JP5028526B2 - Thermally assisted magnetic head and method of assembling the thermally assisted magnetic head - Google Patents

Description

  The present invention relates to a thermally assisted magnetic head that performs magnetic recording while irradiating a magnetic recording medium with light, and a method for assembling the thermally assisted magnetic head.

In recent years, a heat-assisted magnetic recording system has been proposed as a recording system that achieves a recording density of 1 Tb / in ² or more (Non-Patent Document 1). In the conventional magnetic recording apparatus, when the recording density is 1 Tb / in ² or more, loss of recorded information due to thermal fluctuation becomes a problem. To prevent this, it is necessary to increase the coercive force of the magnetic recording medium, but since the magnitude of the magnetic field that can be generated from the recording head is limited, if the coercive force is increased too much, a recording bit is formed on the medium. It becomes impossible to do. In order to solve this, in the heat-assisted magnetic recording system, the coercive force is lowered by heating the medium with light at the moment of recording. As a result, recording on a high coercive force medium becomes possible, and a recording density of 1 Tb / in ² or more can be realized.

  In the heat-assisted magnetic recording apparatus, the spot diameter of the irradiated light needs to be the same size (several tens of nm) as the recording bit. This is because information on adjacent tracks is erased if the light spot diameter is larger than that. Near-field light is used to heat such a minute region. Near-field light is a localized electromagnetic field (light having wavenumber having an imaginary component) existing in the vicinity of a minute object having a wavelength equal to or smaller than the light wavelength, and is generated using a minute aperture or a metal scatterer having a diameter equal to or smaller than the light wavelength. For example, a near-field light generator using a triangular metal scatterer has been proposed as a highly efficient near-field light generator (Non-Patent Document 2). When light is incident on the metal scatterer, plasmon resonance is excited in the metal scatterer, and strong near-field light is generated at the apex of the triangle. By using this near-field light generator, light can be collected with high efficiency in a region of several tens of nm or less.

  In order to realize the heat-assisted magnetic recording, it is necessary to heat the medium near the magnetic pole for applying the magnetic field with light. For this purpose, for example, a waveguide is formed on the side of the magnetic pole, and the light of the semiconductor laser as the light source is guided to the vicinity of the tip of the magnetic pole. At this time, as described in Non-Patent Document 3, the semiconductor laser is placed, for example, at the base of the suspension and guides light from there to a flying slider using a waveguide such as an optical fiber. Alternatively, a semiconductor laser is disposed on the slider so that the emitted light is introduced into a waveguide formed beside the magnetic pole.

  As a method for positioning the semiconductor laser in the waveguide, as described in Patent Document 1, one alignment waveguide is formed next to the waveguide in the slider used for recording. There is a method in which a semiconductor laser is aligned while light used for recording is incident on the waveguide, and then the semiconductor laser is moved by a distance between the alignment waveguide and the recording waveguide.

JP 2008-59694 A

H. Saga, H. Nemoto, H. Sukeda, and M. Takahashi, Jpn. J. Appl. Phys. 38, Part 1, pp.1839 (1999) Technical Digest of 6th international conference on near field optics and related techniques, the Netherlands, Aug. 27-31, 2000, p.55 Kenji Kato et al., Jpn. J. Appl. Phys. Vol. 42, pp. 5102-5106 (2003)

  The waveguide for guiding light from the semiconductor laser to the flying slider (the waveguide between the light source and the slider) or the position of the semiconductor laser placed on the slider is the waveguide formed on the side of the magnetic pole (the waveguide in the slider) If it is not accurately matched, the light coupling efficiency between the waveguide between the light source and the slider and the waveguide in the slider, or the light coupling efficiency between the semiconductor laser and the waveguide in the slider is lowered. As a result, the light intensity introduced into the waveguide in the slider decreases, and the temperature rise of the medium decreases.

  A positioning mark (alignment mark) is formed on the slider upper surface (the surface opposite to the air bearing surface) as one method of accurately determining the position of the waveguide between the light source and the slider, or the semiconductor laser placed on the slider. A method of determining the position based on the mark can be considered. This alignment mark needs to be several μm or more in size when viewed from the slider upper surface direction so that it can be observed with a microscope. Further, it is necessary to form the alignment mark with a material (for example, metal) having a reflectance different from that of the peripheral portion so that the alignment mark can be easily seen. Considering the manufacturing process of the hard disk drive, in order to form such an alignment mark, it is necessary to deposit a film having a thickness of several μm on the portion where the alignment mark is to be formed during the head machining process. However, forming such a thick film causes an increase in manufacturing cost and manufacturing time. Also, if the alignment mark and the waveguide material in the slider are of different materials and dimensions, the alignment mark and the waveguide in the slider must be prepared separately, but the relative position of the alignment mark and the waveguide in the slider If there is a shift, the waveguide between the light source and the slider, or the position of the semiconductor laser placed on the slider will shift.

  As a second method, there can be considered a method (active alignment) in which light is emitted from a waveguide between the light source and the slider or a semiconductor laser on the slider and the emission light from the waveguide in the slider is monitored. However, if alignment is performed while monitoring the emitted light one by one, not only does the alignment work take time, but it takes time to connect the wiring for supplying current to the laser. As a result, the cost increases. In addition, there is a possibility that the semiconductor laser is damaged during the alignment operation, and the cost of laser damage increases.

  As a third method, as described in Patent Document 1, one alignment waveguide is formed beside the waveguide in the slider used for recording, and recording is first performed on the alignment waveguide. There is also a method in which the semiconductor laser is aligned while the light used for is incident, and then the semiconductor laser is moved by a distance between the alignment waveguide and the recording waveguide. However, if the semiconductor laser or the slider is moved in such a state that the light used for recording is lit during the alignment, the semiconductor laser may be damaged due to the generated surge noise. In addition, when supplying the power necessary for the semiconductor laser through the electric wire formed on the suspension, it is necessary to fix the semiconductor laser to the suspension before alignment. Becomes difficult. When the semiconductor laser is moved by the distance between the alignment waveguide and the recording waveguide, the direction in which the recording waveguide is located is determined even if the distance between the alignment waveguide and the recording waveguide is known. Therefore, there is a possibility that the position is shifted (when considering a vector connecting the alignment waveguide and the recording waveguide, the direction is unknown even though the length of the vector is known).

An object of the present invention is to provide a thermally assisted magnetic head capable of highly accurately aligning a waveguide between a light source and a slider or a semiconductor laser placed on the slider and a waveguide in the slider. .
Another object of the present invention is to reduce the cost by aligning the waveguide between the light source and the slider or the semiconductor laser placed on the slider and the waveguide in the slider without turning on the recording laser. It is to provide a method for assembling a heat-assisted magnetic head.

  The heat-assisted magnetic head of the present invention has an alignment waveguide on the side of the waveguide for transmitting recording light in the slider. Positions corresponding to the alignment waveguides on both sides of the output end of the waveguide of a support member for supporting the waveguide for introducing light from the light source, which is fixed to the surface opposite to the air bearing surface of the slider Have an alignment mark. The support member is positioned and bonded and fixed to the slider so that the alignment mark corresponds to the alignment waveguide.

  When the support member is bonded and fixed to the slider, light different from the light used for recording is incident from the end on the air bearing surface side of the alignment waveguide, and the opposite side (end on the slider upper surface side) emits light. To. By observing the image of this light emitting point, the position where the light of the recording waveguide is incident is determined. For example, the positions where the light of the two alignment waveguides and the recording waveguide are incident are aligned in a straight line in the track width direction, and the recording waveguide is positioned at the midpoint of the two alignment waveguides. When the alignment waveguide is formed, the midpoint between the two observed emission points is the position of the recording waveguide. After determining the position of the recording waveguide in this manner, alignment is performed so that the emission point of the waveguide for transmitting light from the light source to the slider and the emission point of the semiconductor laser overlap each other. Thus, the waveguide for transmitting light from the light source to the slider and the semiconductor laser can be arranged at the optimum position (the position where the light is most efficiently coupled).

Light is incident on the alignment waveguide using an optical fiber or a microlens (including a distributed refractive index lens) installed in a pedestal on which a slider is placed. At this time, in order to ensure that light is incident on the alignment waveguide, the maximum value of the distance (shift amount) between the reference point on the pedestal and the reference point on the slider side when the slider is placed on the pedestal is set. When ± d _max is set, the spot diameter Di of the light incident on the alignment waveguide may be set to 2d _max or more.

  In order to increase the intensity of light coupled to the alignment waveguide, a structure for increasing the mode field diameter on the incident side of the waveguide may be formed at the incident end of the alignment waveguide. For example, the mode field diameter may be increased by changing the width of the core of the waveguide or by inserting a layer made of a material having a refractive index intermediate between the refractive index of the core and the refractive index of the cladding.

  The wavelength of light used for the alignment need not be the same as the wavelength of light used for recording.

