Low-insertion loss Raman fiber modulator

Abstract Characteristics of the Raman-effect based modulator for high power Yb-doped fiber lasers have been analyzed by numerical simulation. Insertion loss, backreflection, and contrast ratio are considered as functions of the laser power and Ge concentration in fiber. The optimum GeO 2 doping has been shown to improve the efficiency of the modulator at powers of 5–20 W, providing the insertion loss to be less than 1 dB at 20 W. At higher powers, pure silica fibers become competitive, providing insertion loss of 0.6 dB at laser powers of 80 W.