Energy-assisted magnetic recording head having waveguide capable of providing small beam spots

A method and system for providing an EAMR transducer is described. The EAMR transducer has an ABS and is coupled with a laser. The EAMR transducer includes a write pole, coil(s), and an energy delivery device. The write pole magnetically writes to the media. The coil(s) energize the write pole. The energy delivery device is optically coupled with the laser and includes a top distal from the ABS, a bottom proximate to the ABS, a first side, and a second side opposite to the first side. The first side has a first apex angle from a normal to the ABS and is reflective. The second side has a second apex angle from the normal and is reflective. The first and second apex angles are each at least three and not more than twenty-five degrees. The first and second sides converge such that the top is wider than the bottom.

BACKGROUND

FIG. 1depicts top and side views of a portion of a conventional energy assisted magnetic recording (EAMR) transducer10. For clarity,FIG. 1is not to scale. The conventional EAMR transducer10is used in writing a recording media (not shown inFIG. 1) and receives light, or energy, from a conventional laser (not shown inFIG. 1). The conventional EAMR transducer10includes grating32, a conventional waveguide12including a core13and cladding11, conventional pole30, and near-field transducer (NFT)40. The conventional EAMR transducer10is shown with a laser spot14that is guided by the conventional waveguide12to the NFT40near the air-bearing surface (ABS). The NFT40focuses the light to magnetic recording media (not shown), such as a disk. Other components that may be part of the conventional EAMR transducer10are not shown.

In operation, light from the spot14is coupled to the conventional EAMR transducer10using the grating32. The waveguide12, which is shown as including a planar solid immersion mirror, cladding11, and core13, directs light from the grating32to the NFT40. In other conventional EAMR transducers, the conventional waveguide12could take other forms. The direction of travel of the light as directed by the conventional waveguide12can be seen by the arrows18and20. The NFT40focuses the light from the waveguide12and heats a small region of the conventional media (not shown). The conventional EAMR transducer10magnetically writes data to the heated region of the recording media by energizing the conventional pole30.

Although the conventional EAMR transducer10may function, there are drawbacks. The trend in magnetic recording continues to higher recording densities. As a result, the track width is desired to be made smaller. The track width is defined by the pin width of the NFT40. The smaller the width of the pin of the NFT40, the higher the areal density. However, the efficiency and reliability of fabricating such NFTs may be limited. For example, to obtain an areal density of 2 Tb/in2, a thermal spot size of approximately thirty nanometers at full width half max may be used. Based on this, the pin of the NFT40for such a spot would be approximately thirty nanometers in width. In addition, there is currently approximately a twenty nanometer offset between the optical spot and thermal spot due to the thermal conduction of the media (not shown). The NFT40thus has a smaller width than the desired spot size. In the example above, an NFT40having a width of approximately ten nanometers is desired. This may be an extremely challenging requirement for fabrication. Further, such an NFT40may be more susceptible to failure due to overheating. In other contexts, such in photonic nanojets, a hemisphere may be used to provide a smaller spot. However, it is impractical to place a micron-scale dielectric sphere within the head structure and slider during fabrication. Accordingly, a mechanism for providing a small spot is still desired.

BRIEF SUMMARY OF THE INVENTION

A method and system for providing an energy assisted magnetic recording (EAMR) transducer is described. The EAMR transducer is coupled with a laser for providing energy and has an air-bearing surface (ABS) configured to reside in proximity to a media during use. The EAMR transducer includes a write pole, at least one coil, and an energy delivery device. The write pole is configured to write to a region of the media. The coil(s) are for energizing the write pole. The energy delivery device is optically coupled with the laser and includes a top distal from the ABS, a bottom proximate to the ABS, a first side, and a second side opposite to the first side. The first side has a first apex angle from a normal to the ABS and is reflective. The second side has a second apex angle from the normal to the ABS and is also reflective. The first apex angle is at least three and not more than twenty-five degrees. The second apex angle is also at least three and not more than twenty-five degrees. The first side and the second side converge such that the top is wider than the bottom.

