# Patent

## Title
Heat assisted magnetic recording writer having integrated polarization rotation waveguides

## Abstract

A heat assisted magnetic recording (HAMR) writer is described. The HAMR writer is coupled with a laser that provides energy having a first polarization state. The HAMR writer has an air-bearing surface (ABS) configured to reside in proximity to a media during use, a plurality of waveguides, a main pole and at least one coil. The main pole writes to the media and is energized by the coil(s). The waveguides receive the energy from the laser and direct the energy toward the ABS. The waveguides include an input waveguide and an output waveguide. The input waveguide is configured to carry light having the first polarization state. The output waveguide is configured to carry light having a second polarization state different from the first polarization state. The waveguides are optically coupled and configured to transfer the energy from the first polarization state to the second polarization state.

## Background
BACKGROUND
A conventional heat assisted magnetic recording (HAMR) transducer typically includes at least a waveguide, a near-field transducer (NFT), a main pole and a coil for energizing the main pole. The conventional HAMR transducer uses light, or energy, received from a conventional laser in order to write to a magnetic recording media. Light from the laser is incident on and coupled into the waveguide. Light is guided by the conventional waveguide to the NFT near the ABS. The NFT focuses the light to magnetic recording media (not shown), such as a disk. This region is thus heated. The main pole is energized and field from the pole tip is used to write to the heated portion of the recording media.
Although the conventional HAMR transducer functions, improvements in performance are still desired.



BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS
FIG. 1 is a diagram depicting a side view of an exemplary embodiment of a HAMR disk drive.
FIG. 2 is a diagram depicting an exploded perspective view of an exemplary embodiment of a portion of a HAMR writer.
FIGS. 3 A and 3B are diagrams depicting a cross-sectional and side views of another exemplary embodiment of a portion of a HAMR writer.
FIG. 4 is a diagram depicting a cross-sectional view of another exemplary embodiment of a HAMR writer.
FIG. 5 is a diagram depicting a cross-sectional view of another exemplary embodiment of a HAMR writer.
FIG. 6 is a diagram depicting a cross-sectional view of another exemplary embodiment of a HAMR writer.
FIG. 7 is a diagram depicting a side view of another exemplary embodiment of a HAMR writer.
FIG. 8 is a diagram depicting a side view of another exemplary embodiment of a HAMR writer.
FIG. 9 is a flow chart depicting an exemplary embodiment of a method for fabricating a HAMR write apparatus.
FIG. 10 is a flow chart depicting an exemplary embodiment of a method for fabricating waveguides for a HAMR write apparatus.
FIG. 11 is a flow chart depicting an exemplary embodiment of a method for fabricating waveguides for a HAMR write apparatus.
FIGS. 12-17 depict cross-sectional views of an exemplary embodiment of a wafer during fabrication of waveguides for the HAMR disk drive.



DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 depicts a side view of an exemplary embodiment of a portion of a heat-assisted magnetic recording (HAMR) write apparatus, or disk drive 100. For clarity, FIG. 1 is not to scale. For simplicity not all portions of the HAMR disk drive 100 are shown. In addition, although the HAMR disk drive 100 is depicted in the context of particular components other and/or different components may be used. For example, circuitry used to drive and control various portions of the HAMR disk drive 100 is not shown. For simplicity, only single components are shown. However, multiples of each component and their sub-components, might be used.
The HAMR disk drive 100 includes media 102, a slider 110, a HAMR transducer 120 and a laser subassembly 170. Additional and/or different components may be included in the HAMR disk drive 100. Although not shown, the slider 110, and thus the laser assembly 170 and HAMR transducer 120 are generally attached to a suspension. The laser assembly 170 includes a laser 172 and a submount 174. The submount 174 is a substrate to which the laser 172 may be affixed for improved mechanical stability, heat sinking, ease of manufacturing and better robustness. The laser 172 may be a chip such as a laser diode or other laser. The laser 172 outputs energy having a particular polarization state, indicated as Polarization State 1 (first polarization state) in FIG. 1. In some embodiments, this first polarization state is a TE mode. For example, the light may be linearly polarized in the cross-track direction. The laser 172 outputs this light energy through the surface closest to the HAMR transducer 120.
The HAMR transducer 120 is fabricated on the slider 110 and includes an air-bearing surface (ABS) proximate to the media 102 during use. In general, the HAMR write transducer 120 and a read transducer are present in the HAMR write apparatus 100. However, for clarity, only the HAMR write transducer 120 is shown. As can be seen in FIG. 1, HAMR transducer 120 includes a near-field transducer (NFT) 130, waveguides 140, a main pole 150 and coil(s) 155. The waveguides 140 are optically coupled with the laser 172. The waveguides 140 carry light energy from the laser 172 toward the ABS. The NFT 130 couples a portion of this energy from the waveguides 140 to the media 102. In some embodiments, the NFT 130 occupies a portion of the ABS. The NFT 130 transfers energy to the media 102. The write pole 150 is energized by the coils 155 and writes to the media 102. The coil(s) 155 may be solenoidal or spiral (pancake) coils. Other components including but not limited to other poles and/or shields may also be present.
In some embodiments, the NFT 130 may be configured to propagate a surface plasmon polariton. In such embodiments, the NFT 130 may be desired to utilize a transverse magnetic (TM) mode. This electric field of the mode may be oriented in the down track direction. In other embodiments, the NFT 130 may be configured to receive energy polarized in a particular manner for other reason(s). The desired polarization of light received by the NFT 130 is depicted as Polarization State 2 (second polarization) in FIG. 1. The Polarization State 2 is different from the Polarization State 1 emitted by the laser 172.
The waveguides 140 include an input waveguide that receives the light from the laser 172 and an output waveguide that may provide light to the NFT 130. The waveguides 140 are optically coupled. This may be achieved by overlapping the waveguides in regions where the waveguides are in close proximity. This overlap is shown in FIG. 1 by dashed lines. In the embodiment shown in FIG. 1, there are four waveguides 140. However, in another embodiment, another number of waveguides might be used. The waveguides 140 include at least the input waveguide and the output waveguide. The light energy received by the input waveguide closest to the laser 140 is polarized in the first state (Polarization State 1 in FIG. 1). In some embodiments, the first of the waveguide 140 may also be desired to be excited with linearly polarized light in a TE fashion with the electric field in the cross track direction. In other embodiments, the input waveguide may have improved efficiency for light polarized in another manner. However, the first polarization state of the light output by the laser 172 may be different than that which is desired, for example for use by the NFT 130.
Thus, the energy output by the laser 172 in the first polarization state may not match the energy desired to be input to the NFT 130 in the second polarization state. As a result, the waveguides 140 are optically coupled such that the polarization state of light traversing between the waveguides 140 is transferred from the first polarization state to the second polarization state.
For example, the NFT 130 may be configured for light that is linearly polarized in the down track direction (TM polarization), while the laser 172 outputs light polarized in the cross-track direction (TE polarization). Thus, the waveguides 140 are configured such that as energy from the laser 172 is transferred from one waveguide to another waveguide, the polarization state changes. Thus, the waveguides 140 change the polarization of the energy from the laser 172 to match the desired polarization state.
In operation, the laser 172 emits light having the first polarization state. The light then enters the input waveguide in the first polarization state. The input waveguide is optically coupled to the next waveguide, and so on until the output waveguide is reached. The polarization of light at the output of the output waveguide is the second polarization state. For example, the input waveguide may carry the TE polarized energy, while the output waveguide carries TM polarized light. Thus, while traversing the waveguides 140, particularly in the regions the waveguides 140 are optically coupled, the polarization of the light has been rotated from the first polarization state to the second polarization state. The waveguides 140 also direct the light to the NFT 130. Thus, light entering the NFT 130 has the desired second polarization state. The NFT 128 focuses the light to a region of magnetic recording media 102. High density bits can be written on a high coercivity medium with the pole 150 energized by the coils 155 to a modest magnetic field.
The HAMR disk drive 100 may exhibit enhanced performance. Using the waveguides 140, the polarization of the light energy from the laser 172 can be rotated to the desired direction. Thus, energy having the desired polarization can be provided to the NFT 130. For example, an NFT 130 that propagates surface plasmon polariton can be used in the HAMR transducer 100. In addition, a lower cost laser 172 that produces light linearly polarized in the cross-track direction may be used in the HAMR disk drive 100. Thus, performance of the HAMR disk drive may be improved.
FIG. 2 depicts an exploded perspective view of another exemplary embodiment of a portion of the HAMR disk drive 100′. For clarity, FIG. 2 is not to scale. For simplicity not all portions of the HAMR disk drive 100′ are shown. In addition, although the HAMR disk drive 100′ is 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 HAMR disk drive 100′ is analogous to the HAMR disk drive 100. Consequently, similar components have analogous labels. The HAMR disk drive 100′ thus includes a laser 172 and a HAMR transducer 120′ that are analogous to the lasers 172 and HAMR transducer 120, respectively. The HAMR transducer 120′ includes waveguides 140′ and NFT 130 that are analogous to the waveguides 140 and NFT 130, respectively. For clarity, components such as the pole and coils have been omitted.
