JP4628454B2 - Recording medium and optical information recording / reproducing apparatus - Google Patents

Description

  The present invention relates to a recording medium and an optical information recording / reproducing apparatus capable of reproducing and recording high-density information using near-field light.

  A scanning probe microscope (SPM) typified by a scanning tunneling microscope (STM) or an atomic force microscope (AFM) is used to observe a minute region on the order of nanometers on the sample surface. SPM scans a sample surface with a probe with a sharpened tip, and observes the interaction between the probe and the sample surface, such as tunneling current and atomic force, with an image of resolution depending on the probe tip shape. However, restrictions on the sample to be observed are relatively severe.

  Therefore, near-field optical microscopes that are capable of observing minute areas on the sample surface by focusing on the interaction between the near-field light generated on the sample surface and the probe are drawing attention. .

  In the near-field optical microscope, the surface of the sample is irradiated with propagating light to generate near-field light, and the generated near-field light is scattered by a probe with a sharpened tip. By processing in the same manner as the detection, the limit of the observation resolution by the conventional optical microscope is overcome, and it is possible to observe a finer region. In addition, it is possible to observe the optical properties of the sample in a minute region by sweeping the wavelength of the light applied to the sample surface.

  In addition to being used as a microscope, by introducing relatively high intensity light toward the sample through the optical fiber probe, near-field light with high energy density is generated at the microscopic aperture of the optical fiber probe, and the sample is generated by the near-field light. Application as high-density optical memory recording in which the surface structure or physical properties are locally changed is also possible.

  As a probe used in a near-field optical microscope, for example, as disclosed in US Pat. No. 5,294,790, an opening is formed in a silicon substrate by a semiconductor manufacturing technique such as photolithography, and one of the silicon substrates is formed. There has been proposed a cantilever type optical probe in which an insulating film is formed on the surface and a conical optical waveguide layer is formed on the insulating film opposite to the opening. In this cantilever type optical probe, light can be transmitted through a minute opening formed by inserting an optical fiber into the opening and coating the portion other than the tip of the optical waveguide layer with a metal film.

  Furthermore, it has been proposed to use a planar probe that does not have a sharpened tip like the above-described probe. The planar probe is formed by forming an opening of an inverted pyramid structure on a silicon substrate by anisotropic etching, and its apex is penetrated with a diameter of several tens of nanometers. A plurality of such planar probes can be formed on the same substrate using semiconductor manufacturing technology, that is, can be easily arrayed, and can be used as an optical memory head suitable for reproducing and recording an optical memory using near-field light. . As an optical head using this flat probe, a flying head conventionally used in a hard disk has been proposed which has a flat probe. The flying head is aerodynamically designed to fly about 50 to 100 nm from the recording medium. By forming a minute opening on the recording medium side of this flying head, it is possible to generate near-field light and perform optical recording and reproduction.

  However, an optical memory using near-field light can realize an ultra-high-density optical memory below the diffraction limit of light because it uses near-field light, but has low light utilization efficiency and is received by a light receiving element. There was a problem that the amount of light to be emitted was very weak.

  In order to solve this problem, conventionally, the intensity of the laser beam to be used is increased, or a ball lens or the like is filled in the inverted pyramid structure of the planar probe which is a near-field optical head.

  However, when the laser light intensity is increased, there is a problem that new problems such as heat generation and power consumption occur. In addition, when a ball lens is used, it is necessary to align the ball lens, which causes an increase in cost. Furthermore, due to individual variations in the ball lens, there is a problem that it is difficult to focus the light on the aperture in all near-field optical heads when mass-produced.

  Therefore, when realizing an ultra-high density memory using near-field light, it is difficult to reduce the size and power consumption and to reduce the price by mass production.

  Therefore, the present invention provides a recording medium characterized by the structure of the recording medium, not the near-field optical head, and the recording medium, in order to improve the light utilization efficiency and solve the problems caused by the conventional method described above. An object of the present invention is to provide an optical information recording / reproducing apparatus used.

  In order to solve the above problems, the first recording medium according to the present invention is for generating near-field light in a recording medium that records and reproduces information with a near-field optical head using near-field light. A medium substrate that is transparent to the wavelength of the irradiated light, a data recording unit that records information on the surface of the medium substrate, and a condensing structure for collecting the irradiated light on the data recording unit. It is characterized by.

  According to the present invention, since the recording medium has a condensing structure for condensing the irradiation light irradiated from the outside on the data recording unit, the amount of light irradiated on the data recording unit due to the condensing effect by the condensing structure. As a result, a stronger near-field light is generated in the data recording unit, and the intensity of the propagation light obtained by interacting the near-field light and the near-field light head increases.

  The second recording medium according to the present invention is the same as the first recording medium except that the condensing structure excludes a taper portion in which a reflective film having a taper shape is formed in the thickness direction of the medium substrate and a data recording portion. The region is characterized by comprising a light shielding portion for shielding the irradiation light.

  According to this invention, since the recording medium can be formed by transfer by forming the condensing structure into a tapered shape, the recording medium can be mass-produced and the cost can be easily reduced.

  The third recording medium according to the present invention is characterized in that, in the first or second recording medium, the reflective film also serves as a light shielding portion.

  According to the present invention, the reflective film formed on the tapered portion and the light shielding portion are the same, and the number of steps for manufacturing the recording medium is reduced by one step, so that the cost can be further reduced.

  Further, the fourth recording medium according to the present invention is the first recording medium, wherein the data recording portions are formed on both surfaces of the medium substrate, and the condensing structure is formed of a reflective film having a taper shape in the thickness direction of the medium substrate. The taper portion is formed.

  According to the present invention, the data recording portions can be formed on both sides of the recording medium, so that the capacity per recording medium can be doubled.

