Genetic optimization of magneto-optic Kerr effect in lossy cavity-type magnetophotonic crystals

We have demonstrated an optimization approach in order to obtain desired magnetophotonic crystals (MPCs) composed of a lossy magnetic layer (TbFeCo) placed within a multilayer structure. The approach is an amalgamation between a 4×4 transfer matrix method and a genetic algorithm. Our objective is to enhance the magneto-optic Kerr effect of TbFeCo at short visible wavelength of 405nm. Through the optimization approach, MPC structures are found meeting definite criteria on the amount of reflectivity and Kerr rotation. The resulting structures are fitted more than 99.9% to optimization criteria. Computation of the internal electric field distribution shows energy localization in the vicinity of the magnetic layer, which is responsible for increased light-matter interaction and consequent enhanced magneto-optic Kerr effect. Versatility of our approach is also exhibited by examining and optimizing several MPC structures. ► Structures comprising a highly absorptive TbFeCo layer are designed to work for data storage applications at 405nm. ► Optimization algorithm resulted in structures fitted 99.9% to design criteria. ► More than 10 structures are found exhibiting magneto-optical response of about 1° rotation and 20% reflection. ► The ratio of the Kerr rotation to the Kerr ellipticity is enhanced by a factor of 30.