DETAILED DESCRIPTION OF THE EMBODIMENTS OF THE INVENTION

FIG. 2is a diagram depicting a portion of an EAMR disk drive100including an EAMR head110.FIG. 3is a diagram depicting an exemplary embodiment of the EAMR head110. For clarity,FIGS. 2 and 3are not to scale. Referring toFIGS. 2-3, for simplicity not all portions of the EAMR disk drive100is shown. In addition, although the disk drive100is depicted in the context of particular components other and/or different components may be used. Further, the arrangement of components may vary in different embodiments. The EAMR disk drive100includes a slider102, a laser/light source104, optional optics106for redirecting light from the laser104, an EAMR head110, and media170. In some embodiments, the optics106include an optical coupler, mirror(s), a grating, and/or other components. In some embodiments, the laser104is a laser diode. In some such embodiments, the laser104may be a vertical surface emitting laser (VCSEL). Although shown as mounted on the slider102, the laser104may be coupled with the slider102in another fashion. For example, the laser104might be mounted on a suspension (not shown inFIG. 2) to which the slider102is also attached. In other embodiments, the orientation of the emitting surface of the laser104with respect to the slider102may be different. The media170may include multiple layers, which are not shown inFIG. 2for simplicity. For example, the media170may include a magnetic layer for storing data, a heat sink layer, and/or a soft underlayer.

The EAMR head110includes an optional read transducer112and an EAMR transducer120. The read transducer112includes shields114and118as well as read sensor116. In other embodiments, the read transducer112may be omitted. The EAMR transducer120shown includes a shield122, coils124and126, pole128, energy delivery device150, and light recovery device180. Some portions of the EAMR transducer120may be omitted inFIG. 3. For example an optical coupler, grating or other device that might be used to couple light from the laser104to the energy delivery device150is not shown inFIG. 3. The pole128include pole tip130, back gap region132, and return pole134having pedestal136. In other embodiments, the pole128may have different and/or additional components. Light recovery device180is optional and may include mirror(s) or other reflective surface(s). The light recovery device180might also include an additional laser. The light recovery device180may be used to recover light lost in the energy delivery device150, input additional energy to the energy delivery device150, and/or return the light to the energy delivery device150. Although shown as separate, in some embodiments, the light recovery device180is part of the energy delivery device150. Thus, efficiency of the EAMR head110may be improved.

The energy delivery device150optically is coupled with the laser104. In some embodiments, the energy delivery device is directly coupled to the laser104. In other embodiments, other mechanisms such as a grating or optical coupler may be used to optically couple the energy delivery device150with the laser104. The energy delivery device150includes a bottom151proximate to the ABS and a top153distal from the ABS. The energy delivery device150also has sides (not shown inFIG. 3) in the cross track direction (perpendicular to the page inFIG. 3). The sides in the cross track direction converge and reflect light. Thus, light may be input to the energy delivery device150and plasmons developed at the output/aperture at the bottom151. Thus, a soliton (not shown inFIG. 3) is formed at the bottom, aperture151of the energy delivery device150. For example, the energy delivery device150could correspond to a numerical aperture greater than thirty. In some embodiments, the energy delivery device150has a corresponding numerical aperture of greater than fifty-six. In some such embodiments, the numerical aperture is not more than one hundred thirty. As a result, the energy delivery device150provides energy to the media108.

In operation, the energy delivery device150couples the energy from the laser to the media108, developing a soliton that heats a small region of the media108. The coil(s)124and126energize the pole128, which magnetically writes to the region of the media108. Thus, data may be written to the media108using energy assisted magnetic recording. Because the energy delivery device150can deliver light through the above-described numerical aperture, the spot developed on the media108may be small. In some embodiments, the spot is on the order of twenty-five through thirty-five nanometers or less. Thus, the EAMR head110may be suitable for use in high density recording applications. The energy delivery device150also provides the small spot without requiring complex fabrication of components smaller than the spot size, such as the pin of an NFT. In some embodiments, the ability of the energy delivery device150is also insensitive to lapping. Thus, the energy delivery device150may improve manufacturing yield for the EAMR head110.

FIG. 4is a diagram depicting top and side views of an exemplary embodiment of the energy delivery device150′.FIG. 4is not to scale. The energy delivery device150′ corresponds to the energy delivery device150. Consequently, analogous components have similar labels. The energy delivery device150′ thus has a bottom151′ and a top153′ corresponding to the bottom151and top153, respectively, shown inFIG. 3. The energy delivery device150′ may be used in an EAMR head such as the EAMR head110. In principal, the energy delivery device150′ may be configured for use with light of a particular wavelength. However, the light from the laser may actually have wavelengths in a range around the particular wavelength.