The waveguides 140′ include an input waveguide 142 and an output waveguide 144. The input waveguide 142 is directly coupled with the output waveguide 144. As can be seen in FIG. 2, the laser 172 outputs light having a first polarization state, with the transverse electric (TE) mode in the cross track direction. Light energy polarized with the TE polarization enters the input waveguide 142. The waveguides 142 and 144 are coupled such that the light transmitted from the input waveguide 142 to the output waveguide 144 is the TM mode. Thus, light exiting the output waveguide 144 has the second polarization state, with the electric field oriented in the down track direction. The light is carried from the output waveguide 144 to the NFT 130. Because the polarization of the light is not further changed, the light energy coupled into the NFT 130 has the second polarization state. Stated differently, this light provided to the NFT 130 is polarized in the TM mode. The NFT 130 may then couple the energy from this light to the media (not shown in FIG. 2) and the write pole (not shown in FIG. 2) used to magnetically write to the heated portion of the media.
The HAMR disk drive 100′ shares the benefits of the HAMR transducer 100. Using the input waveguide 142 and output waveguide 144, the polarization of the light energy from the laser 172 can be rotated to be in the desired direction. Thus, energy having the desired polarization can be provided to the NFT 130. Thus, performance of the HAMR disk drive 100′ may be improved.
FIGS. 3A and 3B depict cross-sectional and side views of another exemplary embodiment of a portion of the HAMR write apparatus 200. For clarity, FIGS. 3A-3B are not to scale. For simplicity not all portions of the HAMR disk drive 200 are shown. In addition, although the HAMR write apparatus 200 is 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 HAMR write apparatus 200 is analogous to the HAMR disk drives 100 and 100′. The direction of transmission of light is out of the plane of the page in FIG. 3A (e.g. toward the ABS) and in the direction of the arrows labeled TE Mode and TM Mode in FIG. 3B.
The HAMR write apparatus includes a laser (not shown), an NFT (not shown), a write pole (not shown) for writing to the media, a coil and two waveguides 210 and 220. The waveguides 210 and 220 are analogous to the waveguides 140 and 140′. The waveguide 210 is the output waveguide in the embodiment shown, while the waveguide 220 is the input waveguide. The waveguide 210 includes a core 212 and cladding 214. The output waveguide 220 includes an input core 222 and cladding 224. The light carried by the waveguides 210 and 220 is primarily via the cores 212 and 222. The cores 212 and 222 have a different index of refraction than the cladding 214 and 224. For example, the cores 212 and 222 may be formed of tantalum oxide, while the cladding 214 and 224 may be formed of silicon oxide. In the embodiment depicted in FIGS. 3A-3B the waveguides 210 and 220 are separated by a layer 230. This layer 230 may be an etch stop layer used in fabricating the waveguides 210 and 220. For example, the layer 230 may be an aluminum oxide layer. In some embodiments, such a layer is nominally twenty nanometers thick. However, in other embodiments, the layer 230 may simply be a spacer layer.
The waveguides 210 and 220 are optically coupled and transfer the polarization from a TE mode to a TM mode. Thus, the aspect ratios of the cores differ. For example, the input core 222 has a height h1 and a width w1. The width is larger than the height for the input core 222 (w1>hh1). The output core 212 has a height h2 and w width w2. The height is larger than the width for the output core 212 (h2>w2). Thus, the aspect ratios differ. In particular, the long axes of the cores 212 and 222 are perpendicular to each other (w1 is perpendicular to h2). In the embodiment shown in FIGS. 3A-3B, the aspect ratios (height divided by width) for the waveguides 210 and 220 are not reciprocals (h1/w1≠w2/h2). Thus, the widths and heights of the waveguides 210 and 220 differ. However, in other embodiments, the width of one waveguide 210 or 220 may match the height of the other waveguide 220 or 210, respectively. In general, the aspect ratios of the waveguides 210 and 220 may be optimized for the polarization of the light each waveguide 210 and 220, respectively, is desired to support.
In order to couple the waveguides 210 and 220, the waveguides 210 and 220 are directionally coupled along the coupling length, cl, depicted in FIG. 3B. In other embodiments, the waveguides 210 and 220 might be adiabatically coupled or coupled in another manner. In some embodiments, this length is on the order of eleven microns. The waveguides 210 and 220 are parallel along the coupling length such that light transmitted by the waveguides 210 and 220 have the same direction of transmission along the coupling length. In the embodiment shown in FIGS. 3A and 3B, outside of the coupling length, the waveguides 210 and 220 transmit light in other directions. Stated differently, outside of the coupling length, the waveguides 210 and 220 may have different directions of transmission, may not be in close proximity and are not optically coupled.
In addition, the cores 212 and 222 of the waveguides 210 and 220 are offset. As can be seen in FIGS. 3A-3B, the cores 212 and 222 are offset in the height direction by the spacer layer 230. The cores 212 and 222 are also offset in the width direction by the distance o. In the embodiment shown, the cores 212 and 222 overlap by the offset, o. In other embodiments, the cores 212 and 222 may be offset in the width direction such that they do not overlap and/or are spaced apart. Similarly, the cores 212 and 222 are shown as spaced apart in the height direction by the thickness of the layer 230. In other embodiments, the cores 212 and 222 may partially overlap, may not overlap, or may be spaced apart. In general, the cores 212 and 222 are desired to be offset by not more than their length and/or by not more than their width. In some embodiments, the cores 212 and 222 are offset by not more than one-half of their height and/or width.
In operation, the laser provides light having a first polarization state, with the TE mode with its electric field that may be in the cross track direction. The light having the TE mode polarization enters the input waveguide 220. In the coupling region, the light from the input waveguide 220 is transferred to the output waveguide 210 such that the polarization of the light transferred to the output waveguide 220 is changed to the TM mode. The output waveguide 210 may then transfer the light to the NFT or other component. Thus, this light provided to the NFT is polarized as desired (e.g. in the down track direction). The NFT may then couple the energy from this light to the media (not shown in FIGS. 3A-3B) and the write pole (not shown in FIGS. 3A-3B) used to write to the heated portion of the media.
The HAMR write apparatus 200 shares the benefits of the HAMR transducer(s) 100 and/or 100′. Using the input waveguide 220 and output waveguide 210, the polarization of the light energy from the laser can be transferred to be in the desired direction. Thus, energy having the desired polarization can be provided to the NFT (not shown in FIGS. 3A-3B). Thus, performance of the HAMR disk drive 200 may be improved.
