Use of liquid-crystal-clad fiber as a modal filter for a two-mode fiber-optic interferometer

A novel two-mode fiber-optic interferometer employing a liquid-crystal-clad fiber as a modal filter is proposed. The liquid-crystal-clad fiber can guide one of the second-order modes, TE01, and leak out the other TM01 and HE21 modes. Thus two spatial modes, fundamental mode HE11 and second-order mode TE01 serve as the two arms of the interferometer to detect an external perturbation. The experimental results obtained when this interferometer was used to sense temperatures ranging from 20 to 100 degrees C are demonstrated.