The energy delivery device150′ includes a core152. In some embodiments, the energy delivery device may include optional reflective cladding154and156and optional cladding158and160. The core152may include optically transparent materials including but not limited to Ta2O5. The core152has sides155and157and faces159and161. The sides155and157are in the cross track direction. In the embodiment shown, the sides are planar. However, in other embodiments, the sides155and157may be curved. The sides155and157reflect the energy transmitted by the energy delivery device150′. This reflectivity of the sides155and157may be due to highly reflective cladding154and156. In some embodiments, the highly reflective cladding154and156are formed from the same material and/or at the same processing step. The highly reflective cladding154and/or156may include one or more of Au, Ag, and Pt. In some embodiments, for example, the reflective cladding154and/or156may be Au. However, in other embodiments, different materials and/or different processing steps may be used.

The faces159and161are in the down track direction. In the embodiment shown, the faces159and161are substantially parallel. However in other embodiments, the faces159and161may converge. In the embodiment shown, the faces159and161share an interface with cladding158and160, respectively. In some embodiments, the cladding158and160may have an index of refraction that is lower than the index of refraction of the core152. For example, if the core152is composed of Ta2O5, then the cladding158and160may include materials such as aluminum oxide, silicon oxide, or other silicates which have lower indices of refraction than Ta2O5. In other embodiments, the cladding158and160may be highly reflective. For example, the cladding158and160may include Au, Ag, and/or Pt.

The energy delivery device150′ has apex angles θ1and θ2corresponding to sides155and157, respectively. The apex angles θ1and θ2are selected such that the sides155and157converge toward the ABS. Thus, the energy delivery device150′ transmits the energy toward the ABS. The apex angle are configured such that the energy input to the energy delivery device150′ reflects off of the sides155and157and forms a soliton substantially at the bottom151′ of the energy delivery device150′. In some embodiments, therefore, the first apex angle, θ1is at least three and not more than twenty-five degrees. In some embodiments, the second apex angle, θ2is at least three and not more than twenty-five degrees. The desired apex angles may depend upon the material used for the highly reflective cladding154and156and the plasmon modes supported by the highly reflective cladding154and156. In some embodiments, the second apex angle is equal to the first apex angle. In such embodiments, the sides155and157are symmetric. However, in other embodiments, the first and second apex angles may differ. Further, as can be seen inFIG. 4, the axis of the energy delivery device150′ is normal to the ABS. However, in other embodiments, the axis of the energy delivery device150′ may not be perpendicular to the ABS. The energy delivery device150′ has a height I. The height may vary depending upon the distance between the position at which light energy is coupled into the energy delivery device150′ and the ABS as well as the apex angles. The height is sufficiently short that the energy input to the energy delivery device150′ is not unduly attenuated. In general, the height may be larger for smaller apex angles. In some embodiments, the energy delivery device150′ is up to ten microns in height with a top width at the top153′ of up to one micron. The energy delivery device150′ converges down to a width, w, at the ABS. for example, in some embodiments, the width at the bottom151′, or aperture, is one hundred nanometers or less. In some embodiments, the width is not more than fifty nanometers. In some embodiments, the aperture has a height, h, of one hundred nanometers. As a result, the energy delivery device may have a numerical aperture that is greater than thirty. In some embodiments, the numerical aperture is greater than 56. In addition, in some embodiment, the numerical aperture is not greater than one hundred and thirty.

To further describe the operation of the energy delivery device150′, refer toFIG. 5, which depicts an exemplary embodiment of the energy delivery device150′ as it functions. Referring toFIGS. 4-5, light is input to the energy delivery device150′ at its top153′. The input light reflects off of the sides155and157/highly reflective cladding154and156. The reflected light forms an interference pattern170, which converges as the sides155and157converge. As the sides155and157converge, the energy is in the form of plasmons that form the interference pattern near the bottom151′. At the bottom151′, which is the aperture for the energy delivery device150′, a soliton is formed, and a spot provided on the media. The size of the spot may be controlled by the apex angle, material(s) used for the core152, material(s) used for the highly reflective cladding154and156, and cladding158and160. Because of the interference pattern and the formation of the soliton, the size of the spot may be controlled without requiring the construction of a component smaller than the desired spot.