FIG. 4 depicts a cross-sectional view of another exemplary embodiment of a portion of the HAMR write apparatus 200′. For clarity, FIG. 4 is not to scale. For simplicity not all portions of the HAMR disk drive 200′ are shown. In addition, although the HAMR write apparatus 200′ is 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 HAMR write apparatus 200′ is analogous to the HAMR writers 100, 100′ and/or 200. Thus, similar components have similar labels as in FIGS. 3A-3B. The direction of transmission of light is out of the plane of the page in FIG. 4 (e.g. toward the ABS).
The HAMR write apparatus includes a laser (not shown), an NFT (not shown), a write pole (not shown) for writing to the media, a coil and two waveguides 210′ and 220′. The waveguides 210′ and 220′ are analogous to the waveguides 210 and 220, respectively, as well as the waveguides 140 and 140′. The waveguide 210′ is the output waveguide in the embodiment shown, while the waveguide 220′ is the input waveguide. The waveguide 210′ includes a core 212 and cladding 214. The output waveguide 220′ includes an input core 222 and cladding 224. In the embodiment depicted in FIG. 4 the waveguides 210′ and 220′ are separated by a layer 230, which is analogous to the layer 230 depicted in FIG. 3A.
The waveguides 210′ and 220′ are optically coupled and transfer the polarization from TE to TM. Thus, the aspect ratios of the cores differ in a manner analogous to that described above. The input core 222 has a height h1 and a width w1. The width is larger than the height for the input core 222 (w1>h1). The output core 212 has a height h2 and w width w2. The height is larger than the width for the output core 212 (h2>w2). Thus, the aspect ratios differ. In the embodiment shown, the long axes of the cores 212 and 222 are perpendicular to each other (w1 is perpendicular to h2).
The waveguides 210′ and 220′ may be adiabatically coupled, directionally coupled or coupled in another manner. In addition, the cores 212 and 222 of the waveguides 210′ and 220′ are offset. As can be seen in FIG. 4, the cores 212 and 222 are offset in the width direction such that the right edge of the input waveguide core 222 is aligned with the left edge of the output waveguide core 212. The cores 212 and 222 are offset by the spacer layer 230 in the height direction. In other embodiments, the spacer layer 230 might be omitted. In some such embodiments, the top of the output core 212 may be aligned with the bottom of the input core 222. In such an embodiment, the edges of the cores 212 and 222 (depicted as corners in FIG. 4) may just touch. Different offsets in the height and/or width directions are possible.
The HAMR write apparatus 200′ shares the benefits of the HAMR transducer(s) 100, 100′ and/or 200. Using the input waveguide 220′ and output waveguide 210′, the polarization of the light energy from the laser can be transferred to be in the desired direction. Thus, energy having the desired polarization can be provided to the NFT (not shown in FIG. 4). Thus, performance of the HAMR disk drive 200′ may be improved.
FIG. 5 depicts a cross-sectional view of another exemplary embodiment of a portion of the HAMR write apparatus 200′′. For clarity, FIG. 5 is not to scale. For simplicity not all portions of the HAMR disk drive 200′′ are shown. In addition, although the HAMR write apparatus 200′′ is 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 HAMR write apparatus 200′′ is analogous to the HAMR writers 100, 100′, 200 and/or 200′. Thus, similar components have similar labels as in FIGS. 3A-4. The direction of transmission of light is out of the plane of the page in FIG. 5 (e.g. toward the ABS).
The HAMR write apparatus includes a laser (not shown), an NFT (not shown), a write pole (not shown) for writing to the media, a coil and two waveguides 210′′ and 220′′. The waveguides 210′′ and 220′′ are analogous to the waveguides 210/210′ and 220/220′, respectively, as well as the waveguides 140 and 140′. The waveguide 210′′ is the output waveguide in the embodiment shown, while the waveguide 220′′ is the input waveguide. The waveguide 210′′ includes a core 212 and cladding 214. The output waveguide 220′′ includes an input core 222 and cladding 224. In the embodiment depicted in FIG. 5 the waveguides 210′′ and 220′′ are separated by a layer 230, which is analogous to the layer 230 depicted in FIG. 3A.
The waveguides 210′′ and 220′′ are optically coupled and transfer the polarization from TE to TM. Thus, the aspect ratios of the cores differ in a manner analogous to that described above. The input core 222 has a height h1 and a width w1. The width is larger than the height for the input core 222 (w1>hh1). The output core 212 has a height h2 and w width w2. The height is larger than the width for the output core 212 (h2>w2). Thus, the aspect ratios differ. In the embodiment shown, the long axes of the cores 212 and 222 are perpendicular to each other (w1 is perpendicular to h2).
The waveguides 210′′ and 220′′ may be adiabatically coupled, directionally coupled or coupled in another manner. In addition, the cores 212 and 222 of the waveguides 210′′ and 220′′ are offset. As can be seen in FIG. 5, the cores 212 and 222 are offset in the width and height directions such that there is space between the waveguides 210′′ and 220′′ in both directions. Different offsets in the height and/or width directions are possible.
The HAMR write apparatus 200′′ shares the benefits of the HAMR transducer(s) 100, 100′, 200 and/or 200′. Using the input waveguide 220′′ and output waveguide 210′′, the polarization of the light energy from the laser can be transferred to be in the desired direction. Thus, energy having the desired polarization can be provided to the NFT (not shown in FIG. 5). Thus, performance of the HAMR disk drive 200′′ may be improved.
FIG. 6 depicts a cross-sectional view of another exemplary embodiment of a portion of the HAMR write apparatus 200′′′. For clarity, FIG. 6 is not to scale. For simplicity not all portions of the HAMR disk drive 200′′′ are shown. In addition, although the HAMR write apparatus 200′′′ is 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 HAMR write apparatus 200′′′ is analogous to the HAMR writers 100, 100′, 200, 200′ and/or 200′′. Thus, similar components have similar labels as in FIGS. 3A-5. The direction of transmission of light is out of the plane of the page in FIG. 6 (e.g. toward the ABS).
The HAMR write apparatus includes a laser (not shown), an NFT (not shown), a write pole (not shown) for writing to the media, a coil and two waveguides 210′′′ and 220′′′. The waveguides 210′′′ and 220′′′ are analogous to the waveguides 210/210′/210′′ and 220/220′/220′′, respectively, as well as the waveguides 140 and 140′. The waveguide 210′′′ is the output waveguide in the embodiment shown, while the waveguide 220′′′ is the input waveguide. The waveguide 210′′′ includes a core 212 and cladding 214. The output waveguide 220′′′′ includes an input core 222 and cladding 224. In the embodiment depicted in FIG. 6 the layer 230 depicted in FIGS. 3A-5 is omitted.
The waveguides 210′′′ and 220′′′ are optically coupled and transfer the polarization from TE to TM. Thus, the aspect ratios of the cores differ in a manner analogous to that described above. The input core 222 has a height h1 and a width w1. The width is larger than the height for the input core 222 (w1>hh1). The output core 212 has a height h2 and w width w2. The height is larger than the width for the output core 212 (h2>w2). Thus, the aspect ratios differ. In the embodiment shown, the long axes of the cores 212 and 222 are perpendicular to each other (w1 is perpendicular to h2).
