JP4848447B2 - Information recording / reproducing head and heat-assisted magnetic recording apparatus - Google Patents

Description

  The present invention relates to an information recording / reproducing head having a mechanism for introducing electromagnetic energy such as light and a heat-assisted magnetic recording apparatus equipped with the information recording / reproducing 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. In order 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 recording method, 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 is possible, and a recording density of 1 Tb / in ² or more can be realized.

  In the heat-assisted magnetic recording method, it is necessary to heat the vicinity of the magnetic pole for applying a 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, the semiconductor laser is mounted on the flying slider or guides light from the suspension to the flying slider using a waveguide such as an optical fiber (Non-Patent Document 2). Alternatively, a semiconductor laser may be placed on a suspension, light may be propagated from there to a slider by free propagation light, and the light may be coupled to a waveguide by a grating coupler (Non-patent Document 3).

  However, in the thermally assisted magnetic recording apparatus, the semiconductor laser for light irradiation is disposed on the suspension, the arm located at the base of the suspension, or the flying slider. When placed on the suspension or arm, the light emitted from the semiconductor laser is guided into the slider through a waveguide or free propagation. When the light is guided by the waveguide, the intensity of light transmitted through the waveguide changes due to disturbances such as vibration and temperature change applied to the waveguide connecting the semiconductor laser and the slider. As a result, the intensity of light reaching the slider changes. Also, when the light is guided to the slider by free propagation and the propagated light is coupled to the waveguide formed beside the magnetic pole by the grating coupler, the proportion of the propagation light coupled to the waveguide formed beside the magnetic pole (coupling) (Efficiency) depends on the incident angle of light incident on the grating. Therefore, when the slider or suspension vibrates, the direction of the light incident on the grating changes, so the coupling efficiency to the waveguide changes, and as a result, the intensity of the light transmitted through the waveguide formed beside the magnetic pole fluctuates. End up. When a grating coupler is used, the coupling efficiency to the waveguide depends on the wavelength. When the temperature changes, the wavelength of the semiconductor laser light fluctuates, and the coupling efficiency fluctuates. As a result, the intensity of light traveling through the waveguide formed beside the magnetic pole varies.

When the semiconductor laser is placed on the flying slider, in order to couple the emitted light from the semiconductor laser to the waveguide formed beside the magnetic pole, the semiconductor laser is placed so that the emitting end of the semiconductor laser is in contact with the incident end of the waveguide. Deploy. Alternatively, the light emitted from the semiconductor laser may be collected by a microlens placed on a slider, and the light may be introduced into the waveguide by placing the incident end of the waveguide at the focal point. At this time, the amount of light transmitted through the waveguide may change due to the following factors.
(1) Due to deterioration of the adhesive and solder that fixes the semiconductor laser and the microlens, the position of the semiconductor laser and the microlens shifts when used for a long time, and the coupling efficiency between the waveguide and the incident light changes. .
(2) The heat generated from the semiconductor laser or the heat generated in the drive causes thermal deformation of the slider and the optical element, and the coupling efficiency between the waveguide and the incident light changes.
(3) In order to increase the coupling efficiency between the waveguide and the incident light, it is preferable that the diameter of the light distribution in the waveguide is approximately the same as the spot diameter of the incident light. Here, the mode field diameter refers to the width of the light intensity distribution in the waveguide. Usually, the light spot diameter at the emitting end of the semiconductor laser is several μm. Even if this is condensed by a lens, it can be limited to only about 1 to 2 μm because of the diffraction limit. Therefore, it is preferable to increase the mode field diameter to about 1 to 2 μm. On the other hand, in the heat-assisted magnetic recording, it is preferable that the diameter of the light spot is as small as the recording bit. If the diameter of the light spot is larger than the recording bit, the adjacent bit is heated and the recording bit is erased. In order to solve the problem of adjacent bit erasing, a minute light spot is generated using a near-field light generating element. For example, a near-field light generating element such as a triangular metal scatterer is disposed at the exit end of the waveguide in the slider (see Non-Patent Document 4). At this time, in order to increase the efficiency of generating near-field light, it is preferable to make the spot diameter of light incident on the near-field light generating element as small as possible. That is, it is better to make the mode field diameter in the waveguide as small as possible. As one method that satisfies the above requirements, a method is conceivable in which the width of the waveguide is increased at the entrance of the waveguide, and the width of the waveguide is gradually decreased as the near-field light generating element is approached. In this case, since the width is large at the waveguide entrance, in addition to the fundamental mode, higher-order propagation modes may be excited. When the higher-order mode is excited in this way, the higher-order mode and the fundamental mode cause interference in the waveguide. The light intensity distribution in the waveguide changes due to a disturbance such as temperature. As a result, the intensity of light transmitted to the narrowed portion of the waveguide fluctuates.

