Super-diffraction-limited resolution optical storage medium, preparation method, and data reading and writing method

Abstract

The present invention discloses a super-diffraction-limited resolution optical storage medium, a preparation method and a data reading and writing method, wherein the optical storage medium comprises a periodically stacked multi-layer optical storage medium layer, the wavelengths of the reading and writing laser beams of any two adjacent optical storage medium layers are different, and the thickness of any optical storage medium layer is less than the diffraction-limited spot diameter d1 of the minimum wavelength laser beam in the reading and writing laser beam, and the total thickness D of the optical storage medium layer in each period is ≥ the diffraction-limited spot diameter d2 of the maximum wavelength laser beam in the reading and writing laser beam; the stacking surface of the optical storage medium layer is the reading and writing surface. The optical storage medium disclosed by the present invention can be read and written by a single-beam laser light source, and the limitation of the diffraction limit of single-beam illumination is broken through, so as to achieve the purpose of super-resolution optical storage record reading.

Description

Technical Field

[0001] The present invention relates to the field of optical storage technology, in particular to an optical storage medium with a resolution beyond the diffraction limit. Background Art

[0002] In recent years, the amount of data generated worldwide has grown explosively. Traditional electromagnetic storage methods have been difficult to meet current usage needs. Optical storage technology has many advantages, such as low energy consumption, long life, and data security. It is likely to become the next generation of mainstream data storage system. However, traditional optical storage technology is limited by the resolution size of the optical diffraction limit, and the storage capacity cannot be broken through. Therefore, in recent years, a variety of new super-resolution optical storage technologies have been derived, among which the most representative is the dual-beam super-resolution storage technology based on STED technology.

[0003] The light source of the dual-beam super-resolution technology consists of a writing beam and a suppression beam. The principle is as follows Figure 1 As shown, the two beams of light emitted by the writing beam laser 1 and the suppression beam laser 2 are adjusted to circularly polarized light after passing through the λ / 2 wavelength plate 3 and the λ / 4 wavelength plate 4 respectively. The suppression beam is modulated into a hollow annular beam after passing through the vortex phase plate 10 (VPP). Then, the two beams of light are combined after passing through a dichroic mirror (polarization beam splitter 7). After passing through the objective lens 8 and focusing on the surface of the recording optical storage medium 9, the writing light reacts with the medium material to write data. However, due to the existence of the suppression light, the reaction of the writing light with the material is suppressed. The writing light beam in the hollow part of the suppression beam can retain the reaction with the material. Therefore, the size of the written data point is smaller than the diffraction limit size of a single beam, thereby achieving super-resolution reading and writing.

[0004] The dual-beam super-resolution technology can achieve super-diffraction-limited data reading and writing, but this solution requires the use of two laser sources, which is costly and bulky, and the adjustment of the combined beam path is also very difficult. If the centers of the two beams do not overlap slightly, the quality of data reading and writing will be seriously affected. Therefore, an optical storage medium and system with a simple structure and convenient reading and writing are urgently needed to solve the above problems. Summary of the invention

[0005] The present invention proposes an optical storage medium with a super-diffraction limit resolution to solve the problems that the existing optical storage medium needs to adopt a dual-beam super-resolution system in order to overcome the diffraction limit during the reading and writing process, which leads to complex system structure, high overall cost, large system volume, and complex system adjustment.

[0006] The technical means adopted by the present invention are as follows:

[0007] A super-diffraction-limited resolution optical storage medium comprises a plurality of optical storage medium layers which are periodically stacked, wherein the wavelengths of the read / write laser beams of any two adjacent optical storage medium layers are different, and the thickness of any one of the optical storage medium layers is less than the diffraction-limited spot diameter d1 of the minimum wavelength laser beam in the read / write laser beam, and the total thickness D of the optical storage medium layers in each period is ≥ the diffraction-limited spot diameter d2 of the maximum wavelength laser beam in the read / write laser beam; and the stacked surface of the optical storage medium layer is the read / write surface.

[0008] Furthermore, the number of optical storage medium layers in each period n≥2, and the wavelengths of the reading and writing laser beams of any optical storage medium layer in each period are different.

[0009] Furthermore, the thickness of each optical storage medium layer is equal.

[0010] Furthermore, the thickness of each optical storage medium layer is 50-100 nm.