The waveguides 210′′′ and 220′′′ may be adiabatically coupled, directionally coupled or coupled in another manner. In addition, the cores 212 and 222 of the waveguides 210′′′ and 220′′′ are offset. As can be seen in FIG. 6, the cores 212 and 222 are offset in the width and height directions such that the cores 212 and 222 overlap by a distance o in the height direction and have their edges aligned in the width direction. In addition, the spacer layer 230 has been omitted. Different offsets in the height and/or width directions are possible.
The HAMR write apparatus 200′′′ shares the benefits of the HAMR transducer(s) 100, 100′, 200, 200′ and/or 200′′. Using the input waveguide 220′′′′ and output waveguide 210′′′, the polarization of the light energy from the laser can be transferred to be in the desired direction. Thus, energy having the desired polarization can be provided to the NFT (not shown in FIG. 6). Thus, performance of the HAMR disk drive 200′′′ may be improved.
FIG. 7 depicts a side view of another exemplary embodiment of a portion of the HAMR write apparatus 200′′′′. For clarity, FIG. 7 is not to scale. For simplicity not all portions of the HAMR disk drive 200′′′′ are shown. In addition, although the HAMR write apparatus 200′′′′′ is 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 HAMR write apparatus 200′′′′ is analogous to the HAMR writers 100, 100′, 200, 200′, 200′′ and/or 200′′′. Thus, similar components have similar labels as in FIGS. 3A-6. The direction of transmission of light is in the direction of the TE Mode and TM Mode arrows in FIG. 7.
The HAMR write apparatus includes a laser (not shown), an NFT (not shown), a write pole (not shown) for writing to the media, a coil and two waveguides 210′′′′ and 220′′′′. The waveguides 210′′′′ and 220′′′′ are analogous to the waveguides 210/210′/210′′/210′′′ and 220/220′/220′′/220′′′, respectively, as well as the waveguides 140 and 140′. The waveguide 210′′′′ is the output waveguide in the embodiment shown, while the waveguide 220′′′′ is the input waveguide. The waveguide 210′′′′ includes a core 212′ and cladding 214. The output waveguide 220′′′′ includes an input core 222′ and cladding 224. In the embodiment depicted in FIG. 7 the layer 230 depicted in FIGS. 3A-5 is not shown. The layer 230 might be omitted or might be included.
The waveguides 210′′′′ and 220′′′′ are optically coupled and transfer the polarization from TE to TM. Thus, the aspect ratios of the cores differ in a manner analogous to that described above. The waveguides 210′′′ and 220′′′ are adiabatically coupled in the embodiment shown in FIG. 7. Thus, the core 222′ of the input waveguide 220′′′′ terminates after the coupling region having length cl′. Similarly, the output waveguide 210′′′′ starts just before the coupling region. In the embodiment shown, the waveguides 210′′′′ and 220′′′′ taper near the ends shown. However, in other embodiments, the waveguides 210′′′′ and/or 220′′′′ may terminate in another manner.
The HAMR write apparatus 200′′′′ shares the benefits of the HAMR transducer(s) 100, 100′, 200, 200′, 200′′ and/or 200′′′. Using the input waveguide 220′′′′ and output waveguide 210′′′′, the polarization of the light energy from the laser can be transferred to be in the desired direction. Further, use of adiabatic coupling allows reduces the need for phase matching between the waveguides 210′′′′ and 220′′′′. In addition, the waveguides 210′′′′ and 220′′′′ may be easier to fabricate because tolerances for the waveguides 210′′′ and 220′′′′ may be relaxed. Thus, energy having the desired polarization can be provided to the NFT (not shown in FIG. 7). Thus, performance of the HAMR disk drive 200′′′′ may be improved.
FIG. 8 depicts a side view of another exemplary embodiment of a portion of the HAMR write apparatus 200′′′′′. For clarity, FIG. 8 is not to scale. For simplicity not all portions of the HAMR disk drive 200′′′′′ are shown. In addition, although the HAMR write apparatus 200′′′′′′ is 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 HAMR write apparatus 200′′′′′ is analogous to the HAMR writers 100, 100′, 200, 200′, 200′′, 200′′′′ and/or 200′′′′. Thus, similar components have similar labels as in FIGS. 3A-7. The direction of transmission of light is in the direction of the TE Mode and TM Mode arrows in FIG. 8.
The HAMR write apparatus includes a laser (not shown), an NFT (not shown), a write pole (not shown) for writing to the media, a coil and two waveguides 210′′′′ and 220′′′′′. The waveguides 210′′′′′ and 220′′′′′ are analogous to the waveguides 210/210′/210′′/210′′′/210′′′′ and 220/220′/220′′/220′′′/220′′′′, respectively, as well as the waveguides 140 and 140′. The waveguide 210′′′′′ is the output waveguide in the embodiment shown, while the waveguide 220′′′′′ is the input waveguide. The waveguide 210′′′′′ includes a core 212′′ and cladding 214. The output waveguide 220′′′′′ includes an input core 222′′ and cladding 224. In the embodiment depicted in FIG. 8 the layer 230 depicted in FIGS. 3A-5 is not shown. The layer 230 might be omitted or might be included.
The waveguides 210′′′′′ and 220′′′′′ are optically coupled and transfer the polarization from TE to TM. Thus, the aspect ratios of the cores differ in a manner analogous to that described above. The core 222′′ of the input waveguide 220′′′′′ does not terminates after the coupling region having length cl′. However, the output waveguide 210′′′′′ starts just before the coupling region. In an alternate embodiment, the input waveguide 220′′′′′ might terminate after the coupling region while the output waveguide 210′′′′ does not. Thus, the embodiment shown in FIG. 8 may be considered a combination of the transducer 200 and 200′′′′. In the embodiment shown, the waveguide 220′′′′′ tapers near the end shown. However, in other embodiments, the waveguide 220′′′′′ may terminate in another manner.
The HAMR write apparatus 200′′′′′ shares the benefits of the HAMR transducer(s) 100, 100′, 200, 200′, 200′′, 200′′′ and/or 200′′′′. Using the input waveguide 220′′′′′ and output waveguide 210′′′′′, the polarization of the light energy from the laser can be transferred to be in the desired direction. Thus, energy having the desired polarization can be provided to the NFT (not shown in FIG. 8). Thus, performance of the HAMR disk drive 200′′′′′ may be improved.
It is noted that various configurations of waveguides 140, 140′, 210/220, 210′/220′, 210′′/220′′, 210′′′/220′′′, 210′′′′/220′′′′ and 210′′′′′/220′′′′′ are highlighted in FIGS. 3A-8. However, various characteristics of the waveguides 140, 140′, 210/220, 210′/220′, 210′′/220′′, 210′′′/220′′′, 210′′′′/220′′′′ and/or 210′′′′′/220′′′′′ may be combined in a manner not inconsistent with the discussion herein.
FIG. 9 is a flow chart depicting an exemplary embodiment of a method 300 for fabricating a HAMR write apparatus. The method 300 may be used in fabricating disk drives such as the disk drives 100, 100′, 200, 200′, 200′′, 200′′′, 200′′′′ and/or 200′′′′′, though other transducers might be so fabricated. For clarity, the method 300 is described in the context of the writers 100 and 100′ depicted in FIGS. 1 and 2. For simplicity, some steps may be omitted, performed in another order, interleaved and/or combined. The HAMR writers being fabricated may include a writer and a read transducer (not shown) and resides on a slider. For simplicity, however, the reader is not discussed. The method 300 is also described in the context of forming a transducer. However, the method 300 may be used to fabricate multiple transducer(s) at substantially the same time. The method 300 and system are also described in the context of particular layers. However, in some embodiments, such layers may include multiple sub-layers. The method 300 also may commence after formation of other portions of the disk drive.