  Although the light intensity fluctuation due to disturbance such as temperature change and vibration has been described above, the light intensity also changes due to the deterioration of the semiconductor laser over time. If the intensity of light incident on the surface of the medium fluctuates due to disturbances such as temperature changes and vibrations and deterioration of the semiconductor laser over time, the heating temperature of the medium changes. As a result, the recording condition changes every time, and stable recording cannot be performed (bit error rate increases).

  As a conventional example of a method for stabilizing the intensity of light emitted from a semiconductor laser, for example, as shown in FIG. 2, a photodetector (photodiode) 55 is provided behind the semiconductor laser 31, and the detection output is obtained. There is a method of controlling the drive current of the semiconductor laser 31 by feedback. Further, in Patent Document 1, by providing a mechanism for detecting fluctuations in light intensity coupled in a waveguide, fluctuations in light intensity due to disturbances such as temperature changes and vibrations and deterioration with time of the light source are reduced, and stable recording can be performed. It is proposed to be realized.

JP 2008-204586

H. Saga, H. Nemoto, H. Sukeda, and M. Takahashi, Jpn. J. Appl. Phys. 38, Part 1, pp. 1839 (1999) Kenji Kato et al., Jpn. J. Appl. Phys. Vol. 42, pp. 51025106 (2003) Edward C. Gage et.al, Technical digest of Magneto-optical Recording Internal Symposium 2006, p2 (2006) T. Matsumoto et.al, Optics Letter, Vol.31, p259, (2006)

  However, in the above conventional example, it is necessary to provide a photodetector in or on the slider in order to control the light intensity. In general, a semiconductor detector such as a PIN photodiode is used as the photodetector. However, since the manufacturing process of the semiconductor detector is significantly different from the manufacturing process of the magnetic head slider, it is difficult to integrally form at the wafer level. For this reason, a hybrid configuration in which the slider is assembled after being manufactured by a process separate from that of the slider is caused, resulting in an increase in manufacturing cost and a decrease in yield. In addition, there is a problem that the detection accuracy is reduced due to variations during assembly.

  The most accurate control in heat-assisted recording is the temperature of the recording medium, that is, the amount of energy given to the local area of the recording medium. In the above conventional example, the control is close to the recording medium. The amount of light applied to the near-field light generating device and the waveguide that guides light to the near-field light generating device is not necessarily reflected by the amount of heat absorbed by the near-field light generating element itself. This is because the relationship between the amount of heat absorbed by the near-field light generating element and the amount of irradiation varies depending on interference conditions and fluctuations in the wavelength of light. That is, the conventional example has a problem that the amount of heat given to the near-field light generating element itself cannot be detected accurately.

A first object of the present invention is to provide an information recording / reproducing head that can be integrally formed in a slider without increasing the manufacturing cost and can monitor the amount of energy absorbed by the near-field light generating element. There is to do.
A second object of the present invention is to provide a heat-assisted magnetic recording apparatus capable of controlling the amount of energy absorbed by the near-field light generating element.

