Thermally assisted magnetic recording (HAMR) slider with stray light rejection.

Abstract

A heat-assisted magnetic recording (HAMR) disk drive uses a slider-mounted semiconductor laser to deliver light to a near-field transducer (NFT) through a waveguide located inside the slider. The waveguide includes a core and a cladding material that is transparent to the laser light and surrounds the core. A layer of stray light absorbing material is located inside the slider at opposing edges of the waveguide core in the same plane as the core and on opposing sides of the waveguide core in a plane spaced from the plane of the core. A portion of the waveguide cladding material is located between the waveguide core and the stray light absorbing layer. The stray light absorbing layer absorbs light that leaks into the cladding material, substantially reducing stray light reflected back to the laser to prevent undesirable laser power fluctuations.

Description

[Technical field]

[0001] (CROSS REFERENCE TO RELATED APPLICATIONS) This application claims the benefit of U.S. Non-provisional Application No. 17 / 522,404, filed November 9, 2021, and entitled “HEAT-ASSISTED MAGNETIC RECORDING (HAMR) SLIDER WITH STRAY LIGHT REMOVAL,” the entire contents of which are incorporated by reference into this application for all purposes.

[0002] FIELD OF THEINVENTION The present invention relates generally to heat-assisted magnetic recording (HAMR) in which a laser light source generates light through an optical waveguide to a near-field transducer (NFT) to heat a magnetic recording layer, and more specifically to an improved HAMR slider that eliminates stray light leaking from the waveguide. [Background technology]

[0003] In conventional magnetic recording, thermal instability of the magnetization stored in the recording medium can cause the loss of recorded data. To avoid this, magnetic recording media with high magnetocrystalline anisotropy (K u ) is required. However, K u By increasing K, the coercivity of the medium is also increased, which may exceed the write field capability of the write head. Since the coercivity of the magnetic material in the recording layer is known to be temperature dependent, one proposed solution to the thermal stability problem is thermally assisted magnetic recording (HAMR), in which a high K is applied during writing by the main pole to reduce the coercivity sufficiently for writing to occur. uAlthough the magnetic recording material is locally heated, the coercivity / anisotropy is high enough for thermal stability of the recorded bits at the ambient temperature of the disk drive (i.e., normal operating temperature or "room temperature" of about 15-30°C). In some proposed HAMR systems, the magnetic recording material is heated to near or above its Curie temperature. The recorded data is then read back at ambient temperature by a conventional magnetoresistive read head. HAMR disk drives have been proposed for both conventional continuous media, where the magnetic recording material is a continuous layer on the disk, and bit-patterned media (BPM), where the magnetic recording material is patterned into discrete data islands or "bits".

[0004] HAMR disk drives typically have gas-bearing sliders maintained near the disk surface. Each slider supports a semiconductor laser light source (e.g., a diode laser), a near-field transducer (NFT) for heating the recording material on the disk, and an optical waveguide coupled between the laser and the NFT. The "near-field" transducer refers to "near-field optics," where the path of light is through an element having sub-wavelength features, and the light is coupled to a second element, such as a substrate, such as a magnetic recording medium, located at a sub-wavelength distance from the first element. The NFT is typically located at the gas-bearing surface (GBS) of the gas-bearing slider, which also supports a read / write head and rides or "flies" over the disk surface. Summary of the Invention

[0005] The waveguide is formed inside the slider and includes a core and a cladding material that is transparent to the laser light and surrounds the core. Stray light can leak from the core through the transparent cladding material and reflect off the slider structure and the slider / media interface back to the diode laser. The reflected light can cause mode hops or frequency shifts in the diode laser, resulting in undesirable laser power fluctuations. If the diode laser is misaligned from its desired position on the slider, the reflected light increases. Because of the tolerance in the location of the diode laser during manufacturing, there can always be some misalignment, thus increasing the reflected light.

[0006] In an embodiment of the invention, layers of stray light absorbing material are located within the slider at opposing edges of the waveguide core in the same plane as the core and on opposing sides of the waveguide core in a plane spaced from the plane of the core. Portions of waveguide cladding material are located between the waveguide core and the stray light absorbing layer. The stray light absorbing layer absorbs light that leaks into the cladding material and substantially reduces stray light reflected into the diode laser.