  Further, the fifth recording medium according to the present invention is the second or fourth recording medium, wherein the taper portion in which the reflective film having the taper shape is formed in the thickness direction of the medium substrate is reverse to the reflective film formed. It is a weight-like taper part.

According to the present invention, since the shape of the tapered portion is an inverted quadrangular pyramid shape, the irradiation light can be efficiently condensed on the data recording portion by the four inclined surfaces of the tapered portion on which the reflective film is formed. Therefore, the light flux from the light source can be used more efficiently.

  In the sixth recording medium according to the present invention, in the second or fourth recording medium, the taper portion in which the reflective film having a taper shape is formed in the thickness direction of the medium substrate has a reflective film formed thereon. It is a groove-like taper part.

  According to the present invention, it is possible to perform tracking control using a data recording section created concentrically, and more stable signal reproduction can be performed.

  The first recording medium manufacturing method according to the present invention includes a convex shape creating step for creating a convex shape in a recording medium that records and reproduces information with a near-field optical head using near-field light, and a convex shape. And a reflecting film / light-shielding part creating step for creating a reflective film and a light-shielding part in a concave shape created by the transfer process.

  According to the present invention, since a medium substrate having a taper shape can be formed by transfer, once the mold is formed, mass transfer of the recording medium can be performed by transferring and the cost can be reduced. Easy.

  A second recording medium manufacturing method according to the present invention includes a concave shape creating step for creating a concave shape in a recording medium for recording and reproducing information by a near-field optical head using near-field light, and a concave shape. And a reflection film / light-shielding part creation step for creating a reflection film and a light-shielding part.

  According to the present invention, in addition to the effect of the first recording medium manufacturing method according to the present invention, it is possible to eliminate the step of creating the mold, and accordingly, the cost can be reduced accordingly.

  The first optical information recording / reproducing apparatus according to the present invention is an optical information reproducing apparatus for reproducing information by a near-field optical head using near-field light, and the near-field light composed of a light source and a lens. The irradiation optical system is irradiated for generation, the medium substrate transparent to the wavelength of the irradiation light, and the data recording portion and the data recording portion on the surface of the medium substrate on which information to be recorded and reproduced is formed. It is characterized by comprising a recording medium comprising a light condensing structure for light and a near-field optical head.

According to the present invention, since the recording medium has a condensing structure for condensing the irradiation light irradiated from the outside on the data recording unit, the amount of light irradiated on the data recording unit due to the condensing effect by the condensing structure. And stronger near-field light is generated in the data recording unit.
The intensity of the propagation light obtained by interacting the near-field light and the near-field light head increases.

  The second optical information recording / reproducing apparatus according to the present invention is an optical information reproducing apparatus for recording / reproducing information with a near-field optical head using near-field light, wherein the near-field light comprising a light source and a lens is used. Irradiation optical system irradiated to generate data, a medium substrate transparent to the wavelength of the irradiation light, and a data recording unit and a data recording unit on the surface of the medium substrate on which information to be recorded and reproduced is formed. A recording medium comprising a condensing structure for condensing light, a near-field optical head for reproducing information from the recording medium, and a near-field optical head for recording information on the recording medium It is characterized by.

  According to the present invention, not only the reproduction of information recorded on the recording medium but also the recording of information on the recording medium can be realized. In addition, by matching the positional relationship between the minute aperture used for information reproduction and the recording minute aperture used for information recording with the data recording unit, the data recording being reproduced simultaneously with the reproduction of data from the data recording unit Data can be recorded in a data recording unit different from the unit.

  According to the third optical information recording / reproducing apparatus of the present invention, in the first or second optical information recording / reproducing apparatus, the light condensing structure is provided in a region excluding the tapered portion where the reflective film is formed and the data recording portion. It comprises a light shielding portion for shielding the irradiation light.

According to this invention, since the recording medium can be formed by transfer by forming the condensing structure into a tapered shape, the recording medium can be mass-produced, and the cost of the apparatus can be reduced.

  The fourth optical information recording / reproducing apparatus according to the present invention is characterized in that, in the third optical information recording / reproducing apparatus, the reflection film also serves as a light shielding portion. According to the present invention, the reflective film formed on the tapered portion and the light shielding portion are the same, and the number of steps for manufacturing the recording medium is reduced by one step, so that mass production and cost reduction of the recording medium can be realized.

  According to the fifth optical information recording / reproducing apparatus of the present invention, in the first or second optical information recording / reproducing apparatus, the data recording unit is formed on both surfaces of the medium substrate, and the light collecting structure is formed with a reflective film. It is a taper part.

  According to the present invention, since data recording sections can be formed on both sides of a recording medium, the capacity per recording medium can be doubled, and a large-capacity optical information recording / reproducing apparatus is provided. it can.

  According to the sixth optical information recording / reproducing apparatus of the present invention, in the third or fifth optical information recording / reproducing apparatus, the tapered portion on which the reflective film is formed is an inverted spindle-shaped tapered portion on which the reflective film is formed. It is characterized by being.

  According to this invention, the shape of the taper portion is an inverted pyramid shape, and the recording medium capable of efficiently condensing the irradiation light on the data recording portion by using the plurality of inclined surfaces of the taper portion on which the reflective film is formed is used. Therefore, since the luminous flux from the light source can be used more efficiently, it is not necessary to increase the output of the light source, and it is possible to suppress the increase in power consumption and heat generation by increasing the output of the light source. Electricity becomes easy.

  According to the seventh optical information recording / reproducing apparatus of the present invention, in the third or fifth optical information recording / reproducing apparatus, the tapered portion on which the reflective film is formed is a V-groove tapered portion on which the reflective film is formed. It is characterized by being.

  According to the present invention, it is possible to perform tracking control using a data recording section created concentrically, and more stable signal reproduction can be performed.

