Detailed Description
In some designs, a light detector may be placed for sampling light from the back of the light source. However, such configurations typically use a base that is substantially larger than the size of the light source in order to place the light detector behind the light source. Such large size EAMR assemblies are generally undesirable in view of the mechanical and flight capability requirements of the Head Gimbal Assembly (HGA) in a particular EAMR application. Further, light from the back of the light source is not always well correlated with light from the front of the light source, especially if there is any optical feedback to the front of the light source.
Referring now to the drawings, embodiments of a system and method for monitoring energy of a light source (e.g., a laser) used in Energy Assisted Magnetic Recording (EAMR) are shown that address the above-referenced problems and those mentioned in the background section. The system includes an Energy Assisted Magnetic Recording (EAMR) head including a light source mounted on a base attached to a top surface of a slider. A light detector is attached to or integrated in the base for monitoring the energy of the light beam emitted by the light source by sampling a portion of the light beam after passing through the waveguide in the slide.
In several embodiments, the waveguide is adaptively configured to receive a light beam from the top surface of the slider and route the light beam to near a write pole located at or near the ABS of the slider where the light beam can be used to heat a spot on a recording medium disk near the ABS. The waveguide may also route a portion of the light beam back to the top surface of the slider where the light exits the waveguide and is detected by a light detector positioned above the waveguide to capture at least a portion of the light from the waveguide. Thus, the light source utilizes a novel arrangement of waveguides, light sources and light detectors to provide a portion of the light beam monitored by the light detectors and a portion of the light used to heat the media disk, as will be described in greater detail in various non-limiting embodiments of the present disclosure.
FIGS. 1A and 1B are perspective and side views, respectively, of an EAMR assembly 100 configured to monitor the output energy of a light source using a light detector in accordance with an embodiment of the present invention. Referring to fig. 1A, the EAMR assembly 100 includes a light source 102 (e.g., a laser diode), the light source 102 attached to a first surface of a base 104 mounted on a top surface (or top side) of a slide 106. The top surface is opposite the ABS of slider 106. In one embodiment, the light source 102 has a rectangular shape and includes a laser diode for outputting a beam of light to the lower slide 106. In one embodiment, the base 104 has a rectangular shape and the light detector 108 is integrated along a first surface of the base 104. Here, the light source 102 and the light detector 108 are spaced apart on the first surface and have a length extending in a height direction of the pedestal 104 (e.g., in a Y direction perpendicular to the ABS in fig. 1A).
In one embodiment, the light detector 108 is attached to a first surface of the base 104. In one embodiment, the base 104 and the light source 102 are about the same size. In another embodiment, the base 104 is slightly higher than the light source 102 in the height direction perpendicular to the ABS. In one embodiment, the base 104 may be about 380 microns tall and the light source 102 may be about 350 microns tall. In one embodiment, the light detector 108 includes a photodiode, such as an in-plane photodiode or a discrete photodiode. The light detector 108 may be attached to the surface of the base 104 or integrally formed along the surface of the base 104.
The slide 106 may include one or more pads (not shown) on the top surface that are configured to attach to and be welded to pads (not shown) on the bottom surface of the base 104. The base 104 may include one or more pads (not shown) on the first surface that are configured to attach to and be soldered to pads (not shown) on the back of the light source 102.
In one embodiment, the light source 102 has a thickness (e.g., a dimension along the Z-direction) of about 100 microns, a height (e.g., a dimension along the Y-direction) of about 350 microns, and a width (e.g., a dimension along the X-direction) of about 130 microns. In other embodiments, the light source 102 may have other suitable dimensions. In one embodiment, light source 102 includes a laser that provides approximately 50 milliwatts of energy. In other embodiments, the light source 102 may provide greater than or less than 50 milliwatts. In one embodiment, the light source 102 has a wavelength of approximately 830 nm. The bottom surface of the light source 102 is on the top surface of the slider 106. In one embodiment, the bottom surface of the light source 102 substantially overlaps the top surface of the slider 106 (see fig. 1B).
In one embodiment, the base 104 has a thickness (e.g., dimension along the Z-direction) of about 200 microns, a height (e.g., dimension along the Y-direction) of about 380 microns, and a width (e.g., dimension along the X-direction) of about 500 microns. In other embodiments, the base 104 may have other suitable dimensions.
