JP2013089270A - Optical information recording/reproduction device, and optical information recording method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-density optical information recording/reproduction device and an optical information recording method that can perform stable and synchronous recording on a patterned medium with high precision.SOLUTION: The optical information recording/reproduction device that performs recording/reproduction to and from an information recording medium having discrete cells 102 regularly arranged has a metal antenna 105a for recording and a metal antenna 105b for detection which interact with a cell 102 to change in resonance state according to distance from the cell center, and is characterized in generating a correction value corresponding to the distance between the two metal antennas from change in resonance state of the two metal antennas, and determining the timing when the metal antenna 105a for recording performs recording to the cell 102 according to the change in resonance state of the metal antenna 105b for detection and the correction value.

Description

  The present invention relates to an optical information recording / reproducing apparatus and an information recording method for recording or reproducing information with respect to a patterned medium in which discrete micro regions are regularly arranged.

  2. Description of the Related Art In recent years, attention has been paid to a technique for performing high-density optical information recording / reproduction exceeding the diffraction limit of light by applying near-field light in the field of optical information recording. As a method for achieving high recording density using near-field light, a conventional method described in Patent Document 1 will be described with reference to the accompanying drawings. 16A and 16B are a top view and a side view showing a configuration of a near-field optical head according to the prior art.

  16A and 16B, reference numeral 801 denotes an optical disk, 802 denotes a light source, 803 denotes a prism that transmits the radiated light LB of the light source 802, and 804 denotes a scatterer that generates near-field light NL when LB enters. A heat radiating material 805 is fixed to the light source 802 to radiate heat generated by the light source 802. Reference numeral 806 denotes a detection element that detects reproduction light from the optical disk 801. A light source 802, a prism 803, a scatterer 804, a heat dissipation material 805, and a detection element 806 are held by a slider 807, and the slider 807 is held by a suspension 808 so that the distance between the optical disk 801 and the scatterer 804 is constant. .

  Information is recorded by forming a recording mark by changing the crystal phase of the optical disk 801 that is a phase change material to an amorphous phase by the near-field light NL generated by the scatterer 804. On the other hand, the information is reproduced by detecting the intensity change of the scattered light returning from the optical disk 801 because the ratio of the near-field light NL scattered by the optical disk 801 varies depending on the presence or absence of the recording mark.

  According to Patent Document 1, the light source 802, the prism 803, the scatterer 804, the heat radiation member 805, and the detection element 806 are held by the slider 807 to form a so-called near-field optical probe slider. Thus, a near-field optical head device that records or reproduces information at high density using the near-field light NL on the optical disk 801 can be realized.

  On the other hand, in order to further increase the density of near-field optical recording, a method using an information recording medium in which discrete minute regions having a size equal to or smaller than the wavelength of light are regularly arranged, a so-called patterned medium, has been proposed. ing. Conventional examples described in Patent Document 2 and Patent Document 3 will be described with reference to the accompanying drawings as examples of the configuration of the patterned medium. 17A is a schematic diagram illustrating a configuration of a patterned medium according to the conventional technique described in Patent Document 2, and FIG. 17B is a schematic diagram illustrating a configuration of the patterned medium according to the conventional technique described in Patent Document 3.

  In FIG. 17a, 851 is a substrate such as glass, 852 is a fine structure having diffraction grating-like irregularities formed on the substrate 851, 853 is a metal film functioning as a light shielding film, and 854 is a recording layer made of a phase change material. It is. According to Patent Document 2, information can be recorded and reproduced using a probe having a minute opening at the tip of such a patterned medium, so that light from the minute opening can be efficiently coupled to the recording medium. Good recording marks can be obtained and signals can be reproduced with a high S / N ratio.

  In FIG. 17b, 861 is a fine structure protrusion having a size equal to or smaller than the light source wavelength, 862 is a thermal reaction layer made of a silicon compound material, 863 is a recording layer made of a phase change material, and 864 is for exciting plasmons. It is a metal layer. According to Patent Document 3, when near-field light is coupled to the patterned medium, the near-field light is coupled to plasmons in the metal layer 864 and is transferred to the recording layer 863 after the intensity is enhanced. Further, the heat generated in the recording layer 863 can be confined by the thermal reaction layer 862. For this reason, near-field light can be coupled to the patterned medium with high efficiency.

  By combining the near-field light head and the patterned medium as described above, high-density optical information recording / reproduction exceeding the diffraction limit using near-field light can be performed. In such a high-density optical information recording / reproducing apparatus using a patterned medium, in order to perform recording on one minute area in the patterned medium with high accuracy, recording timing and recording are performed on the minute area. Therefore, synchronous recording is required to match the timing at which the recording element passes through the minute area. However, Patent Document 2 and Patent Document 3 do not describe the method.

  As a method for synchronous recording on a patterned medium, a conventional technique described in Patent Document 4 will be described with reference to the accompanying drawings. FIG. 18 is a diagram schematically showing the main part of a magnetic recording apparatus in heat-assisted magnetic recording according to the prior art.

  In FIG. 18, a magnetic recording medium 901 has a structure in which a recording layer 904 including patterned and regularly arranged ferromagnetic regions 903 is formed on a substrate 902. On the magnetic recording medium 901, there are a recording magnetic pole 905 as a magnetic field applying means and a heating element 906 that overheats the recording layer 904, and the recording magnetic pole 905 and the heating element 906 move in the direction of the arrow in the figure.

  In Patent Document 4, a synchronization signal is generated from reproduction information as means for synchronizing the timing at which the heating element 906 emits a heating pulse with the timing at which the heating element 906 passes over one ferromagnetic region of the recording layer 904. A method has been proposed.

International Publication No. 2007/111304 JP 2003-308632 A JP 2006-164410 A JP 2004-355739 A

  However, the conventional synchronous recording method in the heat-assisted magnetic recording requires not only the synchronization of the heating timing of the overheating element but also the synchronization of the magnetic field application timing of the recording magnetic pole. It was.

  In addition, there is a relative distance between the two elements because the position of the detection element that obtains the reproduction signal for generating the synchronization signal is different from the position of the heating element that is the recording element. For this reason, the timing at which each element passes over the ferromagnetic region is different, and it is necessary to correct the timing shift. Further, when the size of one ferromagnetic region of the patterned medium is several nanometers to several tens of nanometers, the amount of timing deviation is large only by changing the relative distance between the detection element and the recording element on the order of nanometers. Change. If there is a manufacturing variation in the information recording / reproducing apparatus, the amount of timing deviation between the detection element and the recording element varies greatly depending on the individual apparatus. Therefore, it is necessary to correct the timing deviation for each apparatus. In the conventional synchronous recording method in the heat-assisted magnetic recording, such a timing deviation correction method is not shown. Therefore, the timing deviation is not corrected, and there is a problem that synchronous recording cannot be accurately performed on the patterned medium.

  The present invention solves the above-mentioned conventional problems, and provides an apparatus and an information recording method capable of performing synchronous recording with high accuracy in a high-density optical information recording / reproducing apparatus exceeding the diffraction limit. Objective.

  In order to achieve the above object, the present invention provides an optical information recording / reproducing apparatus for recording / reproducing information on / from an information recording medium in which discrete minute regions are regularly arranged. The resonance state changes according to the distance from the minute region that acts and the first resonance element that records in the minute region by near-field light, and the distance from the minute region that interacts with the information recording medium A second resonance element whose resonance state changes according to the first resonance element, a holding element that is arranged with a fixed distance between the first resonance element and the second resonance element, and the first resonance element. A first light source that irradiates light to the element; a second light source that irradiates light to the second resonant element; a first drive circuit that pulse-drives the first light source; and the second light source. A second drive circuit for driving the first resonant element, the first resonant element, and the An optical element that guides light from the first light source and the second light source to two resonance elements, a detection element that detects and outputs a change in the resonance state of the second resonance element, and the second A synchronization circuit that generates a synchronization signal based on a change in the resonance state of the resonance element, and the first drive circuit receives the synchronization signal from the synchronization circuit and receives a pulse to the first resonance element. The light incident timing is determined.

  The present invention also relates to an information recording method in an optical information recording / reproducing apparatus for recording / reproducing information on / from an information recording medium in which discrete minute regions are regularly arranged, wherein the optical information recording / reproducing is performed. The apparatus includes a first resonance element that interacts with the information recording medium, changes a resonance state according to a distance from the minute area, and records in the minute area by near-field light, and the information recording medium. A second resonance element that interacts and changes a resonance state in accordance with a distance from the minute region, a first light source that irradiates light to the first resonance element, and light that is emitted to the second resonance element A second light source for irradiating, the step of making light from the second light source incident on the second resonant element, the step of detecting a change in the resonant state of the second resonant element, Based on the change in the resonance state of the second resonance element, Determining an incident timing of the pulsed light from the first light source to one of the resonance element, was employed comprising information recording methods.