  As described above, according to the first recording medium of the present invention, the recording medium has a condensing structure for condensing the irradiation light irradiated from the outside on the data recording unit. The amount of light irradiated to the data recording unit increases due to the light collecting effect, and a stronger near-field light is generated in the data recording unit. The intensity of the propagation light obtained by interacting this near-field light and the near-field light head Will increase.

  Therefore, smaller data marks can be reproduced and a higher density memory can be realized. Alternatively, the S / N ratio can be improved by increasing the propagation light intensity, and data can be reproduced at a higher speed.

  Furthermore, since the luminous flux from the light source can be used more efficiently, there is no need to increase the output of the light source, and the increase in power consumption and heat generation due to the increased output of the light source can be suppressed. Electricity becomes easy.

  In addition, according to the second recording medium of the present invention, in addition to the effect of the first recording medium, the recording medium can be formed by transfer by forming the condensing structure into a tapered shape. Can be mass-produced, and cost reduction is easy.

  In addition, according to the third recording medium of the present invention, in addition to the effects of the first or second recording medium, the reflective film formed on the tapered portion is the same as the light shielding portion, so that the recording medium is manufactured. Since one step is reduced, the cost can be further reduced.

  Further, according to the fourth recording medium of the present invention, in addition to the effect of the first recording medium, the data recording unit can be formed on both sides of the recording medium, so that the capacity per recording medium can be reduced. It can be doubled. Even if the capacity per recording medium is doubled, the recording medium manufacturing cost does not increase drastically, so the price per unit recording capacity of the recording medium can be reduced.

  Further, according to the fifth recording medium of the present invention, in addition to the effect of the second or fourth recording medium, the shape of the tapered portion is an inverted quadrangular pyramid shape, so that the tapered portion on which the reflective film is formed is provided. Irradiation light can be efficiently collected on the data recording unit by the four inclined surfaces. Therefore, since the luminous flux from the light source can be used more efficiently, it is not necessary to increase the output of the light source, and the increase in power consumption and heat generation due to the large output of the light source can be suppressed. Electricity becomes easy.

  Further, according to the sixth recording medium of the present invention, in addition to the effect of the second or fourth recording medium, it is possible to perform tracking control using a data recording unit created concentrically, More stable signal reproduction can be performed.

  Further, according to the first method for manufacturing a recording medium according to the present invention, a medium substrate having a taper shape can be formed by transfer. Therefore, once a mold is formed, recording is performed by transferring the mold. Medium production is possible and cost reduction is easy.

  In addition, the mold required for transfer can be created by a silicon process, and data pits having a size smaller than the wavelength can be created.

  Further, according to the second recording medium manufacturing method according to the present invention, in addition to the effect of the first recording medium manufacturing method according to the present invention, a step of creating a mold can be eliminated. The cost can be reduced.

  Further, according to the first optical information recording / reproducing apparatus of the present invention, the recording medium has a condensing structure for condensing the irradiation light irradiated from the outside on the data recording unit. Due to the light effect, the amount of light applied to the data recording unit increases, and stronger near-field light is generated in the data recording unit. The intensity of the propagation light obtained by interacting the near-field light and the near-field light head increases.

  Therefore, a smaller data mark can be reproduced, and a higher-density memory can be realized. Alternatively, the S / N ratio can be improved by increasing the propagation light intensity, and data can be reproduced at a higher speed.

  Furthermore, since the luminous flux from the light source can be used more efficiently, there is no need to increase the output of the light source, and the increase in power consumption and heat generation due to the increased output of the light source can be suppressed. Electricity becomes easy.

  Moreover, since the near-field optical head can be formed by a conventional semiconductor manufacturing process, it can be mass-produced and can be easily reduced in cost. In addition, it is easy to create a multi-head in which multiple near-field optical heads are arranged on the same silicon substrate, and it becomes possible to read out a plurality of data recorded in the data recording unit in parallel, enabling further high-speed data reproduction. It becomes possible.

  Further, according to the second optical information recording / reproducing apparatus of the present invention, in addition to the effect of the first optical information recording / reproducing apparatus, not only the reproduction of information recorded on the recording medium but also the information on the recording medium are reproduced. Recording can be realized.

  In addition, by matching the positional relationship between the minute aperture used for information reproduction and the recording minute aperture used for information recording with the data recording unit, the data recording being reproduced simultaneously with the reproduction of data from the data recording unit Data can be recorded in a data recording unit different from the unit.

  In addition, when a near-field optical head for recording and reproduction is used, information can be recorded and reproduced on the recording medium independently, and information can be recorded and reproduced at a higher speed.

  According to the third optical information recording / reproducing apparatus of the present invention, in addition to the effect of the first or second optical information recording / reproducing apparatus, the condensing structure is tapered, so that the recording medium is transferred. Since it can be produced, mass production of recording media is possible, and the cost of the apparatus can be reduced.

  In addition, according to the fourth optical information recording / reproducing apparatus of the present invention, in addition to the effect of the third optical information recording / reproducing apparatus, the reflection film formed on the tapered portion and the light shielding part are the same, and the recording medium is manufactured. Since the number of steps to be performed is reduced, mass production and cost reduction of the recording medium can be realized, and further cost reduction as an apparatus can be achieved.

  Further, according to the fifth optical information recording / reproducing apparatus of the present invention, in addition to the effects of the first or second optical information recording / reproducing apparatus, the data recording unit can be formed on both sides of the recording medium. The capacity per recording medium can be doubled. Even if the capacity per recording medium is doubled, the recording medium manufacturing cost does not increase drastically, so the price per unit recording capacity of the recording medium can be reduced.

  According to the sixth recording medium of the present invention, in addition to the effect of the third or fifth optical information recording / reproducing apparatus, the tapered portion is formed in an inverted quadrangular pyramid shape and formed with a reflective film. Since the recording medium that can efficiently collect the irradiation light on the data recording unit by using the four slopes, the light flux from the light source can be used more efficiently, so there is no need to increase the output of the light source. The increase in power consumption and heat generation due to the increased output of the light source can be suppressed, and the device can be easily reduced in size and power consumption.

