Optical fiber temperature sensor based on modal interferometer comprising two peanut‐shape structures

An all‐fiber temperature sensor based on two peanut‐shape structures modal interferometer is demonstrated. The results show that a high temperature sensitivity of 63.7 pm/°C is acquired for the 30 mm sensor, and the strain sensitivity is as low as −0.86 pm/με. The cross sensitivity is only 0.013°C/με, which is suitable for temperature sensing.