  If the distance between the recording waveguide and the alignment waveguide is too short, light incident on the recording waveguide is also coupled to the alignment waveguide, and the intensity of light used for recording is reduced. In order to prevent this, the distance between the alignment waveguide and the recording waveguide needs to be at least the radius of the incident beam. In order to detect the amount of rotation when the slider is rotated, the distance between the alignment waveguide and the recording waveguide is preferably 100 μm or more.

  The intensity distribution of the light incident on the alignment waveguide is preferably a distribution in which the amount of change in intensity is small near the center and becomes abruptly smaller than a certain spot diameter Di. Such a distribution can be created, for example, by forming a light-shielding film with an opening having a diameter equal to Di on the upper surface of the pedestal on which the slider is placed, and allowing light having a spot diameter larger than Di to enter the opening. By making the distribution of the incident light in this way, it is possible to reduce the intensity change of the light incident on the alignment waveguide caused by the displacement of the slider and to reduce the influence of the background light in the peripheral portion.

  In order to suppress the influence of the background light generated in the periphery, two 45 degree mirrors are inserted in the middle of the alignment waveguide, or the alignment waveguide is bent in a curved shape so that the exit point of the alignment waveguide is The center may be shifted from the center of the incident point. In this way, since the background light and the light emitted from the alignment waveguide do not overlap in the image, the light emitted from the alignment waveguide can be distinguished.

  Further, in order to suppress the influence of background light generated in the periphery, a 45-degree mirror may be formed in the middle of the alignment waveguide so that light can enter from the side surface of the slider. Since the light (background light) that has not been coupled to the alignment waveguide travels in a direction parallel to the slider air bearing surface, it does not enter the observation optical system.

  You may observe the light radiate | emitted from the waveguide for alignment in the state which mounted the waveguide and semiconductor laser for transmitting the light from a light source on a slider. At this time, if an alignment mark having an opening at the center is formed on a waveguide for transmitting light from a light source or a mount for mounting a semiconductor laser, the light passing through the opening is maximized. If the position of the mount is adjusted, a waveguide or a semiconductor laser for transmitting light from the light source can be installed at an optimum position. The intensity of light passing through the opening can be detected using a photodetector such as a photodiode.

  In addition, with a waveguide or a semiconductor laser for transmitting light from the light source placed on the slider, light is incident on the alignment waveguide, and the light returned to the alignment mark on the mount is detected. Thus, alignment may be performed. If an alignment mark exists at the exit point of the alignment waveguide, the intensity of reflected light from the alignment mark changes. By detecting this change, the displacement of the mount can be detected. The alignment mark for this purpose is produced, for example, by embedding a mark of a material different from that of the mount on the mount surface. The mount mark may be a groove formed on the mount surface. In particular, when the wavelength of the light source for alignment is λ, the distance d from the upper surface of the slider to the bottom of the groove of the alignment mark is d = λx (2n + 1) / 4 (n = 0 or greater integer). By doing so, the reflected light at the slider upper surface (the end face at the exit of the waveguide) interferes with the reflected light at the bottom of the groove of the alignment mark, and the intensity of the light returning to the alignment waveguide is weakened. Therefore, when the return light is adjusted to become the weakest, the waveguide and the semiconductor laser for transmitting the light from the light source can be arranged at the optimum position.

  When detecting the return light, in order to exclude the detection of background light, the wave guide for transmitting the light from the light source and the mount on which the semiconductor laser is mounted are vibrated in the horizontal direction at the frequency f and detected by the detector The reflected light component from the alignment mark may be extracted by extracting the component that vibrates at the frequency f in the light intensity.

In addition, when detecting return light, if the inclination of the mount for mounting the waveguide or the semiconductor laser for transmitting the light from the light source is adjusted so that the return light intensities from the two left and right alignment marks are equal, The mount can be set to be horizontal. This is based on the following principle.
(1) Since the reflected light from the end face of the alignment waveguide and the reflected light from the alignment mark interfere with each other, the intensity of the light returning to the waveguide side changes when the distance from the slider upper surface to the alignment mark changes. At this time, when the mount is inclined, the distance from the upper surface of the slider to the alignment mark is different for each alignment mark. Therefore, the intensity of the light returning to the waveguide side differs between the two alignment marks.
(2) When the inclination of the mount is large, the reflected light from the alignment mark travels obliquely. At this time, since the light intensity coupled to the waveguide depends on the distance from the slider upper surface to the alignment mark, the light intensity coupled to the waveguide differs between the two alignment marks.

  The intensity of light emitted from the alignment waveguide is not necessarily equal between the two alignment marks. To correct this, measure the intensity of the light emitted from the alignment waveguide before mounting the mount on the slider, and correct the signal intensity of the photodetector based on it, or Correction may be made by increasing or decreasing the light intensity of the light source.

  The alignment mark may be a groove having a different depth depending on the location, such as a hemispherical groove or a square pyramid-shaped groove. At this time, the reflected light from the alignment mark does not travel isotropically. Therefore, the intensity of the reflected light coupled to the alignment waveguide depends on the distance from the slider upper surface to the alignment mark. Therefore, the inclination of the waveguide mount can be detected by detecting and detecting the return light intensity at the two alignment marks. Further, the absolute distance from the slider upper surface to the alignment mark may be determined by utilizing the fact that the strength changes depending on the distance from the slider upper surface to the alignment mark.

  When detecting the return light, a plurality of lights having different wavelengths may be put in the alignment mark. By separating and detecting the return light of each wavelength, the absolute distance from the slider upper surface to the alignment mark can be known.

  The number of alignment waveguides may be three or more. For example, if four are arranged, the tilt of the mount relative to the slider can be detected in two directions.

  When alignment is performed while measuring transmitted light intensity or reflected light intensity, the alignment light may be light having a wavelength shorter than the wavelength of light used for recording. When light having a short wavelength is used in this way, the light spot diameter at the exit end of the alignment waveguide can be reduced, so that the resolution with respect to the position is improved. Further, the spot diameter of the emitted light may be reduced by forming a minute aperture or a scatterer on the exit surface of the alignment waveguide.

  Instead of forming an alignment mark on the mount side on which the waveguide for transmitting light from the light source or the semiconductor laser is mounted, an alignment waveguide is formed on the mount side and coupled to the alignment waveguide on the mount side The alignment may be performed by detecting the light that has been detected. Alternatively, the alignment may be performed by introducing light into the alignment waveguide on the mount and detecting the intensity of the light coupled to the alignment waveguide in the slider.

  According to the present invention, alignment between a waveguide for transmitting light from a light source to a slider or a semiconductor laser placed on the slider and the waveguide in the slider can be realized with high accuracy. In addition, the alignment of the waveguide for transmitting light from the light source to the slider or the semiconductor laser placed on the slider and the waveguide in the slider can be performed without turning on the recording laser. Assembling of the magnetic head can be realized at low cost.

2 is a cross-sectional view of a thermally assisted magnetic head according to Embodiment 1. FIG. 2A and 2B are diagrams illustrating a part of a thermally-assisted magnetic head according to a first embodiment, in which FIG. 3A is a view of the outflow end from the upper surface of the slider, and FIG. FIG. 3 is a partial perspective view of a near-field light generating element and a main pole of the thermally-assisted magnetic head according to Example 1. It is a figure which shows the method which injects light into the waveguide for alignment, (a) is a figure which shows the case where an optical fiber is utilized, (b) shows the case where a microlens is utilized. It is a figure which shows the waveguide for alignment from which the width | variety changed. It is a figure which shows the relationship between a waveguide width and a mode field diameter. It is a figure which shows the case where the refractive index of the clad of the incident end part of the waveguide for alignment is changed. FIG. 5 is a diagram illustrating a method for assembling the thermally-assisted magnetic head according to the first embodiment. It is a figure which shows the alignment mark formed on the waveguide mount, (a) is a side view, (b) is the figure seen from the air bearing surface side. FIG. 6A is a diagram showing a case where the position of the slider is rotated. FIG. 5A is a diagram of the slider viewed from the side opposite to the air bearing surface. FIG. It is a figure which shows the relationship. It is a figure which shows the case where the waveguide for alignment and the waveguide for recording do not exist on the same line. It is a figure which shows the case where intensity distribution of incident light is not Gaussian distribution, (a) is a figure which shows intensity distribution, (b) is a figure which shows the introduction method of light. FIG. 5 is a diagram showing a case where the central axis on the incident end side and the central axis on the output end side of the alignment waveguide are deviated from each other. FIG. Indicates the case. In the case where light is introduced from the side surface of the slider, (a) shows a case where a mirror is provided, and (b) shows a case where the waveguide is bent in a curved shape. It is a figure which shows the method of aligning while detecting the transmitted light intensity. It is a figure which shows the shape of the alignment mark in the case of aligning while detecting the transmitted light intensity. It is a figure which shows the method of aligning while detecting reflected light intensity. It is a figure which shows the case where a groove | channel is utilized as an alignment mark. It is a figure which shows the case where a waveguide mount inclines. It is a figure which shows the shape of a groove | channel, (a) shows a hemispherical groove | channel, (b) shows the groove | channel which carried out the shape of the square weight. It is a figure which shows the case where four alignment waveguides are formed. It is a figure which shows the case where minute opening is formed in the output end of the waveguide for alignment. It is a figure which shows the case where the waveguide for alignment is formed beside the waveguide for transmitting light from a light source to a slider, (a) is a side view, (b) is the figure seen from the air bearing surface side. It is a figure which shows the case where the alignment waveguide is extended near the light source when the alignment waveguide is formed beside the waveguide for transmitting light from the light source to the slider. 6 is a cross-sectional view of a heat-assisted magnetic head according to Embodiment 2. FIG. FIG. 6 is a diagram of a heat-assisted magnetic head according to Example 2 as viewed from the outflow end side of a slider. FIG. 6 is a diagram illustrating a method for assembling a thermally-assisted magnetic head according to a second embodiment. FIG. 7A is a side view of a heat-assisted magnetic head according to a third embodiment, and FIG. FIG. 10 is a diagram illustrating a modification of the thermally-assisted magnetic head according to the third embodiment. It is a figure which shows the whole structure of the recording / reproducing apparatus carrying a heat-assisted magnetic head.

