Longitudinal Kerr Effect Using a Very Thin Fe Film

Using known materials, the optimum magneto-optical light switch utilizing the longitudinal Kerr effect would operate at a wavelength of ∼1 μ and be made from a very thin [D=2π(thickness/wavelength)≤110] Fe film placed on the surface of a mirror (tangential E=0) in an optical standing wave. A multilayer dielectric structure would be used to couple the incident light to the magnetic film and the maximum possible magnitude of the Kerr coefficient k is calculated to be |k|max∼3.4×10−2. This is about 10 times greater than for a thick Permalloy film operating at visible wavelengths.