In one embodiment, the slider 106 has a thickness (e.g., dimension along the Y-direction) of about 180 microns, a length (e.g., dimension along the Z-direction) of about 1235 microns, and a width (e.g., dimension along the X-direction) of about 700 microns. In other embodiments, the slide 106 may have other suitable dimensions.
The EAMR assembly 100 further includes a waveguide 110 that is mounted in the slider 106 and positioned in such a way as to receive a light beam 112 from the light source 102 at an input end 110a and direct a first portion of the light beam to an NFT portion 110b positioned near an Air Bearing Surface (ABS) of the slider 106 and a second portion of the light beam away from the slider 106 at an output end 110c toward the light detector 108. In operation, the light source 102 can be activated to generate a light beam 112 that is directed by the first arm 110d of the waveguide to the NFT portion 110B of the slider 106 near the ABS where the energy of the light beam 112 can be transmitted to a recording media disk 114 (shown in FIG. 1B) below the ABS and proximate the ABS.
In more detail, the first arm 110d receives the light beam 112 from the light source 102 and routes the light beam to the NFT portion 110b near a primary write pole (not shown) at or near the ABS where some of the energy of the light beam can be transferred to the media disk 114 located below the slider 106. The area of the media disk 114 that receives the light is heated by the optical energy applied by the EAMR. In some examples, the slider 106 may include a near field transducer (not shown) that may focus the optical energy to a spot on the media disk 114. The waveguide 110 also has a second arm 110e that is optically coupled to the first arm 110 d. The second arm 110e receives a second portion of the light beam from the first arm 110d and routes this portion of the light beam to the exit end 110c where the light exits the second arm 110e in a direction toward the light detector 108. Thus, the light detector 108 may capture at least a portion of the divergent light exiting from above the slider 106. Unlike the EAMR assemblies of the related art, the EAMR assembly 100 is configured such that the light sampled or captured by the light detector 108 and the light (or energy) transmitted to the media disk are both from the same output of the light source 102. Here, light enters and exits the waveguide 110 in substantially opposite directions on the same side of the slider 106 (e.g., the top side opposite the ABS).
Referring to fig. 1B, the first portion of the beam has a diverging shape 116 after exiting the second arm 110B. That is, the width of the light beam gradually increases in the direction of light propagation toward the light detector 108, the light detector 108 being arranged along the first surface of the base 104. Thus, at least some of the light may be received or captured by the light detection 108. Although a photodiode is used as one example of the light detector 108, the present invention is not limited thereto. Other suitable light detectors that may be used with the base 104 may also be used. In the embodiment of fig. 1B, the rectangular shaped light source 102 is mounted such that its output emanates from the furthest away from the base (e.g., in a "connection up" configuration). In some embodiments, the light source 102 has a configuration in which the light source is mounted such that its output emanates from a side attached to or immediately adjacent the base (e.g., in a "down connection" configuration). FIG. 2 is a side view of an EAMR assembly configured to monitor the output energy of a light source 102' using a light detector 108 in a "down-link" configuration in accordance with an embodiment of the present invention. However, in other embodiments, the output of the light source 102 may be placed in other suitable locations.
In one embodiment, the pedestal 104 is made of silicon, aluminum nitride, or other suitable material. In one embodiment, light source 102 includes a laser made of gallium arsenide and/or other suitable materials, such as aluminum or indium.
FIG. 1C is a side view of a submount 104 with metal lines (trace) (104-PD +, 104-LD-, 104-PD-) for connecting a light source 102 and a light detector 108 according to an embodiment of the invention. Referring to FIG. 1C, electrical connection points or pads (104-LD + and 104-LD-) are provided for electrically connecting the light source 102 to other circuitry (not shown). For example, a power supply may be connected to connection points 104-LD + and 104-LD-to apply the appropriate drive voltage to light source 102. Electrical connection points or pads (104-PD + and 104-PD-) are provided for electrically connecting the light detector 108 to other circuitry (not shown). For example, the connection points (104-PD + and 104-PD-) may be connected to input buffers, signal conditioners, signal amplifiers, or other suitable circuitry. In some embodiments, soldering using solder-sprayed balls may be used to protect the electrical connections.