Embodiments of the present invention will be described below with reference to the drawings.
1, 2 and 3 show the configuration of the thermally-assisted magnetic head 100 according to the first embodiment. FIG. 1 is a cross-sectional view of a heat-assisted magnetic head 100 attached to a suspension flexure 40 cut in the recording track direction, and also shows a perpendicular magnetic recording medium 14. FIG. 2A is a view showing the outflow end side of the upper surface of the slider (opposite the air bearing surface), and FIG. 2B is a cross-sectional view taken along line AA of FIG. FIG. 3 is a perspective view of the vicinity of the main magnetic pole 2 and the near-field light generating element 1.

A semiconductor laser having a wavelength of 780 nm was used as the light source, and was installed near the base of the suspension 13 (see reference numeral 41 in FIG. 30). In order to transmit light from the light source to the slider 5, the polymer waveguide 10 (in the figure, the core portion is shown) was used. The polymer waveguide 10 was disposed in a groove formed in the waveguide mount (support member) 24. Core width W ₁₀ of the polymer waveguide 10 is 8 [mu] m, the distance W ₁₅ of the thickness of the peripheral portion of the core (cladding) 11 30 [mu] m, from the waveguide bottom surface to the center of the waveguide core is set to 10 [mu] m. The waveguide mount 24 is disposed on the upper surface of the slider 5, and the 45 ° mirror 12 is disposed on the end surface of the polymer waveguide 10 so that light emitted from the polymer waveguide 10 is emitted in a direction perpendicular to the upper surface of the slider 5. Formed. In the present embodiment, the polymer waveguide 10 is used as a waveguide for transmitting light from the light source to the slider 5, but other waveguides such as an optical fiber and a plastic fiber may be used.

In the flying slider 5, a recording waveguide 3 (a core portion is shown in the figure) for guiding light from the opposite side of the medium facing surface 17 to the medium facing surface 17 was formed. The material of the core of the recording waveguide 3 in the slider was Ta ₂ O _5, and the material of the cladding 15 was Al ₂ O ₃ . The core width W _{1 in the} direction perpendicular to the recording track direction was 600 nm, and the core width W _{2 in the} direction parallel to the recording track direction was 300 nm (see FIG. 3). The waveguide 3 may be made of a material having a refractive index of the core larger than that of the clad. For example, the clad material may be Al ₂ O ₃ and the core material may be TiO ₂ . The clad material may be SiO ₂ and the core material may be Ta ₂ O ₅ , TiO ₂ , SiO _x N _y , or Ge-doped SiO ₂ .

  The near-field light generating element 1 was formed as a light irradiating portion in order to generate a light spot having a diameter of several tens of nanometers at the lower part (outgoing end) of the waveguide 3. As the near-field light generating element 1, in order to generate near-field light with high efficiency, a conductive scatterer having a triangular shape is used as shown in FIG. The material of the scatterer was gold, the length Sy of the scatterer was 100 nm, and the height Sh was 150 nm. When light polarized in the y direction is incident on the scatterer, plasmon resonance occurs in the scatterer, and strong near-field light is generated at the scatterer vertex 56.

The magnetic field was generated using the coil 7 of the magnetic head unit 6 having a write head composed of the main magnetic pole 2, the magnetic pole 8 and the coil 7, and the magnetic field was guided to the vicinity of the near-field light generating element 1 by the main magnetic pole 2. If the magnetic pole 8 exists in the vicinity of the core of the waveguide 3, the presence of the magnetic pole 8 attenuates the intensity of light propagating through the waveguide (evanescent light that has oozed into the clad portion hits the magnetic pole, and light is emitted. It is absorbed or scattered by the magnetic pole). Therefore, the distance between the magnetic pole 8 and the waveguide 3 is made as large as possible, and the distance from the main magnetic pole 2 is shortened near the near-field light generating element. The distance between the vertex 56 where the near-field light is generated and the main magnetic pole 2 was set to 10 to 30 nm. When the near-field light generating element 1 is arranged at the center of the waveguide 3, the main magnetic pole 2 enters the waveguide core 3 near the near-field light generating element. However, the main magnetic pole 2 at that time also absorbs the main magnetic pole 2. In order to make the scattered (reflected) light as small as possible, the length W ₁₆ of the main magnetic pole 2 entering the waveguide core 3 is preferably as short as possible. However, if the length W ₁₆ of the main magnetic pole 2 is shortened, the magnetic field strength is lowered, so that it is not necessary to be too short. In this embodiment, W ₁₆ is 200 nm. The width of the magnetic pole at the front end of the main magnetic pole was 200 nm for the width W _{17 in the} y direction and 100 nm for the width W _{18 in the} x direction.

  A reproducing head including a magnetic reproducing element 4 was formed on the side of the write head as shown in FIG. In this embodiment, a Giant Magneto Resistive (GMR) element or a Tunneling Magneto Resistive (TMR) element is used as the magnetic reproducing element 4. A magnetic shield 9 is formed around the magnetic reproducing element 4 to prevent magnetic field leakage. In the above embodiment, the main magnetic pole 2 is formed so as to enter the waveguide 3. However, the main magnetic pole 2 is disposed outside the core so that the light intensity is not reduced by the main magnetic pole 2 entering the waveguide 3. Also good. For example, the main magnetic pole 2 may be disposed so as to contact the side surface of the core. At this time, the position of the near-field light generating element 1 does not need to be at the center of the waveguide 3 and may be arranged close to the main magnetic pole side. As the recording disk 14, a perpendicular recording medium was used. Recording marks were written on the recording layer 14 'by applying a magnetic field while irradiating the medium with light.

In order for the light emitted from the waveguide 10 between the light source and the slider to be efficiently coupled to the waveguide 3 in the slider, it is necessary to align the positions of each other accurately. At this time, it is necessary to know the center position of the waveguide 3. As means for knowing the center position of the waveguide 3, as shown in FIG. 2, two alignment waveguides 16 are formed beside the waveguide 3 in the slider. The distances W ₅ and W ′ ₅ from the waveguide 3 to the waveguide 16 were set such that W ₅ = W ′ ₅ = 200 μm. The center of the waveguide 3 and the center of the alignment waveguide 16 were produced so as to be arranged on a straight line. When performing alignment, light 19 different from the light used for recording is incident from the end opposite to the emission end 18 on the slider upper surface side of the alignment waveguide 16. At this time, light is emitted from the emission end 18 on the slider upper surface side of the alignment waveguide 16 and shines brightly. The position of the waveguide 3 can be known by using the illuminated point as a mark. That is, the midpoint between the two light emitting points is the center position of the waveguide 3. Thus, the use of the waveguide 16 as an alignment mark has the following advantages.
(1) Since the alignment mark emits light, the position of the alignment mark is easy to understand. In particular, when an image on the upper surface of the slider is acquired and the alignment mark position is determined by image analysis, an image with very high contrast can be obtained, so that the position of the alignment mark can be determined accurately.
(2) Since the alignment mark itself emits light, the position of the alignment mark can be determined even if the size of the alignment mark is small. In the case of a normal alignment mark, the size of the alignment mark needs to be several μm or more in order to clearly observe the alignment mark during image observation. In order to form such a large mark on the upper surface of the slider of the hard disk drive, it is necessary to form a thick film. However, forming such a thick film leads to an increase in cost. On the other hand, when the alignment mark emits light as in this embodiment, the film thickness may be thin, and it may be 1 μm or less.
(3) The alignment waveguide 16 can be made of the same material as the core of the recording waveguide 3. That is, the film formation for producing the waveguide 3 and the alignment waveguide 16 need not be performed separately, but can be performed simultaneously. As a result, the production time can be shortened and the material cost can be reduced.
(4) In lithography for processing the alignment waveguide 16, the core portion of the recording waveguide 3 and the core portion of the alignment waveguide 16 can be exposed simultaneously. That is, the core portion of the recording waveguide 3 and the core portion of the alignment waveguide 16 can be exposed with the same mask. As a result, it is possible to reduce the amount of deviation between the waveguide 3 and the alignment waveguide 16 that occurs at the time of fabrication, and to increase the final alignment accuracy.