  According to the seventh recording medium of the present invention, in addition to the effect of either the third or fifth optical information recording / reproducing apparatus, tracking control using a data recording unit formed concentrically. And more stable signal reproduction can be performed.

Hereinafter, a recording medium and an optical information recording / reproducing apparatus according to the present invention will be described in detail with reference to the accompanying drawings.
(Embodiment 1)
FIG. 1 shows a configuration diagram of an optical information recording / reproducing apparatus according to the first embodiment. In the optical information recording / reproducing apparatus of FIG. 1, the near-field optical head 1 is formed in a silicon substrate 2 with a tapered opening 3 penetrating therethrough having a minute opening 4. The minute aperture 4 has a diameter of, for example, several tens of nanometers so as to interact with the near-field light 11 generated in the vicinity of the minute aperture 4 and to extract the propagation light 12 obtained as a result.

  The tapered opening 3 is formed by fine processing using, for example, photolithography or silicon anisotropic etching in a semiconductor manufacturing process. In addition, when the silicon substrate 2 does not have sufficient light shielding properties with respect to the wavelength of the irradiation light 9, a light shielding film such as a metal film such as Au / Cr is necessary and obtained by sputtering or vacuum evaporation. It is done.

  Irradiation light 9 irradiated for reading data recorded on the recording medium 6 is obtained by an irradiation optical system including a light source 7 (for example, a semiconductor laser) and a collimator lens 8.

  FIG. 3 is a structural diagram of the recording medium according to the first embodiment, and FIG. 4 is a perspective view of the recording medium according to the first embodiment.

  The recording medium 6 is formed with an inverted square pyramid tapered portion 32 in which a reflective film is formed on a medium substrate 31 that is transparent to the wavelength of the irradiation light 9. A data recording unit 33 is formed on the upper surface of the medium substrate 31, and a light blocking unit 34 that blocks the irradiation light 9 is formed in a region excluding the data recording unit 33. The reflective film of the taper part 32 is intended to collect light on the data recording part 33. The light shielding part 34 is intended to prevent the irradiation light 9 and the condensed light beam 10 from passing through the tapered part 32 on which the reflection film is formed and irradiating the data recording part 33. The size of the data recording unit 33 is less than the diffraction limit of light (for example, about 100 nm).

  Here, in each data recording section 33, the recorded data need not be one bit, and a plurality of bits may be formed as one data recording section 33.

  Next, an example of a method for manufacturing the recording medium 6 will be described.

FIG. 5 is a diagram illustrating a method for manufacturing a recording medium. This manufacturing method includes (1) a convex shape creating step for creating a convex shape, (2) a transfer step for transferring the convex shape to the medium substrate, and (3) a reflective film and a light shield in the concave shape created by the transfer step. A reflecting film / light-shielding portion creating step for creating a portion, and (4) a data data recording portion creating step on the surface of the medium substrate on which information to be recorded / reproduced is formed.
(1) Convex shape creation step First, SiO ₂ 52 is created on the upper surface of the Si substrate 51 by thermal oxidation or the like. Then, a photoresist 53 film is formed on the SiO ₂ 52 film, and a pattern of the photoresist 53 is created so as to leave only a portion corresponding to the tapered portion 32 of the recording medium 6 (FIG. 5-a). Thereafter, isotropic etching is performed to form a weight-like convex shape 54 (FIG. 5-b), and unnecessary photoresist 53 is removed (FIG. 5-c).
(2) Transfer process Using FIG. 5-c as a mold, the shape of FIG. 5-c is transferred onto a plastic substrate such as PMMA or a glass substrate (FIGS. 5-d and 5-e).
(3) Reflective film / light-shielding part creation step In order to create the inverted tapered shape taper part 32 and the light-shielding part 34 in which the reflective film is formed on the medium substrate 31 to which the shape is transferred, a metal film such as Au or Cr is used. The film is formed and the metal film other than the data recording part 33 is removed so that the metal film is formed only on the tapered part 32 (FIG. 5-f).
(4) Data recording portion creation step Thereafter, a data recording layer for recording a data mark having a size equal to or smaller than the wavelength or a data mark shape having a size equal to or smaller than the wavelength is formed in the data recording portion, thereby forming the recording medium 6.

Next, a method for reproducing information at the minute aperture 4 by placing the recording medium 6 on the optical information recording / reproducing apparatus shown in FIG. Here, the recording medium 6 is a disk-shaped flat substrate, for example, and the near-field optical head 1 is disposed on the upper surface thereof. The disc-shaped recording medium is rotated at high speed by a spindle motor or the like (not shown). In order to allow the near-field light 11 generated in the vicinity of the micro-aperture 4 of the near-field optical head 1 and the micro-aperture 4 to interact, the micro-aperture 4 and the recording medium 6 are brought close to the diameter of the micro-aperture 4. It is necessary to let Therefore, the near-field optical head 1 and the recording medium 6 are filled with a lubricant, and the near-field optical head 1 is formed sufficiently thin so that the near-field optical head 1 and the near-field optical head 1 can be used with the surface tension of the lubricant. The distance from the recording medium 6 can be kept sufficiently small. Furthermore, it can follow the bending of the recording medium 6. Further, the position of the near-field optical head 1 can be controlled by a near-field optical head control mechanism (not shown) so that the minute aperture 4 can be arranged at a desired position on the recording medium 6.

  The proximity state between the near-field optical head 1 and the recording medium 6 may be controlled by an air bearing in the same manner as the flying head used in the hard disk technology, without using the above-described lubricant. You may perform AFM control used for an optical microscope.

