High temperature-sensitivity sensor based on long period fiber grating inscribed with femtosecond laser transversal-scanning method

Abstract

We propose a high temperature-sensitive long period fiber grating (LPFG) sensor fabricated by using the femtosecond laser transversal-scanning method. The femtosecond pulses scan over the whole fiber core and some part of the cladding region; the modified regions are more extended. It is found that the LPFG-I fabricated by the transversal-scanning method shows higher temperature sensitivity and better temperature uniformity than that of LPFG-II written by the femtosecond laser point-by-point method. The LPFG-I with a temperature sensitivity of 75.96 pm/°C in the range of 25°C-400°C is measured. Moreover, in the range from 400°C to 800°C, a higher temperature sensitivity of 148.64 pm/°C and good linearity of 0.99 are achieved, while the temperature sensitivity of LPFG-II is only 95.55 pm/°C. LPFG-I exhibits better temperature characteristics, which, to the best of our knowledge, has the highest sensitivity in silica fiber temperature sensors.

Red shift of absorption edge and band gap shrinkage in perovskite Pb(Zr0.35Ti0.65)O3thin film from heat generation for solar cells application

“…Hence, the values of k at the absorption range have illustrated red shift features with temperature increasing. The red shift of absorption edge indicates two fundamental evolutions: temperature dependence of electron transition line width broadening and thermal driven band gap shift, 24) which is similar to previous reports for AlN, GaN, and ZnSe. 25,26) The real (ε 1 ) and imaginary (ε 2 ) parts of the dielectric functions of PZT thin films with different temperature have been given in Figs.…”

A four-layer Ag-ZnO-LPFG structure for improving temperature sensitivity and coupled-wavelength transmittance stability

“…where Γ m temp is the temperature-sensitivity factor, and its formula is defined as: It can be seen that there are two main factors affecting the sensitivity to temperature: the temperature-sensitivity factor and the thermal expansion coefficient of the grating [23,24].…”

“…However, this is not what we wanted to see. The coupled wavelength transmittance is related to the effective refractive index, which is a function of temperature sensitivity [23,24,29,30]. A disturbance to the coupled wavelength transmittance will inevitably lead to uncertainty about the temperature sensitivity and therefore to experimental error.…”

Fiber optic Fabry–Perot interferometer constructed by quartz capillary and titanium wire for temperature measurement

“…The fiber optic temperature sensors have attracted much attention of researchers due to its advantages such as small size, light weight, high sensitivity and strong anti-electromagnetic interference ability [1]. The sensors based on fiber gratings [2,3], Mach-Zehnder interferometers [4], surface plasmon resonance [5,6] and Fabry-Perot (F-P) interferometers [7][8][9] have been proposed and developed. Among them, the F-P fiber optic temperature sensor has some conspicuous merits, including simple structure and probe mode of measurement.…”