  The present invention relates to a first resonance element (recording resonance element) that interacts with an information recording medium, changes a resonance state according to a distance from the minute area, and records in the minute area by near-field light, and information The second resonance element (detection resonance element) that interacts with the recording medium and changes the resonance state according to the distance from the micro region is fixedly arranged so that the distance between the elements is constant. . Further, the configuration is such that synchronous recording is performed by determining the incident timing of the pulsed light to the recording resonance element from the change in the resonance state of the detection resonance element. In the near-field light recording, recording can be performed by a single recording resonance element, and therefore, it is only necessary to synchronize the incident timing of the pulsed light to the recording resonance element with the timing at which the recording resonance element passes over the minute region. For this reason, the relative distance between the recording detection element and the detection resonance element is fixed, and synchronous recording is performed based on the change in the resonance state of the detection resonance element. The effect is that synchronous recording can be performed.

  Further, the present invention is configured to calculate and output a correction value corresponding to the distance between the resonance elements from the detection signals of the recording resonance element and the detection resonance element. In addition, synchronous recording is performed by making pulsed light incident on the recording resonance element based on the correction value. For this reason, it is possible to correct uncertain elements such as variations during production, and the effect is that stable and highly accurate synchronous recording is possible.

  Further, the present invention employs a recording method for calculating a synchronization signal based on a change in the resonance state of the detection resonance element. For this reason, the detection signal reacts sensitively to changes in the optical constants around the resonant element, and a detection signal with a high degree of modulation is obtained with respect to a minute positional deviation from the minute region. For this reason, a highly accurate synchronization signal can be obtained even for a very small area of several nanometers to several tens of nanometers in size, and there is an effect that synchronous recording can be performed with high precision.

1 is a schematic diagram of an optical information recording / reproducing apparatus in Embodiment 1 of the present invention. It is the perspective view, side view, and top view of a slider in Embodiment 1 of this invention. It is an enlarged view of the metal antenna in Embodiment 1 of this invention. It is a graph which shows the change of the reflected light with respect to the distance from the center of the cell in Embodiment 1 of this invention. It is the schematic of the optical information recording / reproducing apparatus in Embodiment 2 of this invention. It is a side view of the slider in Embodiment 2 of this invention. It is a graph which shows the change of the detection signal with respect to the distance from the center of the cell in Embodiment 2 of this invention. It is a conceptual diagram which shows the concept of the interaction of the metal antenna and cell in Embodiment 2 of this invention. It is a figure which shows an example of the shape of the metal antenna in other embodiment of this invention. It is the schematic of the optical information recording / reproducing apparatus in Embodiment 3 of this invention. It is the perspective view and top view of a metal antenna periphery in Embodiment 3 of this invention. It is a graph which shows the time change of the trigger signal on the reference area | region in Embodiment 3 of this invention. It is a figure which shows an example of the shape of the metal antenna in other embodiment of this invention. It is the schematic of the patterned medium in other embodiment of this invention. It is a flowchart of the information recording method in Embodiment 4 of this invention. It is the top view and side view which show the structure of the near-field optical head by a prior art. It is the schematic of the patterned medium by a prior art. It is a principal part schematic diagram of the magnetic-recording apparatus in the heat-assisted magnetic recording by a prior art.

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

(Embodiment 1)
FIG. 1 is a schematic diagram of an optical information recording / reproducing apparatus according to Embodiment 1 of the present invention.

  In FIG. 1, a disc 101, which is an information recording medium, is a patterned medium in which discrete discrete areas are regularly arranged. Each minute region is called a cell 102. The cells 102 are periodically arranged in the track direction with a period of a distance Pp. The cell 102 is an isolated fine particle formed on a flat plate. As a material constituting the cell 102, for example, a phase change material made of a compound such as Ge, Sb, Te, Bi, Tb, Fe, and Co can be considered. The disk 101 is rotated by a motor 103 that holds and rotates the disk 101.

  The slider 104 which is a holding element holds the metal antenna 105a which is a first resonance element and the metal antenna 105b which is a second resonance element. The two antennas are fixedly arranged on the same track so that the distance is constant. The metal antenna 105a is a recording metal antenna that performs recording in the cell 102 using near-field light. The metal antenna 105b is a detection metal antenna for performing synchronous detection. The metal antennas 105a and 105b, which are resonant elements, interact with the cell 102, and the resonance state changes according to the distance from the center of the cell 102. The slider 104 is held by the suspension 106 so as to face the disk 101, and the distance between the slider 104 and the disk 101 is kept constant by using the same technique as that of a flying head employed in a hard disk drive.

  2A, 2B, and 2C are a perspective view, a side view, and a top view of the slider 104, respectively.

  2A, 2B, and 2C, the semiconductor laser element 107a is a first light source that irradiates light to the recording metal antenna 105a. The semiconductor laser element 107b is a second light source that irradiates the detection metal antenna 105b with light. The polarization directions of the semiconductor laser elements 107 a and b are perpendicular to the surface of the disk 101.

  Waveguides 108a and 108b as optical elements for guiding light to the metal antennas 105a and 105b are Y-shaped waveguides, and the waveguides 108a and 108b extending from the metal antennas 105a and 105b are branched into Y-shapes. Semiconductor laser elements 105a and 105b are respectively disposed at one end of the branched Y-shaped waveguides 108a and 108b, and light receiving elements 109a and 109b are respectively disposed at the other end. Light emitted from the semiconductor laser elements 107a and 107b is individually guided to the metal antennas 105a and 105b through the waveguides 108a and 108b, respectively, and excites plasmon resonance.

  On the other hand, the reflected light from the metal antennas 105a and 105b is guided by the waveguides 108a and 108b, branched by the Y branch, and then individually detected by the light receiving elements 109a and 109b. The light receiving element 109a outputs a detection signal ss1 according to the detected intensity of the reflected light. The light receiving element 109b outputs a detection signal ss2 according to the detected intensity of the reflected light.

  As described above, in the optical information recording / reproducing apparatus according to the first embodiment, the detection element that detects and outputs the change in the resonance state of the second resonance element includes the light receiving element 109b and the waveguide 108b. The second detection element that detects and outputs a change in the resonance state of the resonance element includes a light receiving element 109a and a waveguide 108b.

  FIG. 3 is an enlarged view around the metal antenna 105a in the first embodiment. The shape of the metal antenna 105a is a triangular flat plate shape. The material is gold, silver, copper, titanium, aluminum, chromium, or the like. In FIG. 3, the metal antenna 105 a is arranged so that one vertex of the triangle is closest to the surface of the cell 102. When plasmon resonance is excited by linearly polarized incident light polarized in a direction connecting the metal antenna 105 a and the cell 102, strong near-field light is generated between the apex of the triangle and the cell 102. Non-Patent Document 1 (Confined plasmas in nanofabricated single silver partner pairs:, 7, ss, 2, ss., S. The interaction between the metal particles appears remarkably when the distance between the metal particles is several tens of nm or less, and becomes more prominent at a few nm. That is, the distance between the metal antenna 105a and the cell 102 surface is preferably several tens of nm or less, and more preferably several nm. The metal antenna 105b is also arranged in the same manner as the metal antenna 105a, and strong near-field light is generated between the apex of the triangle and the cell 102.

  FIG. 4A is a graph showing changes in reflected light intensity with respect to the distance from the cell center of the metal antennas 105a and 105b. In FIG. 4 a, the distance Pp is a repetition period with respect to the track direction of the cell 102. In general, the resonance condition of plasmon resonance greatly depends on the dielectric constant of the medium around the resonance element. The metal antennas 105a and 105b are designed so that the plasmon resonance condition is satisfied on the cell 102 with respect to the light frequency of the semiconductor laser elements 107a and 107b. For this reason, the reflected light intensity from the metal antenna is, for example, the maximum at the center of the cell as shown in FIG. 4a, and the minimum at the position where the distance from the center of the cell is half of the repetition period Pp. Furthermore, as shown in FIG. 4a, the metal antennas 105a and 105b are designed such that the strength of the resonance state changes depending on whether the phase change material of the cell 102 is crystalline or amorphous. For this reason, the detection signal ss1 or ss2 can be used as a reproduction signal when reproducing information. That is, information recorded on the information recording medium can be reproduced from a change in the resonance state of the first resonance element or the second resonance element.

  FIG. 4b is a graph showing the time change of the detection signal ss1 from the light receiving element 109a and the detection signal ss2 from the light receiving element 109b. The origin of time 0 is the time when the metal antenna 105a passes through the center of a cell. In FIG. 4b, the time Tp is the time taken for the metal antenna to move the distance Pp, and is the time from when the metal antenna passes through the center of one cell to the center of the adjacent cell. FIG. 4c shows the time change of the clock signals st1, st2 generated from the detection signals ss1, ss2. By using the clock signals st1 and st2 instead of the detection signals ss1 and ss2, a signal having a constant amplitude can be used synchronously regardless of the phase state of the cell and the noise of the detection signal. FIG. 4c shows a case where the distance between the two metal antennas is longer than the repetition period Pp in the cell track direction. In FIG. 4c, the difference between the time when the detection metal antenna 105b passes over the center of one of the cells 102 and the time when the recording metal antenna 105a passes over the center of the same cell is referred to as a timing difference Tse. A remainder obtained by dividing the timing shift Tse by the repetition time Tp is referred to as a net timing shift se.