  To reproduce the information recorded on the recording medium 6, first, the fine aperture 4 is moved to a desired information reproducing position on the recording medium 6 by the above-described control, and the data recording unit 33 is formed by the light source 7 and the collimating lens 8. The recording medium 6 is irradiated with irradiation light 9 from a surface opposite to the surface on which it is applied. The light beam applied to the recording medium 6 is incident between the tapered portion 32 on which the reflective film is formed and the adjacent tapered portion. Then, due to the light condensing effect by the two inclined surfaces of these tapered portions, the irradiation light 9 becomes a condensed light beam 10 and is irradiated to the data recording unit 33. Then, near-field light 11 is generated in the data recording portion of the recording medium 6 close to the minute opening 4 serving as the reproduction position. Due to such a condensing effect, the amount of light applied to the data recording unit 33 is increased, and stronger near-field light is generated.

  Due to the interaction between the near-field light 11 and the minute aperture 4, the propagating light 12 having characteristics such as intensity and phase depending on the recording state of the data recording portion passes through the minute aperture 4 above the tapered aperture 3. It is taken out. Due to the increase in near-field light intensity due to the condensing effect by the tapered portion 32, the light intensity of the extracted propagation light 12 also increases. The propagating light 12 is guided to the light receiving unit 5 and converted into an electric signal, and the recording state of the data recording unit is determined by a signal processing unit (not shown).

  When the intensity of light incident on the light receiving unit 5 increases, a smaller data mark size can be reproduced, and a higher-density memory can be realized. Alternatively, the S / N ratio can be improved by increasing the propagation light intensity, and data can be reproduced at a higher speed.

  In the present embodiment, since the tapered portion 32 has an inverted quadrangular pyramid shape, the data recording portion 33 and the light shielding portion 34 are arranged like a checker pattern as shown in FIG. By making the shape of the tapered portion 32 into an inverted quadrangular pyramid shape, the irradiation light 9 can be efficiently condensed on the data recording portion 33 by the four inclined surfaces of the tapered portion 32 on which the reflective film is formed.

  Furthermore, since the near-field optical head 1 can be formed by a conventional semiconductor manufacturing process, it is easy to arrange a plurality of near-field optical heads 1 on the same silicon substrate. By creating such a multi-head, a plurality of data recorded in the data recording unit can be read in parallel, and further high-speed data reproduction is possible.

  FIG. 2 is a block diagram of another optical information recording / reproducing apparatus according to the first embodiment. In the block diagram of the optical information recording / reproducing apparatus according to Embodiment 1 in FIG. 1, the irradiation optical system is different. Other parts are the same as those in the embodiment of FIG.

  The irradiation optical system of the embodiment of FIG. 2 includes a light source 7 (for example, a semiconductor laser), a collimator lens 7 and a condenser lens 14. After the light beam from the light source 7 is collimated by the collimator lens 8, it is irradiated by the condenser lens 13 as the irradiation light 9 in order to read the data recorded on the recording medium 6. At this time, since the light beam is focused toward the data recording unit 33, the light intensity applied to the data recording unit 33 is increased as compared with the case of irradiating the parallel light beam as shown in FIG. Furthermore, since the angle at which the irradiation light enters the inclined surface of the tapered portion 32 becomes smaller than the inclined surface of the tapered portion 32, the light collection effect by the inclined surface of the tapered portion 32 on which the reflective film is formed is increased.

  Therefore, compared with the embodiment of FIG. 1, the intensity of light incident on the light receiving unit 5 is further increased, the reproduction of a smaller data mark size is possible, and a higher-density memory can be realized. . Alternatively, the S / N ratio can be further improved by further increasing the propagation light intensity, and higher-speed data reproduction is possible.

  Here, in the embodiment shown in FIGS. 1 and 2, the light shielding portion 34 is omitted when the reflective film formed on the tapered portion 32 has a sufficient light shielding property against the irradiation light. You can also.

  In the present embodiment, the size of the data recording unit 33 is not limited to this size, but is as large as several μm if the size of the data recording unit 33 is less than or equal to the diffraction limit of light (for example, about 100 nm). It may be size. Therefore, the tapered shape has been described as the condensing structure. However, in the case where the size of the data recording unit is a large size such as several μm, if the condensing structure has a condensing function, in addition to the tapered shape, a lens or the like But the same effect can be obtained.

  Furthermore, in the present embodiment, the case where the near-field optical head has a tapered opening having a minute opening has been described. However, any structure that can obtain propagating light by interacting with near-field light may be used. A structure in which the light receiving element is positioned above the minute opening without the surface or a combination of the minute protrusion and the light receiving element may be used.

  As described above, according to the first embodiment, in the optical information reproducing apparatus that records and reproduces information by the near-field optical head using near-field light, the medium substrate and the medium that are transparent to the wavelength of the irradiation light Use a recording medium consisting of a data recording unit for recording information on the substrate surface and an inverted spindle-shaped taper part on which a reflective film is formed as a condensing structure for condensing irradiation light on the data recording unit As a result, the intensity of light incident on the light receiving unit can be increased, and higher density memory and faster data reproduction can be achieved. Furthermore, since the luminous flux from the light source can be used more efficiently, it is not necessary to increase the output of the light source, and the increase in power consumption and heat generation due to the increased output of the light source can be suppressed. This facilitates downsizing and low power consumption of the device.

In addition, since the recording medium can be prepared by transfer, mass production of the recording medium is possible and cost reduction is easy.

Further, since the near-field optical head can be formed using a semiconductor manufacturing process, it is suitable for mass production, can be adapted to an array of near-field optical heads, and can perform data reproduction at an ultra-high speed.
(Embodiment 2)
FIG. 6 is a perspective view of a recording medium showing another structure of the recording medium in the first embodiment shown in FIG. 1 and FIG. In addition, the same code | symbol is attached | subjected to the part which is common in Embodiment 1, and description is abbreviate | omitted or partly simplified about the same part as Embodiment 1. FIG.

