All-fiber optical isolator based on Faraday rotation in highly terbium-doped fiber.

An all-fiber isolator with 17 dB optical isolation is demonstrated. The fiber Faraday rotator uses 56 wt. % terbium (Tb)-doped silicate fiber, and the fiber polarizers are Corning SP1060 single-polarization fiber. The effective Verdet constant of the Tb-doped fiber is measured to be -24.5+/-1.0 rad/(Tm) at 1053 nm, which is 20 times larger than silica fiber and 22% larger than previously reported results.