Transparent Ferromagnetic Light Modulator Using Yttrium Iron Garnet

Abstract

A method of preparation of yttrium iron garnet crystals from Y₂O₃ and Fe₂O₃, using PbO as a solvent, is described. The transmission spectrum from 0.5 to 16 μ of ground and polished slabs cut from the crystals shows strong absorption at wavelengths shorter than 0.7 μ; other absorption occur at 0.89, 5.7, 7.8, 8.6, 10.9, 11.6, and 14 μ. Faraday rotation brought about by spontaneous magnetization normal to the slab can be applied to the design of light modulators. Three of these are described and the construction and operation of one is discussed. It is an axially ac magnetized slab, passing polarized tungsten light to an analyzer 45° out of the plane of polarization.