  FIG. 6 is a perspective view of a recording medium according to the second embodiment. The structural diagram showing the end face of the recording medium is exactly the same as FIG. The difference in structure from the recording medium in the first embodiment is that, instead of the inverted tapered taper portion on which the reflective film is formed, a v-groove tapered portion 62 having one long length is provided. is there. Further, the width of the data recording unit 33 is equal to or less than the light diffraction limit (for example, about 100 nm).

Therefore, as in the case of the first embodiment, the recording medium 6 has a v-groove taper portion 62 in which a reflective film is formed on a medium substrate 61 that is transparent to the wavelength of irradiation light. A data recording unit 63 is formed on the upper surface of the medium substrate 61, and a light blocking unit 64 that blocks the irradiation light 9 is formed in an area excluding the data recording unit 33. In addition, a plurality of bits of data are recorded in the data recording unit 63 having a long one direction.

Next, an example of a method for manufacturing the recording medium 6 will be described. The recording medium shown in FIG. 6 can be manufactured even by using the manufacturing method of the recording medium 6 described in the first embodiment. Here, another manufacturing method will be described. This manufacturing method includes (1) a concave shape creating step for creating a concave shape, (2) a reflective film / light shielding portion creating step for creating a reflective film and a light shielding portion in the concave shape, and (3) information to be recorded / reproduced A data data recording part creation step on the surface of the medium substrate on which is formed.
(1) Concave Shape Creation Step FIG. 7 is a diagram for explaining a recording medium manufacturing method according to the second embodiment. A V-groove taper portion 62 is cut as a concave shape on a medium substrate 61 (FIG. 7A) having a parallel flat substrate shape such as a plastic such as PMMA or a glass substrate by a super-precision cutting technique used for creating a grating or the like. (Figure 7-b).
(2) Reflective film / light-shielding portion creation step In order to create the V-groove tapered portion 62 and the light-shielding portion 64 in which the reflective film is formed on the medium substrate 61 in which the shape of the tapered portion 62 is cut, Au, Cr, or the like Then, the metal film other than the data recording portion 63 is removed so that the metal film is formed only on the tapered portion 62 (FIG. 7C).
(3) Data recording part creation process Then, the data recording layer for recording the data mark of the size below a wavelength and the data mark shape of the size below a wavelength are formed in the data recording part, and it is set as the recording medium 6.

  Next, a method for reproducing information in the minute aperture 4 by arranging the above-described recording medium in FIG. 6 in the optical information recording / reproducing apparatus in FIG. 1 described in the first embodiment will be described. Of course, the optical information recording / reproducing apparatus of FIG. 2 can also be used.

  The recording medium 6 is, for example, a disk-shaped flat substrate, and the near-field optical memory head 1 is disposed on the upper surface thereof. The recording medium 6 which is a disk-shaped flat substrate has a V-groove tapered portion 62 as shown in FIG. 6, and is similar to a CD or an analog record with respect to the rotation direction of the disk-shaped substrate. The V-groove tapered portion 62 is formed, and the data recording portion 63 is formed concentrically around the rotation axis of the recording medium 6. Since the information reproducing method using such a recording medium 6 is exactly the same as in the first embodiment, the description thereof is omitted.

  As a tracking signal detection method for accurately tracking the near-field optical head 1 on the data recording unit, there are a three-spot type and a wobbling type. Here, a wobbling type tracking signal detection method will be described.

  When the near-field optical head 1 having the minute aperture 4 is slightly swung with respect to the recording medium 6 on which the concentric data recording unit 63 is formed, and the minute aperture 4 passes through the data pit on the data recording unit. A tracking signal can be obtained by taking a difference between signals obtained from the respective data pits. In this way, it is also possible to perform tracking control using the data recording unit 63 and the light shielding unit 64 created concentrically.

  As in the first embodiment, the width of the data recording unit 33 is set to be equal to or less than the diffraction limit of light (for example, about 100 nm) in the present embodiment, but the size of the data recording unit 33 is limited to this size. It may be a large size such as several μm. Therefore, the tapered shape has been described as the condensing structure. However, in the case where the size of the data recording unit is a large size such as several μm, if the condensing structure has a condensing function, in addition to the tapered shape, a lens or the like But the same effect can be obtained.

  Furthermore, in the present embodiment, the case where the near-field optical head has a tapered opening having a minute opening has been described. However, any structure that can obtain propagating light by interacting with near-field light may be used. A structure in which the light receiving element is positioned above the minute opening without the surface or a combination of the minute protrusion and the light receiving element may be used. In the present embodiment, when the reflective film formed on the tapered portion 62 has a sufficient light shielding property against the irradiation light, the light shielding portion 64 may be omitted.

  As described above, according to the second embodiment, in the optical information reproducing apparatus that records and reproduces information by the near-field optical head using near-field light, the medium substrate and the medium that are transparent to the wavelength of the irradiation light Use a recording medium comprising a data recording part for recording information on the substrate surface and a V-groove tapered part on which a reflective film as a condensing structure for condensing irradiation light is formed on the data recording part. As a result, the light intensity incident on the light receiving portion can be increased.

  Therefore, as in the first embodiment, higher density memory and higher speed data reproduction are possible. Furthermore, since the luminous flux from the light source can be used more efficiently, it is not necessary to increase the output of the light source, and the increase in power consumption and heat generation due to the increased output of the light source can be suppressed. This facilitates downsizing and low power consumption of the device.

  In addition, since the near-field optical head can be formed using a semiconductor manufacturing process, it is suitable for mass production, can be adapted to an array of near-field optical heads, and can perform data reproduction at an ultra-high speed.