[0007] For a fuller understanding of the nature and advantages of the present invention, reference should be made to the following detailed description taken in conjunction with the accompanying drawings. [Brief description of the drawings]

[0008] [Figure 1] 1 is a top view of a thermally assisted magnetic recording (HAMR) disk drive according to one embodiment of the present invention. [Diagram 2] 1 is a side cross-sectional view of a gas bearing slider used in a HAMR disk drive and a portion of a HAMR disk according to the prior art, not drawn to scale due to the difficulty of showing very small features. [Diagram 3] 1 is a side cross-sectional view of a slider according to the prior art illustrating the problem of stray light. [Figure 4]The percentage of coupling efficiency at a near-field transducer (NFT) (curve 200) and the percentage of mode hop power variation at the NFT (curve 210) are shown as a function of cross-track misalignment of a diode laser on the flex surface of a slider. [Diagram 5] FIG. 2 is a side cross-sectional view through a plane containing a waveguide core, showing two layers (layers 3 and 4) of stray light absorbing material located at opposing edges of the waveguide core in the plane of the core, according to one embodiment of the invention. [Figure 6] FIG. 6 is a view of section 6-6 of FIG. 5, which is a plane parallel to the first and second planes of the slider, showing cladding material substantially surrounding the waveguide core and four layers of stray light absorbing material, in accordance with one embodiment of the present invention. [Figure 7A] 3 shows the shape of a stray light absorbing layer according to an embodiment of the present invention in the plane of the layer. [Figure 7B] 1 illustrates an embodiment of a stray light absorbing layer, according to an embodiment of the present invention, where an edge of the layer proximate to the flex surface forms an angle with respect to the flex surface. [Figure 7C] 1 illustrates an embodiment of a stray light absorbing layer, according to an embodiment of the present invention, where an end of the layer proximate to the flex surface forms a curved end relative to the flex surface. [Figure 8] 3 is a graph of a computer simulation showing the reflectance without a stray light absorbing layer (curve 300) and with a stray light absorbing layer formed from Ru (curve 310) as a function of cross-track offset of a diode laser (diode laser). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Figure 1 is a top view of a thermally assisted magnetic recording (HAMR) disk drive 100 in accordance with one embodiment of the present invention. In Figure 1, the HAMR disk drive 100 is depicted with a disk 150 having a magnetic recording layer 31 of conventional continuous magnetic recording material arranged in radially spaced circular tracks 118. Only a few representative tracks 118 near the inner and outer diameters of the disk 150 are shown. However, instead of a conventional continuous magnetic recording layer, the recording layer may be a bit-patterned media (BPM) layer having discrete data islands.

[0010] The drive 100 has a housing or base 112 that supports an actuator 130 and a drive motor for rotating a magnetic recording disk 150. The actuator 130 may be a voice coil motor (VCM) rotary actuator having a rigid arm 131 that rotates about a pivot 132 as indicated by arrow 133. The head suspension assembly includes a suspension 135 having one end attached to the end of the actuator arm 131 and a head carrier, such as a gas bearing slider 120, attached to the other end of the suspension 135. The suspension 135 allows the slider 120 to be maintained in close proximity to the surface of the disk 150 and allows the slider 120 to "pitch" and "roll" on a bearing of gas (typically air or helium) generated by the disk 150 as it rotates in the direction of arrow 20. The slider 120 supports a HAMR head (not shown) that includes a magnetoresistive read head, an inductive write head, a near-field transducer (NFT), and an optical waveguide. A semiconductor laser 88 with a wavelength of 780-980 nm may be used as a HAMR light source and is depicted as being supported on top of the slider 120. As the disk 150 rotates in the direction of arrow 20, movement of the actuator 130 allows the HAMR head on the slider 120 to access different data tracks 118 on the disk 150. The slider 120 is typically formed from a composite material, such as a composite material made of alumina-titanium carbide (Al2O3 / TiC). Although only one disk surface with an associated slider and read / write head is shown in FIG. 1, there are typically multiple disks stacked on a hub rotated by a spindle motor, with a separate slider and HAMR head associated with each surface of each disk.

