Near-field hybrid recording with a mode index waveguide lens

Abstract

This paper describes a design for a near field hybrid recording system that uses a mode index waveguide lens in place of a SIL or optical fiber. The mode index waveguide lens is fabricated on the back of an air bearing slider with a thin film magnetic head and giant magneto resistance (GMR) sensor for reading and writing. The optical spot from the waveguide heats the media to its Curie temperature such that within the spot a region with a reduced coercive field (`Curie cylinder') is created. The thin film head then applies a magnetic field to switch the magnetization within the Curie cylinder thereby recording a written mark. In the system proposed here, the track width of the optical spot is less than that of the thin film head and as such defines the recording track width. A GMR sensor is used to sense the flux leakage from the surface of the media and may also be laser assisted. Calculations predict an aerial density of 70 Gbits/inch<SUP>2</SUP> when using a simple mode index lens fabricated from a SiO<SUB>2</SUB>/SiN<SUB>x</SUB>/SiO<SUB>2</SUB> waveguide. Furthermore, by using advanced lens designs and innovative materials, the track width can be reduced further thereby offering a promising way to achieve 500 Gb/inch<SUP>2</SUP>.