Optical Absorption and Faraday Rotation in Pb- and Ca-Substituted YIG Films

Abstract

The optical absorption loss a and Faraday rotation θ_F in the wavelength region λ=0.5∼2.5μm are investigated for YIG films incorporated with a small amount of Pb, Ca and other ions. The contribtuions of pb²⁺, Pb⁴⁺, Fe²⁺ and Fe⁴⁺ ions to α and θ_F are studied by reducing the Ca-free and Ca-droped YIG films grown by LPE method. It turns out that the absorption enhancement due to Pb²⁺ is remarkable near the optical absorption edge, and that due to Pb⁴⁺ is remarkable at λ∼0.56μm. The strong absorption at λ∼0.56μm is thought to originate in the combined presence of Fe³⁺ and Pb⁴⁺. As for the Faraday rotation, it is found that the contribution by Fe⁴⁺ is negative in the θ_F spectra in the near infrared recion like that bv Pb²⁺, while the Fe²⁺ contribution is negligible in the measured wavelength region.