Erbium-doped fiber laser based on intermodal interference between single-mode fiber and suspended core fiber for strain and temperature sensing

In this paper, a strain and temperature sensing system based on an erbium-doped fiber laser (EDFL) is proposed and experimentally verified. The cavity mirror of the fiber laser is composed of an optical coupler (OC) and a circulator. An intermodal interference between a single-mode fiber and a 12.4-mm suspended core fiber (SCF) is used as a frequency-selective device. The period and wave height of the SCF transmission spectrum is 6.30 nm and 4.188 dB. The fiber laser has a peak wavelength and power of 1564.46 nm and −14.729 dBm, respectively. The peak wavelength of the fiber laser drifts toward a short wavelength as the SCF is stretched from zero to 1200 με. The laser undergoes the transition from a single wavelength to a dual wavelength. According to the measurement results, the system's strain sensitivity is 1.80 pm/με, and its linearity is 98.30%. A temperature rise experiment from 100 °C to 1000 °C is carried out on the SCF, and the peak wavelength of the fiber laser drifts toward a long wavelength. The temperature sensitivity of the system is 1.88 pm/°C, and the linearity is 98.58%.