Fabrication of fluoride single-mode fibers for optical amplifiers

A modified jacketing method, which uses a preform produced by suction casting and a tapered jacketing tube for fiber drawing, was developed to fabricate low-loss, high-Delta n fluoride single-mode fibers for optical amplifiers. A fabricated 500 m long ZrF4,-based fiber had a constant core diameter and an almost constant mean strength of similar to 435 MPa over its whole length. Low transmission losses below 20 dB/km were achieved in rare earth-doped ZrF4(-)based single-mode fibers with a Delta n of 3.7%. An InF3-based single-mode fiber with a Delta n of 3.6%, a loss of 114 dB/km at 1.23 mu m and a signal gain coefficient of 0.18 dB/mW at 1.30 mu m was fabricated using this jacketing method.