In order to achieve the first object of the present invention, the following means were used.
(1) A slider, a magnetic recording / reproducing element provided on the slider, a near-field light generating element provided on the air bearing surface side of the slider, and a guide for supplying light energy to the near-field light generating element An information recording / reproducing head having a waveguide includes a first temperature detecting element for detecting the temperature of the near-field light generating element, and a pair of electrodes electrically connected to the first temperature detecting element.
This makes it possible to accurately detect the temperature of the near-field light generating element due to the irradiation of light energy, so that the amount of energy absorbed by the near-field light generating element can be monitored.
(2) The first temperature detecting element is also used as the near-field light generating element.
(3) The first temperature detection element may be a thermal resistance detection element provided adjacent to the near-field light generating element via an insulating film. Since the thermal resistance detection element has a simple structure, temperature detection is possible without an increase in manufacturing cost.
(4) It is desirable that the thermal resistance of the thermal resistance detecting element is equal to or smaller than the thermal capacity of the near-field light generating element itself. As a result, sufficient detection sensitivity for the introduced energy can be secured, so that the energy introduced into the near-field light generating element can be detected more accurately and at high speed.
(5) In addition to the first temperature detection element, it is desirable that a second temperature detection element for ambient temperature calibration is disposed in a portion away from the waveguide and the near-field generating element. This makes it possible to detect the influence of temperature changes (such as ambient temperature changes) caused by factors other than the introduced light, so that the introduced light power control is performed by offsetting the effects of temperature changes caused by factors other than the introduced light. It becomes easy.
(6) a slider, a magnetic recording / reproducing element provided on the slider, a near-field light generating element provided on the air bearing surface side of the slider, and a guide for supplying light energy to the near-field light generating element. An information recording / reproducing head having a waveguide has a pair of electrodes that are electrically connected to the near-field light generating element.
This makes it possible to detect the electrical characteristics (electric resistance, etc.) of the near-field light generating element itself, so the temperature of the near-field light generating element due to light energy irradiation is accurately detected by the thermal resistance effect, etc. This makes it possible to monitor the amount of energy absorbed by the near-field light generating element. Depending on the structure of the near-field light generating element, it is possible to monitor the influence of temperature by measuring capacitance and inductance in addition to resistance measurement. It is also possible to control the amount of energy introduced into the near-field light generating element. For example, energy control according to the flying height can be performed by a capacitance monitor.

A typical heat-assisted magnetic recording apparatus for achieving the second object includes a magnetic recording medium, and further includes a slider, a magnetic recording / reproducing element provided on the slider, and a flying surface side of the slider. A provided near-field light generating element; a waveguide for supplying optical energy to the near-field light generating element; a first temperature detecting element for detecting a temperature of the near-field light generating element; An information recording / reproducing head having a pair of electrodes electrically connected to one temperature detection element, and passing a current through the pair of electrodes to the first temperature detection element, A resistance value is detected, and the intensity of light energy introduced into the waveguide is controlled based on the detected resistance value.
This makes it possible to accurately monitor the temperature of the near-field light generating element due to light energy irradiation and control the temperature to be constant, that is, to control the amount of light absorption to be constant. Realization of recording becomes easy.

  According to the present invention, the element for monitoring the amount of energy absorbed by the near-field light generating element can be integrally formed in the slider without increasing the manufacturing cost. In the heat-assisted magnetic recording apparatus, the amount of energy absorbed by the near-field light generating element can be controlled to an appropriate value.

1 is a diagram illustrating a schematic structure of an information recording / reproducing head according to Example 1. FIG. It is a figure which shows schematic structure of the conventional head for thermal assist recording. 1 is a diagram illustrating an overall configuration of a heat-assisted magnetic recording apparatus according to Example 1. FIG. It is a figure which shows the relationship between input power and near-field light intensity. It is a figure which shows the relationship between the resistance value of a near-field light generating element, and near-field light intensity. It is a figure which shows the method of detecting the temperature of a near field light generation element. 6 is a diagram illustrating a schematic structure of an information recording / reproducing head according to Embodiment 2. FIG. It is a figure which shows an example of the temperature change of the near field light generation element by light irradiation. It is a figure which shows the effect of this invention, and is a figure which shows the relationship between input power and near-field light intensity. 1 is a perspective view of a near-field light generating element according to Example 1. FIG. It is the top view which looked at the near-field light generating element by Example 2 from the air bearing surface side.

  Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a schematic structure of an information recording / reproducing head according to the first embodiment. A near-field light generating element 32 is disposed in the vicinity of the air floating surface (ABS) of the slider 30, and a magnetic recording / reproducing element 34 is provided in the vicinity of the near-field light generating element 32. Although not shown, the magnetic recording element 34 is formed by laminating a recording element composed of a single pole head and a reproducing element composed of a CPP / GMR type sensor element. A semiconductor laser (laser diode unit) 31 that emits light having a wavelength of 780 nm as a light generating / introducing element (light source) is mounted on the surface of the slider 30 opposite to the ABS, and the light emitted from the laser diode unit 31 Is irradiated to the near-field light generating element 32 through the waveguide 33. The waveguide 33 has a refractive index of 1.6 around the core of Ta ₂ O ₅ having a refractive index of 2.1 having a long side of 500 nm and a short side of 300 nm so as to be in a single mode with respect to light having a wavelength of 780 nm. It is a structure covered with a clad made of Al ₂ O ₃ . In this waveguide 33, the mode diameter of the guided light is approximately the same as the size of the waveguide core. That is, the energy of the guided light is substantially confined in the core. The near-field light generating element 32 is connected to the electrode pads 40 and 41 through conducting wires 42 and 43. In the information recording / reproducing head of Example 1, the near-field light generating element 32 is also used as a temperature detecting element (thermal resistance detecting element).

  The near-field light generating element 32 of this embodiment is made of gold (Au) having the shape of an isosceles triangular prism shown in FIG. 9, and has a base W of 100 nm, a hypotenuse L of 130 nm, and a height H of 200 nm. The apex portion of the isosceles triangular prism is processed into an arc shape with a radius of curvature of about 10 nm, and the spot diameter of the generated near-field light is about 25 nm. Returning to FIG. 1, although not shown in detail here, in order to improve the coupling efficiency when the light from the laser diode unit 31 is incident on the waveguide 33, a spot diameter conversion mechanism or the like is provided directly below the laser diode unit. It is good to form in. By irradiating the light coupled to the waveguide 33, the near-field light generating element 32 generates near-field light on the ABS and the surface of the recording medium according to a principle such as plasmon resonance, and the temperature of the medium surface rises. When the power of light applied to the near-field light generating element 32 in the example is about 10 mW, the local temperature of the medium surface magnetic film rises to about 200 degrees. At the same time, the temperature of the near-field light generating element 32 also increases by about 150 degrees, and the resistance of the near-field light generating element 32 increases due to the influence of heat scattering. This is because the near-field light generating element 32 is made of a noble metal such as gold or silver, that is, a good conductor, so that it is affected by scattering of conduction electrons due to thermal fluctuation of the lattice, and as a result, the electric resistance increases. The rate of change in electrical resistance at that time is about 0.4% / degree, and in the case of a temperature change of 150 degrees, the resistance changes by about 60%, and this change can be easily detected.

  Next, the configuration of the heat-assisted magnetic recording apparatus equipped with the information recording / reproducing head according to the first embodiment will be described with reference to FIG. The slider 30 supported by the suspension 12 flies over the magnetic recording medium 11 with a flying height of about 3 nm, and is driven by a voice coil motor (VCM) actuator 79 for track direction access and tracking servo. . Although not described in detail in the present embodiment, an additional actuator composed of a piezo element or the like may be provided on the suspension or the like in order to realize a higher accuracy of track positioning. In addition, a thermally driven actuator is mounted on the slider for precise control of the flying height.

  In the reproduction, a resistance value of a CPP / GMR type sensor element (not shown) mounted on the slider is detected by a reproduction control circuit 51, and equalized by a signal detection circuit 22 incorporated in the controller (SOC) 20. Is sent to the signal processing circuit 25. The signal processing circuit 25 synchronizes based on position data and timing information in the position / address detection circuit 23, and sends the synchronized signal to the demodulation circuit 24. The demodulating circuit 24 performs the demodulating process, and the data subjected to the final processing such as error correction by the decoding circuit 26 is sent to the microprocessor 27 and transferred to the host apparatus 99. The servo circuit 54 controls the VCM actuator 79 based on the data detected by the position / address detection circuit 23.

