News Column

Patent Issued for Near-Field Transducers for Focusing Light

May 13, 2014



By a News Reporter-Staff News Editor at Journal of Technology -- A patent by the inventors Lee, Lien (St. Paul, MN); Jin, Xuhui (Shakopee, MN); Gao, Kaizhong (Shoreview, MN); Itagi, Amit (Hugo, MN); Challener, William A. (Schenectady, NY), filed on August 21, 2012, was published online on April 29, 2014, according to news reporting originating from Alexandria, Virginia, by VerticalNews correspondents.

Patent number 8711662 is assigned to Seagate Technology LLC (Cupertino, CA).

The following quote was obtained by the news editors from the background information supplied by the inventors: "Heat assisted magnetic recording (HAMR) generally refers to the concept of locally heating a recording medium to reduce the coercivity of the recording medium so that the applied magnetic writing field can more easily direct the magnetization of the recording medium during the temporary magnetic softening of the recording medium caused by the heat source. For heat assisted magnetic recording (HAMR) a tightly confined, high power laser light spot is used to heat a portion of the recording medium to substantially reduce the coercivity of the heated portion. Then the heated portion is subjected to a magnetic field that sets the direction of magnetization of the heated portion. In this manner the coercivity of the medium at ambient temperature can be much higher than the coercivity during recording, thereby enabling stability of the recorded bits at much higher storage densities and with much smaller bit cells.

"In heat assisted magnetic recording, information bits are recorded on a storage layer at elevated temperatures, and the heated area in the storage layer determines the data bit dimension. Focusing devices such as a solid immersion lens (SIL) or a solid immersion mirror (SIM) can focus light down to a spot size that is of the order of half or quarter of a wavelength. To focus light down to spot sizes that are of the order of a tenth of a wavelength, near-field transducers (NFTs) are needed.

"One approach for directing light onto a storage layer uses a planar solid immersion mirror or lens (PSIM), fabricated on a planar waveguide and a near-field transducer, in the form of an isolated metallic nanostructure placed near the PSIM focus. The near-field transducer is designed to reach a local surface plasmon (LSP) condition at a designated light wavelength. At LSP, a high field surrounding the near-field transducer appears, due to collective oscillation of electrons in the metal. Part of the field will tunnel into an adjacent storage medium and get absorbed, raising the temperature of the medium locally for recording. This design is sensitive of the shape of the NFT, and the location of the NFT in the waveguide. A larger amount of light is absorbed if the isolated near-field transducer is buried in a dielectric of lower thermal dissipation than the medium."

In addition to the background information obtained for this patent, VerticalNews journalists also obtained the inventors' summary information for this patent: "In a first aspect, the invention provides an apparatus including a waveguide shaped to direct light to a focal point, and a near-field transducer positioned adjacent to the focal point, wherein the near-field transducer includes a dielectric component and a metallic component positioned adjacent to at least a portion of the dielectric component.

"In another aspect, the invention provides an apparatus including a waveguide shaped to direct light to a focal point, and a near-field transducer positioned adjacent to the focal point, wherein the near-field transducer includes a first metallic component, a first dielectric layer positioned adjacent to at least a portion of the first metallic component, and a second metallic component positioned adjacent to at least a portion of the first dielectric component."

URL and more information on this patent, see: Lee, Lien; Jin, Xuhui; Gao, Kaizhong; Itagi, Amit; Challener, William A.. Near-Field Transducers for Focusing Light. U.S. Patent Number 8711662, filed August 21, 2012, and published online on April 29, 2014. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=52&u=%2Fnetahtml%2FPTO%2Fsearch-bool.html&r=2566&f=G&l=50&co1=AND&d=PTXT&s1=20140429.PD.&OS=ISD/20140429&RS=ISD/20140429

Keywords for this news article include: Seagate Technology LLC.

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Source: Journal of Technology


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