Long Period Fiber Grating Based Temperature Sensing Scheme with High Sensitivity

LPFGs are band rejection fiber filters with wavelength dependent loss. Its resonance wavelengths shift towards the direction of longer wavelength with reduced cladding diameter. The shift for resonance wavelengths is produced with environmental temperature and external refractive index. According to this a temperature sensing scheme with enhanced sensitivity is proposed. The relation between resonance wavelengths of LPFG and environmental temperature is modeled. A LPFG is UV written in the core of a piece of fiber, whose diameter is beforehand corrosively reduced. Then the LPFG is recoated with polymer material. Sensing characteristics is measured for the device. The result of experiment is accordant with that of simulation. And its temperature sensitivity is more than 5.2 nm/℃.