FIGS. 3A and 3B are perspective and side views, respectively, of an EAMR assembly 200 configured to monitor the output energy of a light source using a light detector in accordance with an embodiment of the present invention. The EAMR assembly 200 is substantially similar to the EAMR assembly 100 and redundant description of embodiments may be omitted for brevity. Referring to fig. 3A, the EAMR assembly 200 includes a light source 202 (e.g., a laser diode) attached to a first surface of a base 204 mounted on a top surface (or side surface) of a slider 206. The top surface is opposite the ABS of slider 206. In one embodiment, light source 202 includes a laser diode for outputting a beam of light below slide 206. In one embodiment, the base 204 has a light detector 208 integrated along a first surface of the base 204. Here, the light source 202 and the light detector 208 are spaced apart on the first surface and have a length extending in a height direction of the base 204 (e.g., in the Y direction perpendicular to the ABS of fig. 3A).
In one embodiment, the light detector 208 comprises a photodiode, such as an in-plane photodiode or a discrete photodiode. The light detector 208 may be attached to a surface of the base 204 or integrally formed along the surface of the base 204.
The EAMR assembly 200 also includes a double-tap waveguide 300 in the slider 206. The waveguide 300 comprises a first arm 300a for receiving light from the light source 202 at a first end 302 or input port. A suitable input device (e.g., a grating or coupling lens) may be used to couple incident light into the waveguide 300. The waveguide 300 further includes a second arm 300b and a third arm 300c optically coupled to the first arm 300 a. The first arm 300a branches into two coupling waveguides 304. In one embodiment, the second and third arms 300b, 300c are adjacent to or spaced apart from the coupling waveguide 304 to enable light coupling between the first, second, and third arms 300a, 300b, 300c to a preselected degree. Waveguide 300 may be formed of a dielectric oxide layer, an organic material, glass, or other suitable material.
Waveguide 300 guides a portion of the received light to NFT end 300c disposed near the ABS of slider 206. A first portion of the light may be transmitted at end 300c to the recording media disk 214 disposed near the ABS of the slider (see fig. 3B). A second portion of the light received by the first arm 300a is transmitted to the second arm 300b and exits the second arm 300b at the end 306 toward the light detector 208. A third portion of the light received by the first arm 300a is transmitted to the third arm 300c and exits the waveguide at the end 308 or output port. The waveguide 300 may include a suitable output device (e.g., a grating or coupling lens) at the end 308 of the third arm 300 c. In one embodiment, a third portion of the light exits from the trailing edge surface 222 of the slider 206 and may be monitored by another light detector (not shown) in a device used during testing or manufacturing of the EMAR assembly 200.
Referring to fig. 3B, the first portion of the beam has a diverging shape 216 after exiting the second arm 300B. That is, the width of the light beam gradually increases in the direction of light propagation towards the light detector 208, the light detector 208 being arranged along the first surface of the base 204. Thus, at least some of the light may be received or captured by the light detector 208. In one embodiment, the light detector 208 may comprise a photodiode, although the invention is not limited in this respect. Other suitable light detectors that may be used with the base 204 may also be used. In the embodiment of fig. 3B, the rectangular shaped light source 202 is mounted such that its output emanates from the farthest from the base 204 (e.g., in an "connection up" configuration). In some embodiments, the light source 202 has a configuration in which the light source is mounted such that its output emanates from a side attached to or proximate to the base 204 (e.g., in the "down connection" configuration of fig. 2). However, in other embodiments, the output of the light source 202 may be placed in other appropriate locations.
Fig. 4 is a flow diagram of a process 400 of assembling an EAMR assembly (e.g., EAMR assemblies 100 and 200) configured to monitor the output energy of a light source using a light detector, a base, and a waveguide in a slider, according to an embodiment of the invention. The process provides (402) a slider (e.g., slider 106, 206) including a waveguide (e.g., waveguides 110 and 300). The process attaches 404 a light source (e.g., light source 102, 202) to a first base side of a base (e.g., base 104, 204). Here, the light source is configured to transmit light to the waveguide. Electronic pads may be provided on opposite sides of the light source and the base for attaching the light source to the base. In some embodiments, the light source and the base may be attached by welding or other suitable means known in the art.
