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Patent Issued for Near-Field Light Generating Element, Method of Manufacturing Near-Field Light Generating Element, Near-Field Light Head, Method of...

August 6, 2014



Patent Issued for Near-Field Light Generating Element, Method of Manufacturing Near-Field Light Generating Element, Near-Field Light Head, Method of Manufacturing Near-Field Light Head, and Informatio

By a News Reporter-Staff News Editor at Electronics Newsweekly -- From Alexandria, Virginia, VerticalNews journalists report that a patent by the inventors Hirata, Masakazu (Chiba, JP); Chiba, Norio (Chiba, JP); Oumi, Manabu (Chiba, JP); Shinohara, Yoko (Chiba, JP); Tanabe, Sachiko (Chiba, JP); Tanaka, Yoshikazu (Chiba, JP), filed on September 13, 2011, was published online on July 22, 2014.

The patent's assignee for patent number 8787127 is Seiko Instruments Inc. (JP).

News editors obtained the following quote from the background information supplied by the inventors: "The present invention relates to a near-field light generating element that records and plays a variety of information on a magnetic recording medium using a near-field light with focused light flux, a method of manufacturing a near-field light generating element, a near-field light head, a method of manufacturing a near-field, light head, and an information recording and playback device.

"In recent years, along with an increase in the capacity of a hard disk or the like in computer equipment, the recording density of information in a single recording surface has increased. For example, in order to increase the recording capacity of a magnetic disk per unit area, there is a need to increase the surface recording density. Incidentally, as the recording density increases, the recording area occupied per bit on the recording medium is reduced. When the bit size is reduced, energy held by one bit of information comes close to the heat energy of room temperature, whereby there is a problem of thermal demagnetization in which the recorded information is reversed or disappears owing to thermal fluctuations or the like.

"Although the in-plane recording method generally used is a method of recording the magnetism so that a direction of magnetization faces the in-plane direction of the recording medium, in this method, the recording information is easily lost due to the thermal demagnetization mentioned above. Thus, in order to solve the disadvantage, in recent years, a perpendicular recording method is adopted in which a magnetization signal is recorded in a direction perpendicular to the recording medium. This method is to record the magnetic information using the principle of causing a single magnetic pole to approach the recording medium. According to this method, the recording magnetic field faces a direction that is substantially perpendicular to a recording film. Since N-pole and S-pole are difficult to make form a loop within the recording film surface, information recorded in the vertical magnetic field easily maintains energetic stability. For that reason, the perpendicular recording method becomes resistant to the thermal demagnetization compared to the in-plane recording method.

"However, recent recording media require further increasing high densities in response to the needs for performing the recording and playback of larger amounts and higher densities of information, or the like. For that reason, in order to suppress the influence between the adjacent magnetic domains or the thermal fluctuations to the minimum, one having strong coercive force is begun to be adopted as the recording medium. For that reason, even in the perpendicular recording method mentioned above, it is difficult to record information on the recording medium.

"Thus, in order to solve the disadvantage mentioned above, a hybrid magnetic recording-type recording and playback head is provided in which the magnetic domain is locally heated using a spot light with the focused light or the near-field light to temporarily lower the coercive force, thereby performing the writing onto the recording medium in the meanwhile.

"Among such recording and playback heads, a recording and playback head (hereinafter, referred to as near-field light head) using the near-field light mainly includes a slider, a recording element having a main magnetic pole and an return pole that are placed on the slider, a near-field light generating element that generates the near-field light from the irradiate laser light, a laser light source that irradiates laser light toward the near-field light generating element, and an optical waveguide that guides laser light generated from the laser light source to the near-field light generating element (for example, JP-A-2008-152897). The near-field light generating element has a core that propagates laser light while reflecting the same, a light flux propagation element having a cladding that comes into close contact with the core and seals the core, and a metal film that is placed between the core and the cladding to generate the near-field light from the laser light. The core is drawn so that the cross-sectional area perpendicular to the propagation direction of laser light facing from one end side (light incident side) to the other end side (light emission side) is gradually reduced, and is configured so as to propagate the laser light toward the other end side while focusing the same. Moreover, the metal film mentioned above is placed on a side surface of the other end side in the core.