In this embodiment, the core material of the alignment waveguide 16 is Ta ₂ O ₅ and the clad material is Al ₂ O ₃ . The core width W _{3 in the} direction perpendicular to the direction of the recording track was 600 nm, and the core width W _{4 in the} direction parallel to the direction of the recording track was 300 nm. The alignment waveguide 16 may be made of any material as long as the refractive index of the core is larger than the refractive index of the clad. For example, the clad material may be Al ₂ O ₃ and the core material may be TiO ₂ . The clad material may be SiO ₂ and the core material may be Ta ₂ O ₅ , TiO ₂ , SiO _x N _y , or Ge-doped SiO ₂ .

FIG. 4 shows a method for introducing light into the alignment waveguide 16. In the example shown in FIG. 4A, the light 19 that enters the alignment waveguide 16 is introduced using the optical fiber 21. As a light source, a semiconductor laser having a wavelength of 670 nm was used. The optical fiber 21 is disposed so as to be embedded in the pedestal 20, and the light is introduced into the alignment waveguide 16 by placing the slider 5 on the pedestal 20. The alignment of the slider 5 and the pedestal 20 was performed by aligning a reference point (slider corner, etc.) on the slider side with a reference point provided on the pedestal. At this time, the alignment waveguide 16 and the optical fiber 21 may be misaligned. In order to introduce light into the alignment waveguide 16 even when the position of the optical fiber 21 is shifted, when the slider 5 is placed on the pedestal 20, the distance between the reference point on the pedestal and the reference point on the slider side When the maximum value of (deviation amount) is ± d _max , the light spot diameter Di (the diameter at the position where the central intensity is 1 / e ² ) at the emission position of the optical fiber 21 is 2d _max or more. Just do it. In this example, since the maximum value of the deviation amount is ± 7 μm, the spot diameter Di of the optical fiber 21 is set to 16 μm. In the example of FIG. 4B, the micro lens 22 is used to introduce the light 19 into the alignment waveguide 16. A pedestal 20 on which the slider 5 is placed is made of a material having optical transparency, and a microlens 22 is placed therein. The position of the microlens 22 was adjusted so that the center of the alignment waveguide 16 was positioned at the focal point of the microlens 22. At this time, in order to allow light to enter the alignment waveguide 16 even if the focal point of the microlens 22 is shifted from the center of the alignment waveguide 16, when the slider 5 is placed on the pedestal 20, a reference on the pedestal is used. When the maximum value of the distance (shift amount) between the point and the reference point on the slider side is ± d _max , the light spot diameter Di at the focal point may be set to 2 d _max or more. In this example, the maximum deviation amount is ± 7 μm, so the spot diameter at the focal point is set to 16 μm. As the microlens 22, a spherical lens may be used, but a cylindrical distributed refractive index lens may be used.

In order to increase the amount of light coupled to the alignment waveguide 16 as much as possible, the mode field diameter (light spot diameter in the waveguide) on the incident end side of the alignment waveguide 16 should be as large as possible. good. Therefore, in this embodiment, as shown in FIG. 2B, the waveguide width W ₇ on the incident end side is made larger than the waveguide width W ₃ on the output end side, so that the incident end side Increased the mode field diameter. The waveguide width W ₇ on the incident end side is 2 μm. In addition, as shown in FIG. 5, the mode field diameter on the incident end side may be increased by conversely reducing the width of the waveguide on the incident end side. That is, in general mode field diameter becomes smaller the smaller the width of the waveguide, as shown in FIG. 6, when less than a certain value (W _0), mode field diameter increases conversely. Accordingly, the mode field diameter of the alignment waveguide 16 on the incident end side can be increased by making the waveguide width W ₇ on the incident end side smaller than W ₀ . In this embodiment, the waveguide width W ₇ on the incident end side is set to 150 nm.

In order to further increase the mode field diameter on the incident end side of the alignment waveguide 16, as described in FIG. 2 in IEEE Journal of Selected Topics in Quantum Electronics, Vol. 11, No. 1, 2005, p232 A spot diameter converter may be formed on the incident end side of the alignment waveguide 16. In this embodiment, the core material of the alignment waveguide 16 is Ta ₂ O ₅ (refractive index = 2.18), and the cladding 15 is Al ₂ O ₃ (refractive index = 1.63). As shown in FIG. 7, the width of the core is made small near the entrance of the waveguide, and around the core of Ta ₂ O ₅ , there is an intermediate between the refractive index of the core of the alignment waveguide 16 and the refractive index of the cladding 15. A layer 25 made of a material having a refractive index was formed. The material of the intermediate refractive index layer 25 is SiO _x N _y, and the ratio of SiO _x N _y to O and N is such that the refractive index of SiO _x N _y is 0.05 larger than the refractive index of Al ₂ O _3. It was adjusted. The width of the core of the alignment guide 16 has a width W ₃ 600 nm, the W ₄ 300 nm, the width W ₇ of the entrance end side and 150 nm. The width W ₁₂ of the intermediate refractive index layer 25 is 10 μm, the width W ₁₃ is 5 μm, and the length W ₁₄ is 200 μm.

  In the above embodiment, a semiconductor laser with a wavelength of 670 nm was used as the light source, but laser light with a different wavelength may be used, for example, a He-Ne laser with a wavelength of 633 nm, an Ar laser with a wavelength of 488 nm, a wavelength of 445 nm, A semiconductor laser having a wavelength of 785 nm, 890 nm, 1.3 μm, or 1.5 μm may be used.

The smaller the spot diameter of the light emitted from the alignment waveguide 16, the higher the accuracy of alignment (the smaller the size of the spot when observed, the more accurately the position can be determined). Therefore, as shown in FIG. 5, the light spot diameter may be reduced by narrowing the width W ₈ of the emission end 18. However, as shown in FIG. 6, if the width is made too small, the spot diameter becomes conversely large. Accordingly, the width W ₈ needs to be larger than the width W _{0 at} which the mode field diameter is minimized. In this embodiment, the width W ₈ was 0.3 [mu] m.

FIG. 8 shows the alignment procedure. The slider 5 was placed on the pedestal 20 and light was incident on the alignment waveguide 16. The light exiting from the exit end 18 of the alignment waveguide 16 is observed by an observation optical system 29 (a combination of a lens for enlarging an image and a CCD camera), and the recording waveguide is measured from two measured positions. The position of 3 was determined. On the other hand, the polymer waveguide 10 placed on the slider was disposed on a polymer waveguide mount (support member) 24 as shown in FIG. Alignment marks 23 were formed on both sides of the emission end so that the spot position of the light emitted from the mirror 12 formed at the emission end of the polymer waveguide 10 can be seen. In this embodiment, the mount 24 is made of SiO ₂ , a groove for arranging the waveguide 10 is formed on the mount, and the waveguide 10 is arranged therein. The material of the mount 24 may be Si, plastic, or metal. As the alignment marks 23 arranged on both sides of the light emitting position, a metal mark having a square shape with a side length of 3 μm was prepared so as to be embedded in the SiO ₂ surface. The metal material was chromium. The material may be anything as long as it is different from the surrounding material (SiO ₂ ), and may be gold, silver, copper, aluminum, titanium, or the like. Further, a groove may be formed instead of embedding a mark of another material. The distances W ₆ and W ′ ₆ between the two alignment marks 23 and the waveguide 10 were W ₆ = W ′ ₆ = 200 μm. The alignment marks as described above were observed using an observation optical system 29, as shown in FIG. 8, and the position of the end of the polymer waveguide 10 (the position where light was emitted) was determined. The waveguide mount 24 is fixed to the holder 28 by vacuum suction or the like, and the position of the holder 28 can be moved by a piezo stage. After the position of the end of the waveguide 3 and the position of the end of the polymer waveguide 10 are determined, the holder 28 is moved using a piezo stage so that the end of the waveguide 3 and the end of the polymer waveguide 10 overlap. I did it. Thereafter, the polymer waveguide mount 24 and the slider 5 were fixed using an ultraviolet curing adhesive. In the above method, the waveguide 10 side is moved, but the slider 5 may be moved.

  In the above alignment, the position of the end of the polymer waveguide 10 (the position where the light is emitted) is determined by observing the alignment mark formed on the side of the polymer waveguide 10, but the light is incident on the waveguide 10. The position of the end of the polymer waveguide 10 (the position where the light is emitted) may be determined by observing the light emitted from the end of the waveguide 10. When the alignment mark 23 formed on the waveguide mount 24 is used, the position of the alignment mark 23 and the end of the polymer waveguide 10 (position where light is emitted) may be shifted. It becomes difficult to accurately determine the position of the end portion. On the other hand, if light is actually put into the polymer waveguide 10 and the place where the light is emitted is observed, the position where the light is emitted can be directly known. Therefore, the alignment accuracy is not lowered due to the displacement between the alignment mark 23 formed on the waveguide mount 24 and the position of the end of the waveguide 10. However, it is necessary to turn on the recording laser for each component at the time of alignment, which has a demerit that increases the time required for the alignment work.