[0011] In the following figures, the X-axis indicates the axis perpendicular to the air bearing surface (GBS) of the slider, the Y-axis indicates the track width or cross-track axis, and the Z-axis indicates the along-track axis. FIG. 2 is a schematic cross-sectional view of an example of a prior art HAMR head configuration. In FIG. 2, a disk 150 is depicted with a recording layer 31, which is a conventional continuous magnetic recording layer of magnetizable material having magnetized regions or "bits" 34. The air bearing slider 120 is supported by a suspension 135 and has a GBS facing the disk 150 and supporting a magnetic write head 50, a read head 60, and magnetically permeable read head shields S1 and S2. The recording magnetic field is generated by a write head 50 consisting of a coil 56, a main pole 53 for transmitting the magnetic flux generated by the coil 56, a main pole 52 connected to the main pole 53, and a return pole 54 coupled to the main pole 53 and the main pole 52. The magnetic field generated by the coil 56 is transferred through the main pole 53 to the main pole 52, which is positioned adjacent to an optical near-field transducer (NFT) 74. FIG. 2 shows the write head 50 with the well-known "pancake" coil 56, where the coil segments are substantially in the same plane. However, the coil may alternatively be a well-known "helical" coil, where the coil is wrapped around the main pole 53. During recording, the recording layer 31 of the disk 150 is heated by the near-field light generated by the NFT 74 while regions or "bits" 34 are magnetized and thus written to the recording layer 31 by applying the recording magnetic field generated by the main pole 52.

[0012] The semiconductor laser 90 is mounted on the top surface of the slider 120. A diode laser is one type of semiconductor laser. Other types include vertical cavity surface emitting lasers (VCSELs). An optical waveguide has a core 73 for guiding light from the laser 90 to the NFT 74. The waveguide includes the core 73 and a surrounding cladding material (not shown) and is formed inside the slider 120. A material may be used for the waveguide core 73 to ensure that the refractive index of the waveguide core 73 is greater than the refractive index of the surrounding cladding material. For example, Al2O3 or SiO2 may be used as the cladding material, and TiO2, Ta2O5 or SiO2 may be used as the cladding material. x N y may be used as the core material.

[0013] FIG. 3 is a side cross-sectional view of a slider according to the prior art, illustrating the problem of stray light. A semiconductor laser, preferably a diode laser, is mounted on a submount that is mounted on a first or top surface (also called the flex surface) of a head carrier, which may be a gas bearing slider. The slider includes contact pads for electrically connecting various slider components (e.g., read and write heads, fly-height control heaters) to the disk drive hardware. The NFT is located on a second surface or GBS of the slider, substantially parallel to the flex surface. The diode laser transmits light through the gap to a spot-size converter (SSC) formed at the end of the waveguide core. An anti-reflective coating (e.g., Ta2O5+SiO2) is typically formed on the flex surface. A waveguide core is formed inside the slider and transmits light to the NFT. In this example, unlike the straight shape of the waveguide core in FIG. 2, the waveguide core may have multiple bends. The waveguide includes a cladding material (not shown) that is optically transparent and surrounds the core. Stray light leaks from the core through the transparent cladding material and reflects off the slider structure and the slider / media interface back to the diode laser. The reflected light causes mode hops or frequency shifts in the diode laser, resulting in undesirable diode laser power fluctuations.

[0014] Even if the diode laser is precisely aligned on the slider flex surface, light leaks from the waveguide cladding, and thus stray light is reflected back to the diode laser. However, experimental studies have shown that if the diode laser is slightly misaligned from the desired position on the slider flex surface, the reflected stray light increases, which leads to instability in the diode laser power. Since there is a tolerance in the location of the diode laser during manufacturing, some diode laser misalignment may always exist, thus increasing the reflected light. FIG. 4 shows the coupling efficiency (in arbitrary units au) in the NFT (curve 200) and the amplitude (power fluctuation) of mode hops (in arbitrary units au) in the NFT (curve 210) as a function of the cross-track misalignment of the diode laser. At zero misalignment, the coupling efficiency is highest and the amplitude of mode hops is lowest, but with increasing misalignment, the coupling efficiency decreases and the mode hop power fluctuation increases.

[0015] In an embodiment of the invention, the stray light absorbing material is located within the cladding material and spaced around the core with portions of the cladding material located between the stray light absorbing material and the core. The stray light absorbing material extends from the first slider surface toward the second slider surface. The stray light absorbing material may be formed as a layer located within the slider at opposing edges of the waveguide core in the same plane as the core and at opposing sides of the waveguide core in a plane spaced from the plane of the core. FIG. 5 is a side cross-sectional view through a plane containing the waveguide cores, showing two layers (layer 3 and layer 4) of stray light absorbing material located at opposing edges of the waveguide core in the plane of the core. FIG. 5 also shows cladding material 1 located in the same plane as the waveguide core adjacent the core edge. The cladding material may cover the entire surface of the plane containing the waveguide cores as shown in FIG. 5, or may extend a certain distance from the core edge.