A main pole 150 is provided. Step 150 may include multiple substeps such as forming a trench for the main pole in a layer, plating the high saturation magnetization material(s) for the main pole and planarizing these materials.
At least one coil 155 for energizing the main pole is provided, via step 304. Step 304 generally includes multiple deposition and removal steps to form the coil. The coil 155 may be a spiral coil, a toroidal coil or have another shape.
The waveguides 140/140′ are also provided, via step 306. The waveguides 140/140′ include an input waveguide such as the waveguide 142 and an output waveguide 144. The waveguides 140/140′ provided in step 306 receive energy from the laser 172 and for direct the energy toward the ABS. The waveguides 140/140′ are optically coupled and configured to transfer the polarization of the energy from the input polarization state to the output polarization state. For example, the waveguides may be configured to transfer the energy from a TE mode to a TM mode.
Using the method 300, the HAMR devices 100, 100′, 200, 200′, 200′′, 200′′′, 200′′′′ and/or 200′′′′′ may be fabricated. The benefit(s) of one or more of the HAMR writer(s) 100, 100′, 200, 200′, 200′′, 200′′′, 200′′′′ and/or 200′′′′′ may thus be achieved.
FIG. 10 is a flow chart depicting an exemplary embodiment of a method 310 for fabricating a portion of a HAMR writer. For example, the method 310 may primarily be used in forming the waveguides 140, 140′, 210/220, 210′/220′, 210′′/220′′, 210′′′/220′′′, 210′′′′/220′′′′ and/or 210′′′′′/220′′′′′. However, other waveguides might be fabricated. For clarity, the method 310 is described in the context of the writer 100′ depicted in FIG. 2. For simplicity, some steps may be omitted, performed in another order, interleaved and/or combined. The HAMR writers being fabricated may include a writer and a read transducer (not shown) and resides on a slider. For simplicity, however, the reader is not discussed. The method 310 is also described in the context of forming a transducer. However, the method 310 may be used to fabricate multiple transducer(s) at substantially the same time. The method 310 and system are also described in the context of particular layers. However, in some embodiments, such layers may include multiple sub-layers. The method 310 also may commence after formation of other portions of the disk drive.
The input waveguide 142 configured for TE light is provided, via step 312. Step 312 typically includes forming a core having the appropriate geometry and substantially surrounding the core with cladding.
The output waveguide 144 is provided, via step 314. The output waveguide configured such that it is optically coupled with the input waveguide 142 and so that the light carried by the output waveguide 144 has a TM polarization.
Using the method 310, the waveguides for the HAMR devices 100, 100′, 200, 200′, 200′′, 200′′′, 200′′′′ and/or 200′′′′′ may be fabricated. The benefit(s) of one or more of the HAMR writer(s) 100, 100′, 200, 200′, 200′′, 200′′′, 200′′′′ and/or 200′′′′′ may thus be achieved.
FIG. 11 is a flow chart depicting an exemplary embodiment of a method 320 for fabricating a portion of a HAMR writer. For example, the method 320 may primarily be used in forming the waveguides 140, 140′, 210/220, 210′/220′, 210′′/220′′, 210′′′/220′′′, 210′′′′/220′′′′ and/or 210′′′′′/220′′′′′. However, other waveguides might be fabricated. FIGS. 12-17 depict a portion of a HAMR write apparatus 350 during fabrication of the waveguides using the method 320. FIGS. 12-17 are not to scale and not all components of the writer 350 are shown. For simplicity, some steps may be omitted, performed in another order, interleaved and/or combined. The HAMR writers being fabricated may include a writer and a read transducer (not shown) and resides on a slider. However, the reader is not discussed. The method 320 is also described in the context of forming a single transducer. However, the method 320 may be used to fabricate multiple transducer(s) at substantially the same time. The method 320 and system are also described in the context of particular layers. However, in some embodiments, such layers may include multiple sub-layers. The method 320 also may commence after formation of other portions of the disk drive.
The core of the lower waveguide (closer to the underlying substrate) is provided, via step 322. Step 322 may include depositing a material having the desired index of refraction, such as tantalum oxide. The regions desired to form the core are then covered in a mask and the exposed regions removed. FIG. 12 depicts a cross-sectional view of the writer 350 after step 322 is performed. Thus, the core 362 of the lower waveguide 360 is formed on the underlying cladding. Note that this lower waveguide 360 could be the input waveguide, the output waveguide or another waveguide (if any) between the input and output waveguides.
A layer of cladding for the lower waveguide is provided, via step 324. Step 324 may include blanket depositing a cladding material, such as silicon oxide, then planarizing the material. FIGS. 13-14 depict the writer 350 during and after step 324. The cladding layer 364 is shown as being deposited in FIG. 13. Thus, the cladding 364 covers the lower core 362. FIG. 14 depicts the transducer 350 after the device has been planarized. Thus, the top surfaces of the core 362 and cladding 364 are substantially flat.
An etch stop layer is optionally deposited, via step 326. The etch stop layer is resistant to removal by an etch that removes the upper core and/or upper cladding. For example, an aluminum oxide layer that is nominally twenty nanometers thick may be provided in step 326. FIG. 15 depicts the writer 350 after step 326 is performed. Thus, the stop layer 370 is shown. In other embodiments, step 326, and thus the etch stop layer 370, may be omitted.
The core of the upper waveguide (further from the underlying substrate) is provided, via step 328. Step 328 may include depositing a material having the desired index of refraction, such as tantalum oxide. The regions desired to form the core are then covered in a mask and the exposed regions removed. The etch stop layer 370 may prevent damage to the underlying core 362 during formation of the core. FIG. 16 depicts a cross-sectional view of the writer 350 after step 326 is performed. Thus, the core 382 of the upper waveguide 380 is formed on the cladding 364 and core 362. Note that this upper waveguide 380 could be the input waveguide, the output waveguide or another waveguide (if any) between the input and output waveguides. In addition, particular offsets between the lower core 362 and upper core 382 are shown in FIGS. 16-17. In other embodiments, different offsets may be used.
A layer of cladding for the upper waveguide 380 is provided, via step 330. Step 330 may include blanket depositing a cladding material, such as silicon oxide, then planarizing the material. FIG. 17 depict the writer 350 after step 330. The cladding layer 384 for the upper waveguide 380 is shown. Thus, the cladding 384 covers the upper core 382 and etch stop layer 370.
Using the method 320, the HAMR writer 350 may be fabricated. The writer 350 is analogous to the writers 100, 100′, 200, 200′, 200′′, 200′′′, 200′′′, and/or 200′′′′. Performance and/or reliability of the disk drive 350 may thus be improved in a manner analogous to the HAMR disk drives 100, 100′, 200, 200′, 200′′, 200′′′, 200′′′′ and/or 200′′′′′.