  In order to perform synchronous recording, first, a correction value corresponding to the distance between the metal antenna 105a and the metal antenna 105b is determined. In the first embodiment, the net timing shift se is used as the correction value. Returning to FIG. 1, the circuit configuration will be described. A drive circuit 111a as a first drive circuit drives the semiconductor laser element 107a by direct current. A drive circuit 111b as a second drive circuit drives the semiconductor laser element 107b by direct current. Continuous light emitted from the semiconductor laser elements 107a and 107b is incident on the metal antennas 105a and 105b. Reflected light from the metal antennas 105a and 105b is detected by the light receiving elements 109a and 109b, and detection signals ss1 and ss2 are input to the arithmetic circuit 112. The arithmetic circuit 112 includes synchronization circuits 113a and 113b, a correction circuit 114, and a delay circuit 115. The synchronization circuit 113a outputs a clock signal st1 synchronized with the detection signal ss1 based on the detection signal ss1 from the recording antenna 105a. The synchronization circuit 113b outputs a clock signal st2 synchronized with the detection signal ss2 based on the detection signal ss2 from the detection antenna 105b. As shown in FIG. 4c, the clock signals st1 and st2 have a timing shift Tse corresponding to the distance between the two metal antennas. The correction circuit 114 calculates the net timing shift se as a correction value based on the clock signals st1 and st2 output from the two synchronization circuits 113a and 113b, and stores it in the internal memory. The stored value is output.

  Subsequently, synchronous recording is performed using the correction value. The drive circuit 111b drives the semiconductor laser element 107b in a direct current and makes continuous light incident on the metal antenna for detection 105b. The delay circuit 115 receives the clock signal st2 generated from the detection signal ss2, and outputs the recording clock signal ST delayed by the net timing shift se, which is a correction value, as a synchronization signal. At this time, when the repetition time of the clock signal st2 changes, the delay circuit 115 calculates and delays the net timing shift se according to the change of the repetition time. For this reason, stable synchronous recording can be performed even if the repetition time changes due to changes in linear velocity at the inner and outer peripheral portions of the disc 101. The recording clock signal ST is input to the drive circuit 111a. The drive circuit 111a outputs a recording pulse modulated based on the modulation signal generated from the data in accordance with the recording clock signal ST, and drives the semiconductor laser element 107a in pulses. The pulsed light emitted from the semiconductor laser element 107a is incident on the recording metal antenna 105a. The metal antenna 105a performs near-field optical recording on the cell 102 by the excited near-field light. With this configuration, the recording pulse is irradiated at a timing when the metal antenna 105a passes through the center of the cell 102. For this reason, stable and highly accurate synchronous recording can be performed. As a result, the possibility of erroneously writing information to an adjacent cell or erasing information when recording information in a desired cell is reduced, and an optical information recording / reproducing apparatus with a low error rate can be configured. it can.

  As described above, the optical information recording / reproducing apparatus of the first embodiment detects the change in the resonance state of the first resonance element and outputs the second detection element (waveguide 108a and light receiving element 109a). A correction circuit 114 that generates a correction value according to the distance between the first resonance element and the second resonance element from signals output from the detection element and the second detection element is provided. The synchronization circuit 113b and the delay circuit 115 include A synchronization signal is generated based on the correction value generated by the correction circuit.

  In the first embodiment, an example in which the metal antennas 105a and 105b are arranged perpendicular to the disk 101 is shown. The metal antennas 105 a and 105 b are excited by plasmon resonance with light polarized perpendicular to the disk 101. Therefore, the area on the disk 101 that interacts with the metal antennas 105a and 105b is narrow, and high resolution can be obtained.

  Further, in the first embodiment, by using a technique similar to that of a flying head employed in a hard disk drive, a position of several nm to several tens of nm can be scanned on the disk 101 without contacting the slider 104 and the disk 101. Therefore, precise gap control can be performed without causing the disk 101 and the slider 104 to wear.

  In the first embodiment, light from the semiconductor laser elements 107a and 107b is individually incident on the metal antennas 105a and 105b using the waveguides 108a and 108b. Further, the reflected light from the metal antennas 105a and 105b is individually detected using the waveguides 108a and 108b and the light receiving elements 109a and 109b. For this reason, the complicated structure for isolate | separating light is not required. Moreover, since it is integrated, a mechanism for adjusting the optical axis is not necessary.

  In the first embodiment, since the metal antennas 105a and 105b are arranged on the same track, the repetition times of the clock signals st1 and st2 are equal. For this reason, it is not necessary to correct the difference between the repetition times of the clock signals st1 and st2, and a complicated circuit configuration may not be used.

  Further, in the first embodiment, by using the detection signal of the metal antenna 105b as a reproduction signal, information can be reproduced without using a complicated configuration.

  In the first embodiment, the configuration in which the cells 102 are isolated fine particles formed in a planar shape is used. Therefore, a detection signal with a high S / N ratio can be obtained as compared with the case where the recording layer is uniformly formed on the fine structure.

  In the first embodiment, the net timing shift se is used as the correction value. In this configuration, it is only necessary to detect the time difference between one clock signal st2 and the subsequent clock signal st1, so that the circuit system can be simplified.

  In the first embodiment, the Y-shaped waveguide is used as the waveguide. However, the configuration of the waveguide is not particularly limited as long as the reflected light from the two metal antennas can be separated.

  In the first embodiment, the reflected light from the two metal antennas is individually detected using the waveguide and the light receiving element. However, the light receiving element is arranged in a range where the near-field light generated at the tip of the metal antenna can be detected. And the structure which detects the change of near-field light intensity directly separately may be sufficient.

  In the first embodiment, the semiconductor laser element, the metal antenna, and the light receiving element are arranged on the end face of the slider. However, these elements are arranged inside the slider, or these elements are integrated on one chip. Or may be produced.

  In the first embodiment, a structure in which isolated phase change fine particles are formed on a substrate is used as the configuration of the patterned medium. However, the structure is described in Patent Document 2 and Patent Document 3 shown in FIGS. 17a and 17b. It may be configured as shown.

  In the first embodiment, air is used between the cells. For example, the cell is filled with a dielectric or resin to protect the cells, or the cells are embedded. May be.

(Embodiment 2)
Next, an optical information recording / reproducing apparatus according to Embodiment 2 of the present invention will be described.

  FIG. 5 is a schematic diagram of an optical information recording / reproducing apparatus according to Embodiment 2 of the present invention. 5, the same components as those in FIGS. 1 and 2 are denoted by the same reference numerals, and the description thereof is omitted.

  In FIG. 5, the disk 101 on which the discretized cells 102 are regularly arranged is rotated by a motor.

  The slider 201 that is a holding element holds a metal antenna 202a that is a first resonance element and a metal antenna 202b that is a second resonance element. The metal antenna 202a is a recording metal antenna used for performing near-field optical recording, and the metal antenna 202b is a detection metal antenna used for performing synchronous detection. The two antennas are fixedly arranged on the same track so that the distance is constant. The slider 201 is held opposite to the disk 101 by the suspension 106, and the distance between the slider 201 and the disk 101 is kept constant by using the same technique as that of the flying head employed in the hard disk drive.

  The semiconductor laser element 203a is a first light source. The semiconductor laser element 203b is a second light source. The semiconductor laser elements 203a and 203b have different output wavelengths. In this embodiment, for example, the semiconductor lasers 203a and 203b emit light having wavelengths of 780 nm and 630 nm in this order, and the polarization is linearly polarized in the direction perpendicular to the disk. The light emitted from the semiconductor laser elements 203 a and 203 b is collimated by the lens 204 and reflected by the half mirror 205. Thereafter, the reflected light is collected by the lens 206 and is incident on the metal antennas 202 a and 202 b disposed on the end face of the slider 201. At this time, the spot size is adjusted so that the metal antennas 202a and 202b enter the spot of the convergent light.

  In the second embodiment, the lens 204, the half mirror 205, the lens 206, and the like function as optical elements that guide light from the light source to the first resonance element and the second resonance element.

  FIG. 6 shows a side view of the slider 201.