  At the time of recording, the VCM actuator 79 is servo-controlled based on the position / address signal detected by the position / address detection circuit 23 in the same manner as at the time of reproduction, and the information recording / reproducing head is positioned in the sector designated by the host device 99. After that, the user data encoded by the recording control circuit 52 is supplied to the laser driver 53 to drive the laser unit 31 mounted on the slider 30, and the user data is supplied to the recording element to thermally assist. Make a record. In heat-assisted recording, it is necessary to heat a local area on a magnetic recording medium to an appropriate temperature at the time of recording and apply a recording magnetic field to the portion by a recording element, but in order to heat to an appropriate temperature, It is necessary to precisely control the drive current of the laser diode unit 31. In the present embodiment, the resistance value of the near-field light generating element 32 is detected by the resistance detection circuit 50, thereby monitoring the temperature of the near-field light generating element 32 and driving current of the laser diode unit 31 based on the temperature information. Is precisely controlled.

  FIG. 5 illustrates a resistance value detection method. The constant current source 80 in the resistance detection circuit 50 energizes the near-field light generating element 32 through the electrode pads 40 and 41, and at this time, the voltage between the electrodes is detected by the voltage detection circuit 81, and the resistance value = voltage value. / Calculate the resistance value by calculating the current value. In this embodiment, since the resistance value of the near-field light generating element 32 is as small as about 0.2 ohm at room temperature, the conductor in the 100 nm region immediately adjacent to the near-field light generating element 32 is confined to 10 nm × 10 nm, and the resistance value is set. Is increased to about 400Ω to improve detection sensitivity. When measuring the resistance value, care should be taken because the temperature of the near-field light generating element 32 may rise due to Joule heat if an excessive current is passed. In this embodiment, when a constant current of 2 mA is passed, the Joule heat is 0.15 mW, which is sufficiently smaller than the heat generated by laser irradiation, and the influence of Joule heat can be ignored. In order to improve the accuracy of resistance measurement, it is effective to increase the applied current. In this case, it is preferable to detect the change in voltage synchronously by modulating and driving in pulses to reduce Joule heat.

  Next, a method for controlling the input energy to the near-field light generating element 32 of this embodiment will be described with reference to FIGS. 4A and 4B. FIG. 4A shows the intensity of laser light emitted from the laser diode unit 31, that is, the intensity of near-field light when the input power to the head is controlled to 50 mW and 100 mW. Since it is difficult to directly measure the intensity of the near-field light, a CoPd-based multilayer film medium having a known recording sensitivity was prepared in advance, and the intensity of the near-field light was estimated from the change in the recording state (track width). Here, seven elements were measured. The near-field light intensity varies greatly due to variations in the elements themselves, positional displacement between the laser diode unit 31 and the waveguide 33, changes in the laser interference state, and the like. FIG. 4B shows the measured resistance value of the near-field light generating element 32 at that time. It can be seen that there is a linear correlation between the intensity of near-field light and the resistance value.

Since there is a linear correlation between the intensity of near-field light and the resistance value, feedback control is performed so that the resistance value of the near-field light generating element 32 is constant (target), thereby causing element variations, interference conditions, and the like. Regardless of this, the intensity of near-field light can be precisely controlled. Actually, the recording control circuit 52 performs this control. The bandwidth of the feedback control is set to 10 to 100 kHz so as to cope with temperature fluctuations of the laser and the like, mode hopping and the like. As shown in FIG. 7, since the temperature of the near-field light generating element 32 responds with a time constant of 1 μs or less, control in a band up to about 1 MHz is possible, but interference with recording data (crosstalk), etc. In consideration of the above, the control band is set to 100 kHz or less. FIG. 8 shows that the intensity of near-field light can be controlled to target values (1 × 10 ¹² , 2 × 10 ¹² W / m ² ) using this control method. It can be seen that the near-field light intensity error is suppressed to about 2 to 3%, which is not a problem in practice.

