Far infra-red Faraday effect in rare-earth iron garnets

The optical and magneto-optical properties of polycrystalline spinel ferrites and single-crystal rare-earth iron garnets have been determined at a wavelength of 337 μm using a HCN gas maser source. The relative performance of these materials as Faraday rotators in the far infra-red is discussed and the observed rotations are compared with theoretical predictions.