Ultrafast laser diagnostics and modeling for high-speed recording heads

A comparison of experiment and modeling in high-speed recording heads is given from study of the dependence of flux rise times on yoke lengths. A brief overview is given of optical methods for characterizing the response of devices and materials for high data rate recording. Several abilities of the technique and, in particular, measurements of current and flux rise times on high-speed writers are presented. A micromagnetic model that takes into account gyromagnetic effects and eddy currents gives calculations that agree well with experimental data. Flux rise times are found to decrease with shorter yoke lengths for both unlaminated and laminated heads for a current rise time of 0.8 ns.