Er/Yb Codoped Double Clad Fiber Modal Interferometer and Its Application as Fiber Sensor

An Er/Yb codoped double clad fiber (EYDF) modal interferometer and its application as fiber sensor are proposed and demonstrated. It has the single mode fiber (SMF)-EYDF-SMF structure with two asymmetrical splice joints. The MI is sensitive to refractive index (RI) and temperature. Experimental results show that the pump power can tune its operation wavelength, and the higher power will lead to the more redshift of its transmission spectrum. What's more, appropriate change of RI can improve the wavelength tuning range induced by pump power. Moreover, its RI and thermal sensitivities are pump power dependent, and higher pump power will lead to its lower RI sensitivity and lower thermal sensitivity.