Abstract: There is disclosed a Faraday rotator device suitable for radiation phase shifters, isolators and shutters, that operate in the visible and infrared regions of the electromagnetic spectrum. The device includes (1) means for supplying polarized, electromagnetic radiation, (2) a lithia-silica-terbia glass article capable of effecting Faraday rotation when subjected to a magnetic field, and (3) means for inducing a magnetic field within the glass article, the glass generally comprising about 61-80 mole percent SiO.sub.2, 15-27.5 mole percent Li.sub.2 O, 3-9 mole percent Tb.sub.2 O.sub.3, and optionally, up to about 3 mole percent of R.sub.2 O.sub.3, such as Al.sub.2 O.sub.3 or B.sub.2 O.sub.3 --and optionally, minor amounts of Na.sub.2 O, K.sub.2 O or CaO, providing the sum of Li.sub.2 O + Na.sub.2 O + K.sub.2 O + CaO is not substantially greater than about 32.5 mole percent.