We describe and characterize an active height control system for near-field data storage applications using a commercial laser diode as a direct position sensor. The self-mixing interference signal was experimentally characterized and the effective spot size of the laser sensor was also measured. A control system utilizing interference in the laser as feedback signal was constructed to drive a conventional DVD pickup with the laser sensor mounted. The residual position error is ±9nm when the rotation speed of a glass disk was 1500rpm and the vertical runout was 16μm. The approach limit was estimated to be 25nm when the laser size is reduced to 100μm.
An experimental test bed for investigating the hybrid recording process and that allows for the precise visual alignment of the optical spot and magnetic head is described. Using this spin stand experiments have been performed on three types of hybrid recording where the critical bit dimensions are determined by using either, or both, the thermal and magnetic field profiles. By changing the relative alignment of the optical spot and magnetic head in the down track position four distinct types of marks unique to the hybrid recording process are observed.
Results of an ongoing project aimed at demonstrating optical recording densities of 100 Gb/in<SUP>2</SUP> are presented. The technologies focused on by the project include Solid Immersion Lenses (SIL), Center Aperture Detection Magnet Super Resolution media, Laser Pumped Magnetic Field Modulation recording, near field spot characterizations and turbo coding techniques. Significant progress towards achieving a 100 Gb/in<SUP>2</SUP> optical recording density has been made. A super-SIL has been designed and fabricated. The super-SIL has been characterized and integrated into a recording system.