating (FBG) Sensors in a High-Scattering Optical Fiber Doped with MgO Nanoparticles for Polarization-Dependent Temperature Sensing

2019 ◽  
Vol 9 (15) ◽  
pp. 3107 ◽  
Author(s):  
Carlo Molardi ◽  
Tiago Paixão ◽  
Aidana Beisenova ◽  
Rui Min ◽  
Paulo Antunes ◽  
...  
Keyword(s):  
Fiber Bragg Grating ◽  
Rayleigh Scattering ◽  
Near Infrared ◽  
Thermal Sensitivity ◽  
Single Mode ◽  
Temperature Sensing ◽  
Phase Mask ◽  
Bragg Grating ◽  
Mgo Nanoparticles ◽  
Fbg Sensors

The characterization of Fiber Bragg Grating (FBG) sensors on a high-scattering fiber, having the core doped with MgO nanoparticles for polarization-dependent temperature sensing is reported. The fiber has a scattering level 37.2 dB higher than a single-mode fiber. FBGs have been inscribed by mean of a near-infrared femtosecond laser and a phase mask, with Bragg wavelength around 1552 nm. The characterization shows a thermal sensitivity of 11.45 pm/°C. A polarization-selective thermal behavior has been obtained, with sensitivity of 11.53 pm/°C for the perpendicular polarization (S) and 11.08 pm/°C for the parallel polarization (P), thus having 4.0% different sensitivity between the two polarizations. The results show the inscription of high-reflectivity FBGs onto a fiber core doped with nanoparticles, with the possibility of having reflectors into a fiber with tailored Rayleigh scattering properties.

Characterization of Thermal Stress Phenomena Induced Into a Packaged Planar Lightwave Circuit Using Fiber Bragg Grating Sensors

2005 ◽  
Author(s):  
Amelia G. Grobnic ◽  
Robert James ◽  
Ping Lu ◽  
Stephen J. Mihailov
Keyword(s):  
Thermal Stress ◽  
Fiber Bragg Grating ◽  
Thermal Sensitivity ◽  
Photonic Devices ◽  
Design Parameters ◽  
Bragg Grating ◽  
Element Analysis ◽  
Package Design ◽  
Planar Lightwave Circuit ◽  
Planar Lightwave

We present a technique for the characterization and analysis of the thermal stress in the optical substrate of packaged photonic devices. This method allows optimization of the package geometry in order to improve the passive compensation of the thermal sensitivity of photonic devices. To the best of our knowledge, we report for the first time the use of strongly chirped, weakly apodized fiber Bragg grating (FBG) sensors to evaluate the stress distribution induced by the package in the planar lightwave circuit (PLC) substrate. We also evaluated the substrate thermal stress using finite element analysis (FEA). We investigated some of the package design parameters that can be used to control and tune the amount of stress that can be applied to the photonic device optical substrate. Our goal is to optimize the design of a package that applies tensile stress to the optical device to compensate unwanted effects due to ambient temperature variation.

scholarly journals Experimental Strain Measurement Approach Using Fiber Bragg Grating Sensors for Monitoring of Railway Switches and Crossings

Sensors ◽  
2021 ◽  
Vol 21 (11) ◽  
pp. 3639
Author(s):  
Abdelfateh Kerrouche ◽  
Taoufik Najeh ◽  
Pablo Jaen-Sola
Keyword(s):  
Fiber Bragg Grating ◽  
Experimental Tests ◽  
Cost Effective ◽  
Measuring Method ◽  
Bragg Grating ◽  
Railway Network ◽  
System Failures ◽  
Railway Infrastructure ◽  
Train Speed ◽  
And Control

Railway infrastructure plays a major role in providing the most cost-effective way to transport freight and passengers. The increase in train speed, traffic growth, heavier axles, and harsh environments make railway assets susceptible to degradation and failure. Railway switches and crossings (S&C) are a key element in any railway network, providing flexible traffic for trains to switch between tracks (through or turnout direction). S&C systems have complex structures, with many components, such as crossing parts, frogs, switchblades, and point machines. Many technologies (e.g., electrical, mechanical, and electronic devices) are used to operate and control S&C. These S&C systems are subject to failures and malfunctions that can cause delays, traffic disruptions, and even deadly accidents. Suitable field-based monitoring techniques to deal with fault detection in railway S&C systems are sought after. Wear is the major cause of S&C system failures. A novel measuring method to monitor excessive wear on the frog, as part of S&C, based on fiber Bragg grating (FBG) optical fiber sensors, is discussed in this paper. The developed solution is based on FBG sensors measuring the strain profile of the frog of S&C to determine wear size. A numerical model of a 3D prototype was developed through the finite element method, to define loading testing conditions, as well as for comparison with experimental tests. The sensors were examined under periodic and controlled loading tests. Results of this pilot study, based on simulation and laboratory tests, have shown a correlation for the static load. It was shown that the results of the experimental and the numerical studies were in good agreement.

A Fiber Bragg Grating acceleration sensor with temperature compensation

Optik ◽  
2021 ◽  
pp. 166993
Author(s):  
Xianfeng Zhao ◽  
Zhen’an Jia ◽  
Wei Fan ◽  
Wangfei Liu ◽  
Hong Gao ◽  
...  
Keyword(s):  
Fiber Bragg Grating ◽  
Temperature Compensation ◽  
Bragg Grating ◽  
Acceleration Sensor
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