  The effect of the present embodiment will be described with reference to FIG. Although the amount of energy introduced (input power) varies due to variations in device manufacturing and assembly errors, the near-field light intensity is controlled to be constant. This is because the temperature of the near-field light generating element has a correlation with the amount of energy given to the near-field light generating element. This shows that the amount of energy to be controlled can always be controlled to an appropriate value. That is, since the recording conditions for high-density recording using energy assist can always be appropriately controlled, the quality of the recording signal is improved and the reliability is improved. In addition, there is no need for an assembling operation that causes a reduction in the productivity of device components such as a head, and thus there is no increase in manufacturing cost.

  In this example, the resistance value of the near-field light generating element itself was measured, but a metal element (thermal resistance element) dedicated to temperature detection provided adjacent to the near-field light generating element 32 and electrically insulated was used. May be. In that case, the temperature detecting metal element is preferably provided via an insulating film of about 1 to 2 nm so as to be thermally coupled to the near-field light generating element sufficiently. In this case, since the metal material and shape of the temperature detecting element can be selected independently of the near-field light generating element itself, a material having an appropriate resistance value suitable for resistance detection can be selected.

FIG. 6 shows a schematic structure of an information recording / reproducing head according to the second embodiment. A near-field light generating element 32 ′ is disposed in the vicinity of the air floating surface (ABS) of the slider 30. In FIG. 6, the magnetic recording / reproducing element is omitted. A laser diode unit 31 that emits light having a wavelength of 780 nm is mounted as a light generating / introducing element (light source) on the surface opposite to the ABS of the slider, and the light emitted from the laser diode unit 31 passes through the waveguide 33 in the vicinity. The field light generating element 32 'is irradiated. The waveguide 33 is made of SiO ₂ having a refractive index of 1.5 around the core of Ta ₂ O ₅ having a refractive index of 2.1 having a long side of 450 nm and a short side of 300 nm so as to be in a single mode with respect to light having a wavelength of 780 nm. _This is a structure covered with a clad made of ₂ . In this waveguide 33, the mode diameter of the guided light is approximately the same as the size of the waveguide core. That is, the energy of the guided light is substantially confined in the core. The near-field light generating element 32 ′ is connected to the electrode pads 40 and 41 through the conductive wires 42 and 43. In the present embodiment, a temperature detecting element 35 for ambient temperature calibration is provided in a place that is not affected by laser irradiation away from the near-field light generating element 32 ′ and the waveguide 33. Combined. In order to save the number of electrode pads, the electrode pad 41, which is one of the electrode pads, is shared with the near light generating field element 32 '. Although not shown in this schematic diagram, it is possible to use a common terminal as a common electrode for recording magnetic field application, flying height control, and reproducing element.

  The near-field light generating element 32 'of this embodiment is made of gold (Au) having the shape shown in FIG. FIG. 10 is a plan view of the near-field light generating element 32 ′ viewed from the air floating surface (ABS) side. W0 = 40 nm, W1 = 800 nm, D0 = 30 nm, D1 = 50 nm, D2 = 300 nm, and the thickness (high A) 80 nm. The apex portion is processed into an arc shape with a radius of curvature of about 8 nm, and the spot diameter of the generated near-field light is about 20 nm.

  Although details are not shown here, in order to improve the coupling efficiency when the light from the laser diode unit 31 enters the waveguide 33, a spot diameter conversion mechanism or the like is formed immediately below the laser diode unit. Is good. By irradiation with light coupled to the waveguide 33, the near-field light generating element 32 'generates near-field light on the ABS and the recording medium surface according to a principle such as plasmon resonance, and the temperature of the recording medium surface rises. When the power of the light applied to the near-field light generating element 32 ′ of this embodiment is about 10 mW, the local temperature of the medium surface magnetic film rises to about 250 degrees. At that time, the temperature of the near-field light generating element 32 'also rises by about 80 degrees, and the resistance of the near-field light generating element 32' increases due to the influence of heat scattering. This is because the near-field light generating element 32 'is made of a noble metal such as gold or silver, that is, a good conductor, so that it is affected by the scattering of conduction electrons due to thermal fluctuations of the lattice, resulting in an increase in electrical resistance. The rate of change in electrical resistance at that time is about 0.4% / degree, and in the case of a temperature change of 80 degrees, the resistance changes by about 32%, and this change can be easily detected. The configuration of the hard disk drive apparatus using the information recording / reproducing head of the present embodiment is the same as that of the first embodiment shown in FIG.