If the distance W ₅ between the alignment waveguide 16 formed on the side of the waveguide 3 in the slider and the waveguide 3 is too short, the intensity of the recording light transmitted through the waveguide 3 is affected by the alignment waveguide 16. Will become smaller. That is, in order for light incident on the waveguide 3 in the slider to be efficiently coupled to the waveguide 3, it is necessary to increase the mode field diameter on the entrance side of the waveguide 3 (if the mode field diameter is small, When the position of the incident light is slightly shifted, the coupling efficiency is greatly reduced). Therefore, as shown in FIG. 5, the mode field diameter on the entrance side is reduced by reducing the width W ₇ on the entrance side of the waveguide 3 or by providing a low refractive index layer 25 as shown in FIG. Need to spread. At this time, the spot diameter of the light incident on the waveguide 3 needs to be increased accordingly. Here, if the distance between the waveguide 3 and the alignment waveguide 16 is too short, the recording light enters the alignment waveguide 16 and the intensity of the light emitted from the waveguide 3 decreases. End up. In order to prevent this, the distance W ₅ between the alignment waveguide 16 and the waveguide 3 must be at least the radius of the incident beam. For example, when the radius of the incident beam is 2 μm, the distance W ₅ needs to be at least 2 μm. Further, when the orientation of the slider 5 is adjusted based on the alignment waveguide 16, the distance W ₅ between the alignment waveguide 16 and the waveguide 3 needs to be further increased. That is, even if the waveguide 3 is positioned at the midpoint between the two alignment waveguides 16, the slider 5 is rotated in a plane parallel to the slider upper surface as shown in FIG. (FIG. 10A is a view of the upper surface of the slider 5). Thus, if the slider 5 is bonded in a rotated state, the polarization direction of the light introduced into the waveguide 3 is rotated. Since the near-field light generating element has polarization dependency, if the polarization direction is deviated, the intensity is reduced. Further, when the slider 5 is bonded in a rotated state, the slider 5 becomes unstable in floating. Considering such influence on polarization and flying stability, the rotation amount θ needs to be suppressed to 1 degree or less. The rotation amount θ can be known by measuring the displacement amount a as shown in FIG. FIG. 10B shows the relationship between W ₅ and the displacement amount a when θ is 1 degree. Thus, the greater the distance W ₅ between the alignment waveguide 16 and the waveguide 3, the greater the displacement amount a. Here, if the displacement amount a is smaller than the resolution of the observation optical system, the displacement amount cannot be measured. Now, when observing blue light (wavelength 0.45 μm) with a 10 × objective lens (numerical aperture = 0.25), the resolution is 450 / 0.25 = 1.8 μm. Therefore, in order to detect the rotation amount of θ = 1 degree, the displacement amount a needs to be 1.8 μm or more. For this purpose, the distance W ₅ between the alignment waveguide 16 and the waveguide 3 is 100 μm or more. Is preferable.

In the above embodiment, the distance between the two alignment waveguides 16 and the waveguide 3 is W ₅ = W ′ ₅ , but W ₅ and W ′ ₅ may be different from each other. For example, when W ₅ = 100 μm and W ′ ₅ = 200 μm, a point that divides a straight line connecting two points 18 (light emitting points) into 1: 2 may be the position of the waveguide 3. Two alignment waveguides may be formed not on both sides of the waveguide 3 but on one side of the waveguide 3. In the above embodiment, the recording waveguide 3 and the alignment waveguide 16 are on a straight line. However, as shown in FIG. 11, they may be displaced in the longitudinal direction (y direction) of the slider. When the amount of deviation between the recording waveguide 3 and the alignment waveguide 16 is b and the distance between the two alignment waveguides 16 and the waveguide 3 is W ₅ = W ′ ₅ , two points 18 (light is emitted) The position shifted from the midpoint by b in the y direction may be the position of the recording waveguide 3.

In the above embodiment, the incident light is introduced into the alignment waveguide 16 using the optical fiber 21 or the microlens 22 disposed on the lower side (medium facing surface side) of the slider 5. Is a Gaussian distribution as shown by the dotted line in FIG. At this time, if the distance (shift amount) between the reference point on the pedestal and the reference point on the slider side increases, the intensity of light incident on the alignment waveguide 16 decreases. This can be prevented by making the beam diameter Di of the incident light sufficiently larger than twice the maximum deviation value d _max , but at this time, the light that is not coupled to the alignment waveguide 16 is not reflected in the background light. As many will occur. When this background light enters the observation optical system, the contrast of the light image at the exit end 18 is lowered. In order to prevent this, the intensity distribution of the incident light should be such that the amount of change in intensity is small in the vicinity of the center and rapidly becomes smaller than the diameter Di as indicated by the solid line in FIG. . For example, as shown in FIG. 12B, such a distribution is obtained by forming a light-shielding film 59 having an opening having a diameter W ₂₀ equal to Di on the upper surface of the pedestal 20 and having a spot diameter larger than W _20. Can be made to enter the aperture. By making the distribution of the incident light in this way, the change in the intensity of the light incident on the alignment waveguide 16 due to the displacement of the slider 5 can be reduced, and the influence of the background light in the peripheral portion can be reduced. . In this embodiment, light is collected by the distributed refractive index lens 60 having a beam diameter of 30 μm at the emission end face, and a light shielding film 59 having an opening with an opening diameter of 16 μm is formed on the end face. As a result, it is possible to create a distribution as shown by a solid line in FIG. 12A where Di = 16 μm.

In order to prevent the influence of the background light, as shown in FIG. 13, the alignment waveguide 16 is bent halfway so that the center of the exit point 18 of the alignment waveguide 16 is shifted from the center of the incident point. Also good. If the centers are shifted in this way, the incident light 19 and the outgoing light 61 from the alignment waveguide 16 do not overlap in the image, and therefore the outgoing light 61 from the alignment waveguide 16 can be distinguished. . In the example of FIG. 13A, the center of the emission point 18 and the center of the incident point are shifted by forming two 45-degree mirrors 27 in the alignment waveguide 16. In the example of FIG. 13B, the center of the emission point 18 and the center of the incident point are shifted by bending the alignment waveguide 16 in a curved shape. The shift amount W ₉ between the incident position and the output position is preferably greater than or equal to the radius of the incident beam. In this embodiment, the radius of the incident beam was 8 μm, so the shift amount W ₉ was set to 10 μm.

  In order to suppress the influence of background light, the alignment waveguide 16 may be bent halfway as shown in FIG. By bending in this way, light (background light) that has not been coupled to the alignment waveguide 16 travels in a direction parallel to the slider air bearing surface, and thus does not enter the observation optical system. In the example of FIG. 14A, the optical path is bent 90 degrees by forming a 45-degree mirror 27 in the middle of the alignment waveguide 16. Incident light 19 was introduced into the alignment waveguide 16 by bringing the optical fiber 21 closer to the slider side surface. In the example of FIG. 14B, the alignment waveguide 16 is bent into a curved shape so that light is emitted to the upper surface of the slider. The radius of curvature of the bent portion was 100 μm.

In the alignment described above, the light emitted from the alignment waveguide 16 was observed before the waveguide mount 24 was placed on the slider. However, as shown in FIG. May be. That is, the alignment mark 23 is formed on the waveguide mount 24 and observed by the upper observation optical system, and at the same time, the light emitted from the alignment waveguide 16 in the slider is also observed by the upper observation optical system. Alignment is performed so that the positional relationship between the alignment mark 23 on the waveguide mount and the alignment waveguide 16 is appropriate, and the waveguide mount 24 is bonded to the slider 5 when the position is determined. In this example, as shown in FIG. 16, two alignment marks 23 having an opening at the center are formed on the waveguide mount 24. The waveguide mount 24 is made of SiO ₂ and the alignment mark 23 is made of chrome. The shape of the alignment mark 23 was a square with a side of 10 microns, and a square opening with a side of 1 μm was formed at the center. The distances W ₆ and W ′ ₆ between the alignment mark 23 and the polymer waveguide 10 are W ₆ = W ′ ₆ = 200 μm, and the distances W ₅ and W ′ ₅ between the waveguide 3 in the slider and the alignment waveguide 16 are W ₅ = W ′ ₅ = 200 μm. The light emitted from the alignment waveguide 16 and the alignment mark 23 were observed by a detector 30 (after being imaged by a lens 31, the image was detected by a photodetector 32 such as a CCD element). The waveguide mount 24 was fixed to the holder 28 by vacuum suction or the like, and the position of the holder 28 was moved using a piezo element. In the detected image, the position of the waveguide mount 14 was adjusted so that the position of the light emitted from the alignment waveguide 16 and the alignment mark 23 on the waveguide mount 24 overlapped. At this time, if the detected light quantity is maximized (the light transmitted through the alignment mark 23 is maximized), the optimum position can be obtained.

  In the alignment described above, light emitted from the alignment waveguide 16 is observed using a CCD element, but may be detected by a photodetector 32 such as a photodiode. If the position of the waveguide 10 is moved so that the amount of light detected by the photodetector 32 is maximized, it can be adjusted to the optimum position.

