A smart bending sensor with a novel temperature- and strain-insensitive long-period grating

Abstract A simple bending sensor is performed with a novel insensitive long-period fiber grating (LPG). The characteristic of the insensitive LPG has been experimentally presented, which has the pitch and the notch wavelength of 440 μm and 1516.2 nm at 20 °C. We have investigated temperature and strain insensitivities. The temperature coefficient is about 0.003 nm/°C from 10 to 50 °C, and the strain coefficient is only about 15 nm/e, which are about 1/30 and 1/100, compared with the corresponding coefficients of the conventional devices with typical values of 0.083 nm/°C and 1521 nm/e, respectively. It is fabricated as a bending sensor without any treatment to eliminate the temperature and strain effects, and the bending sensitivity is the same order as the ordinary one. At the same time, the temperature- and strain-insensitive LPG will have wide prospect for other smart fiber sensors and communication devices.

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