Intensity detection scheme of sensors based on the modal interference effect of few mode fiber

The transmission spectrum and power of the few mode fiber (FMF) under different strain/temperature are studied theoretically and experimentally. Significant shift of the critical wavelength of FMF can be produced when the measurement range is large. An intensity detection scheme with broadband source is proposed to overcome the problem encountered by the traditional measurement methods such as peaks shifts detection and transmission detection at a fixed single wavelength. And the scheme show larger dynamic range and larger linear operating range when the length of FMF is shorter, which can make the sensor more compact. The experimental result agrees well with the theoretical calculation.