In-Fiber Gratings for Simultaneous Monitoring Temperature and Strain in Ultrahigh Temperature (original) (raw)

2015, IEEE Photonics Technology Letters

In this letter, a pair of regenerated gratings with Bragg wavelengths of 1547 and 1304 nm in a single piece of singlemode fiber has been fabricated for simultaneous monitoring of temperature and strain in ultrahigh temperature environment. A 3 × 3 matrix is used to characterize the cross sensitivity of the proposed sensor in which the strain sensitivity varies with temperature change. The proposed structure exhibits the deviation of 28.3 με and 4.1°C at the ranges of 0-1000 με and 25°C− 900°C, respectively. Index Terms-Fiber Bragg gratings, regenerated grating, temperature and strain sensing, ultra-high temperature. I. INTRODUCTION F OR the application of strain and stress monitoring in ultrahigh temperature (UHT) environment such as aerospace engine, high temperature pipelines in oil and gas industry, hydroelectric turbine and high voltage transformers, it is essentially important to acquire multiple physical parameters i.e., strain, temperature, and pressure for comprehensive monitoring of the system. For example, the conventional electric strain gauges are performing well up to 350°C temperature. Beyond that range, the performance of gauges degrades due to the effects of high temperature on gauge bonding, gauge backing durability, electrical properties and the low ability to maintain the actual strain by compensating the thermal apparent strain simultaneously. These reveal the shortcomings of strain gauges employment in UHT environment. In this regard, optical fiber sensors particularly fiber Bragg gratings (FBGs) have emerged as promising substitutions for replacing the conventional sensors in various sensing Manuscript