"In the case of using the near-field light head configured in this manner, a variety of information is recorded on the recording medium by generating the near-field light and applying the recording magnetic field. That is, laser light emitted from the laser light source is incident to the light flux propagation element via the optical waveguide. Moreover, laser light incident to the light flux propagation element is propagated through the cores and reaches the metal film. Then, since free electron within the metal film is uniformly vibrated by laser light, plasmon is excited and generates the near-field light on the other end side of the core in the state of being localized. As a result, the magnetic recording layer of the magnetic recording medium is locally heated by the near-field light and coercive force is temporarily lowered.

"Furthermore, by providing the driving electric current to the recording element simultaneously with the irradiation of the laser light mentioned above, the recording magnetic field is locally applied to the magnetic recording layer of the magnetic recording medium adjacent to the tip of the main magnetic pole. As a result, it is possible to record a variety of information on the magnetic recording layer in which the coercive force is temporarily lowered. That is, by the cooperation of the near-field light with magnetic field, the recording to the magnetic recording medium can be performed.

"However, in order to promote new high density of the recording medium, there is a need to reduce a spot size of the near-field light and more locally heat the magnetic recording layer of the magnetic recording medium, thereby suppressing the influence of the thermal fluctuation phenomenon mentioned above or the like. In order to reduce the spot size of the near-field light, a reduction in the width (width of the interface between the metal film and the core when viewed from the propagation direction of laser light) of the metal film is considered.

"In this case, in the related art, since the core is formed according to the width of the metal film, the width (a width of an interface between the core and the metal film when viewed from the propagation direction of laser light) of the core is reduced along with the reduction in metal film.

"However, when reducing the width of the core, the loss of the laser light propagated through the core is increased, whereby there is a problem in that a sufficient amount of light cannot be obtained. That is, the spot size of the near-field light can be reduced, but the amount of light is lowered."

As a supplement to the background information on this patent, VerticalNews correspondents also obtained the inventors' summary information for this patent: "Thus, the present invention was made in view of such situation, and an object thereof is to provide a near-field light generating element which can ensure an amount of light and then can reduce the spot size of the near-field light, a method of manufacturing the near-field light generating element, a near-field light head, a method of manufacturing the near-field light head, and an information recording and playback device.

"The present invention provides means as below so as to solve the problems mentioned above.

"According to the present invention, there is provided a near-field light generating element which propagates the light flux introduced to one end side while focusing the light flux toward the other end side and emits the light flux to the outside after creating the near-field light, the element having a core that propagates the light flux toward the other end side, and a near-field light generating portion which is placed along the propagation direction of the light flux facing from the one end side toward the other end side in the core to propagate the light flux along the interface between the near-field light generating element and the core, and generates the near-field light from the light flux, the core includes a first core, and a second core that covers the first core from the opposite side of the near-field light generating portion with the first core interposed therebetween, and an external end portion of the second core is situated further to the outside than an external end portion of the near-field light generating portion when viewed from the propagation direction.

"According to this configuration, since the external end portion in the second core is situated further to the outside than the external end portion of the near-field light generating portion, the width of the near-field light generating portion is formed to be narrower than the width between core and the near-field light generating portion in the entire core when viewed from the propagation direction. For that reason, it is possible to generate the near-field light having the spot size smaller than the width of the interface between the cores and the near-field light generating portion in the entire core, and suppress a decline in propagation efficiency of light flux along with a reduction in spot size. As a result, it is possible to reduce the spot size of the near-field light after ensuring the amount of light.

"Furthermore, the first core and the second core are formed of the same material.

"According to this configuration, it is possible to prevent the reflection or the absorption of the light flux in the interface between the first core and the second core, thereby effectively diffusing the light flux from one end side of the cores toward the other end side thereof.

"Furthermore, the near-field light generating element further has a cladding that covers the core in the state of exposing the other end surface of the core to the outside, and the first core, the second core, and the cladding are configured so that the refractive index is increased in the order of the cladding, the second core, and the first core.

"According to the configuration, since the light flux totally reflected on the interface between the second cores and the cladding can be gradually focused toward the center (the first core), the propagation efficiency of the light flux can be improved.

"Furthermore, the other end surface of the core is formed in a triangular shape or a trapezoidal shape when viewed from the propagation direction.

"According to this configuration, it is possible to effectively reflect the light flux propagated through the core toward the near-field light generating portion.

"Furthermore, a light shielding film is formed so as to cover the second core from the opposite side of the first core with the second core interposed therebetween.