Furthermore, in addition to the effects of the first embodiment, it is possible to perform tracking control using the data recording unit 63 and the light shielding unit 64 created concentrically, and more stable signal reproduction can be performed.
(Embodiment 3)
FIG. 8 shows a configuration diagram of an optical information recording / reproducing apparatus according to the third embodiment. In addition, the same code | symbol is attached | subjected to the part which is common in Embodiment 1 and Embodiment 2, and description is abbreviate | omitted or partly simplified about the same part as Embodiment 1 or Embodiment 2. FIG.

  In the optical information recording / reproducing apparatus of FIG. 8, the near-field optical head 81 has a taper opening 3 and a recording taper opening 83 penetrating through the silicon substrate 82, and the micro-opening 4 and the recording micro-opening 84, respectively. Is formed.

  The minute opening 4 is used for reading information recorded on the recording medium 6, and the recording minute opening 84 is used for recording information on the recording medium 6.

  The microscopic aperture 4 for reproducing the information recorded on the recording medium 6 interacts with the near-field light 1 generated in the vicinity of the microscopic aperture 4 so that the propagation light 12 obtained as a result can be extracted. For example, it has a diameter of several tens of nanometers. Irradiation light 9 irradiated for reading data recorded on the recording medium 6 is obtained by an irradiation optical system including a light source 7 (for example, a semiconductor laser) and a collimator lens 8.

  Further, the recording light source 85 irradiates the recording taper opening 83 with light by the recording lens 86. The micro aperture 84 for recording information on the recording medium 6 has a diameter of, for example, several tens of nanometers so that near-field light is generated in the vicinity of the recording micro aperture 84. The near-field light in the vicinity of the recording micro-openings 84 becomes writing light for recording information on the recording medium 6 by performing a writing operation.

  The taper opening 3 and the recording taper opening 83 are formed, for example, by fine processing using photolithography, silicon anisotropic etching, or the like in a semiconductor manufacturing process. Further, when the silicon substrate 82 does not have sufficient light shielding properties with respect to the wavelength of the irradiation light 9 and the recording light source 85, a light shielding film such as a metal film such as Au / Cr is necessary, and sputtering is performed. Or by vacuum deposition.

  As the structure of the recording medium, the recording medium 6 used in the first embodiment in FIG. 4 or the recording medium 6 used in the second embodiment in FIG. 6 can be used. Here, in order to record information, the data recording unit 64 needs to have a data recording layer capable of recording information.

  Here, an embodiment in which the recording medium 6 of FIG. 6 is used will be described.

  In the optical information recording / reproducing apparatus of FIG. 8, the method of arranging the field optical memory head 81 on the recording medium 6 of FIG. 6 and reproducing information at the minute aperture 4 is exactly the same as in the second embodiment. Description is omitted. Next, a description will be given of a method in which the field-of-view light memory head 81 is arranged on the recording medium 6 and information is recorded in the recording minute opening 84.

  As in the case of reproducing information, the disk-shaped recording medium is rotated at high speed by a spindle motor or the like (not shown). Then, in order to cause the near-field light generated in the vicinity of the recording aperture 84 of the near-field optical head 81 and the recording medium 6 to interact, the recording aperture between the recording aperture 84 and the recording medium 6 is small. It is necessary to make it close to the diameter of the opening 84. Then, the distance between the near-field optical head 81 and the recording medium 6 is kept sufficiently small by the same method as when reproducing information from the recording medium 6. Further, the position of the near-field optical head 81 is controlled by a near-field optical head control mechanism (not shown) so that the recording minute opening 84 can be arranged at a desired position on the recording medium 6.

  In order to record information on the recording medium 6, first, the minute opening 84 is moved to a desired information recording position on the data recording unit 63 of the recording medium 6 by the above-described control. Then, the recording taper opening 83 is irradiated with light using the recording light source 85 and the recording lens 86. Then, near-field light is generated in the vicinity of the recording micro-opening 84, and by performing a writing operation, information can be recorded at a desired position by the interaction between the near-field and the recording medium 6.

  Further, by making the positional relationship between the minute opening 4 used for reproducing information and the recording minute opening 84 used for recording information coincide with that of the data recording unit, reproduction is performed simultaneously with the reproduction of data from the data recording unit. Data can be recorded in a data recording unit different from the data recording unit.

  Here, in the present embodiment, information recording and reproduction are realized as one near-field optical head, but can be divided into a reproduction near-field optical head and a recording near-field optical head. . In such a case, information can be recorded and reproduced independently at the same time.

  As described above, in the optical information reproducing apparatus that records and reproduces information by the near-field optical head using near-field light as in the second embodiment, the medium substrate and the medium that are transparent to the wavelength of the irradiation light Use a recording medium comprising a data recording part for recording information on the substrate surface and a V-groove tapered part on which a reflective film as a condensing structure for condensing irradiation light is formed on the data recording part. As a result, the light intensity incident on the light receiving portion can be increased.

Furthermore, according to the present embodiment, not only information reproduction in the first and second embodiments but also information recording can be performed simultaneously.
(Embodiment 4)
FIG. 9 is a structural diagram of a recording medium used in the optical information recording / reproducing apparatus according to the fourth embodiment. The recording medium of the present embodiment can also be used as the recording medium 6 of the embodiment of FIGS.

  The recording medium 6 in FIG. 9 is a case where data recording units are arranged on both sides of the recording medium in the recording medium in the first embodiment (FIGS. 3 and 4) and the recording medium in the second embodiment (FIG. 6). It is an embodiment.

  A tapered portion 92 having a reflective film formed on a medium substrate 91 that is transparent to the wavelength of irradiation light for reproducing information and recording light for recording information is formed through the medium substrate 91. This reflective film has a sufficient light shielding property with respect to the wavelength of irradiation light for reproducing information and recording light for recording information. An upper data recording unit 93 is formed on the upper surface of the medium substrate 91, and a lower data recording unit 94 is formed on the lower surface of the medium substrate 91. The widths of the upper data recording unit 93 and the lower data recording unit 94 are equal to or smaller than the wavelength of the light used, for example, about several tens of nm.