In the above embodiment, the material of the mount 24 is SiO ₂ that is transparent to visible light. However, another material such as Si may be used. In the case of Si, visible light is not transmitted. However, if light having a long wavelength such as a wavelength of 980 nm is used as light used for alignment, light can be transmitted through the waveguide mount 24. The light emitted from the alignment waveguide 16 and the alignment mark 23 can be observed.

In the above alignment, the light transmitted through the waveguide mount 24 is detected. However, as shown in FIG. 17, alignment is performed by detecting the light reflected by the alignment mark 23 on the waveguide mount 24. Also good. In this example, an alignment mark 23 having a square shape with a side of 1 μm is formed below the SiO ₂ waveguide mount 24. The alignment mark 23 is made of aluminum. The distances W ₆ and W ′ ₆ between the alignment mark 23 and the polymer waveguide 10 are W ₆ = W ′ ₆ = 200 μm, and the distances W ₅ and W ′ ₅ between the waveguide 3 in the slider and the alignment waveguide 16 are W ₅ = W ′ ₅ = 200 μm. The light 19 used for alignment was light having a wavelength of 633 nm, and the incident light was introduced through the optical fiber 21. The light emitted from the alignment waveguide 16 hits the surface of the waveguide mount 24 or the alignment mark 23 and returns to the alignment waveguide 16. The returned reflected light 62 was separated by a beam splitter 63 and detected by a photodetector 32 such as a photodiode. When the alignment waveguide 16 and the alignment mark 23 are in the same position, the intensity of the reflected light returning to the alignment mark 23 increases. Therefore, if the alignment is performed so that the light detected by the photodetector 32 is maximized, the waveguide 10 can be installed at the optimum position.

  When the reflected light intensity is detected as described above, the alignment mark on the waveguide mount 24 may be a groove 33 formed on the surface of the waveguide mount 24 as shown in FIG. In particular, when the wavelength of the light source for alignment is λ, the distance d from the upper surface of the slider 5 to the bottom of the groove 33 of the alignment mark is d = λx (2n + 1) / 4 (n = 0 or greater integer) As a result, the reflected light on the upper surface of the slider 5 (the end face at the exit of the waveguide 16) interferes with the reflected light on the bottom of the groove 33 of the alignment mark, and the intensity of the light returning to the alignment waveguide 16 becomes weaker. . Therefore, when the return light is adjusted so as to be weakest, the waveguide 10 can be arranged at the optimum position.

  When the reflected light intensity is detected as described above, background light such as light reflected from the bottom surface of the slider 5 enters the photodetector 32 in addition to the reflected light from the alignment mark 23. When background light is incident in this way, the signal / noise ratio of the detection signal decreases. In order to remove the influence of the background light, the position of the waveguide mount 24 may be modulated. That is, the position of the holder 28 of the waveguide mount 24 is vibrated in a sine wave shape in the x direction at a frequency f using a piezoelectric element. At this time, the intensity of the light reflected by the alignment mark 23 and returning to the alignment waveguide 16 vibrates at the frequency f. On the other hand, the intensity of the reflected light from the portion not hitting the alignment mark 23 does not change. Therefore, by extracting the component that vibrates at the frequency f from the light intensity detected by the detector 32, the reflected light component from the alignment mark 23 can be extracted. In this example, the vibration amplitude of the holder 28 is 1 μm, the frequency f is 1 kHz, and a component that vibrates at a frequency of 1 kHz is extracted by a lock-in amplifier. When the vibration components are adjusted so as to be the largest, the waveguide 10 can be arranged at the optimum position. After the alignment, the vibration of the holder 28 was stopped and the waveguide holder 24 was fixed to the slider 5. In the above example, the waveguide 10 side is vibrated, but the slider 5 and its pedestal 20 may be vibrated.

  When the reflected light intensity is detected as described above, it is possible to detect the inclination of the waveguide mount 24 as shown in FIG. That is, when the waveguide mount 24 is tilted, the intensity of the light 62 returning to the alignment waveguide 16 side differs between the two alignment marks 23 (A, B) for the following reason. Since the reflected light 64 from the end face of the alignment waveguide 16 and the reflected light 65 from the alignment mark 23 interfere with each other, when the distance (Da and Db) from the slider upper surface to the alignment mark 23 (A, B) changes, The intensity of the light 62 returning to the alignment waveguide 16 side changes.

  When the waveguide mount 24 is inclined, the distance from the slider upper surface to the alignment mark is different in each alignment mark 23 (A, B) (values of Da and Db are different). Therefore, the intensity of the light 62 returning to the alignment waveguide 16 side differs between the alignment marks A and B.

  When the inclination of the waveguide mount 24 is large, the reflected light 65 from the alignment mark 23 travels obliquely. At this time, since the light intensity coupled to the alignment waveguide 16 depends on the distances (Da and Db) from the slider upper surface to the alignment mark 23, the light intensity coupled to the alignment waveguide 16 is the same as that of the alignment mark A. Different in B.

  Therefore, when the intensity of the light 62 returning to the alignment waveguide 16 side is matched so that the alignment marks A and B are equal, the waveguide mount 24 can be installed so that the inclination φ becomes zero. The intensity of light emitted from the emission end 18 of the alignment waveguide 16 is not necessarily equal between the alignment marks A and B. This is because the amount of light introduced into the alignment waveguide 16 changes depending on the distance (shift amount) between the reference point on the base and the reference point on the slider side when the slider 5 is placed on the base 20. This is because the amount of light introduced into the alignment waveguide 16 is not necessarily equal. In order to correct this, before placing the waveguide mount 24 on the slider 5, the intensity of the light emitted from the emission end 18 of the alignment waveguide 16 is measured, and the photodetector is used as the basis. 32 signal strengths may be corrected. For example, before the waveguide mount 24 is placed on the slider 5, it is assumed that the intensity of light emitted from the emission end 18 of the alignment waveguide 16 is PA and PB in the alignment marks A and B. When the signal intensity of the photodetector 32 on each of the A side and B side is SA and SB, the signal intensity on the B side is multiplied by PA / PB, and SA and (SB / PA / PB) are compared. It is possible to correct a difference in intensity of light emitted from the emission end 18 of the alignment waveguide 16. Further, instead of correcting the signal intensity of the detector 32, adjustment may be made by changing the intensity of the incident light 19 (light intensity of the light source). That is, the intensity of the light source may be adjusted so that the intensity of the light emitted from the emission end 18 of the alignment waveguide 16 is equal in the alignment marks A and B.

In the above alignment, a flat alignment mark is used. However, as shown in FIG. 20, a groove 33 having a different depth depending on the location may be used. For example, in the example of FIG. 20A, the hemispherical groove 33 is formed. The diameter d1 was 1 μm. In the example of FIG. 20B, a groove 33 having a square pyramid shape is formed. This groove 33 was produced by using anisotropic etching of SiO ₂ . The width d2 of the groove 33 was 1 μm. When the groove 33 having such a shape is used, the reflected light 65 from the alignment mark does not travel isotropically. Therefore, the intensity of the reflected light coupled to the alignment waveguide 16 depends on the distance D from the slider upper surface to the alignment mark groove 33. Therefore, the inclination of the waveguide mount 24 can be detected by detecting the return light intensity 62 at the A, B, and two alignment marks 23. In the above example, a groove is used, but a protrusion may be used.

The absolute position in the z direction of the waveguide mount 24 may be adjusted using the method of detecting the reflected light intensity as described above. That is, the absolute position in the z direction can be adjusted by the following method.
Method 1: When grooves having different depths are used depending on the location, the intensity of the light 62 returning to the alignment waveguide 16 changes when the position of the waveguide mount 24 in the z direction changes. Therefore, the absolute position in the z direction can be determined based on the magnitude of the absolute value of the return light intensity.
Method 2: When the shape of the alignment mark is flat, the reflected light 64 from the exit end face of the alignment waveguide 16 and the reflected light 65 from the alignment mark 23 interfere with each other, so the distance from the slider upper surface to the alignment mark 23 ( When d) changes, the intensity I of the light 62 returning to the alignment waveguide 16 side changes. At this time, there is a relationship of I = I ₀ cos ² (2dπ / λ) between the intensity I and the distance d (I ₀ is a constant, and λ is a wavelength). Since there is periodicity in this way, the value of d cannot be determined simply by detecting the intensity I. In order to determine the absolute value of d, light of a plurality of wavelengths is introduced into the alignment waveguide 16, and the return light 65 is separated for each wavelength using a filter or the like. At this time, the return light intensity of each wavelength varies with a different period with respect to the distance d. Therefore, the absolute value of the distance d can be known by measuring the return light intensity of each wavelength. Thus, by knowing the absolute value of the distance d, the thickness of the adhesive between the waveguide mount 24 and the slider 5 can be accurately adjusted (the thickness of the adhesive can be adjusted with respect to the mount 24 and the slider 5). When pressing in the direction of, it is done by adjusting the pressing weight).

