Optical Fiber Thermometer Based on Fiber Bragg Gratings

Ultracompact optical fiber high‐temperature sensor based on the angled fiber end face

“…Although the hightemperature sustainable FBG can be fabricated by using a femtosecond laser, expensive equipment is involved. [8][9][10][11][12][13][14][15] Optical fiber FPI is also widely used because of its simple structure, low cross-sensitivity, and small sensor head. 16,17 To achieve high-temperature monitoring in a spatially limited environment, fiber in-line FPIs based on in-fiber reflection mirrors, inner air-cavity, microchannels, and splicing different types of fibers have been adopted, [18][19][20][21][22][23][24][25] Deng et al, reported a high-temperature sensing device based on multiple reflection mirrors inscribed in an optical fiber by femtosecond laser, the temperature sensitivity of the device obtained was 10.15 and 16.92 pm/°C, within the temperature region between 100°C and 400°C, and between 400°C and 1100°C, respectively.…”

“…However, such an FBG cannot sustain a temperature up to 700°C, as the grating structure would be erased. Although the high‐temperature sustainable FBG can be fabricated by using a femtosecond laser, expensive equipment is involved 8–15 …”