Genetic-Algorithm-Based Design of Magneto-Optical Films with Disordered Multilayer Structures

A novel technique for designing magneto-optical films is presented: the algorithm, which automatically determines the multilayer structures of films with designated optical and magneto-optical properties, is regarded as an extension of the genetic algorithm. The film properties are designated by a simple fitness function f (x), and the film structure that maximizes f (x) is chosen as the optimum one. The present technique has been used to determine two kinds of film structure: one exhibits the largest Faraday rotation θF and the other exhibits high transmissivity T and large θF simultaneously. These films were obtained after the evolution of about 2000 generations: in one, T=29% but θF = -28 deg/μm at λ = 1.15μm, while in the other, T = 70% and θF = -16 deg/μm at the same wavelength of light.