  As described above, when the width of the upper data recording unit 93 and the lower data recording unit 94 is set to a size less than or equal to the wavelength of the light, when the irradiation light is irradiated from the lower side of the medium substrate 91, the lower data recording unit 94 and its The light irradiated between the adjacent lower data recording units is irradiated to the upper data recording unit 93 due to the condensing effect of the taper unit 92, and near-field light is generated in the vicinity of the upper data recording unit.

  On the other hand, when the lower data recording unit 94 is irradiated with irradiation light from the lower side, the size of the lower data recording unit 94 is less than a wavelength, for example, about several tens of nm, and thus exceeds the light diffraction limit. Therefore, light cannot pass through the lower data recording unit 94 to the upper surface of the medium substrate 91. Therefore, when irradiation light is irradiated from the lower side of the medium substrate 91, near-field light is generated near the upper data recording unit 93 on the upper surface of the medium substrate 91, and other near-field light or propagating light transmitted through the medium substrate is generated. There is no.

  Similarly, when the irradiation light is incident from the upper side of the medium substrate 91, the near-field light is only generated near the lower data recording unit 94.

  Therefore, the information recorded on the recording medium can be reproduced by receiving the propagation light generated by the interaction between the near-field light generated on the surface of the recording medium and the minute opening of the near-field optical head by the light receiving element. It becomes possible. Therefore, the information recording surface is double-sided, and the recording capacity per recording medium is doubled.

  In the embodiment shown in FIGS. 1, 2, and 5, the near-field optical head and the irradiation optical system described above are arranged on both sides of the recording medium, so that both sides can be reproduced or recorded simultaneously.

  As described above, in the optical information reproducing apparatus that records and reproduces information by the near-field optical head using near-field light, as in the first, second, and third embodiments, the irradiation light A medium substrate that is transparent to the wavelength, a data recording unit that records information on the surface of the medium substrate, and a tapered unit that is formed with a reflective film that is a condensing structure for condensing irradiation light on the data recording unit By using such a recording medium, the intensity of light incident on the light receiving portion can be increased. As described in the third embodiment, not only information reproduction but also information recording can be performed simultaneously.

  In addition, since data recording portions can be formed on both sides of the recording medium, the capacity per recording medium can be doubled.

1 is a configuration diagram showing an optical information recording / reproducing apparatus according to Embodiment 1 of the present invention. FIG. It is a block diagram which shows the other optical information recording / reproducing apparatus by Embodiment 1 of this invention. 1 is a structural diagram showing a recording medium according to Embodiment 1 of the present invention. It is a perspective view which shows the recording medium by Embodiment 1 of this invention. It is a figure which shows the manufacturing method of the recording medium by Embodiment 1 of this invention. It is a perspective view which shows the recording medium by Embodiment 2 of this invention. It is a figure which shows the manufacturing method of the recording medium by Embodiment 2 of this invention. It is a block diagram which shows the optical information recording / reproducing apparatus by Embodiment 3 of this invention. It is a structural diagram which shows the recording medium by Embodiment 3 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,81 Near-field optical head 2,82 Silicon substrate 3 Tapered opening part 4 Micro opening 5 Light receiving element 6 Recording medium 7 Light source 8 Collimating lens 9, 14 Irradiation light 10, 15 Condensing light beam 11 Near-field light 12 Propagation light 13 Collection Optical lens 31, 61, 91 Medium substrate 32, 62, 92 Tapered portion 33, 63 Data recording portion 34, 64 Light shielding portion 51 Si substrate 52 SiO ₂ layer 53 Photo resist 54 Convex shape 83 Recording taper opening 84 Recording minute opening 85 Recording light source 86 Recording lens 93 Upper data recording unit 94 Lower data recording unit

Claims (7)

In a recording medium that records and reproduces information with a near-field optical head using near-field light,
A medium substrate having a medium transparent to the wavelength of the irradiation light and a condensing structure for collecting the irradiation light to generate the near-field light,
Each of both surfaces of the medium substrate has a part of the light collecting structure and a data recording unit on which information to be recorded and reproduced is formed and irradiated with the irradiation light collected by the light collecting structure, A recording medium which records and reproduces information on both sides of the medium substrate.   The recording medium according to claim 1, wherein the condensing structure is a tapered portion in which a reflective film having a tapered shape is formed in a thickness direction from the surface of the medium substrate. The recording medium according to claim 2, wherein the tapered portion on which the reflective film is formed is a V-groove tapered portion. In an optical information recording / reproducing apparatus for recording / reproducing information with a near-field optical head using near-field light,
An irradiation optical system configured of a light source and a lens, which irradiates irradiation light for generating the near-field light;
A medium transparent to the wavelength of the irradiation light and a medium substrate having a condensing structure for collecting the irradiation light to generate the near-field light, and both surfaces of the medium substrate are A recording medium having a part and a data recording unit on which information to be recorded / reproduced is formed and irradiated with the irradiation light collected by the light collecting structure, and recording / reproducing information on both sides of the medium substrate When,
An optical information recording / reproducing apparatus comprising: at least one near-field optical head for reproducing information formed in the data recording unit. 5. The optical information recording / reproducing apparatus according to claim 4 , further comprising at least one near-field optical head for recording information in the data recording unit. The light converging structure, an optical information recording reproducing apparatus according to claim 4 or claim 5, characterized in that in the thickness direction of the medium substrate is a tapered portion which reflecting film is formed to have a tapered shape . 7. The optical information recording / reproducing apparatus according to claim 6 , wherein the tapered portion on which the reflective film is formed is a V-groove tapered portion.

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