## Claims

1. A heat assisted magnetic recording (HAMR) write apparatus coupled with a laser for providing energy having a first polarization state, the HAMR write apparatus including an air-bearing surface (ABS) configured to reside in proximity to a media during use and comprising:
a main pole;
at least one coil for energizing the main pole; and
a plurality of waveguides for receiving the energy from the laser and for directing the energy toward the ABS, the plurality of waveguides including an input waveguide and an output waveguide, the input waveguide configured to carry light having the first polarization state, the output waveguide configured to carry light having a second polarization state different from the first polarization state, the plurality of waveguides being optically coupled and configured to transfer the energy from the first polarization state to the second polarization state, the input waveguide having an input long axis and an input short axis in a first plane perpendicular to a first direction of energy propagation in the input waveguide, the output waveguide having an output long axis and an output short axis in a second plane perpendicular to a second direction of energy propagation in the output waveguide, the input long axis being substantially perpendicular to the output long axis.

2. The HAMR write apparatus of claim 1 further comprising:
a near-field transducer (NFT) proximate to the ABS for focusing the energy onto a region of the media, the NFT being optically coupled with the output waveguide and receiving the energy having the second polarization state.

3. The HAMR write apparatus of claim 2 wherein the plurality of waveguides consists of the input waveguide and the output waveguide coupled with the input waveguide.

4. The HAMR write apparatus of claim 3 wherein the plurality of waveguides include at least one of a plurality of directionally coupled waveguides and a plurality of adiabatically coupled waveguides.

5. The HAMR write apparatus of claim 1 wherein the input waveguide and the output waveguide are offset in a direction perpendicular to the first direction and the second direction in a coupling region for the input waveguide and the output waveguide.

6. The HAMR write apparatus of claim 5 wherein the input waveguide and the output waveguide are offset by not more than the input long axis.

7. The HAMR write apparatus of claim 5 wherein the input waveguide and the output waveguide are offset by not more than the output short axis.

8. The HAMR write apparatus of claim 5 wherein the coupling region has a coupling length in the direction of transmission and wherein the first direction of propagation and the second direction of propagation are equal in the coupling region.

9. The HAMR write apparatus of claim 8 wherein at least one of the input waveguide and the output waveguide tapers along the coupling length such that the at least one of the input waveguide terminates at a first end of the coupling length and the output waveguide terminates at a second end of the coupling length opposite to the first end.

10. A heat assisted magnetic recording (HAMR) disk drive comprising:
a media;
a laser for providing energy having a first polarization state;
a slider having an air-bearing surface (ABS) and a HAMR write transducer, the HAMR write transducer including a main pole, at least one coil for energizing the main pole and a plurality of waveguides, the plurality of waveguides receiving the energy from the laser and directing the energy toward the ABS, the plurality of waveguides including an input waveguide and an output waveguide, the input waveguide configured to carry light from the laser having the first polarization state, the output waveguide configured to carry light having a second polarization state different from the first polarization state, the plurality of waveguides being optically coupled and configured to transfer the energy from the first polarization state to the second polarization state, the input waveguide having an input long axis and an input short axis in a first plane perpendicular to a first direction of energy propagation in the input waveguide, the output waveguide having an output long axis and an output short axis in a second plane perpendicular to a second direction of energy propagation in the output waveguide, the input long axis being substantially perpendicular to the output long axis.

11. The HAMR disk drive of claim 10 wherein the HAMR write transducer further includes:
a near-field transducer (NFT) proximate to the ABS and for focusing the energy onto a region of the media, the NFT being optically coupled with the output waveguide and receiving energy having the second polarization state.

12. The HAMR disk drive of claim 11 wherein the plurality of waveguides consists of the input waveguide and the output waveguide coupled with the input waveguide, wherein the input waveguide and the output waveguide are offset in a direction perpendicular to the first direction and the second direction in a coupling region for the input waveguide and the output waveguide.