[0011] Furthermore, the optical storage medium layer is made of photochromic material.

[0012] A method for preparing an optical storage medium with a resolution beyond the diffraction limit disclosed in the present invention comprises the following steps: using an alternating composite process to periodically stack different optical storage medium layer materials in sequence to form a multi-layer optical storage medium layer, the wavelengths of the read / write laser beams of any two adjacent optical storage medium layers are different, and the thickness of any one of the optical storage medium layers is less than the diffraction limit spot diameter d1 of the minimum wavelength laser beam in the read / write laser beam, and the total thickness D of the optical storage medium layer in each period is ≥ the diffraction limit spot diameter d2 of the maximum wavelength laser beam in the read / write laser beam; the stacked surface of the optical storage medium layer is the read / write surface.

[0013] Furthermore, it also includes cutting the multiple optical storage medium layers along a direction perpendicular to the stacking direction to form a sheet-like optical storage medium.

[0014] Furthermore, the alternating composite process is a coating process.

[0015] A data reading and writing method using the super-diffraction limit resolution optical storage medium of the present invention, comprising a data writing method and a data reading method;

[0016] The steps of the data writing method are as follows:

[0017] Selecting a laser beam with a wavelength corresponding to a certain optical storage medium layer in a period of the multi-layer optical storage medium layer as a writing laser beam in sequence, and completing data writing to all optical storage medium layers corresponding to the writing laser beam in the multi-layer optical storage medium layer by using the writing laser beam;

[0018] The steps of the data reading method are as follows:

[0019] A laser beam with a wavelength corresponding to a certain optical storage medium layer in a period of the multi-layer optical storage medium layer is selected in sequence as a reading laser beam, and data reading of all optical storage medium layers corresponding to the reading laser beam in the multi-layer optical storage medium layer is completed through the reading laser beam.

[0020] Furthermore, the data reading and writing light source adopts a frequency-adjustable laser.

[0021] Compared with the prior art, the super-diffraction limit resolution optical storage medium disclosed in the present invention has the following beneficial effects: since the optical storage medium disclosed in the present invention is composed of multiple layers of optical storage medium layers, the wavelengths of the read and write laser beams of any two adjacent optical storage medium layers are different, and the thickness of any one of the optical storage medium layers is less than the diffraction limit spot diameter d1 of the minimum wavelength laser beam in the read and write laser beam, the optical storage medium disclosed in the present invention can be read and written using a single-beam laser light source, and breaks through the limitation of the diffraction limit of single-beam illumination, thereby achieving the purpose of super-resolution optical storage record reading. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a structural diagram of an existing dual-beam super-resolution storage system;

[0023] Figure 2 Schematic diagram of diffraction spot in single beam optical storage technology;

[0024] Figure 3 A structural diagram of the super-diffraction limit resolution optical storage medium disclosed by the present invention;

[0025] Figure 4 A schematic diagram of the principle of writing data to the super-diffraction limit resolution optical storage medium disclosed in the present invention;

[0026] Figure 5 A schematic diagram of the principle of data reading of the super-diffraction limit resolution optical storage medium disclosed in the present invention;

[0027] Figure 6 A schematic diagram of the preparation process of the super-diffraction limit resolution optical storage medium disclosed in the present invention;

[0028] Figure 7 A structural diagram of a single beam system for a super-diffraction-limited resolution optical storage medium disclosed in the present invention;

[0029] Figure 8 A schematic diagram of writing data by laser beams of different wavelengths in one embodiment of an optical storage medium with a super-diffraction limit resolution disclosed in the present invention;

[0030] Fig. 9 A schematic diagram of writing data to an embodiment of an optical storage medium with a resolution beyond the diffraction limit disclosed in the present invention;

[0031] Fig.10 A schematic diagram of the data storage capacity of an embodiment of a conventional diffraction-limited resolution optical storage medium disclosed in the present invention;

[0032] Fig.11 A schematic diagram of data reading from an embodiment of the super-diffraction limit resolution optical storage medium disclosed in the present invention.