  That is, in order to precisely control the drive current of the laser diode unit 31, the resistance value of the near-field light generating element 32 ′ is detected by the resistance detection circuit 50, thereby monitoring the temperature of the near-field light generating element 32 ′. Based on the temperature information, the drive current of the laser diode unit 31 is precisely controlled.

  In this embodiment, since the resistance value of the near-field light generating element is about 32 ohms at room temperature, there is no need for current confinement as in the first embodiment. The slider temperature detecting element 35 has a resistance value at room temperature of 400Ω and a temperature coefficient of 0.4% / degree.

  In this embodiment, in addition to the resistance value of the near-field light generating element 32 ', the resistance value of the slider temperature detecting element 35 is measured, and the temperature difference between the near-field light generating element 32' and the slider temperature detecting element 35 becomes constant. Control as follows. This makes it possible to control the near-field light intensity at a constant level regardless of variations in the ambient temperature and slider temperature, in addition to variations in element variations and interference conditions, improving the near-field light intensity control accuracy. To do. The bandwidth of the feedback control is set to 10 to 100 kHz so as to cope with temperature fluctuations of the laser and the like, mode hopping and the like.

  From the viewpoint of precise control of the heat-assisted recording conditions, it is preferable to correct the target near-field light intensity in accordance with the temperature detected by the temperature detecting element 35 in addition to the above-described constant temperature difference control. When the slider temperature, that is, the temperature in the drive is high, the temperature of the medium is originally high. Therefore, the temperature of the local area of the medium rises to an appropriate recording temperature even with a low near-field light power. In practice, it is preferable to learn the appropriate recording power while changing the ambient temperature in various ways, store it as a power table in the nonvolatile memory in the drive, and correct the laser power during recording based on this table.

In the above embodiment, Ta ₂ O ₅ (refractive index = 2.18) is used as the core material of the waveguide 33 and SiO ₂ (refractive index = 1.5) is used as the cladding material. However, the refractive index of the core is the refractive index of the cladding. The core and clad material may be other materials, for example, the core is made of Al ₂ O ₃ (refractive index = 1.6), TiO ₂ (refractive index = 1.5) for the cladding of SiO ₂ (refractive index = 1.5). 2.4). The material of the cladding may be MgF ₂ (refractive index n = 1.4) whose refractive index is smaller than that of SiO ₂ . Further, as the material of the core, SiO ₂ doped with other materials such as Ge may be used.

  The present invention can be used for an information recording / reproducing head capable of monitoring the amount of energy absorbed by the near-field light generating element. Further, the present invention can be applied to a heat-assisted magnetic recording apparatus that can control the amount of energy absorbed by the near-field light generating element.

DESCRIPTION OF SYMBOLS 11 ... Recording medium, 12 ... Suspension, 20 ... Controller (SOC), 22 ... Signal detection circuit, 23 ... Position address detection circuit, 24 ... Demodulation circuit, 25 ... Signal processing circuit, 26 ... Decoding circuit, 27 ... Microprocessor, DESCRIPTION OF SYMBOLS 29 ... Memory, 30 ... Slider, 31 ... Laser diode unit, 32, 32 '... Near field light generation element, 33 ... Waveguide, 34 ... Magnetic recording / reproducing element, 35 ... Temperature detection element, 40, 41 ... Electrode pad, 42, 43 ... conductive wire, 44 ... electrode pad, 45 ... conductive wire, 50 ... resistance detection circuit, 51 ... reproduction control circuit, 52 ... recording control circuit, 53 ... laser driver, 54 ... servo circuit, 55 ... photodetector (PD) ), 76 ... Motor, 79 ... VCM actuator, 80 ... Constant current source, 81 ... Voltage measuring element, 99 ... Host device.

