Fabrication of optical comb filter using tapered fiber based ring resonator

A tapered fiber based ring resonator is fabricated and its optical characteristic is investigated. Fiber taper is firstly made by heating and stretching a piece of optical fiber, after the polymer protective cladding has been removed. The ring resonator is fabricated by twisting the tapered fiber and manipulating the two ends of the fiber. The comb filter with a constant spacing and an extinction ratio of 4.2dB can be obtained with the ring resonator. The free spectral range (FSR) of tapered fiber ring resonator can be varied from 0.08nm to 0.33nm by controlling the diameter of the ring. The filtering characteristic of the resonator is maintained after packaging with low index polymer.