The process attaches (406) the base to the slide after the light source is attached to the base. Electronic pads may be provided on opposite faces of the base and the slider for attaching the base to the slider. In some embodiments, the base and slider may be attached together by welding or other suitable means known in the art. The base includes a suitable light detector (e.g., light detectors 108, 208) positioned along a first base side of the base and spaced apart from the slide. The light detector is configured to receive a first portion of the light transmitted to the waveguide. In this embodiment, light enters and exits the waveguide on the same side or surface of the slider. Light enters and exits the waveguide in opposite directions. In one embodiment, the base and the light source have the same height in a direction perpendicular to the ABS. In one embodiment, the light source and the light detector extend side by side in the height direction of the base.
In one embodiment, the process may perform the sequence of operations in a different order. In another embodiment, the process may skip one or more operations. In other embodiments, one or more operations may be performed concurrently. In some embodiments, additional operations may be performed.
In one embodiment, the present invention relates to a head gimbal assembly. FIG. 5 illustrates a disk drive 500 including a Head Gimbal Assembly (HGA)508, the Head Gimbal Assembly (HGA)508 configured to monitor an output energy of a light source using a light detector, according to an embodiment of the present invention. The disk drive 500 may include one or more disks 502 to store data. The disks 502 reside on a spindle assembly 504 mounted to a drive housing 506. Data may be stored along tracks in the magnetic recording layer of the magnetic disk 502. HGA508 includes a suspension assembly 510 and an Energy Assisted Magnetic Recording (EAMR) assembly 512 (e.g., EAMRs 100, 200).
Disk drive 500 also includes a spindle motor (not shown) that rotates spindle assembly 504 and disks 502 to position EAMR assembly 512 at specific locations along desired disk tracks. The position of EAMR assembly 512 relative to disk 502 may be controlled by position control circuit 514. Components of disk drive 500 are well known in the art and are not necessary to an understanding of the present invention and may be omitted for the sake of brevity.
Fig. 6-9 are diagrams conceptually illustrating various waveguide designs, according to embodiments of the present invention. In certain embodiments, these waveguides may be used as waveguides in the slides 106 and 206. Fig. 6 illustrates a single tap waveguide 600 for an EAMR assembly according to an embodiment of the present invention. The waveguide 600 includes a first arm 600a and a second arm 600b optically coupled to the first arm 600 a. In certain embodiments, the first arm 600a may be coupled to the second arm 600b by a third arm (not shown). The waveguide 600 may comprise a suitable input device (e.g. a grating) at the first end 602 or input port of the first arm 600a for coupling light into the first arm 600 a. In other embodiments, other suitable optical structures (e.g., coupling lenses) may be used to couple light into the waveguide 600. Waveguide 600 may be formed from dielectric oxides, organic materials, glass, or other suitable materials. The waveguide 600 also includes an NFT end 600c that is positioned near the ABS of the slider (e.g., sliders 106, 206). A first portion of the light received by the first arm 600a can be transmitted at the home end 600c to a recording media disk (e.g., recording media disks 114, 214) positioned near the ABS of a slider having such a waveguide. A second portion of the light received by the first arm 600a is transmitted to the second arm 600 b. A second portion of the light is directed by the second arm 600b to the second end 604 or an output port thereof. In certain embodiments, the waveguide 600 may include an output device (e.g., a grating or coupling lens) at the second end 604. The waveguide 600 may be formed of an organic material, glass, or other suitable material.
Fig. 7 is a diagram conceptually illustrating a dual tap coupled waveguide 700 for an EMAR assembly, in accordance with an embodiment of the present invention. The waveguide 700 may be used as a waveguide in the sliders 106 and 206. Referring to fig. 7, the waveguide 700 includes a first arm 700a for receiving light from a light source (e.g., light source 102 in fig. 1A) at a first end 702 or input port. A suitable input device (e.g., a grating or coupling lens) may be used to couple incident light into the waveguide 700. The waveguide 700 further includes a second arm 700b and a third arm 700c optically coupled to the first arm 700 a. The first arm 700a branches (e.g., splits) into two coupled waveguides 704. In one embodiment, the second and third arms 700b, 700c are adjacent or spaced apart from the coupling waveguide 704 to enable optical coupling between the first, second, and third arms 700a, 700b, 700c to a preselected degree. Waveguide 700 may be formed from an organic material, glass, or other suitable material.