  In FIG. 6, the metal antennas 202a and 202b are triangular flat plates made of, for example, gold, silver, copper, titanium, aluminum, chrome, or the like. The two metal antennas are arranged perpendicular to the surface of the disk 101 so that one vertex of the triangle is closest to the surface of the cell 102. The distance between the metal antennas 202a and 202b and the surface of the cell 102 is preferably several tens of nm or less, more preferably several nm, as in the first embodiment. When vertically polarized light is incident on the surface of the disk 101, plasmon resonance is excited, and strong near-field light is generated between the apex of the triangle and the cell 102. The metal antenna 202a is designed so that the maximum plasmon resonance is excited on the cell 102 by light having a wavelength of 780 nm of the semiconductor laser element 203a. The metal antenna 202b is designed so that the maximum plasmon resonance is excited on the cell 102 by light having a wavelength of 630 nm of the semiconductor laser element 203b. For this reason, two metal antennas differ in shape or material. The resonant state of the metal antennas 202a and 202b, which are resonant elements, interacts with the information recording medium 101 and changes depending on the distance from the center of the cell 102. In other words, the metal antenna 202a is a first resonance element that interacts with the information recording medium, changes the resonance state according to the distance from the minute area, and records in the minute area with near-field light. The metal antenna 202b This is a second resonance element that interacts with the information recording medium and changes the resonance state in accordance with the distance from the minute region. Further, the metal antennas 202a and 202b are also resonant elements having different shapes or materials with the respective light frequencies of two light sources having different wavelengths as resonance frequencies.

  Scattered light emitted from the metal antennas 202a and 202b is collimated by the lens 206, passes through the half mirror 205, and then passes through the light shielding plate 207. The light shielding plate 207 is shielded at the central portion, and only the scattered light forming the peripheral portion is transmitted by shielding the light at the central portion including the reflected incident light. The polarizing prism 208 reflects polarized light perpendicular to the disk 101 and transmits polarized light in the track direction. After passing through the light shielding plate 207, the scattered light is separated into polarized light in the track direction and polarized light perpendicular to the disk by the polarizing prism 208.

  The polarized light perpendicular to the disk is reflected by the polarizing prism 208, then passes through the wavelength filter 209 that transmits only the light of wavelength 630 nm of the semiconductor laser element 203 b, is condensed by the lens 210, and is detected by the light receiving element 211. Is done. When the metal antenna 202b is designed so that the strength of the resonance state changes depending on whether the phase change material of the cell 102 is crystalline or amorphous, the detection signal of the light receiving element 211 can be used as a reproduction signal.

  On the other hand, the polarized light in the track direction passes through the polarizing prism 208, is diffracted by the diffraction grating 212 at different angles for each wavelength, and is condensed and detected by the lens 213 on the corresponding light receiving elements 109a and 109b.

  FIG. 7a is a graph showing changes in detection signal intensity with respect to the distance from the cell center of the metal antennas 202a and 202b. In FIG. 7 a, the distance Pp is a repetition period with respect to the track direction of the cell 102. FIG. 7B is a graph showing temporal changes in the detection signal ss1 from the light receiving element 109a and the detection signal ss2 from the light receiving element 109b. The origin of time 0 is the time when the metal antenna 202b passes through the center of a cell. In FIG. 7b, time Tp is the time it takes for the metal antenna to move the distance Pp, and is the time from when the metal antenna passes through the center of one cell to the center of the next cell. The detection signals ss1 and ss2 have a phase shift pe according to the distance between the recording metal antenna 202a and the detection metal antenna 202b.

  FIG. 8 shows the concept of the detection method of the detection signals ss1 and ss2. FIG. 8 a is a conceptual diagram of dipole radiation when the metal antenna 202 a is on the cell 102. It is attracted to the dipole excited inside the metal antenna 202a by plasmon resonance, and polarization is generated on the surface of the cell 102, and a strong dipole is excited between the apex of the metal antenna 202a and the surface of the cell 102. Scattered light is generated when the excited dipole generates dipole radiation. At this time, since the apex of the metal antenna 202 a is on the cell 102, the generated dipole is in the direction perpendicular to the disk 101, and the scattered light emitted is also polarized light in the direction perpendicular to the disk 101.

  On the other hand, FIG. 8 b is a conceptual diagram of dipole radiation when the metal antenna 202 a is located at a position shifted from the cell 102. Polarization is induced on the surface of the cell 102 by the dipole excited inside the metal antenna 202 a by plasmon resonance, and a strong dipole is excited between the vertex of the metal antenna 202 a and the surface of the cell 102. Scattered light is generated when the excited dipole generates dipole radiation. At this time, since the apex of the metal antenna 202a is located at a position shifted from the cell 102, the dipole generated between the metal antenna 202a and the cell 102 is inclined from the direction perpendicular to the disk 101 in the track direction. For this reason, the scattered light emitted includes light polarized in the direction perpendicular to the disk 101 and light polarized in the track direction. By detecting only the polarized light in the track direction using the polarizing prism, the signal value is small at the cell center and the signal value between the cells is large as shown in FIG. 7a according to the distance from the cell center. A changing detection signal ss1 is obtained. Similarly, the detection signal ss2 can be detected for the metal antenna 202b. In addition, by using a structure having a metal film on the cell surface described in Patent Document 3 as shown in FIG. 17B as an information recording medium, the dipole between the metal antenna 202a and the cell is enhanced and the modulation degree is increased. High detection signal can be obtained.

  As described above, in the second embodiment, the light sources that make light incident on the two resonant elements are the light sources (semiconductor laser elements 203a and 203b) having different wavelengths. Further, the two resonance elements are formed of resonance elements (metal antennas 202a and 202b) having different shapes or materials with the respective light frequencies as resonance frequencies. At this time, the detection element that individually detects and outputs the change in the resonance state of each of the two resonance elements separates the light receiving elements 109a and 109b and light having different wavelengths from the resonance elements, and the polarization direction is information. A third optical element (diffraction grating 212 and polarization prism 208) that separates light in a direction parallel to the surface of the recording medium and guides the light to a corresponding light receiving element.

  Returning to FIG. 5, the circuit system of this embodiment will be described. In order to perform synchronous recording, first, a correction value corresponding to the distance between the recording metal antenna 202a and the detection metal antenna 202b is determined. In the second embodiment, the phase shift pe is used as the correction value. The drive circuit 111a drives the semiconductor laser element 203a by direct current. The drive circuit 111b drives the semiconductor laser element 203b by direct current. The semiconductor laser elements 203a and 203b make continuous light beams having different wavelengths incident on the metal antennas 202a and 202b. The light receiving elements 109a and 109b detect changes in the resonance state of the metal antennas 202a and 202b, output detection signals ss1 and ss2, and input them to the arithmetic circuit 220. The arithmetic circuit 220 includes a correction circuit 221, a delay circuit 222, and a synchronization circuit 223. The correction circuit 221 calculates the phase shift pe between the detection signals ss1 and ss2, and stores it in the internal memory as a correction value. The stored value is output as a correction value.

  Subsequently, synchronous recording is performed using the phase shift pe which is a correction value. The drive circuit 111b drives the semiconductor laser element 203b by direct current and makes continuous light incident on the metal antenna for detection 202b. The detection signal ss2 output by the light receiving element 109b is input to the delay circuit 222 in the arithmetic circuit 220. The delay circuit 222 outputs the detection signal ss3 corrected by delaying the phase of the detection signal ss2 by the phase shift pe. At this time, even if the repetition time of the detection signal ss2 changes due to a change in the linear velocity, the phase shift amount pe between the detection signal ss1 and the detection signal ss2 does not change. For this reason, stable synchronous recording can be performed even if the repetition time changes due to changes in linear velocity at the inner and outer peripheral portions of the disc 101. The synchronization circuit 223 generates a recording clock signal ST based on ss3 output from the delay circuit 222 and outputs it as a synchronization signal. The recording clock signal ST is input to the drive circuit 111a. The drive circuit 111a outputs a recording pulse modulated based on the modulation signal generated from the data in accordance with the recording clock signal ST, and drives the semiconductor laser element 203a in pulses. The pulsed light emitted from the semiconductor laser element 203a is incident on the recording metal antenna 202a. The metal antenna 202a performs near-field optical recording on the cell 102 by the excited near-field light. With this configuration, the recording pulse is irradiated at a timing when the metal antenna 202a passes through the center of the cell 102. For this reason, stable and highly accurate synchronous recording can be performed. As a result, the possibility of erroneously writing information to an adjacent cell or erasing information when recording information in a desired cell is reduced, and an optical information recording / reproducing apparatus with a low error rate can be configured. it can.

  As described above, the optical information recording / reproducing apparatus of the second embodiment detects the change in the resonance state of the first resonance element and outputs the second detection element (the diffraction grating 212, the polarization prism 208, and the light receiving element). 109a) and a correction circuit 221 that generates a correction value according to the distance between the first resonance element and the second resonance element from the signals output from the detection element and the second detection element, and the synchronization circuit 223 includes A synchronization signal is generated based on the correction value generated by the correction circuit.

  In the second embodiment, an example in which the metal antennas 202a and 202b are arranged perpendicular to the disk 101 is shown. The metal antennas 202 a and 202 b are excited for plasmon resonance by polarized light perpendicular to the disk 101. For this reason, the area on the disk 101 which interacts with the metal antennas 202a and 202b is narrow, and high resolution can be obtained.