"In this configuration, by forming the light shielding film so as to cover the second core, the light flux incident to the core is propagated toward the other end side while being reflected from the interface between the light shielding film and the second core without leaking to the outside. As a result, it is possible to effectively make the light flux incident to the near-field light generating portion, which can improve the generation efficiency of the near-field light.

"Furthermore, the first core has a plurality of side surfaces that is extended along the propagation direction, the plurality of side surfaces has a first side surface on which the near-field light generating element is placed, and a second side surface placed along a direction intersecting the plane direction of the first side surface on both sides of the first side surface when viewed from the propagation direction, and the external end portion of the near-field light generating portion is placed on the same surface as the second side surface of the first core when viewed from the propagation direction.

"According to this configuration, since the first core and the near-field light generating portion are placed so as to overlap with each other when viewed in a direction perpendicular to the propagation direction, it is possible to make the light flux propagated up to the other end side of the core incident to the near-field light generating portion without leaking. Thus, the generation efficiency of the near-field light can be improved.

"Furthermore, according to the present invention, there is provided a method of manufacturing the near-field light generating element which propagates the light flux introduced to one end side while focusing the light flux toward the other end side and emits the light flux to the outside after creating the near-field light, the element having a core that propagates the light flux toward the other end side, and a near-field light generating portion which is placed along a propagation direction of the light flux facing from the one end side toward the other end side in the core to propagate the light flux along an interface between the near-field light generating element and the core, and generates the near-field light from the light flux, the method including a near-field light generating portion forming process of forming a base material of the near-field light generating portion; a first core forming process of forming a base material of a first core among the cores so as to cover the near-field light generating portion; a patterning process of collectively patterning the base material of the first core, and the base material of the near-field light generating portion; and a second core forming process of forming a second core of the core so as to cover the first core from the opposite side of the near-field light generating portion with the first core interposed therebetween.

"According to this configuration, by collectively patterning the base material of the first core and the base material of the near-field light generating portion by the same patterning process, the width of the interface between the near-field light generating portion and the first core can be equally formed. Moreover, by forming the second core so as to cover the first core after the patterning process, it is possible to simply form the near-field light generating portion having the width narrower than the width of the interface between the near-field light generating portion when viewed from the propagation direction and the core in the entire core. In addition, for example, unlike a case where the first core and the near-field light generating portion are patterned by separate processes, respectively, the near-field light generating portion and the first core can be accurately positioned.

"Furthermore, according to the present invention, there is provided a method of manufacturing a near-field light head which heats a magnetic recording medium rotating in a given direction using the method of manufacturing the near-field light generating element of the present invention and causes a magnetization reversal by applying recording magnetic field to the magnetic recording medium to record information, the method include a magnetic pole forming process of forming a base material of the magnetic pole generating the recording magnetic field before the near-field light generating portion forming process, and in the patterning process, the base material of the magnetic pole is collectively patterned by the same process together with the base material of the first core and the base material of the near-field light generating portion.

"According to this configuration, by collectively patterning the base material of the magnetic pole by the same patterning process together with the first cores and the base material of the near-field light generating portion, the first core and the external end portion of the near-field light generating portion and the magnetic pole are placed on the same surface when viewed from the propagation direction. As a result, for example, unlike a case where the first core, the near-field light generating portion, and the magnetic pole are patterned by separate processes, respectively, it is possible to accurately position the near-field light generating portion, the core, and the magnetic pole. In addition, since the cores, the near-field light generating portion, and the magnetic pole can be positioned without using an expensive positioning device, the cost of the device can be reduced.

"In this case, the magnetic pole is formed so as to cover the near-field light generating portion from the opposite side of the first core with the near-field light generating element interposed therebetween. For that reason, it is possible to accurately position the generation position of the near-field light and the generation position of the magnetic field from the magnetic pole, whereby the reliability of the writing of the near-field light head itself can be raised to promote increased quality.

"Furthermore, even in a case where Plasmon resonance is not generated in the near-field light generating portion but the light flux transmits through the near-field light generating portion, the light flux can be incident to the near-field light generating portion again by reflecting the light flux to the magnetic pole to return into the core. As a result, the generation efficiency of the near-field light generating portion can be further improved. In addition, since it is possible to suppress that the light flux leaks to the outside without generating the Plasmon resonance in the near-field light generating portion, the spot of the extremely small near-field light can be created only in the vicinity of the core.