Claims (20)

  A slider, a magnetic recording / reproducing element provided on the slider, a near-field light generating element provided on the air bearing surface side of the slider, and a waveguide for supplying light energy to the near-field light generating element The information recording / reproducing head includes a first temperature detecting element for detecting a temperature of the near-field light generating element, and a pair of electrodes electrically connected to the first temperature detecting element. Information recording / reproducing head.   2. The information recording / reproducing head according to claim 1, wherein the first temperature detecting element is also used as the near-field light generating element.   2. The information recording / reproducing head according to claim 1, further comprising a light source provided on an incident end of the waveguide on a rear surface of the slider.   4. The information recording / reproducing head according to claim 3, wherein the light source is a semiconductor laser.   2. The information recording / reproducing head according to claim 1, wherein the first temperature detecting element is a thermal resistance detecting element provided adjacent to the near-field light generating element via an insulating film.   6. The information recording / reproducing head according to claim 5, wherein a heat capacity of the thermal resistance detecting element is equal to or smaller than a heat capacity of the near-field light generating element.   2. A second temperature detection element for ambient temperature calibration, and a pair of electrodes that are electrically connected to the second temperature detection element, at a position away from the waveguide and the near-field light generating element. Item 4. The information recording / reproducing head according to Item 1.   The one of the pair of electrodes that are electrically connected to the second temperature detecting element is shared with one of the pair of electrodes that are electrically connected to the first temperature detecting element. Information recording / reproducing head.   A slider, a magnetic recording / reproducing element provided on the slider, a near-field light generating element provided on the air bearing surface side of the slider, and a waveguide for supplying light energy to the near-field light generating element An information recording / reproducing head having a pair of electrodes that are electrically connected to the near-field light generating element.   The information recording / reproducing head according to claim 9, further comprising a light source provided at a rear surface of the slider and at an incident end of the waveguide.   10. The apparatus according to claim 9, further comprising: a temperature detection element for ambient temperature calibration, and a pair of electrodes that are electrically connected to the temperature detection element, at a position away from the waveguide and the near-field light generating element. Information recording / reproducing head.   12. The information recording according to claim 11, wherein one of the pair of electrodes that are electrically connected to the temperature detecting element is shared with one of the pair of electrodes that are electrically connected to the near-field light generating element. Play head. A magnetic recording medium;
A slider, a magnetic recording / reproducing element provided on the slider, a near-field light generating element provided on the air bearing surface side of the slider, a waveguide for supplying light energy to the near-field light generating element, An information recording / reproducing head having a first temperature detecting element for detecting the temperature of the near-field light generating element and a pair of electrodes electrically connected to the first temperature detecting element;
The intensity of light energy introduced into the waveguide based on the detected resistance value by detecting the resistance value of the first temperature detecting element by flowing a current through the pair of electrodes to the first temperature detecting element. Is a heat-assisted magnetic recording apparatus.   14. The heat-assisted magnetic recording apparatus according to claim 13, wherein the intensity of light energy introduced into the waveguide is controlled so that the resistance value of the first temperature detection element is constant.   14. The heat-assisted magnetic recording apparatus according to claim 13, wherein the first temperature detection element is also used as the near-field light generating element.   14. The heat-assisted magnetic recording apparatus according to claim 13, further comprising a light source provided on the rear surface of the slider and at an incident end of the waveguide.   14. The heat-assisted magnetic recording apparatus according to claim 13, wherein the first temperature detection element is a thermal resistance detection element provided adjacent to the near-field light generating element via an insulating film.   18. The heat-assisted magnetic recording apparatus according to claim 17, wherein a heat capacity of the thermal resistance detection element is equal to or smaller than a heat capacity of the near-field light generating element.   2. A second temperature detection element for ambient temperature calibration, and a pair of electrodes that are electrically connected to the second temperature detection element, at a position away from the waveguide and the near-field light generating element. Item 14. The heat-assisted magnetic recording apparatus according to item 13.   21. One of the pair of electrodes that are electrically connected to the second temperature detecting element is shared with one of the pair of electrodes that are electrically connected to the first temperature detecting element. Thermally assisted magnetic recording device.

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