13. A method for fabricating a heat assisted magnetic recording (HAMR) write apparatus coupled with a laser for providing energy having a first polarization state, the HAMR write apparatus including an air-bearing surface (ABS) configured to reside in proximity to a media during use, the method comprising:
providing a main pole;
providing at least one coil for energizing the main pole; and
providing a plurality of waveguides for receiving the energy from the laser and for directing the energy toward the ABS, the plurality of waveguides including an input waveguide and an output waveguide, the input waveguide configured to carry light having the first polarization state, the output waveguide configured to carry light having a second polarization state different from the first polarization state, the plurality of waveguides being optically coupled and configured to transfer the energy from the first polarization state to the second polarization state, the input waveguide having an input long axis and an input short axis in a first plane perpendicular to a first direction of energy propagation in the input waveguide, the output waveguide having an output long axis and an output short axis in a second plane perpendicular to a second direction of energy propagation in the output waveguide, the input long axis being substantially perpendicular to the output long axis.

14. The method of claim 13 further comprising:
providing a near-field transducer (NFT) proximate to the ABS and for focusing the energy onto a region of the media, the NFT being optically coupled with the output waveguide and receiving energy having the second polarization state.

15. The method of claim 13 wherein the input waveguide and the output waveguide are offset in a direction perpendicular to the first direction and the second direction in a coupling region for the input waveguide and the output waveguide.

16. The method of claim 15 wherein the step of providing the plurality of waveguides includes at least one of providing a plurality of directionally coupled waveguides and providing a plurality of adiabatically coupled waveguides.

17. A heat assisted magnetic recording (HAMR) write apparatus coupled with a laser for providing energy having a first polarization state, the HAMR write apparatus including an air-bearing surface (ABS) configured to reside in proximity to a media during use and comprising:
a main pole;
at least one coil for energizing the main pole; and
a plurality of waveguides for receiving the energy from the laser and for directing the energy toward the ABS, the plurality of waveguides including an input waveguide and an output waveguide, the input waveguide configured to carry light having the first polarization state, the output waveguide configured to carry light having a second polarization state different from the first polarization state, the plurality of waveguides being optically coupled and configured to transfer the energy from the first polarization state to the second polarization state, the input waveguide having an input long axis and an input short axis in a first plane perpendicular to a first direction of energy propagation in the input waveguide, the output waveguide having an output long axis and an output short axis in a second plane perpendicular to a second direction of energy propagation in the output waveguide, the input long axis being substantially perpendicular to the output long axis, the input waveguide and the output waveguide being offset in a direction perpendicular to the first direction and the second direction in a coupling region for the input waveguide and the output waveguide;
wherein the input waveguide and the output waveguide are separated by an etch stop layer.

18. A method for fabricating a heat assisted magnetic recording (HAMR) write apparatus coupled with a laser for providing energy having a first polarization state, the HAMR write apparatus including an air-bearing surface (ABS) configured to reside in proximity to a media during use, the method comprising:
providing a main pole;
providing at least one coil for energizing the main pole; and
providing a plurality of waveguides for receiving the energy from the laser and for directing the energy toward the ABS, the plurality of waveguides including an input waveguide and an output waveguide, the input waveguide configured to carry light having the first polarization state, the output waveguide configured to carry light having a second polarization state different from the first polarization state, the plurality of waveguides being optically coupled and configured to transfer the energy from the first polarization state to the second polarization state, the input waveguide having an input long axis and an input short axis in a first plane perpendicular to a first direction of energy propagation in the input waveguide, the output waveguide having an output long axis and an output short axis in a second plane perpendicular to a second direction of energy propagation in the output waveguide, the input long axis being substantially perpendicular to the output long axis, the input waveguide and the output waveguide being offset in a direction perpendicular to the first direction and the second direction in a coupling region for the input waveguide and the output waveguide, wherein the step of providing the plurality of waveguides further includes:
providing an output waveguide core for the output waveguide;
providing cladding surrounding at least a portion of the output waveguide core;
depositing an etch stop layer on at least the output waveguide core;
depositing an input waveguide core layer for the input waveguide;
removing an extraneous portion of the input waveguide core layer, an input waveguide core for the input waveguide including a remaining portion of the input waveguide core layer; and
depositing an additional cladding layer covering at least the input waveguide core.

19. A method for fabricating a heat assisted magnetic recording (HAMR) write apparatus coupled with a laser for providing energy having a first polarization state, the HAMR write apparatus including an air-bearing surface (ABS) configured to reside in proximity to a media during use, the method comprising:
providing a main pole;
providing at least one coil for energizing the main pole; and
providing a plurality of waveguides for receiving the energy from the laser and for directing the energy toward the ABS, the plurality of waveguides including an input waveguide and an output waveguide, the input waveguide configured to carry light having the first polarization state, the output waveguide configured to carry light having a second polarization state different from the first polarization state, the plurality of waveguides being optically coupled and configured to transfer the energy from the first polarization state to the second polarization state, the input waveguide having an input long axis and an input short axis in a first plane perpendicular to a first direction of energy propagation in the input waveguide, the output waveguide having an output long axis and an output short axis in a second plane perpendicular to a second direction of energy propagation in the output waveguide, the input long axis being substantially perpendicular to the output long axis, the input waveguide and the output waveguide being offset in a direction perpendicular to the first direction and the second direction in a coupling region for the input waveguide and the output waveguide, wherein the step of providing the plurality of waveguides further includes:
providing an input waveguide core for the input waveguide;
providing cladding surrounding at least a portion of the input waveguide core;
depositing an etch stop layer on at least the input waveguide core;
depositing an output waveguide core layer for the output waveguide;
removing an extraneous portion of the output waveguide core layer, an output waveguide core for the output waveguide including a remaining portion of output waveguide core layer; and
depositing an additional cladding layer covering at least the output waveguide core.