Energy assisted magnetic recording head having a reflector for improving efficiency of the light beam

A method and system for providing an EAMR transducer is described. The EAMR transducer is coupled with a laser for providing energy and has an ABS that resides near a media during use. The EAMR transducer includes a write pole, coil(s) that energize the pole, a near field transducer (NFT) proximate to the ABS, a waveguide, and a reflector. The write pole has a back gap region and writes to a region of the media. The NFT focuses the energy onto the media. The waveguide directs the energy from the laser toward the NFT at an incident angle with respect to the ABS. A first portion of the energy reflects off of the ABS at a reflected angle. The reflector receives the first portion of the energy from the ABS and reflects a second portion of the energy toward the ABS. The NFT resides between the waveguide and the reflector.

BACKGROUND

FIG. 1depicts 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 a conventional waveguide12, coil connection18, a conventional grating20, a conventional near-field transducer (NFT)22, and a conventional pole30. Light from a laser (not shown) is incident on the grating20, which coupled light to the waveguide12. Light is guided by the conventional waveguide12to the NFT22near the air-bearing surface (ABS). In the embodiment shown, the conventional waveguide12is a parabolic solid immersion mirror. The NFT22focuses the light to magnetic recording media (not shown), such as a disk. The coil connection18provides a mechanism for electrically coupling the coils to a current source (not shown). The portion of the pole30shown corresponds to the back gap of the pole30.

In operation, light from the laser is coupled to the conventional EAMR transducer10using the grating20. The waveguide12directs light from the grating12to the NFT22. The NFT22focuses 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. For certain types of NFTs22, a longitudinal polarization is desired. Generally, this polarization is achieved by combining a half-pitch shifted grating for the grating20with parabolic solid immersion mirror for the waveguide12. However, the back gap of the pole30and coil connection18block a portion of the light from the waveguide12. In particular, dashed lines14and16inFIG. 1indicate the region in which light coupled in by the grating20is blocked. Consequently, this portion of the light is not coupled into the NFT22. This portion of the light is also generally the most intense. As a result, the NFT22cannot make use of the most intense portion of the light from the laser. Efficiency of the NFT22, and thus the EAMR transducer10, is adversely affected.

Accordingly, what is needed is a system and method for improving efficiency and performance of an NFT.

BRIEF SUMMARY OF THE INVENTION

A method and system for providing an EAMR transducer is described. The EAMR is coupled with a laser for providing energy and has an ABS configured to reside in proximity to a media during use. The EAMR transducer includes a write pole, at least one coil, an NFT, a waveguide, and reflector. The write pole has a back gap region and is configured to write to a region of the media. The coil(s) energize the write pole. The NFT is proximate to the ABS and focuses the energy onto the region of the media. The waveguide is configured to direct the energy from the laser toward the NFT at an incident angle with respect to the ABS. A first portion of the energy reflects off of the ABS at a reflected angle. The reflector is configured to receive the first portion of the energy at the reflected angle from the ABS and to reflect a second portion of the energy toward the ABS. The NFT resides between the waveguide and the reflector.

DETAILED DESCRIPTION OF THE EMBODIMENTS OF THE INVENTION

FIG. 2is a diagram depicting a portion of an EAMR disk drive100. For clarity,FIG. 2is not to scale. For simplicity not all portions of the EAMR disk drive100are 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, a mirror or other optics106for redirecting light from the laser104, media108, and an EAMR head110. In some embodiments, the laser104is a laser diode. 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. The laser104may also be oriented differently and/or optically coupled with the EAMR transducer120in another manner. The media108may include multiple layers, which are not shown inFIG. 2for simplicity.

The EAMR head110includes an EAMR transducer120. The EAMR head110may also include a read transducer (not shown inFIG. 2). The read transducer may be included if the EAMR head110is a merged head. The EAMR transducer120includes optical components (not shown inFIG. 2) as well as magnetic components (not shown inFIG. 2).

FIG. 3is a diagram depicting another exemplary embodiment of the EAMR head110shown inFIG. 2. Consequently, analogous components are labeled similarly. For simplicity,FIG. 3is not to scale. In addition, portions of the EAMR transducer120may be omitted inFIG. 3. For example a grating that may be used to couple light from the laser104into the EAMR transducer120is not shown inFIG. 3. In addition to the EAMR transducer120, optional read transducer122is also shown. The read transducer112includes shields114and118as well as read sensor116. In other embodiments, the read transducer112may be omitted.

The EAMR transducer120shown includes a shield122, NFT124, coils130and132having connection134, pole140, and waveguide150. The coils130and132shown are pancake coils having the connection134. In other embodiments, for example if helical coils are used, the connection134may be omitted and/or the positions of the coils may be changed. The NFT124may include a disk portion126and a pin portion128. However, in another embodiment, another type of NFT124may be used. The NFT124is in proximity to the ABS and is used to focus light from the laser104onto the media108. The pole140includes pole tip142and back gap region144. In other embodiments, the pole140may have different and/or additional components. When energized by the coil(s)130and132, the pole140writes to a region of the media108.