  Further, in the second embodiment, by using the same technique as that of a flying head employed in a hard disk drive, a position of several nm to several tens of nm can be scanned on the disk 101 without contacting the slider 201 and the disk 101. Therefore, precise gap control can be performed without causing the disk 101 and the slider 201 to wear.

  In the second embodiment, the individual resonance states of the metal antennas 202a and 202b are detected using the difference in wavelength. For this reason, it is not necessary to integrate a light source, a detection element, a waveguide, and a resonance element in a minute region, and the device can be easily manufactured.

  Furthermore, in the second embodiment, since the individual resonance states of the metal antennas 202a and 202b are detected by using the change in the polarization direction, the detection signal having a higher degree of modulation than in the case of detecting the intensity change of the scattered light. Can be obtained.

  In the second embodiment, since the metal antennas 202a and 202b are arranged on the same track, the repetition periods of the detection signals ss1 and ss2 are equal. For this reason, it is not necessary to correct the difference between the repetition times of the detection signals ss1 and ss2, and a complicated circuit configuration may not be used.

  Further, in the second embodiment, information is reproduced without using a complicated configuration by using, as a reproduction signal, a detection signal having a light intensity in a direction perpendicular to the disk among detection signals of the metal antenna 202b. Can do.

  In the second embodiment, the metal antenna is arranged perpendicular to the disk. However, the resonance element may be arranged inclined from the direction perpendicular to the disk.

  In Embodiments 1 and 2, a disk is used as an information recording medium. However, the slider may be configured to move over the entire area of the disk, and the shape of the information recording medium is not limited to a circle.

  In Embodiments 1 and 2, a triangular flat plate is used as the shape of the metal antenna. However, the shape is not particularly limited to the above example. For example, in addition to the triangular flat plate, as shown in FIGS. The shape is also conceivable and is not particularly limited as long as plasmon resonance occurs on the cell and the plasmon resonance state efficiently changes according to the distance from the cell. If a rectangular flat plate as shown in FIG. 9a is used, the analysis is easier than the triangular flat plate because it is a vertical object, and the area can be larger than that of the triangular plate. In addition, if the disc is as shown in FIG. 9b, the pattern can be easily produced as compared with the triangular plate. Further, if a probe-type metal antenna as shown in FIG. 9C is used, near-field light can be generated more efficiently at the probe tip.

  In the first and second embodiments, the two metal antennas are arranged on the same track. However, even when the two metal antennas are arranged on different tracks, a configuration for calculating and correcting the difference in repetition time can be provided. What is necessary is just and it is not limited to the structure arrange | positioned on the same track | truck.

(Embodiment 3)
Next, an optical information recording / reproducing apparatus in Embodiment 3 of the present invention will be described.

  FIG. 10 is a schematic diagram of an optical information recording / reproducing apparatus according to Embodiment 3 of the present invention. 10, the same components as those in FIGS. 1, 2, 5, and 6 are denoted by the same reference numerals, and the description thereof is omitted.

  In FIG. 10, reference numeral 301 denotes a disk as an information recording medium in which discretized cells 102 are regularly arranged. The space between the cells 102 is filled with a dielectric or resin. The disc 301 has a reference area in which cells 102 as shown in FIG. 12a are arranged in a specific pattern. The pattern of the reference region is configured using, for example, the presence / absence of the cell 102 or configured by the phase state of the cell 102. The disk 301 is fixed and held by a motor.

  The semiconductor laser elements 203a and 203b and the semiconductor laser element 313 are light sources having different output wavelengths. In this embodiment, the semiconductor laser elements 203a, 203b, 313 emit light having wavelengths of 780 nm, 630 nm, and 400 nm in this order. The polarization directions of the semiconductor laser elements 203a and 203b coincide with the resonance directions of the metal antenna 302a that is the first resonance element and the metal antenna 302b that is the second resonance element. The polarization of the semiconductor laser element 313 is linearly polarized light. The semiconductor laser element 203a is used for recording information. The semiconductor laser element 203b is used for synchronous detection. The semiconductor laser element 313 is used for gap detection.

  FIG. 11 is a perspective view and a top view of the periphery of the metal antennas 302a and 302b in the third embodiment. The shapes of the metal antenna 302a and the metal antenna 302b are triangular flat plate shapes. The material is gold, silver, copper, titanium, aluminum, chromium, or the like. The metal antenna 302a is a recording metal antenna used for recording. The metal antenna 302b is a detection metal antenna used for synchronous detection. The metal antenna 302a is designed so that plasmon resonance is excited by the light emitted from the semiconductor laser element 203a. The metal antenna 302b is designed so that plasmon resonance is excited by the light emitted from the semiconductor laser element 203b. In addition, the two metal antennas are designed for maximum plasmon resonance when the triangle apex is on the cell. For this reason, two metal antennas differ in shape or material. The two metal antennas are arranged parallel to the surface of the disk 301 so that the resonance direction is a direction perpendicular to the track. As shown in FIG. 11b, the two metal antennas are fixed and arranged so that the apexes of the metal antennas are on the same track. At this time, the detection metal antenna 302b is disposed so as to precede the recording metal antenna 302a in the track direction. When light polarized in a direction perpendicular to the track enters, plasmon resonance is excited, and strong near-field light is generated between the apex of the triangle and the cell 102. The metal antennas 302a and 302b, which are resonance elements, interact with the information recording medium 301, and the resonance state changes according to the distance from the center of the cell 102. That is, the metal antenna 302a is a first resonance element that interacts with the information recording medium, changes the resonance state according to the distance from the minute area, and records in the minute area by near-field light. The metal antenna 302b This is a second resonance element that interacts with the information recording medium and changes the resonance state in accordance with the distance from the minute region. Furthermore, the metal antennas 302a and 302b are also resonant elements having different shapes or materials with the respective light frequencies of two light sources (semiconductor laser elements 203a and 203b) having different wavelengths as resonant frequencies.

  In FIG. 10, light receiving elements 109a and 109b function as detection elements that individually detect and output changes in the resonance states of the metal antennas 302a and 302b, and individually detect scattered light from the metal antennas 302a and 302b. To detect. The light receiving element 314 functions as a detection element that detects the distance between the metal antennas 302 a and 302 b and the disk 301. In the solid immersion lens 310 as a holding element, the metal antennas 302a and 302b formed on the bottom surface are arranged on the same track with a fixed distance. The lens holder 311 holds the positions of the solid immersion lens 310 and the lens 305 relatively fixed. The actuator 312 drives the lens holder 311 in a direction perpendicular to the surface of the disk 301 based on the gap signal GS.

  Regarding the operation of the optical information recording / reproducing apparatus in the third embodiment, first, a gap detection method will be described.

  The light emitted from the semiconductor laser element 313 is collimated by the lens 303. Then, after passing through the half mirror 306, it is converted into circularly polarized light by the quarter wave plate 308. Further, after being reflected by the dichroic mirror 307, the light is condensed by the lens 305 and the solid immersion lens 310. When the distance between the disk 301 and the solid immersion lens 310 is long, light having a high NA component is totally reflected on the bottom surface of the solid immersion lens 310. The totally reflected light passes through the lens 305, is reflected by the dichroic mirror 307 that reflects light having a wavelength of 500 nm or less, and passes through the quarter-wave plate 308 again. The totally reflected light is shifted in phase between the polarized light perpendicular to the reflecting surface and the polarized light parallel to the reflecting surface as compared with the light before the total reflection. For this reason, light having the same polarization as the light emitted from the semiconductor laser element 313 is included even after passing through the quarter-wave plate again. Thereafter, the light is reflected by the half mirror 306, and only light having the same polarization as the light emitted from the semiconductor laser element 313 is transmitted by the polarizer 309. The transmitted light is collected by the lens 304 and detected by the light receiving element 314.

  On the other hand, the phase difference between the polarized light perpendicular to the reflecting surface and the polarized light parallel to the reflecting surface does not change in the low NA component light that is reflected and returned by reflection that is not total reflection. For this reason, by passing through the quarter-wave plate 308 twice, the polarization direction is inclined by 90 degrees with respect to the polarization direction of the semiconductor laser element 313 and is shielded by the polarizer 309.

  When the distance between the solid immersion lens 310 and the disk 301 approaches approximately half of the wavelength, the near field light generated on the bottom surface of the solid immersion lens 310 interacts with the disk 301. At this time, light having a high NA component is coupled into the disk 301 without being totally reflected by the bottom surface of the solid immersion lens 310. For this reason, the intensity of the totally reflected light on the bottom surface of the solid immersion lens 310 becomes weaker as the distance between the solid immersion lens 310 and the disc 301 approaches. With the above-described configuration, the gap control is performed by detecting the intensity of light totally reflected by the bottom surface of the solid immersion lens 310 to generate the gap signal GS and inputting it to the actuator 312.

  Next, the synchronization detection and information recording method will be described.