  In the first embodiment, the number of alignment waveguides 16 is two, but may be three or more. For example, in the example of FIG. 21, two are formed on a straight line including the recording waveguide 3 and two are formed on a straight line shifted from the recording waveguide 3 in the longitudinal direction (y direction) of the slider. When the alignment waveguide 16 is thus formed and the reflected light intensity is detected, the inclination of the waveguide mount 24 relative to the slider 5 can be detected not only in the x direction but also in the y direction.

When the alignment is performed while measuring the transmitted light intensity and the reflected light intensity as described above, the alignment light may be light having a shorter wavelength than the light used for recording. For example, semiconductor laser light having a wavelength of 450 nm may be used. When light having a short wavelength is used in this way, the light spot diameter at the exit end 18 of the alignment waveguide 16 can be reduced, so that the resolution with respect to the position is improved. In order to reduce the light spot diameter, it is necessary to reduce the widths W ₃ and W ₄ of the alignment waveguide 16. In this example, W ₃ = W ₄ = 250 nm. However, when detecting light transmitted through the waveguide mount 24, the light needs to pass through the waveguide mount 24, and thus may not have a short wavelength.

When the alignment is performed while measuring the transmitted light intensity and the reflected light intensity as described above, the spot diameter of the emitted light is formed by forming the minute opening 34 on the emission end face of the alignment waveguide 16 as shown in FIG. May be reduced. In the example of FIG. 22, a light shielding film made of chromium is formed on the emission end face, and a square minute opening 34 having a side length W ₂₁ of 200 nm is formed in the central portion of the alignment waveguide 16. By this minute opening 34, near-field light is generated, and a light spot smaller than the wavelength can be created. Therefore, the resolution with respect to the position is improved. Such near-field light may be generated by using a C-shaped aperture or a scatterer having a shape such as a triangle, a rectangle, or a sphere instead of the square minute aperture.

  In the first embodiment, the alignment mark is formed on the waveguide mount 24. However, the polymer waveguide 10 may be disposed directly on the flexure 40 of the suspension, and the alignment mark may be formed on the flexure 40.

  Further, the alignment mark may be formed on the polymer waveguide 10. For example, the alignment mark may be formed by forming irregularities in the clad part of the polymer waveguide 10 or its peripheral part, or by aligning materials having different refractive indexes.

Further, in place of the alignment mark, an alignment waveguide 38 is formed as shown in FIG. 23, and the position of the mount 24 is aligned by detecting the light intensity coupled to the alignment waveguide 38 on the mount. May be. In the example of FIG. 23, two alignment waveguides 38 are formed beside the waveguide 10 between the light source and the slider. As the waveguide, a polymer waveguide was used and disposed on the flexure 40 of the suspension 13. The alignment waveguide 38 was made of the same material as the polymer waveguide 10. The end face 12 of the waveguide 38 was cut at 45 degrees as in the waveguide 10. Thereby, the light emitted from the alignment waveguide 16 in the slider 5 is coupled to the waveguide 38. A mirror 27 is formed in the middle of the waveguide 38 so that light is emitted in the direction of the side surface of the slider 5. The light emitted in the side direction of the slider 5 was collected by a lens and detected by a detector such as a photodiode. The distances W ₆ and W ′ ₆ between the waveguide 10 between the light source and the slider and the alignment waveguide 38 on the waveguide 10 side are the distances W ₅ and W between the alignment waveguide 16 and the recording waveguide 3 in the slider. 'Made equal to ₅ . In this example, W ₅ = W ′ ₅ = W ₆ = W ′ ₆ = 200 μm. When the light coupled to the two waveguides 38 is matched so as to be the strongest, the position of the waveguide 10 can be set at an optimum position. Note that the alignment waveguide 38 may be extended to the vicinity of the light source as shown in FIG.

Next, the configuration of the thermally-assisted magnetic head according to the second embodiment and the method for fixing the slider and the semiconductor laser will be described with reference to FIGS. In the thermally-assisted magnetic head 102 according to the second embodiment, the semiconductor laser 41 as a light source is directly disposed on the slider 5.
As shown in FIG. 25, the semiconductor laser 41 is disposed on the slider 5. A mirror 42 was formed on one emitting surface of the semiconductor laser 41 by etching the element at an angle of 45 degrees. Thereby, the laser beam is emitted in a direction perpendicular to the upper surface of the slider 5. Light emitted from the semiconductor laser 41 was directly introduced into the waveguide 3 in the slider. In practice, as shown in FIG. 26, the semiconductor laser 41 was fixed to a laser mount 43, and the laser mount 43 was fixed to a holder 44 by a vacuum chuck or the like. The position of the holder 44 was moved by a fine movement stage. On the surface of the semiconductor laser 41, as in the case of the polymer waveguide, alignment marks were formed on both sides of the laser emission point. In this embodiment, the grooves 33 having a square shape are formed on both sides. The depth of the groove 33 was such that the distance D from the bottom of the groove 33 to the upper surface of the slider 5 was 1/4 of the wavelength of the alignment light source. Light 19 having a wavelength of 450 nm was introduced into the alignment waveguide 16. By detecting the reflected light 62 from the groove 33 of the alignment mark, the position is adjusted so that the position of the alignment mark groove 33 and the position of the alignment waveguide 16 coincide with each other. A semiconductor laser 41 was fixed on the slider 5.

  FIG. 27 shows a modification of the second embodiment. In this example, a deep groove for inserting the semiconductor laser 41 is formed on the upper side of the laser mount 43, and the semiconductor laser 41 is fixed to the bottom thereof. Under the emission point of the semiconductor laser 41, an opening 46 for transmitting the recording laser beam was formed. The light transmitted through the opening 46 was coupled to the recording waveguide 3. Two openings 45 for alignment are formed on the side of the semiconductor laser 41 at the bottom of the groove. The position of the semiconductor laser 41 with respect to the laser mount 43 was adjusted in advance so that the alignment aperture 45 and the position of the emitted light of the semiconductor laser 41 were aligned. Light having a wavelength of 450 nm was introduced into the alignment waveguide 16. When the alignment waveguide 16 and the alignment opening 45 are in the same position, the light emitted from the alignment waveguide 16 passes through the opening 45. It was detected by a photodetector 31 such as a photodiode. A CCD element may be used instead of the photodiode. If the position of the laser mount 43 is adjusted so that the light transmitted through the opening 45 is the strongest, the position of the semiconductor laser 41 can be adjusted to the optimum position.

Next, the configuration of the thermally-assisted magnetic head according to the third embodiment and the method for fixing the waveguide mount 24 on which the semiconductor laser is mounted on the slider will be described with reference to FIG.
As shown in FIG. 28, in the thermally-assisted magnetic head 104 according to the third embodiment, a semiconductor laser 41 having a mirror formed at one end is mounted on a waveguide mount (support member) 24 ′, and the waveguide mount 24 is mounted. 'Is fixed to the slider 5. The electrode of the semiconductor laser 41 was supplied from an electrode pad formed on the waveguide mount 24 '. A waveguide 66 is formed on the waveguide mount 24 '(in the figure, 66 indicates a core portion of the waveguide). Mirrors 68 and 12 were formed at both ends of the waveguide 66 (manufactured by obliquely etching). The light emitted from the semiconductor laser 41 is reflected by the mirror 68 and introduced into the waveguide 66. The light transmitted through the waveguide 66 is reflected by the mirror 12 and is emitted in a direction perpendicular to the surface of the waveguide mount 24 ′. The material of the waveguide mount 24 'is Si. This material may be another material such as AlN or AlTiC. The material of the waveguide core was SiOxNy, and the refractive index was adjusted by changing the ratio of O and N. The material of the clad 67 was SiO ₂ . On both sides of the emission end of the waveguide 66, grooves 33 serving as alignment marks were formed by etching. The shape of the groove 33 was a square having a side length of 1 μm. The waveguide 66 was aligned by observing the light emitted from the alignment waveguide 16 provided on the slider side and the groove 33 of the alignment mark on the waveguide mount 24 'side.

  In the above embodiment, the optical coupling efficiency between the waveguide 66 formed on the waveguide mount 24 ′ and the waveguide 3 in the slider is equal to the mode field diameter of the waveguide 66 and the mode field diameter of the waveguide 3. It becomes the highest when it becomes. The optical coupling efficiency between the waveguide 66 and the semiconductor laser 41 is also highest when the mode field diameter of the waveguide 66 and the spot diameter of the emitted light from the semiconductor laser 41 are equal. When the mode field diameter of the waveguide 3 and the spot diameter of the emitted light from the semiconductor laser 41 are different, the mode field diameter of the waveguide 66 is increased on the semiconductor laser 41 side in order to increase the overall optical coupling efficiency. The mode field diameter in the waveguide 66 is preferably changed so that it is equal to the spot diameter of the emitted light of the semiconductor laser and equal to the mode field diameter of the waveguide 3 on the waveguide 3 side. For that purpose, the width of the waveguide in the waveguide 66 may be changed as shown in FIG. 5 or the mode field diameter may be changed by making the core of the waveguide 66 a two-layer structure as shown in FIG. .

