A group of researchers from Korea and the United States take a step closer to the realization of HAMR and tackle several issues toward this end. One of the challenges for HAMR is the integration of optics with the magnetic head on a small footprint. Cho et al. introduced a polymeric light waveguide delivery system integrated on a conventional magnetic head. This new light delivery design offers advantages such as low cost, easy fabrication, and process compatibility with the current magnetic technology. The polymer material used in the waveguide’s fabrication has the potential for inexpensive HAMR heads, which will be crucial for widespread availability in the consumer market. The low process temperature for the polymer waveguides makes it also compatible with the current magnetic head fabrication. Another advantage of the design by Cho et al. is its use of fiber-based waveguide couplers with a small footprint. Currently proposed HAMR devices are based on free-space optics such as lenses, making the magnetic head too bulky for real hard drive applications.
The biggest requirement for the realization of HAMR is still the availability of an optical spot on the nanometer scale, which needs to be comparable to the size of the magnetic bits. The smallest optical spot available with conventional diffraction-limited optics, e.g, with a lens, is still orders of magnitude larger than the magnetic grains. This makes plasmonics, or metal-optics, instrumental for the future of HAMR. Plasmonics that uses metals for optics has the potential to enhance and confine light on a nanoscale through surface plasmons in metals. All the HAMR approaches proposed to date rely on plasmonic designs to achieve a tiny laser spot to heat the magnetic medium locally. The design by Cho et al. is no exception; it uses a C-shaped aperture in a metal surface to achieve a 100-nm optical spot.
Even though HAMR is emerging as a potential technology, real deployment of HAMR in commercial hard drives is still many years ahead. At this point, the proof-of-concept devices demonstrated cannot offer areal densities higher than those available with the current magnetic hard disk drives. Many practical aspects of HAMR such as thermal management, e.g. what happens when the heat is elevated to 300K locally, need to be addressed first. Let us watch closely whether we will indeed have any lasers in our hard drives in the future.
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