[0033] In the figure: 1. writing beam laser, 2. suppressing beam laser, 3. λ / 2 wavelength plate, 4. λ / 4 wavelength plate, 5. reading detector, 6. reading objective lens, 7. polarization beam splitter, 8. objective lens, 9. optical storage medium, 10. VPP plate, 11. diffraction limited spot diameter, 12. recording point area, 13. high reflection area, 14. low reflection area, 15. frequency-tunable laser, 16. filter color wheel. DETAILED DESCRIPTION

[0034] like Figure 3 As shown in the present invention, a super-diffraction limit resolution optical storage medium is disclosed, including a plurality of optical storage medium layers periodically stacked, the wavelengths of the read-write laser beams of any two adjacent optical storage medium layers are different, preferably, the optical storage medium layers are made of photochromic materials, and the thickness of any one of the optical storage medium layers is less than the diffraction limit spot diameter d1 of the minimum wavelength laser beam in the read-write laser beam, and the total thickness D of the optical storage medium layers in each period is ≥ the diffraction limit spot diameter d2 of the maximum wavelength laser beam in the read-write laser beam; the stacking surface of the multi-layer optical storage medium layer is the read-write surface.

[0035] Specifically, Figure 3As shown, in this embodiment, three different optical storage medium materials are used as an example for explanation in each period. In each period, optical storage medium A0, optical storage medium B0 and optical storage medium C0 are sequentially arranged to form a layer unit structure. The wavelengths of the read and write laser beams of optical storage medium A0, optical storage medium B0 and optical storage medium C0 are different. The optical storage medium can adopt a film structure formed by a coating process, and then periodically stacked to form a multi-layer optical storage medium layer with a certain thickness. The structure of the multi-layer optical storage medium layer is optical Storage medium A0, optical storage medium B0, optical storage medium C0…Optical storage medium A0, optical storage medium B0 and optical storage medium C0 (abbreviated as A0, B0, C0, A0, B0, C0…A0, B0, C0), the thickness of each optical storage medium layer is less than the diffraction limited spot diameter d1 of the minimum wavelength laser beam in the read-write laser beam, the total thickness D of the optical storage medium layer in each period is ≥ the diffraction limited spot diameter d2 of the maximum wavelength laser beam in the read-write laser beam, and the stacking surface of the formed multi-layer optical storage medium is the read-write surface of the data.

[0036] like Figure 2 As shown, a light beam emitted by an object point is converged by a circular aperture optical lens and formed on the image plane. Due to the limitation of the diffraction limit, even if the lens has no aberration at all, it will not form a perfect image point, but a circular diffraction spot. Therefore, the minimum light information point size that can be recorded and read by single-beam optical storage technology depends on the diffraction limit spot diameter.