[0016] FIG. 6 is a view of section 6-6 of FIG. 5, a plane parallel to the first and second planes of the slider, showing the cladding material substantially surrounding the waveguide core and four layers of stray light absorbing material. Cladding material 1 may be SiO2 and is substantially in the same plane as the core. Layers 3 and 4 are located at opposite edges of the core, with cladding material 1 being substantially in the same plane as the core. Cladding material 2 may be Al2O3 and is on opposite sides of the core and in a plane substantially parallel to the core plane. The stray light absorbing layers are located around the cladding material substantially surrounding the core, thus absorbing light that escapes from the surrounding cladding material, thereby preventing or substantially reducing reflections that bounce back to the diode laser. Layers 1 and 2 have preferred thicknesses in the range of 20-400 nm. Layers 3 and 4 have preferred thicknesses in the range of 20-400 nm. If layers 3 and 4 are thicker than about 300 nm, they may contribute additional reflections.

[0017] FIG. 7A shows the shape of the stray light absorbing layer in the plane of the layers. The width W of layers 1 and 2 are depicted as having the same width as the width W of layers 3 and 4 combined. Layers 3 and 4 are spaced apart on opposing edges of the waveguide core to allow the width of the cladding material between the core and layers 3 and 4 to be at least four times the width of the core. In one example, the core may have an edge-to-edge width of about 0.4-0.8 mm, W may be about 20 mm, and Wg may be about 6 mm. The layer has a preferred length L that extends from the flex surface to at least the first bend of the core as shown in FIG. 7A, or all the way to near the NFT if the core is a straight line from the flex surface to the GBS. FIG. 7B shows an embodiment of the layer where the end of the layer close to the flex surface forms an angle with respect to the flex surface, and FIG. 7C shows an embodiment of the layer where the end of the layer close to the flex surface forms a curved end with respect to the flex surface. In both embodiments, the tapered ends of the layers can reduce reflections back into the diode laser.

[0018] The stray light absorbing layer should be made of a material with a high extinction coefficient k at the diode laser wavelength to allow effective absorption of stray light. The material must also be able to withstand high thermal stress. Preferred materials include both metal and metal alloy materials such as Ru, Co, Cr, W, NiFe, CoFe, NiTa and RuAl (k is preferably greater than 1), or metal alloys containing at least 10 atomic percent of one or more of Cr, Ni, Ta and Ru, as well as lossy dielectric materials such as C, GaAs and Si (k is preferably greater than 0.3). The stray light absorbing layer may also be a multilayer of different ones of these materials, and may be a multilayer in which, in addition to a layer of stray light absorbing material, one of the layers is a layer of a highly thermally conductive material such as Cu or Au, which acts as a heat sink to avoid high temperature rise caused by light absorption.

[0019] 8 is a graph of a computer simulation showing the reflectivity without a stray light absorbing layer (curve 300) and with a stray light absorbing layer made from Ru (curve 310) as a function of cross-track offset of the diode laser. The total internal reflection bouncing back to the diode laser is reduced by about 80% by the stray light absorbing layer.