  FIG. 29 shows a modification of the third embodiment. In this example, an alignment waveguide 38 for receiving light emitted from the alignment waveguide 16 in the slider is formed on the waveguide mount 24 '. Like the waveguide 66, mirrors were formed at both ends of the alignment waveguide 38 by etching. When the waveguide mount 24 'is arranged so that the light from the waveguide 66 in the waveguide mount 24' is most efficiently coupled to the recording waveguide 3 in the slider, the alignment guide in the slider is arranged. The alignment waveguide 38 is formed on the waveguide mount 24 'so that the light from the waveguide 16 is most efficiently coupled to the alignment waveguide 38 on the waveguide mount 24'. The alignment light coupled to the alignment waveguide 38 is emitted in a direction perpendicular to the surface of the waveguide mount 24 ′ by the output-side mirror. The emitted light 69 was detected by a photodetector such as a photodiode. By adjusting the position of the waveguide mount 24 ′ so that the intensity of light detected by this photodetector is maximized, the waveguide mount 24 ′ is installed at the optimum position.

  In the third embodiment, the light emitted from the alignment waveguide 16 in the slider is received by the alignment waveguide 38 on the waveguide mount, and the position is adjusted by detecting the light 69 emitted from the opposite side. did. On the other hand, light is introduced from the opposite side of the alignment waveguide 38 on the waveguide mount (arrow 70 in FIG. 29), and the light is introduced into the alignment waveguide 16 in the slider. It may be made to enter from. In this case, the emitted light is detected from the medium facing surface side (floating surface side) of the alignment waveguide 16 in the slider. By aligning the emitted light so as to be maximized, the waveguide mount 24 'can be installed at the optimum position. Note that the alignment waveguide 38 formed on such a waveguide mount may simply be used as an alignment mark for indicating the emission position of the central waveguide 66. That is, light is put into the alignment waveguide 38 as indicated by an arrow 70, and light is emitted from the opposite side. If the emission point of the central waveguide 66 is positioned on a straight line connecting the positions of the emission points, the light emitted from the alignment waveguide 38 can be used as a flashing alignment mark. That is, the exit position of the alignment waveguide 38 can be known by observing it with the observation optical system.

  FIG. 30 shows the overall configuration of a recording / reproducing apparatus equipped with the heat-assisted magnetic head according to the first embodiment. The slider 5 of the heat-assisted magnetic head is fixed to the suspension 13 and floats on the magnetic disk 14 with a flying height of 10 nm or less, and is positioned at a desired track position on the magnetic disk 14 by an actuator including a voice coil motor 49. The magnetic disk 14 is fixed and rotated by a spindle 53 that is rotationally driven by a motor. The semiconductor laser 41 is fixed on the submount 51 with solder, and the submount 51 is fixed to the base of the arm to which the suspension 13 is attached (the part called e-block). The driver of the semiconductor laser 41 is mounted on a circuit board 52 arranged beside the e-block. The circuit board 52 is also mounted with a driver for a thermally assisted magnetic head. The submount 51 on which the semiconductor laser 41 is mounted may be disposed directly on the e-block or may be disposed on the circuit board 52. Light emitted from the semiconductor laser 41 is coupled to the waveguide 10 by coupling the waveguide 10 directly to the semiconductor laser 41 or by inserting a lens between the waveguide 10 and the semiconductor laser 41. At this time, the waveguide 10, the semiconductor laser 41, and elements and components for coupling the waveguide 10 may be integrated as a module and disposed on the e-block or a circuit board next to the e-block. . Further, in order to extend the life of the semiconductor laser 41, the inside of the module may be hermetically sealed. The recording signal is generated by the signal processing circuit 54, and the recording signal and the power supply for the semiconductor laser are supplied to the circuit board 52 through an FPC (flexible printed circuit) 50. At the moment of recording, a magnetic field is generated by a coil provided in the slider 5 and at the same time, the semiconductor laser 41 emits light, thereby forming a recording mark (data) on the magnetic disk 14. Data recorded on the magnetic disk 14 is reproduced by the magnetic reproducing element 4 formed in the slider 5. The signal processing of the reproduction signal is performed by the signal processing circuit 54.

  In the recording apparatus shown in FIG. 30, the heat-assisted magnetic head according to the first embodiment is mounted, but the basic configuration is the same when the heat-assisted magnetic head according to the second and third embodiments is mounted. Only the mounting position of 41 differs.

  The present invention is applicable to a heat-assisted magnetic recording apparatus that realizes a high recording density.

1 ... near-field light generating element,
2 ... Main pole,
3. Recording waveguide,
4 ... reproducing element,
5 ... Slider,
6 ... Magnetic head part,
7 ... Coil,
8 ... Magnetic pole,
9 ... Shield,
10: Polymer waveguide,
11 ... clad,
12 ... Mirror,
13 ... Suspension,
14 ... Magnetic disk,
14 '... recording layer,
15 ... clad,
16 ... waveguide for alignment,
17 ... Medium facing surface (floating surface),
18 ... the emission end,
19: Incident light,
20 ... pedestal,
21: Optical fiber,
22 ... Microlens,
23 ... Alignment mark,
24, 24 '... Waveguide mount,
25 ... Intermediate refractive index layer,
27 ... Mirror,
28 ... Holder,
29 ... Observation optical system,
30: Photodetector,
31 ... Lens,
32. Photodiode or CCD element,
33 ... Groove,
34 ... a small opening,
38 ... Waveguide for alignment,
40 ... flexure,
41. Semiconductor laser,
42 ... Mirror,
43 ... Laser mount,
44 ... Holder,
45 ... Alignment opening,
46. Recording laser beam transmitting aperture,
56 ... vertex where near-field light is generated,
59 ... light shielding film,
60: distributed refractive index lens,
61 ... outgoing light,
62 ... reflected light,
63 ... beam splitter,
64 ... reflected light from the emission end face,
65 ... reflected light from the alignment mark,
66 ... waveguide,
67 ... Clad,
68. Incident side mirror,
69. Light emitted from the alignment waveguide;
70: Light incident on the alignment waveguide;
100, 102, 104: Thermally assisted magnetic head.

Claims (8)

A light source;
And the medium facing surface, the magnetic head for generating a magnetic field, a light irradiation unit provided in the vicinity of the medium facing surface in the vicinity of the magnetic head, to the light irradiation section light emitted from the light source A thermally assisted magnetic head comprising: a slider having a guiding waveguide;
The alignment guide on the side of the waveguide of the slider possess two or more, has an alignment mark on the side of the light emitting point of the light source, said light source is mounted on the opposite side of the medium facing surface of the slider thermally assisted magnetic head is characterized in that there. 2. The heat-assisted magnetic head according to claim 1, wherein the light source is a semiconductor laser . 2. The heat-assisted magnetic head according to claim 1, wherein the alignment mark is a groove . Preparing a laser substrate having alignment marks on both sides of the light emission point, or a supporting member having a first waveguide for introducing light and having alignment marks on both sides of the first waveguide;
A medium facing surface, a magnetic head unit that generates a magnetic field, a light irradiation unit provided in the vicinity of the magnetic head unit and in the vicinity of the medium facing surface, and an incident end on the opposite side of the medium facing surface. Preparing a slider having a second waveguide for guiding light to the light irradiation section, and alignment waveguides having the same spacing as the alignment marks on both sides of the second waveguide;
A step of disposing the light source or the support member on the side opposite to the medium facing surface of the slider with the side having the alignment mark facing;
Introducing light different from light introduced into the second waveguide from the medium facing surface side into the alignment waveguide of the slider;
Adjusting the position of the slider and the light source or support member so that the position of the light emitted from the alignment waveguide and the alignment mark overlap;
Fixing the slider and the light source or the support member;
A method for assembling a thermally assisted magnetic head , comprising: 5. The method of assembling a thermally-assisted magnetic head according to claim 4 , wherein the step of adjusting the positions of the slider and the light source or the support member detects the intensity of light transmitted through the alignment mark, and the detected light intensity is maximum. Alternatively , a method of assembling a thermally assisted magnetic head , characterized by being a step of adjusting to a minimum . 5. The method of assembling a thermally-assisted magnetic head according to claim 4 , wherein the step of adjusting the position of the slider and the light source or the support member detects the intensity of light reflected by the alignment mark, and the detected light intensity is A method of assembling a thermally assisted magnetic head , characterized by being a step of adjusting to a maximum or minimum . 7. The method of assembling a thermally-assisted magnetic head according to claim 6 , wherein the step of adjusting the positions of the slider and the light source or the support member detects the intensity of light reflected by the alignment mark for each of the alignment waveguides. A method for assembling a thermally assisted magnetic head , comprising the step of adjusting the inclination of the light source or the support member by comparing the respective intensities . The method of assembling the thermally-assisted magnetic head according to claim 5 or 6 , wherein the step of adjusting the position of the slider and the light source or the support member vibrates the light source or the support member, and includes the detected light intensity, A method for assembling a thermally-assisted magnetic head , comprising the step of detecting a component modulated at the frequency of the vibration .

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