[0037] The super-diffraction-limited resolution optical storage medium disclosed in the present invention can break through the limitation of the single-beam illumination diffraction limit and achieve the purpose of super-resolution optical storage recording and reading. Specifically, Figure 3 , Figure 4 and Figure 5As shown, since the optical storage medium disclosed in the present invention is composed of a plurality of periodically stacked optical storage medium layers made of a plurality of different optical storage medium materials, the wavelengths of the read / write laser beams of any two adjacent optical storage medium layers are different, and the thickness of any one of the optical storage medium layers is less than the diffraction limit spot diameter d1 of the minimum wavelength laser beam in the read / write laser beam, and the total thickness D of the optical storage medium layer in each period is ≥ the diffraction limit spot diameter d2 of the maximum wavelength laser beam in the read / write laser beam; therefore, when it is necessary to use the super-diffraction limit resolution optical storage medium disclosed in the present invention for data reading and writing, each acquisition The data of the corresponding optical storage medium layer is read and written by using a laser beam of a specific wavelength that only acts on one of the optical storage media. Since the currently incident laser beam of a specific wavelength can only act on one of the optical storage medium layers, and does not act on the medium layers made of other optical storage medium materials, and at the same time, the thickness of each optical storage medium layer is smaller than the diffraction limit spot diameter d1 of the minimum wavelength laser beam in the read-write laser beam, that is, when the incident light of a specific wavelength is irradiated on the optical storage medium disclosed in the present invention, only a small part of the area of ​​the entire diffraction spot area reacts to generate recording points, such as Figure 4 As shown; when reading data, when using a specific wavelength of incident light to illuminate the optical storage medium of the present invention, only a small part of the area component material in the entire diffraction spot area has a high reflectivity to the incident light, and the other area components have a very low reflectivity to the incident light, which can form a light signal for reading information, such as Figure 5 As shown. Therefore, the diffraction spot area that could originally only record one optical information data point can now record multiple optical information data points, producing a super-resolution optical storage effect. For example, in this embodiment, when data is written to a super-diffraction limit resolution optical storage medium made of three optical storage media A0, B0 and C0, when data is written using a laser beam with a wavelength of λ1, the laser beam with a wavelength of λ1 only interacts with the optical storage medium A0, as shown in FIG. Figure 8 As shown, at this time, the optical storage medium A0 reacts with the laser beam with a wavelength of λ1 to generate the optical storage medium A1, and the optical storage media B0 and C0 do not change, that is, only the optical storage medium A0 is written with data. When the laser beam with a wavelength of λ2 is used to write data, the laser beam with a wavelength of λ2 only acts on the optical storage medium B0, as shown in FIG. Figure 8 As shown, at this time, the optical storage medium B0 reacts with the laser beam with a wavelength of λ2 to generate the optical storage medium B1, and the optical storage media A0 and C0 do not change, that is, only the optical storage medium B0 is used for data writing. When the laser beam with a wavelength of λ3 is used for data writing, the laser beam with a wavelength of λ3 only acts on the optical storage medium C0, as shown in FIG. Figure 8As shown, at this time, the optical storage medium C0 reacts with the laser beam with a wavelength of λ3 to generate the optical storage medium C1, and the optical storage media A0 and B0 do not change, that is, only the optical storage medium C0 is written with data. The data reading process is similar to the data writing process, and the laser beams with wavelengths of λ4, λ5 and λ6 are used to read the data in the optical storage media A1, B1 and C1 respectively, thereby breaking through the limitation of the diffraction limit of single-beam illumination and achieving the purpose of super-resolution optical storage record reading. At the same time, since only a single beam is needed for reading and writing, the system structure is simple, the overall cost is low, the system size is small, and the system adjustment is simple. In the above description, optical storage media A0, B0 and C0 respectively represent dielectric layers made of optical storage materials A0, B0 and C0, optical storage media A1, B1 and C1 respectively represent dielectric layers formed after optical storage media A0, B0 and C0 react with corresponding laser light beams, and optical storage media A0, B0 and C0 use photochromic materials. Each photochromic material only reacts with a specific wavelength of incident light to generate optical storage media A1, B1 and C1, and its reactants (optical storage media A1, B1 and C1) also only show a higher reflectivity to incident light of a specific wavelength.

[0038] Furthermore, the number of optical storage medium layers n in each period is ≥ 2, and the wavelength of the reading and writing laser beams of any optical storage medium layer in each period is different. Preferably, the number of optical storage medium layers n in each period is 2 or 3. This can reduce the types of optical storage medium layers to reduce the manufacturing cost of the optical storage medium, and at the same time simplify the structure of the optical storage medium manufacturing system to further reduce costs.

[0039] Furthermore, the thickness of each layer of the optical storage medium is equal, and the thickness of each layer is equal, which can reduce the difficulty of controlling the movement of the laser beam, and can move at an equal distance each time to facilitate data reading and writing. The thickness of the optical storage medium layer can also be unequal, but the thickness difference is small, so that the laser can read and write it in a scanning manner.

[0040] Furthermore, the thickness of each optical storage medium layer is 50-100 nm to ensure good reading and writing performance.

[0041] The method for preparing the optical storage medium with a resolution beyond the diffraction limit disclosed in the present invention comprises the following steps: using an alternating composite process to periodically stack different optical storage medium layer materials in sequence to form a multi-layer optical storage medium layer, the wavelengths of the read / write laser beams of any two adjacent optical storage medium layers are different, and the thickness of any one of the optical storage medium layers is less than the diffraction limit spot diameter d1 of the minimum wavelength laser beam in the read / write laser beam, and the total thickness D of the optical storage medium layer in each period is ≥ the diffraction limit spot diameter d2 of the maximum wavelength laser beam in the read / write laser beam; the stacking surface of the optical storage medium layer is the read / write surface.