Waveguide 700 can include an NFT end 700d disposed near a write pole of a slider (e.g., slider 106 in fig. 1A). A first portion of the light received by the first arm 700a may be transmitted at the NFT end 700d to a recording media disk (e.g., media disk 114 in fig. 1A) disposed near the ABS of the slider. A second portion of the light received by the first arm 700a is transmitted to the second arm 700b and exits the second arm 700b at the tip 706 or an output port of the second arm 700 b. A suitable output device (e.g., a grating or coupling lens) may be disposed at the end 706 of the second arm 700 b. A third portion of the light received by the first arm 700a is transmitted to the third arm 700c and exits the waveguide at the end 708 or an output port of the third arm 700 c. The waveguide 700 may include a suitable output device (e.g., a grating or coupling lens) at the end of the third arm 700 c. In one embodiment, light exiting the end 708 of the third arm 700C may be monitored by a light detector in a device used during testing or manufacturing of an EMAR assembly including the waveguide 700, while light exiting the end 706 may be monitored by a light detector on the base (e.g., the light detector 108 in fig. 1A, 1B, and 1C). The width of second arm 700b and third arm 700c gradually increases toward respective ends 706 and 708.
Fig. 8 is a diagram conceptually illustrating a dual tap coupled waveguide 800 for an EMAR assembly, in accordance with an embodiment of the present invention. The waveguide 800 may be used as a waveguide in the sliders 106 and 206. Referring to fig. 8, the waveguide 800 includes a first arm 800a, the first arm 800a for receiving light from a light source at a first end 802 or input port. The waveguide 800 further includes a second arm 800b and a third arm 800c optically coupled to the first arm 800 a. The first arm 800a branches (e.g., splits) into two waveguides 804. In one embodiment, second arm 800b and third arm 800c are adjacent to first arm 800a or spaced apart from first arm 800a such that light coupling between first arm 800a, second arm 800b and third arm 800c is enabled to a preselected degree. Waveguide 800 may be formed of an organic material, glass, or other suitable material.
Waveguide 800 also includes an NFT end 800d disposed near a write pole of a slider (e.g., slider 106 in fig. 1A). A first portion of the light received by the first arm 800a can be transmitted at this end 800d to a recording media disk (e.g., media disk 114 in fig. 1A) disposed near the ABS of the slider. A second portion of the light received by the first arm 800a is transmitted to the second arm 800b and exits the second arm 800b at the tip 806 or an output port of the second arm 800 b. A third portion of the light received by the first arm 800a is transmitted to the third arm 800c and exits the waveguide at the tip 808. The waveguide 800 may include a suitable output device (e.g., a grating or coupling lens) at the end 808 of the third arm 800 c. The width of the third arm 800c gradually increases toward the tip 808.
Although the second and third arms 800b and 800c in the drawings are illustrated as having particular widths and lengths, the illustrated shapes and sizes are merely exemplary, and embodiments of the present invention are not limited to any particular sizes and shapes. In certain aspects, the second arm 800b and the third arm 800c have substantially the same width at least in certain segments. In certain aspects, the second arm 800b and the third arm 800c may be symmetrical or asymmetrical with respect to the first arm 800 a. In certain aspects, the second arm 800b and the third arm 800c may be coupled to other portions of the first arm 800 a. In some examples, the second arm 800b and the third arm 800c may be coupled to the same side of the first arm 800a (left side in fig. 8), and in some other examples, the second arm 800b and the third arm 800c may be coupled to different sides of the first arm 800 a. In other examples, the segments of 800b and 800c (e.g., those immediately adjacent segments) coupled with arm 800a may have different lengths than those shown in fig. 8. In one such example, the lengths of the segments are the same, rather than different as shown in FIG. 8. The coupling segments of 800b and 800c may be placed in different configurations than those shown. For example, the coupling segments of 800b and 800c may be adjacent to each other rather than having an offset as shown in FIG. 8.