The EAMR transducer120also includes optics150and152. In particular, a waveguide150and optional reflector152are used. The waveguide150directs the energy from the laser104toward the ABS at an incident angle, θ. At least a portion of the energy directed by the waveguide150reflects off of the ABS, away from the media (not shown inFIG. 3) and toward the reflector152. The NFT124resides between the incident portion of the waveguide150and the reflector152. Although reflector152is shown, in other embodiments, the reflector152may be omitted. However, in such embodiments, less control over the polarization may be achieved and lower efficiently may be obtained

As can be seen inFIG. 3, the waveguide150directs the energy at an incident angle, θ, from the ABS. The incident angle θ may be an acute angle. The incident angle is such that the waveguide150directs the energy from the laser104around the pole140, particularly around the back gap144and connection134to the coils. However, some space may be desired to be reserved between the back gap144and the waveguide150to reduce the absorption. There is, therefore, a maximum desired incident angle that is somewhat less than one that would bring the waveguide150into contact with the back gap144. The incident angle is also desired to be sufficiently large that energy leaked into the air gap at the ABS is not larger than desired. The incident angle is, therefore, greater than zero. In general, the incident angle is desired to be as large as possible to reduce leakage through the ABS, while achieving total internal reflection as described below.

In some embodiments, the energy from the laser104is desired to undergo total internal reflection at the ABS. To undergo total internal reflection, the incident angle, θ, is the critical angle for the light energy. The critical angle is the incident angle such that the energy undergoes total internal reflection. In such an embodiment, substantially all of the energy from the laser is transferred to the reflector152. However, in practice, the incident angle, θ, of the waveguide150is not greater than the critical angle. In some embodiments, the critical angle is at least fifty six degrees and not more than seventy-one degrees. However, in other embodiments in which the waveguides have different indices of refraction, the critical angles may be different. Thus, in some embodiments the incident angle is at least twenty degrees and not more than sixty-five degrees. In some such embodiments, the incident angle is at least thirty and not more than fifty degrees. The portion of the waveguide150between the NFT124and the reflector152is generally desired to be symmetric with the portion of the waveguide150to the right of the NFT124. However in other embodiments, the portions of the waveguide150need not be symmetric.

In addition to directing energy from the laser104toward the ABS such that the energy does not intersect the back gap144, the waveguide may be narrow in width. In some embodiments, the waveguide150has a width, w, substantially perpendicular to a direction of travel of the energy of at least three hundred and not more than six hundred nanometers. In some such embodiments, the width is not more than four hundred nanometers. The width of the waveguide150may thus be selected to be able to achieve single lateral mode for energy propagation. However, in other embodiments, other modes may be supported.

The optional reflector152receives the reflected energy at a reflected angle. In the embodiment shown, the reflected angle is the same as the incident angle. The reflector152may be a grating and/or a mirror. The reflector152reflects energy back toward the ABS, as shown inFIG. 3. In some embodiments, the angle of incidence for the reflected energy is the same as the reflected angle. However, in other embodiments, the angle of incidence for the reflected energy is different from the reflected angle. Because the reflector152is used, light may be recycled to the NFT124.

The EAMR transducer120may have improved efficiency. In particular, energy from the laser104is not lost to the back gap144. Instead, the waveguide150directs the energy from the laser104around the back gap144. Consequently, more of the energy from the laser104may be coupled into the NFT124. Thus, optical efficiency of the NFT124is improved. Further, as discussed below, the desired polarization may be obtained using the waveguide150and reflector152.

FIGS. 4-5depict embodiments of the EAMR transducer120′ and120″ in which the energy at the NFT124′/124″ has the desired polarization. The waveguides150′ and150″ and reflectors152′ and152″ are analogous to the waveguide150and reflector152. Consequently, the components are labeled similarly. In the embodiment shown inFIG. 4, the distance, d′, between the reflector152′ and the NFT124′ is such that the path difference between the incident energy and energy reflected by the reflector152′ (2d′) is an even integer, n, multiplied by the effective wavelength. The reflected light also undergoes a phase change upon reflection at the reflector152″. As a result, the phase difference between the reflected light at the NFT124′ and the incident light at the NFT124′ is an odd integer multiplied by π. This configuration results in a longitudinal polarization. For example, as shown inFIG. 4, the reflected light has electric field Er, while the incident light has electric field Ei. As can be seen inFIG. 4, the components of the electric fields in the plane of the ABS cancel. Consequently, the total electric field for at the NFT124′ is Et.

Conversely,FIG. 5depicts an embodiment in which the distance, d″, between the reflector152″ and the NFT124″ is such that the path difference between the incident energy and the energy reflected by the reflector152″ (2d″) is an odd integer, m, multiplied by the effective wavelength. Taking into account a phase change occurring when the energy reflects off of the reflector152, the phase difference between the reflected light and the incident light at the NFT124″ is an even integer multiplied by π. This configuration results in a lateral polarization. For example, as shown inFIG. 5, the reflected light has electric field Er′, while the incident light has electric field Ei′. As can be seen inFIG. 4, the components of the electric fields perpendicular to the plane of the ABS cancel. Consequently, the total electric field for at the NFT124″ is Et′. Note that if the path difference is different, the phase difference may not be an integer multiplied by π. In such embodiments the phase difference results in other orientations of the total electric field. Thus, in addition to improving the efficiency of the NFT124/124′/124″, the desired polarization for the NFT124/124′/124″ may be achieved. Thus, using the EAMR transducer120/120′/120″, optical efficiency may be improved and flexibility enhanced.

FIG. 6depicts an exemplary embodiment of a method200of forming a portion of an EAMR head. For simplicity, some steps may be omitted, combined, and/or performed in another sequence. The method200is described in the context of the EAMR disk drive100and EAMR head110. However, the method200may be used to fabricate other EAMR heads. In addition, the method200is 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 method200may be interleaved.

The write pole140and its constituents are provided, via step302. The coil(s) for energizing the pole130are also provided in step304. The NFT is also fabricated, via step306. The waveguide150/150′/150″ is provided, via step308. Finally, the reflector152/152′/152″ is formed opposite to the waveguide150′/150″, via step310.

Using the method200, the EAMR heads110,110′, and/or110″ may be obtained. Consequently, the benefits of such devices may be achieved.