Abstract: An all-fiber optic Faraday rotator and isolator is presented. The device has a multicomponent glass optical fiber having a core having a first doping concentration of 55%-85% (wt./wt.) of a first rare-earth oxide and a cladding having a section doping concentration of 55%-85% (wt./wt.) of a second rare-earth oxide, where the first rare-earth oxide and the second rare earth oxide are one or more of Pr2O3, Nd2O3, Pm2O3, Sm2O3, Eu2O3, Gd2O3, Tb2O3, Dy2O3, Ho2O3, Er2O3, Tm2O3, Yb2O3, La2O3, Ga2O3, Ce2O3, and Lu2O3, and where the refractive index of the cladding is lower than a refractive index of the core. The fiber optic device further includes multiple magnetic cells each formed to include a bore extending there through, where the fiber is disposed in the bore of one of the magnetic cells.