  The light emitted from the semiconductor laser elements 203a and 203b is collimated by the lens 204, reflected by the half mirror 205, and then condensed by the lens 305 and the solid immersion lens 310, and formed on the bottom surface of the solid immersion lens 310. , B.

  In the third embodiment, the lens 204, the half mirror 205, the lens 305, and the like are optical elements that guide light from the light source to the first resonance element (metal antenna 302a) and the second resonance element (metal antenna 302b). Function as.

  The incident light excites plasmon resonance in the corresponding metal antennas 302a and 302b. Each excited plasmon resonance generates scattered light of a corresponding wavelength. The scattered light is collimated by the solid immersion lens 310 and the lens 305, passes through the half mirror 205, and then passes through the light shielding plate 207. The light shielding plate 207 is shielded at the central portion, and only the scattered light forming the peripheral portion is transmitted by shielding the light at the central portion including the reflected incident light. After passing through the light shielding plate 207, the scattered light is diffracted by the diffraction grating 212 at different angles for each wavelength, and is individually collected by the lens 213 onto the corresponding light receiving elements 109 a and 109 b. The light receiving elements 109a and 109b detect incident scattered light and output detection signals ss1 and ss2, respectively.

  As described above, in the third embodiment, the light sources are light sources (semiconductor laser elements 203a and 203b) having different wavelengths. In addition, the first resonance element (metal antenna 302a) and the second resonance element (metal antenna 302b) are formed of resonance elements having different shapes or materials with the respective light frequencies as resonance frequencies. At this time, the detection element that individually detects and outputs the change in the resonance state of each of the two resonance elements separates light having different wavelengths from the light reception elements 109a and 109b and the corresponding light reception. This is a second optical element (diffraction grating 212) guided to the element.

  As described above, the metal antennas 302a and 302b are designed so that the maximum plasmon resonance can be obtained when the apex of the triangle is on the cell with respect to the light emitted from the semiconductor laser elements 203a and 203b, respectively. For this reason, the scattered light intensity becomes maximum when the apex of the triangle is on the center of the cell, and becomes minimum at the position where the center distance between the apex of the triangle and the cell is half the repetition period. That is, the scattered light intensity from the metal antennas 302a and 302b changes as shown in FIG. 4a according to the distance from the center of the cell, similarly to the reflected light intensity in the first embodiment. Further, the time changes of the detection signals ss1 and ss2 also show the changes as shown in FIG. When the metal antenna 302b is designed so that the strength of the resonance state changes depending on whether the phase change material of the cell 102 is crystalline or amorphous, the detection signal ss2 can be used as a reproduction signal when reproducing information.

  Returning to FIG. 10, the circuit system of this embodiment will be described. In order to perform synchronous recording, first, a correction value corresponding to the distance between the metal antennas 302a and 302b is determined. In the third embodiment, as the correction value, a timing shift Tse that is a difference between the time when the metal antenna 302b passes over one center of the cell 102 and the time when the metal antenna 302a passes over the center of the same cell is used. . A drive circuit 111a as a first drive circuit drives the semiconductor laser element 203a by direct current. A drive circuit 111b as a second drive circuit drives the semiconductor laser element 203b by direct current. The semiconductor laser elements 203a and 203b make continuous light incident on the metal antennas 302a and 302b. The light receiving elements 109a and 109b input the detection signals ss1 and ss2 to the arithmetic circuit 320 according to the resonance state of the metal antennas 302a and 302b. The arithmetic circuit 320 includes synchronization circuits 321a and 321b, a correction circuit 322, and a delay circuit 115. The synchronization circuit 321a binarizes the detection signal ss1 of the recording antenna 302a and outputs a trigger signal tr1. The synchronization circuit 321b binarizes the detection signal ss2 of the recording antenna 302b and outputs a trigger signal tr2. The metal antennas 302a and 302b scan on the reference area as shown in FIG. 12a formed on the disk 301 in order to determine the timing shift Tse. FIG. 12b shows the time change of the trigger signals tr1 and tr2 when the reference area is scanned. As shown in FIG. 12b, tr1 and tr2 have a timing shift Tse. The correction circuit 322 calculates the timing shift Tse as a correction value from the time change of the two trigger signals tr1 and tr2 when the reference area is scanned, and stores the correction value in the internal memory. Also output as a correction value.

  Subsequently, synchronous recording is performed using the correction value. The drive circuit 111b drives the semiconductor laser element 203b by direct current, and makes continuous light incident on the detection metal antenna 302b. The delay circuit 115 receives the trigger signal tr2 generated from the detection signal ss2, and outputs the recording trigger signal TR delayed by the timing shift Tse, which is a correction value, as a synchronization signal. At this time, when the repetition time of the trigger signal tr2 changes, the delay circuit 115 calculates and delays the timing shift Tse corresponding to the change of the repetition time. For this reason, stable synchronous recording can be performed even if the repetition time changes due to changes in the linear velocity at the inner and outer peripheral portions of the disc 301.

  The recording trigger signal TR is input to the drive circuit 111a. The drive circuit 111a generates a clock signal inside the circuit in response to the recording trigger signal TR, and outputs a recording pulse modulated based on the modulation signal generated from the data in synchronization with the clock signal. The element 203a is pulse-driven. The pulsed light emitted from the semiconductor laser element 203a is incident on the recording metal antenna 302a. The metal antenna 302a performs near-field optical recording on the cell 102 by the excited near-field light. With this configuration, the recording pulse is irradiated at a timing when the metal antenna 302a passes through the center of the cell 102. For this reason, stable and highly accurate synchronous recording can be performed. As a result, the possibility of erroneously writing information to an adjacent cell or erasing information when recording information in a desired cell is reduced, and an optical information recording / reproducing apparatus with a low error rate can be configured. it can.

  As described above, in the third embodiment, the individual resonance states of the metal antennas 302a and 302b are detected using the difference in wavelength. For this reason, it is not necessary to integrate a light source, a detection element, a waveguide, and a resonance element in a minute region, and the device can be easily manufactured.

  In the third embodiment, the metal antennas 302a and 302b are arranged so as to be parallel to the surface of the disk 301, and plasmon resonance is excited by incident light having a polarization direction parallel to the surface of the disk 301. For this reason, it is not necessary to hold the metal antennas 302a and 302b perpendicular to the disk, and the fabrication is easy.

  Further, in the third embodiment, the gap control is performed by detecting a change in the intensity of the reflected light. For this reason, the technique used in the conventional optical pickup can be easily applied, and at the same time, it can be applied to a removable information recording medium.

  Further, in the third embodiment, since the metal antennas 302a and 302b are arranged on the same track, the timing deviation Tse is shorter than when arranged on different tracks. For this reason, the error of timing deviation Tse can be suppressed, and highly accurate synchronous recording can be performed.

  In the third embodiment, the detection metal antenna 302b is arranged to precede the recording metal antenna 302a in the track direction. Further, the synchronization timing shift Tse is determined as a correction value by using the reference area. For this reason, even if the cell spacing varies due to disc manufacturing errors or the like, or the cells are missing, synchronous recording can be stably performed on the cells.

  In the third embodiment, a triangular flat plate is used as the shape of the metal antenna. However, the shape is not particularly limited to the above example, and for example, shapes other than the triangular flat plate as shown in FIGS. As long as plasmon resonance occurs on the cell and the plasmon resonance state efficiently changes in accordance with the distance from the cell center, there is no particular limitation. In the fan plate as shown in FIG. 13A, the influence of the parasitic light at the bottom portion is reduced as compared with the triangular plate. Further, in the bow tie type as shown in FIG. 13b, near-field light can be generated more efficiently than the triangular plate at the portion where the apexes of the metal antennas face each other. Moreover, if the nano beak structure as shown in FIG. 13C is used, the near-field light can be condensed three-dimensionally and the near-field light can be generated efficiently.

  In the third embodiment, the resonance state of the metal antenna is separated using the difference in the wavelength of the scattered light. However, the recording metal antenna and the detection metal antenna are arranged so that their directions are orthogonal to each other. The scattered light from the recording metal antenna and the detection metal antenna may be separated using the difference in polarization direction. If such a configuration is used, a signal can be easily separated using a polarizer, and thus the configuration is simplified.

  In the third embodiment, the metal antenna is arranged so that the resonance direction of the metal antenna is perpendicular to the track. However, the metal antenna may be arranged so that the resonance direction is the track direction.

  In the third embodiment, the disk is used as the information recording medium. However, the metal antenna may be configured to move over the entire area of the disk, and the shape of the information recording medium is not limited to a circle.

