FIBER LOOP MIRROR FILTER WITH TWO-STAGE HIGH BIREFRINGENCE FIBERS

A flber loop mirror (FLM) with two-stage high birefrin- gence (Hi-Bi) flbers is theoretically and experimentally studied for var- ious rotation angles and Hi-Bi flber lengths. The experimental spectra are observed to be in good agreement with the theoretical spectra, ver- ifying our theoretical model. The wavelength interval of the comb fllter depends on the Hi-Bi flber lengths and rotation angles. By varying the rotation angle from 0 - to 90 - , a comb-like transmission spectrum with small wavelength spacing is evolving into an exotic but periodic trans- mission spectrum and eventually become a larger wavelength spacing transmission spectrum. The FLM is useful in many applications such wavelength division multiplexing power equalization and management, switchable multi-wavelength flber laser, optical switch and etc.