The energy delivery device150′ provides the small spot without requiring complex fabrication of components smaller than the spot size, such as the pin of an NFT. Thus, an EAMR head110suitable for higher density recording may be provided. In some embodiments, the ability of the energy delivery device150is also insensitive to lapping. This is because the apex angle of the energy delivery device150/150′ may be small. Thus, an error in lapping the bottom151′ of the energy delivery device150′ does not affect the width, w. Further, the faces159and161may be parallel and perpendicular to the ABS. Thus, fabrication of the energy delivery device150′ in the down track direction may be made with discrete changes in materials used in various processing steps. Consequently, processing of the energy delivery device150′ is further simplified. Thus, the energy delivery device150′ may also improve manufacturing yield for the EAMR head110. The energy delivery device150′ has a large surface area, which may improve cooling of the energy delivery device150′, for example by the use of cladding158and160that is conductive. Performance of the EAMR head110may thus be improved. The energy delivery device150′ may also be directly coupled to the laser104. Thus, design of the EAMR head110may be simplified.

FIG. 6depicts another embodiment of an energy delivery device150″. For clarity,FIG. 6is not to scale. The energy delivery device150″ corresponds to the energy delivery devices150and150′. Consequently, analogous components have similar labels. The energy delivery device150″ thus has a bottom151″, top153″, core152′ and highly reflective cladding154′ and156′ corresponding to the bottom151, top153, core152, and highly reflective cladding, respectively, shown inFIG. 4. The energy delivery device150″ may be used in an EAMR head such as the EAMR head110. In principal, the energy delivery device150″ may be configured for use with light of a particular wavelength. However, the light from the laser may actually have wavelengths in a range around the particular wavelength. The energy delivery device150″ functions in an analogous manner to the energy delivery device150/150′. However, the sides155′ and157′ are not straight. Instead, the sides155′ and157′ curve outward near the top153″. In other embodiments, the sides155′ and157′ may be curved a different amount. The curvature of the sides155′ and157′ improve the coupling of light into the energy delivery device150″. The energy delivery device150″ may have improved efficiency and reduced propagation losses.

Similarly,FIG. 7depicts another embodiment of an energy delivery device150″′. For clarity,FIG. 7is not to scale. The energy delivery device150″′ corresponds to the energy delivery devices150,150′, and150″. Consequently, analogous components have similar labels. The energy delivery device150″′ thus has a bottom151″, top153″′, core152″ and highly reflective cladding154″ and156″ corresponding to the bottom151, top153, core152′, and highly reflective cladding, respectively, shown inFIG. 4. The energy delivery device150″′ may be used in an EAMR head such as the EAMR head110. In principal, the energy delivery device150″′ may be configured for use with light of a particular wavelength. However, the light from the laser may actually have wavelengths in a range around the particular wavelength. The energy delivery device150″′ functions in an analogous manner to the energy delivery device150/150′/150″. However, the sides155″ and157″ are not straight. Instead, the sides155″ and157″ have an “s” curve near the top153″′. In other embodiments, the sides155″ and157″ may be curved a different amount. The light delivery devices150″ and150″′ function in an analogous manner to the light delivery devices150and150′. Thus, the benefits of the light delivery devices150and150′ may be achieved. The curvature of the sides155″ and157″ improve the coupling of light into the energy delivery device150″′. In addition, the energy delivery device150″ and150″′ may have improved efficiency and reduced propagation losses.

FIG. 8is a flow chart depicting another exemplary embodiment of a method300for fabricating an EAMR head including an energy delivery device. For simplicity, some steps may be omitted, combined, and/or performed in another sequence. The method300is described in the context of the EAMR disk drive100, EAMR head110, and energy delivery device150′. However, the method300may be used to fabricate other EAMR heads. In addition, the method300is described in the context of fabricating a single disk drive100. However, multiple transducers may be fabricated substantially in parallel. Further, although described as separate steps, portions of the method300may be interleaved.

The write pole130and its constituents are provided, via step302. The coil(s)124and126for energizing the pole130are also provided in step304. The core152of the energy delivery device is provided, via step306. The highly reflective cladding154and156is provided, via step308. The cladding148and160may optionally be provided in step310. Thus, the energy delivery devices150,150′,150″, and/or150″′ may be provided in the EAMR head110.

Using the method300, the EAMR head110including the energy delivery device150,150′,150″, and/or150″′ may be obtained. Consequently, the benefits of such devices may be achieved.