Feasibility Analysis of On-Wafer Microfocal Lens for Optical Coupling in Heat-Assisted Magnetic Recording Systems

An on-wafer microfocal lens was previously reported to assist external optical coupling in heat-assisted magnetic recording (HAMR) systems. In this paper, we report a thorough analysis of lens performance over the range of industry practical wavelengths (400-830 nm) with discussion on the beam polarization dependence. Manufacturing tolerance of the on-wafer microfocal lens is also evaluated based on industry conventional top-down fabrication process. The 3-D numerical simulation results show that the lens design is robust for industry manufacturability. Further comparison of the focal spot sizes and dimensions of other reported optical components shows that high-efficiency internal optical coupling is also achievable between the lens output beam and other near-field transducers. Thus, the on-wafer microfocal lens could potentially provide a low-cost large-volume manufacturing solution for HAMR optical coupling in the hard disk drive industry.