Optical Absorption and Faraday Rotation in Pb- and Ca-Substituted Y1G Films

Optical absorption losses a and Faraday rotation ¿F in the wavelength region ¿=0.5 to 2.5 ¿m were investigated for YIG films doped with Pb, Ca and other ions. The contributions of Pb²⁺, Pb⁴⁺, Fe²⁺ and Fe⁴⁺ ions to the values of a and ¿F were studied by reducing Ca-free and Ca-doped YIG films grown by LPE. The absorption enhancement due to Pb²⁺ is prominent near the optical absorption edge, and that due to Pb⁴⁺ is marked near 0.56 ¿m. The strong absorption near ¿=0.56 ¿m is thought to originate in the combined presence of Fe³⁺ and Pb⁴⁺. The contribution of Fe⁴⁺ to the ¿F spectra in the near-infrared is negative, similar to the case for Pb²⁺; but the contribution of Fe²⁺ is negligible in the wavelength range measured.