APPARATUS TO IMPROVE THE EXTINCTION RATIO OF OPTICAL PULSES

摘要

An apparatus for improving an extinction ratio of an optical pulse is provided to reduce a noise by using an optical loop mirror. An optical loop mirror lets an inputted optical signal pass or reflects the inputted optical signal according to strength of the inputted optical signal. The optical loop mirror includes the first polarization controller(120), an optical splitter(130), the second polarization controller(140) and a DSF(Dispersion Shift Fiber)(150). The first polarization controller controls polarization of the inputted optical signal. The optical splitter forces the optical signal that passes through the first polarization controller to circulate in a loop(160) dividedly into two directions opposite to each other. The optical splitter reflects or transmits the optical signal according to its power. The second polarization controller controls polarization of the optical signal that circulates in the loop. The DSF has a nonlinear index so that optical signals which proceed to opposite directions in the loop have different phase variation.