  In the first, second, and third embodiments, the cell array may be a patterned medium in which cells are arranged in a honeycomb shape as shown in FIG. 14b. By arranging the cells in a honeycomb shape, it is possible to increase the recording density while keeping the distance from adjacent cells constant. Also, as shown in FIG. 14a, the patterned medium is divided into several blocks and cells are arranged in a honeycomb shape to form a linear track, so that all tracks in one area are aligned in the track direction. The repetition interval can be made equal. At this time, a buffer area is provided between each block. The buffer area has information such as an address, and has an effect of buffering a mismatch at the end of each block. In such a patterned medium, even when the recording metal antenna and the detection metal antenna are arranged on different tracks, synchronous recording is performed based on the detection signal of the detection metal antenna without correcting the repetition time. be able to. Further, since the net synchronization timing shift se due to the arrangement of the two antennas on different tracks is limited to 0 or Tp / 2, the clock signal can be easily corrected. As shown in FIG. 14a, the number of blocks in the circumference may be changed depending on the zone in the radial direction.

  In the first to third embodiments, the shape of the cell is circular, but the present invention is not limited to this. It may be rectangular or hexagonal. In the case of a rectangle or hexagon, the cell area can be increased even at the same interval, and stable information recording and reproduction can be performed.

  In the first to third embodiments, the correction interval is constant. However, in order to cope with changes in the rotation speed of the disk, the disk having different cell intervals on the inner and outer circumferences, the change in the distance between the antennas due to temperature, etc. The timing correction value may be determined again when a change is detected, the radial position of the head with respect to the disk, or the value of the temperature sensor.

  In addition to the sensor value, in order to correct the change over time, the timing correction value may be determined again at regular time intervals after the start of recording.

  Further, the correction value may change due to a cell interval error for each disk, and the correction value may be determined before starting recording after loading the disk.

  In the first to third embodiments, the recording antenna and the detection antenna are paired with each other, but there are a plurality of detection antennas, and even if the recording timing is determined by calculation from these timing signals. Good. In this case, even if an error occurs in the timing signal from a certain detection antenna due to noise, the influence can be reduced. The plurality of detection antennas may also serve as tracking detection antennas and gap detection antennas.

  The main configuration of the optical information recording / reproducing apparatus described in the first embodiment, the second embodiment, and the third embodiment is described below.

  The optical information recording / reproducing apparatus described in the first embodiment, the second embodiment, and the third embodiment records / reproduces information on / from an information recording medium in which discrete minute regions are regularly arranged. In the optical information recording / reproducing apparatus for performing, the first resonance element that interacts with the information recording medium, changes a resonance state according to a distance from the minute area, and records in the minute area by near-field light The distance between the second resonance element that interacts with the information recording medium and changes the resonance state in accordance with the distance from the minute region, and the first resonance element and the second resonance element is constant. A holding element that is fixedly disposed on the first light source, a first light source that irradiates light to the first resonance element, a second light source that irradiates light to the second resonance element, and the first light source. A first driving circuit for pulse driving and the second light source; A second driving circuit that moves, an optical element that guides light from the first light source and the second light source to the first resonant element and the second resonant element, and a second resonant element A detection element that detects and outputs a change in the resonance state; and a synchronization circuit that generates a synchronization signal based on a change in the resonance state of the second resonance element. The first drive circuit includes the synchronization signal It receives the synchronization signal from the circuit, and determines the incident timing of the pulsed light to the first resonance element.

  As described above, the optical information recording / reproducing apparatus interacts with the information recording medium, the resonance state changes according to the distance from the minute area, and the first resonance element performs recording in the minute area with near-field light. (Recording resonance element) and the second resonance element (detection resonance element) that interacts with the information recording medium and changes the resonance state according to the distance from the minute region so that the distance between the elements is constant. It was set as the structure fixed to. Further, the configuration is such that synchronous recording is performed by determining the incident timing of the pulsed light to the recording resonance element from the change in the resonance state of the detection resonance element. In the near-field light recording, recording can be performed by a single recording resonance element, and therefore, it is only necessary to synchronize the incident timing of the pulsed light to the recording resonance element with the timing at which the recording resonance element passes over the minute region. For this reason, the relative distance between the recording detection element and the detection resonance element is fixed, and synchronous recording is performed based on the change in the resonance state of the detection resonance element. Information recording with a low error rate, which reduces the possibility of accidentally writing or erasing information in an adjacent minute area when recording information in a desired minute area. / Has the effect of realizing playback.

  The optical information recording / reproducing apparatus is configured to calculate and output a correction value corresponding to the distance between the resonance elements from the detection signals of the recording resonance element and the detection resonance element. In addition, synchronous recording is performed by making pulsed light incident on the recording resonance element based on the correction value. For this reason, it is possible to correct uncertain elements such as variations during production, and the effect is that stable and highly accurate synchronous recording is possible.

  In addition, the optical information recording / reproducing apparatus employs a recording method for calculating a synchronization signal based on a change in the resonance state of the detecting resonance element. For this reason, the detection signal reacts sensitively to changes in the optical constants around the resonant element, and a detection signal with a high degree of modulation is obtained with respect to a minute positional deviation from the minute region. For this reason, a highly accurate synchronization signal can be obtained even for a very small area of several nanometers to several tens of nanometers in size, and there is an effect that synchronous recording can be performed with high precision.

(Embodiment 4)
Next, the recording method of the present invention will be described using the optical information recording / reproducing apparatus in the first embodiment.

  FIG. 15 shows a flowchart of the information recording method in Embodiment 1 of the present invention.

  The information recording method in Embodiment 1 will be described along the flowchart of FIG.

  In the first step 401, continuous light is incident on the metal antenna 105a, which is the first resonance element, from the semiconductor laser element 107a, which is the first light source. Further, continuous light is incident on the metal antenna 105b, which is the second resonance element, from the semiconductor laser element 107b, which is the second light source. The two metal antennas are excited for plasmon resonance by incident light. The metal antenna 105a is used for recording information. The metal antenna 105b is used for synchronization detection.

  The metal antennas 105a and 105b are designed so that the plasmon resonance condition is satisfied on the cell 102, and the plasmon resonance becomes weaker as the deviation from the cell center increases.

  In the second step 402, the reflected light from the metal antenna 105a is guided to the light receiving element 109a using the waveguide 108a. The reflected light from the metal antenna 105b is guided to the light receiving element 109b using the waveguide 108b. The two light receiving elements 109a and 109b detect the reflected light and output detection signals ss1 and ss2, respectively. The reflected light from the metal antennas 105a and 105b varies depending on the plasmon resonance resonance state of the metal antennas 105a and 105b. Therefore, by detecting the reflected light from the metal antennas 105a and 105b, it is possible to detect changes in the resonance state of the individual metal antennas 105a and 105b.

  The intensity of the reflected light takes a maximum value at the cell center with respect to the distance from the cell center as shown in FIG. 4a and takes a minimum value at a position away from the cell center by half of the repetition period Pp. For this reason, if the time taken for the metal antenna to move the distance Pp is time Tp, the detection signals ss1 and ss2 show temporal changes as shown in FIG. 4b.

  In the third step 403, the detection signal ss1 is input to the synchronization circuit 113a, and the clock signal st1 synchronized with the detection signal ss1 is output. Further, the detection signal ss2 is input to the synchronization circuit 113b, and the clock signal st2 synchronized with the detection signal ss2 is output. The clock signals st1 and st2 have a timing shift Tse as shown in FIG. 4c according to the distance between the metal antennas 105a and 105b. A remainder obtained by dividing the timing shift Tse by the repetition time Tp is referred to as a net timing shift se.

  In the fourth step 404, the clock signals st1 and st2 are input to the correction circuit 114, and the net timing shift se is calculated and stored as a correction value.

  In a fifth step 405, the semiconductor laser element 107b is DC driven, and continuous light is incident on the detection metal antenna 105b.

  In a sixth step 406, the clock signal st 2 and the net timing shift se that is a correction value are input to the delay circuit 115. The delay circuit 115 delays the clock signal st2 by the net timing shift se to generate the recording clock signal ST. At this time, when the repetition time of the clock signal st2 changes, the delay circuit 115 calculates and delays the net timing shift se according to the change of the repetition time.

  In the seventh step 407, the semiconductor laser element 107a is pulse-driven based on the modulation signal generated from the data in accordance with the recording clock signal ST. Information is recorded in the cell 102 by irradiating pulsed light from the semiconductor laser element 107 a to excite near-field light on the metal antenna 105 a.

  By repeating the above steps 406 and 407, synchronous recording can be performed on the cell 102 stably and with high accuracy.

  In the fourth embodiment, the change in the resonance state of the first resonance element (metal antenna 105a) is detected, and the change in the resonance state of the first resonance element and the resonance state of the second resonance element (metal antenna 105b) are detected. Based on this change, a method of generating a correction value according to the distance between the first resonant element and the second resonant element was adopted. In addition, a method of determining the incident timing of the pulsed light from the first light source (semiconductor laser element 107a) to the first resonant element based on the correction value is adopted. For this reason, uncertain elements such as variations during production can be corrected, and stable and highly accurate synchronous recording is possible.

  Note that the correction value determination method may be a method of calculating the phase shift pe between the detection signals ss1 and ss2, as described in the second embodiment. Further, as described above in the third embodiment, a method of correcting the timing shift Tse using the reference region may be used.