[0020] While the present invention has been particularly shown and described with reference to preferred embodiments, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention. Accordingly, the disclosed invention is to be considered merely as illustrative and limited only in scope as defined in the appended claims. The following items are elements that are claimed in the international application: (Item 1) 1. A thermally assisted magnetic recording (HAMR) head carrier having first and second spaced apart, substantially parallel surfaces, the head carrier comprising: a semiconductor laser on the first surface; a near-field transducer (NFT) having an output end on the second surface; a waveguide on the head carrier, the waveguide including a core in a plane substantially perpendicular to the first and second head carrier surfaces and extending from the first head carrier surface toward the second head carrier surface, the core being optically coupled to the laser and the NFT, and a cladding material surrounding the core; and stray light absorbing material located within the cladding material and spaced about the core, a portion of the cladding material being located between the stray light absorbing material and the core, the stray light absorbing material extending from the first head carrier surface toward the second head carrier surface. (Item 2) Item 2. The HAMR head carrier of item 1, further comprising an anti-reflective coating on the first surface of the head carrier. (Item 3) 2. The HAMR head carrier of claim 1, wherein the waveguide core further comprises a spot size converter near the first surface of the head carrier. (Item 4) Item 2. The HAMR head carrier according to item 1, wherein the stray light absorbing material is formed from a material having an extinction coefficient k greater than 0.3. (Item 5) 2. The HAMR head carrier of item 1, wherein the stray light absorbing material is selected from Ru, Co, Cr, W, NiFe, CoFe, NiTa, RuAl, alloys (containing at least 10 atomic percent of one or more of Cr, Ni, Ta, and Ru), and C, GaAs, and Si. (Item 6) 2. The HAMR head carrier of claim 1, wherein the waveguide core includes at least two bends between the laser and the NFT, the core extends in a substantially straight line from the first head carrier surface to the bend closest to the first head carrier surface, and the stray light absorbing material extends from the first head carrier surface to the bend closest to the first head carrier surface. (Item 7) the cladding material includes an edge cladding material located at an edge of the core in substantially the same plane as the core, and a side cladding material located on an opposite side of the plane containing the core and edge cladding material, and the stray light absorbing material is first and second stray light absorbing layers on opposite sides of the side cladding material and extending from near the first head carrier surface toward the second head carrier surface, the first and second stray light absorbing layers being substantially parallel to the planes of the core and edge cladding materials; 2. The HAMR head carrier of claim 1, further comprising: third and fourth stray light absorbing layers at opposing edges of the edge cladding material and extending from near the first head carrier surface toward the second head carrier surface, the third and fourth stray light absorbing layers being substantially coplanar with the first and second stray light absorbing layers and substantially parallel to the first and second stray light absorbing layers. (Item 8) 8. The HAMR head carrier of item 7, wherein one or more of the stray light absorbing layers comprises multiple layers of different materials. (Item 9) 1. A thermally assisted magnetic recording (HAMR) disk drive, comprising: Item 1, a HAMR head carrier further comprising a magnetic write head and a magnetoresistive read head on the head carrier; A HAMR disk drive comprising: a magnetic recording disk having a magnetic recording layer. (Item 10) 1. A thermally assisted magnetic recording (HAMR) slider having first and second spaced apart, substantially parallel surfaces, the slider comprising: a diode laser on the first surface; a near-field transducer (NFT) having an output end on the second surface; a waveguide on the slider, the waveguide including: a core in a plane substantially perpendicular to the first and second slider surfaces and optically coupled to the diode laser and the NFT; an edge cladding material located at an edge of the core in substantially the same plane as the core; and a side cladding material located on opposite sides of the plane containing the core and the edge cladding material; first and second stray light absorbing layers on opposite sides of the side cladding material and extending from near the first slider surface toward the second slider surface, the first and second stray light absorbing layers being substantially parallel to the planes of the core and edge cladding materials; and third and fourth stray light absorbing layers at opposing edges of the edge cladding material and extending from near the first slider surface toward the second slider surface, the third and fourth stray light absorbing layers being substantially coplanar with and substantially parallel to the first and second stray light absorbing layers. (Item 11) Item 11. The HAMR slider of item 10, further comprising an anti-reflective coating on the first surface of the slider. (Item 12) Item 11. The HAMR slider of item 10, wherein the waveguide core further comprises a spot size transformer near the first surface of the slider. (Item 13) Item 11. The HAMR slider of item 10, wherein the waveguide core includes at least two bends between the diode laser and the NFT. (Item 14) Item 13. The HAMR slider of item 12, wherein each of the stray light absorbing layers extends from the first slider surface to the bend closest to the first slider surface. (Item 15) Item 11. The HAMR slider of item 10, wherein one or more of the ends of the stray light absorbing layer near the first slider surface are tapered to the first surface of the slider. (Item 16) Item 11. The HAMR slider of item 10, wherein the stray light absorbing layer is formed from a material having an extinction coefficient k greater than 0.3. (Item 17) Item 11. The HAMR slider of item 10, wherein one or more of the stray light absorption layers are formed from a material selected from Ru, Co, Cr, W, NiFe, CoFe, NiTa, RuAl, alloys (containing at least 10 atomic percent of one or more of Cr, Ni, Ta, and Ru), and C, GaAs, and Si. (Item 18) 1. A thermally assisted magnetic recording (HAMR) disk drive, comprising: 11. The HAMR slider of claim 10, further comprising a magnetic write head and a magnetoresistive read head on the slider; A HAMR disk drive comprising: a magnetic recording disk having a magnetic recording layer.

Claims

1. A thermally assisted magnetic recording (HAMR) head carrier having spaced apart and substantially parallel first and second surfaces, the HAMR head carrier comprising: a semiconductor laser on the first surface; a near field transducer (NFT) having an output end at the second surface; a waveguide on the HAMR head carrier, the waveguide including a core in a plane substantially perpendicular to the first and second surfaces and extending from the first surface toward the second surface, the core being optically coupled to the semiconductor laser and the NFT, and a cladding material surrounding the core; a stray light absorbing material located within the cladding material and spaced about the core; A HAMR head carrier, wherein the portion of the cladding material is located between the stray light absorbing material and the core, and the stray light absorbing material extends from the first surface toward the second surface.