"Furthermore, according to the present invention, there is provided a near-field light head which heats a magnetic recording medium rotating in a given direction and causes the magnetization reversal by applying the recording magnetic field to the magnetic recording medium to record information, the near-field light head includes a slider that is placed opposite on a surface of the magnetic recording medium; a recording element that is placed on a tip side of the slider and has a magnetic pole generating the recording magnetic field; the near-field light generating element according to a first aspect that is fixed adjacent to the recording element in the state where the other end side faces the magnetic recording medium side; and light flux introduction means that is fixed to the slider and introduces the light flux from the one end side into the core.

"According to this configuration, since the near-field light generating element of the present invention is included, it is possible to suppress the influence of the thermal fluctuation phenomenon or the like to perform stable recording. Thus, the reliability of the near-field light head itself can be raised, which can promote increased quality.

"Furthermore, the first core has a plurality of side surfaces that is extended along the propagation direction, the plurality of side surfaces has a first side surface on which the near-field light generating element is placed, and a second side surface that is placed along a direction intersecting the plane direction of the first side surface on both sides of the first side surface when viewed from the propagation direction, the magnetic pole is placed opposite to the first side surface of the first core with the near-field light generating portion therebetween, and an external end portion of the magnetic pole is placed on the same surface as the second side surface of the first core when viewed from the propagation direction.

"According to this configuration, since the magnetic pole is formed so as to cover the near-field light generating portion from the opposite side of the core with the near-field light generating element interposed therebetween, the generation position of the near-field light and the generation position of the magnetic field can be accurately positioned, which can raise the reliability of the writing of the near-field light head itself to promote increased quality.

"Furthermore, even in a case where Plasmon resonance is not generated in the near-field light generating portion but the light flux transmits through the near-field light generating portion, the light flux can be incident to the near-field light generating portion again by reflecting the light flux to the magnetic pole to return into the core. As a result, the generation efficiency of the near-field light generating portion can be further improved. In addition, since it is possible to suppress that the light flux leaks to the outside without generating the Plasmon resonance in the near-field light generating portion, the spot of the extremely small near-field light can be created in the vicinity of the core only.

"Furthermore, between the near-field light generating portion and the magnetic pole, a separation film is formed which forms an image between the near-field light generating portion and the magnetic field.

"According to this configuration, when the near-field light generating portion and the magnetic pole are formed of a metallic material having conductivity, the near-field light generating portion and the magnetic pole can be electrically insulated, and the alloying of the near-field light generating portion can be suppressed. Thus, the movement of free electrons in the near-field light generating portion is not adversely affected. For that reason, the generation efficiency of the near-field light can be further improved.

"Furthermore, according to the present invention, there is provided an information recording and playback device which includes the near-field light head of the present invention; a beam that is movable in a direction parallel to the surface of the magnetic recording medium and supports the near-field light head on a tip side in the state of being rotatable around two axes which are parallel to the surface of the magnetic recording medium and are perpendicular to each other; a light source that makes the light flux incident to the light flux introduction means; an actuator that supports a proximal end side of the beam and moves the beam toward a direction parallel to the surface of the magnetic recording medium; a rotation driving portion that rotates the magnetic recording medium in the given direction; and a control portion that controls the operation of the recording element and the light source.

"According to this configuration, since the near-field light head of the present invention is included, the reliability of the writing can be raised, which can promote increased quality.

"According to the near-field light generating element according to the present invention and the method of manufacturing the same, the spot size of the near-field light can be reduced after ensuring the quantity of light.

"According to the near-field light head and the information recording and playback device according to the present invention, it is possible to suppress the influence of the thermal fluctuation phenomenon or the like mentioned above to perform stable recording. Thus, the reliability of the writing is high and it is possible to support the high quality recording, whereby the high quality can be promoted."

For additional information on this patent, see: Hirata, Masakazu; Chiba, Norio; Oumi, Manabu; Shinohara, Yoko; Tanabe, Sachiko; Tanaka, Yoshikazu. Near-Field Light Generating Element, Method of Manufacturing Near-Field Light Generating Element, Near-Field Light Head, Method of Manufacturing Near-Field Light Head, and Information Recording and Pl. U.S. Patent Number 8787127, filed September 13, 2011, and published online on July 22, 2014. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=8787127.PN.&OS=PN/8787127RS=PN/8787127

Keywords for this news article include: Electronics, Seiko Instruments Inc.

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Source: Electronics Newsweekly


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