  In the fourth embodiment, a method of irradiating the recording metal antenna with pulse light at the timing when the recording metal antenna passes over the cell center is adopted. It may be a method of shifting forward or backward with respect to the timing of passing above.

  As described above, the information recording method of the fourth embodiment is an information recording method in an optical information recording / reproducing apparatus for recording / reproducing information on / from an information recording medium in which discrete minute regions are regularly arranged. is there. The optical information recording / reproducing apparatus includes a first resonance element that interacts with the information recording medium, changes a resonance state according to a distance from the minute area, and records in the minute area by near-field light. A second resonance element that interacts with the information recording medium and changes a resonance state in accordance with a distance from the minute region, a first light source that irradiates light to the first resonance element, and the second And a second light source for irradiating the resonance element with light. At this time, in the information recording method of the fourth embodiment, the step of entering light from the second light source into the second resonance element, the step of detecting a change in the resonance state of the second resonance element, Determining the incident timing of the pulsed light from the first light source to the first resonance element based on the change in the resonance state of the second resonance element.

  As described above, in the information recording method of the fourth embodiment, the resonance state changes in accordance with the distance from the minute area by interacting with the information recording medium, and the first area is recorded in the minute area by the near-field light. The resonance element (recording resonance element) and the second resonance element (detection resonance element) that interacts with the information recording medium and changes the resonance state in accordance with the distance from the microregion, the distance between the elements is constant. It was set as the structure arrange | positioned so that it may become. Further, the configuration is such that synchronous recording is performed by determining the incident timing of the pulsed light to the recording resonance element from the change in the resonance state of the detection resonance element. In the near-field light recording, recording can be performed by a single recording resonance element, and therefore, it is only necessary to synchronize the incident timing of the pulsed light to the recording resonance element with the timing at which the recording resonance element passes over the minute region. For this reason, the relative distance between the recording detection element and the detection resonance element is fixed, and synchronous recording is performed based on the change in the resonance state of the detection resonance element. The effect is that synchronous recording can be performed.

  In the information recording method of the fourth embodiment, the correction value corresponding to the distance between the resonance elements is calculated and output from the detection signals of the recording resonance element and the detection resonance element. In addition, synchronous recording is performed by making pulsed light incident on the recording resonance element based on the correction value. For this reason, it is possible to correct uncertain elements such as variations during production, and the effect is that stable and highly accurate synchronous recording is possible.

  In the information recording method of the fourth embodiment, an information recording method for calculating a synchronization signal based on a change in the resonance state of the detection resonance element is employed. For this reason, the detection signal reacts sensitively to changes in the optical constants around the resonant element, and a detection signal with a high degree of modulation is obtained with respect to a minute positional deviation from the minute region. For this reason, a highly accurate synchronization signal can be obtained even for a very small area of several nanometers to several tens of nanometers in size, and there is an effect that synchronous recording can be performed with high precision.

  The optical information recording / reproducing apparatus according to the present invention can perform stable recording with high accuracy and stability on a patterned medium in a high-density optical information recording / reproducing apparatus exceeding the diffraction limit. Therefore, it is useful for realizing a high-density optical information recording / reproducing apparatus. Such a high-density optical information recording / reproducing apparatus can be applied to many uses such as an optical disc player / recorder, a computer, and a data server.

101, 301 Disc 102 Cell 103 Motor 104, 201 Slider 105a, b, 202a, b, 302a, b Metal antenna 106 Suspension 107a, b, 203a, b, 313 Semiconductor laser element 108a, b Waveguide 109a, b, 211, 314 Light receiving element 111a, b Drive circuit 112,220,320 Arithmetic circuit 113a, b, 223,321a, b Synchronous circuit 114,221,322 Correction circuit 115,222 Delay circuit 204,206,210,213,303,304, 305 Lens 205, 306 Half mirror 207 Shading plate 208 Polarizing prism 209 Wavelength filter 212 Diffraction grating 307 Dichroic mirror 308 1/4 wavelength plate 309 Polarizer 310 Solid immersion lens 311 Lens Holder 312 Actuator

Claims (13)

In an optical information recording / reproducing apparatus for recording / reproducing information on / from an information recording medium in which discrete micro regions are regularly arranged,
A first resonance element that interacts with the information recording medium, changes a resonance state according to a distance from the minute region, and records in the minute region by near-field light;
A second resonance element that interacts with the information recording medium and changes a resonance state according to a distance from the minute region;
A holding element that arranges the distance between the first resonant element and the second resonant element fixedly constant;
A first light source that irradiates light to the first resonant element; a second light source that irradiates light to the second resonant element;
A first drive circuit for driving the first light source in pulses; a second drive circuit for driving the second light source;
An optical element for guiding light from the first light source and the second light source to the first resonance element and the second resonance element;
A detection element that detects and outputs a change in the resonance state of the second resonance element;
A synchronization circuit that generates a synchronization signal based on a change in the resonance state of the second resonance element,
The optical information recording / reproducing apparatus, wherein the first drive circuit receives the synchronization signal from the synchronization circuit and determines the incident timing of the pulsed light to the first resonance element. A second detection element that detects and outputs a change in the resonance state of the first resonance element;
A correction circuit that generates a correction value according to a distance between the first resonance element and the second resonance element from signals output from the detection element and the second detection element;
2. The optical information recording / reproducing apparatus according to claim 1, wherein the synchronization circuit generates a synchronization signal based on the correction value generated by the correction circuit. A detection element that detects and outputs a change in the resonance state of the second resonance element, and a second detection element that detects and outputs a change in the resonance state of the first resonance element,
A light receiving element;
A waveguide for guiding light from the first resonance element and the second resonance element to the light receiving element;
The optical information recording / reproducing apparatus according to claim 1 or 2, characterized by comprising: The first light source and the second light source are light sources having different wavelengths;
The first resonant element is a resonant element having a shape or material that resonates with light having a wavelength emitted from the first light source,
The second resonant element is a resonant element that resonates with light having a wavelength emitted from the second light source and has a shape or material different from that of the first resonant element.
A detection element that detects and outputs a change in the resonance state of the second resonance element, and a second detection element that detects and outputs a change in the resonance state of the first resonance element,
A light receiving element;
A second optical element that separates light having different wavelengths from the first resonant element and the second resonant element and guides the light to the corresponding light receiving element;
The optical information recording / reproducing apparatus according to claim 1 or 2, characterized by comprising: The first light source and the second light source are light sources having different wavelengths;
The first resonant element is a resonant element having a shape or material that resonates with light having a wavelength emitted from the first light source,
The second resonant element is a resonant element that resonates with light having a wavelength emitted from the second light source and has a shape or material different from that of the first resonant element.
A detection element that detects and outputs a change in the resonance state of the second resonance element, and a second detection element that detects and outputs a change in the resonance state of the first resonance element,
A light receiving element;
Separating light having different wavelengths from the first resonance element and the second resonance element, and separating light having a polarization direction parallel to the surface of the information recording medium and guiding it to the corresponding light receiving element. 3 optical elements;
The optical information recording / reproducing apparatus according to claim 1 or 2, characterized by comprising: 2. The optical information recording / reproducing apparatus according to claim 1, wherein the first resonance element and the second resonance element are arranged on the same track. 2. The optical information recording / reproducing apparatus according to claim 1, wherein information recorded on the information recording medium is reproduced from a change in a resonance state of the second resonance element. 2. The optical information recording / reproducing apparatus according to claim 1, wherein the second resonance element is arranged in the track direction ahead of the first resonance element. 2. The optical information recording / reproducing apparatus according to claim 1, wherein the discretized minute region is an isolated fine particle formed on a flat plate. 2. The optical information recording / reproducing apparatus according to claim 1, wherein the discretized minute regions are arranged in a honeycomb shape. 3. The optical information recording / reproducing apparatus according to claim 2, wherein the information recording medium has a reference area in which the discrete minute areas are arranged in a specific pattern. An information recording method in an optical information recording / reproducing apparatus for recording / reproducing information on / from an information recording medium in which discrete micro regions are regularly arranged,
The optical information recording / reproducing apparatus comprises:
A first resonance element that interacts with the information recording medium, changes a resonance state according to a distance from the minute region, and records in the minute region by near-field light;
A second resonance element that interacts with the information recording medium and changes a resonance state according to a distance from the minute region;
A first light source that irradiates light to the first resonant element; and a second light source that irradiates light to the second resonant element;
Injecting light from the second light source into the second resonant element;
Detecting a change in a resonance state of the second resonance element;
Determining an incident timing of pulsed light from the first light source to the first resonance element based on a change in a resonance state of the second resonance element;
An information recording method comprising: Detecting a change in a resonance state of the first resonance element;
Based on the change in the resonance state of the first resonance element and the change in the resonance state of the second resonance element, a correction value is generated according to the distance between the first resonance element and the second resonance element. And steps to
Determining an incident timing of pulsed light from the first light source to the first resonant element based on the correction value;
The information recording method according to claim 12, further comprising:

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