2. The HAMR head carrier of claim 1 , further comprising an anti-reflective coating on the first surface of the HAMR head carrier.

3. The HAMR head carrier of claim 1 , wherein the core further comprises a spot size transformer proximate the first surface of the HAMR head carrier.

4. 2. The HAMR head carrier of claim 1, wherein the stray light absorbing material is formed from a material having an extinction coefficient k greater than 0.

3.

5. 2. The HAMR head carrier of claim 1, wherein the stray light absorbing material is selected from Ru, Co, Cr, W, NiFe, CoFe, NiTa, RuAl, alloys (containing at least 10 atomic percent of one or more of Cr, Ni, Ta, and Ru), and C, GaAs, and Si.

6. 2. The HAMR head carrier of claim 1, wherein the core includes at least two bends between the semiconductor laser and the NFT, the core extends in a substantially straight line from the first surface to the bend closest to the first surface, and the stray light absorbing material extends from the first surface to the bend closest to the first surface.

7. the cladding material includes an edge cladding material located at an edge of the core in substantially the same plane as the core, and a side cladding material located on an opposite side of the plane containing the core and the edge cladding material; The stray light absorbing material is first and second stray light absorbing layers on opposite sides of the side cladding material and extending from near the first surface toward the second surface, the first and second stray light absorbing layers being substantially parallel to the planes of the core and edge cladding materials; 2. The HAMR head carrier of claim 1, further comprising: third and fourth stray light absorbing layers at opposing edges of said edge cladding material and extending from near said first surface toward said second surface, said third and fourth stray light absorbing layers being substantially coplanar with and substantially parallel to said first and second stray light absorbing layers.

8. 8. The HAMR head carrier of claim 7, wherein one or more of the first through fourth stray light absorbing layers comprises multiple layers of different materials.

9. 1. A thermally assisted recording (HAMR) disk drive, comprising:

2. The HAMR head carrier of claim 1 further comprising a magnetic write head and a magnetoresistive read head on the HAMR head carrier; a magnetic recording disk having a magnetic recording layer.

10. A thermally assisted magnetic recording (HAMR) slider having spaced apart and substantially parallel first and second surfaces, the HAMR slider comprising: a diode laser on the first surface; a near field transducer (NFT) having an output end at the second surface; a waveguide on the HAMR slider, the waveguide including: a core in a plane substantially perpendicular to the first and second surfaces and optically coupled to the diode laser and the NFT; an edge cladding material located at an edge of the core in substantially the same plane as the core; and a side cladding material located on opposite sides of the plane containing the core and the edge cladding material; first and second stray light absorbing layers on opposite sides of the side cladding material and extending from near the first surface toward the second surface, the first and second stray light absorbing layers being substantially parallel to the planes of the core and edge cladding materials; and third and fourth stray light absorbing layers at opposing edges of the edge cladding material and extending from near the first surface toward the second surface, the third and fourth stray light absorbing layers being substantially coplanar with and substantially parallel to the first and second stray light absorbing layers.

11. The HAMR slider of claim 10 further comprising an anti-reflective coating on the first surface of the HAMR slider.

12. The HAMR slider of claim 10 , wherein the core further comprises a spot size transformer proximate the first surface of the HAMR slider.

13. The HAMR slider of claim 10 , wherein the core includes at least two bends between the diode laser and the NFT.

14. 14. The HAMR slider of claim 13, wherein each of the first through fourth stray light absorbing layers extends from the first surface to the bend closest to the first surface.

15. A HAMR slider as described in claim 10, wherein one or more of the ends near the first surface of the first to fourth stray light absorption layers are tapered with respect to the first surface of the HAMR slider.

16. 11. The HAMR slider of claim 10, wherein the first through fourth stray light absorbing layers are formed from a material having an extinction coefficient k greater than 0.

3.

17. 11. The HAMR slider of claim 10, wherein one or more of the first through fourth stray light absorbing layers are formed from a material selected from Ru, Co, Cr, W, NiFe, CoFe, NiTa, RuAl, alloys (containing at least 10 atomic percent of one or more of Cr, Ni, Ta, and Ru), C, GaAs, and Si.

18. 1. A thermally assisted recording (HAMR) disk drive, comprising:

11. The HAMR slider of claim 10, further comprising a magnetic write head and a magnetoresistive read head on the HAMR slider; a magnetic recording disk having a magnetic recording layer.

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