Figure 9 is a diagram conceptually illustrating a dual tap coupled waveguide 900 for use in an EAMR assembly, in accordance with an embodiment of the present invention. The waveguide 900 may be used as a waveguide in the sliders 106 and 206. Referring to fig. 9, the waveguide 900 includes a first arm 900a for receiving light from a light source (e.g., light source 102 in fig. 1A) at a first end 902 or input port. The waveguide 900 further includes a second arm 900b and a third arm 900c optically coupled to the first arm 900 a. The first arm 900a branches (e.g., splits) into two waveguides 904 and 906. Second arm 900b is adjacent to first arm 900a or spaced apart from first arm 900a such that light coupling between first arm 900a and second arm 900b can reach a preselected degree. The third arm 900c is adjacent to the waveguide 906 or spaced apart from the waveguide 906 such that light coupling between the waveguide 906 and the third arm 900c can be achieved to a preselected degree. Waveguide 900 may be made of organic material, glass, or other suitable material.
Waveguide 900 also includes an NFT end 900d that is positioned near the write pole of a slider (e.g., slider 106 in fig. 1A). A first portion of the light received by the first arm 900a can be transmitted at this end 900d to a recording media disk (e.g., media disk 114 in fig. 1A) disposed near the ABS of the slider. A second portion of the light received by the first arm 900a is transmitted to the second arm 900b and exits the second arm 900b at the end 908 or an output port of the second arm 900 b. A third portion of the light received by the first arm 900a is transmitted to the third arm 900c and exits the waveguide at the end 910. Waveguide 900 may include a suitable output device (e.g., a grating or coupling lens) at end 910. In one embodiment, the beam exiting the tip 910 may be monitored by a light detector in a device used during testing or manufacturing of the EAMR assembly including the waveguide 900, while the beam exiting the tip 908 may be monitored by a light detector on the base (e.g., light detector 108 in fig. 1A, 1B, 1C). The width of the third arm 900c gradually increases toward the tip 910. Fig. 6-9 are illustrative embodiments of waveguides used in the present invention, which are not limited thereto.
In the above embodiments, light may be emitted from the waveguide in a direction substantially perpendicular to the top surface of the slider and may be captured by a light detector along the side of the base. However, the location of the exit waveguide and the active area of the photodetector may not be ideally located due to design and manufacturing constraints. For example, the position away from the waveguide may be different for 8-pad and 9-pad sliders. FIGS. 10 and 11 are diagrams depicting EAMR assemblies 1000 and 1100 in which light is emitted at an angle (e.g., a non-ninety degree angle) to a top surface of a slider, in accordance with an embodiment of the invention.
In FIG. 10, the EAMR assembly 1000 includes a light source 1002 and a light detector 1004 attached to a surface of a pedestal 1006. The base 1006 may be mounted to the top surface of the 8-pad slide 1008. A waveguide 1200 in the slider 1008 (similar to the waveguide 300 in fig. 3A) receives light from the light source 1002 and emits a portion 1010 of the received light between two pads 1012 at an angle 1202 relative to the top surface of the slider 1008 (e.g., not perpendicular to the top surface of the slider 1008). In FIG. 11, the EAMR assembly 1100 includes a light source 1102 and a light detector 1104 attached to a surface of a base 1106. The base 1106 is mounted on the top surface of the 9-pad slide 1108. A waveguide 1300 (similar to the waveguide 300) in the slider 1108 receives light from the light source 1102 and emits a portion 1110 of the received light between the pads 1112 at an angle 1302 relative to the top surface of the slider 1108 (e.g., not perpendicular to the top surface of the slider 1108).
In fig. 10 and 11, the angle may be adjusted based on the allowable position of the waveguide and the light detection region of the light detector 1004. The actual angle of emission will depend on the geometrical angle and refractive index of the waveguide material and the hard driving environment.
While the above description contains many specifics of the invention, these should not be construed as limitations on the scope of the invention, but rather as exemplifications of particular embodiments thereof. Thus, the scope of the invention should be determined not by the embodiments illustrated, but by the appended claims and their equivalents.