[0042] Specifically, this embodiment is still described by taking the super diffraction limit resolution optical storage medium made of three optical storage media A0, B0 and C0 as an example. The optical storage media A0, B0 and C0 are three photochromic materials. With the three photochromic materials A0, B0 and C0 as the basic materials, a multi-layer optical storage medium layer can be formed by repeatedly alternating and compounding to a certain thickness by using processes such as coating. The structure of the multi-layer optical storage medium layer is optical storage medium A0, optical storage medium B0, optical storage medium C0...optical storage medium A0, optical storage medium B0 and optical storage medium C0 (abbreviated as A0, B0, C0, A0, B0, C0...A0, B0, C0), the thickness of each optical storage medium layer is less than the diffraction limit spot diameter d1 of the minimum wavelength laser beam in the read-write laser beam, the total thickness D of the optical storage medium layer in each period ≥ the diffraction limit spot diameter d2 of the maximum wavelength laser beam in the read-write laser beam, and then as shown in Figure 6 As shown, the multi-layer optical storage medium layers are cut along a direction perpendicular to the stacking direction to form a sheet optical storage medium. The stacking surface of the formed multi-layer optical storage medium is the reading and writing surface of the data. The sheet optical storage medium is placed at the focal point of the objective lens of the reading and writing system and is parallel to the direction of travel of the incident light beam for use.

[0043] A data reading and writing method using the super-diffraction limit resolution optical storage medium of the present invention, comprising a data writing method and a data reading method;

[0044] The steps of the data writing method are as follows:

[0045] Selecting a laser beam with a wavelength corresponding to a certain optical storage medium layer in a period of the multi-layer optical storage medium layer as a writing laser beam (the laser beam with the corresponding wavelength is a laser beam that can react with the optical storage medium layer), and completing the writing of data to all optical storage medium layers corresponding to the writing laser beam in the multi-layer optical storage medium layer through the writing laser beam;

[0046] The steps of the data reading method are as follows:

[0047] A laser beam with a wavelength corresponding to a certain optical storage medium layer in a period of the multi-layer optical storage medium layer is selected in sequence as a reading laser beam (the laser beam with the corresponding wavelength refers to a laser beam with a higher reflectivity with the optical storage medium layer), and the reading laser beam is used to complete data reading of all optical storage medium layers corresponding to the reading laser beam in the multi-layer optical storage medium layer.

[0048] Furthermore, the data reading and writing light source adopts a frequency-adjustable laser.

[0049] Specifically, Figure 7The data reading and writing system for the optical storage medium with a super-diffraction limit resolution of the present invention is shown, comprising a data reading and writing light source 15, a λ / 2 wavelength plate 2, a λ / 4 wavelength plate 4, a polarization beam splitter 7, an objective lens 4, a filter color wheel 16, a reading objective lens 6 and a reading detector 5. Preferably, the data reading and writing light source adopts a frequency-adjustable laser, which can emit laser beams of various wavelengths. The laser beam emitted by the frequency-adjustable laser is incident on the λ / 2 wavelength plate 2, the λ / 4 wavelength plate 4 and the polarization beam splitter 7, and then is incident on the optical storage medium 9 through the λ / 4 wavelength plate 4 and the objective lens 4. The optical storage medium 9 is the optical storage medium with a super-diffraction limit resolution disclosed in the present invention. This embodiment still takes the super-diffraction limit resolution optical storage medium made of three optical storage media A0, B0 and C0 as an example to illustrate the data reading and writing process, as shown in FIG. Figure 8 As shown in FIG. 1 , when the read-write system is used to write data, the wavelength of the frequency-adjustable laser is first modulated to λ1, and a laser beam with a wavelength of λ1 is focused and irradiated onto the super-diffraction-limited resolution optical storage medium. In the super-diffraction-limited resolution optical storage medium, only the optical storage medium layer A0 is transformed into the optical storage medium layer A1 after being irradiated by the λ1 laser beam, and the components B0 and C0 do not react with the λ1 light. Figure 8 and Fig. 9 As shown, when data is written, the laser beam moves along the stacking direction of the optical storage medium layer to write data to A0 in all layers in turn (write data in one column of A0), and then moves a certain distance (the moving distance is generally the diffraction limit spot diameter) parallel to a certain optical storage medium layer to write data to all A0 layers in the next column, and the data writing of all A0 layers in the entire plane is completed in sequence; then the laser wavelength is modulated to λ2, so that the λ2 light is focused and irradiated to the surface of the material, and only the B0 component in the material will be converted into B1 material after being irradiated by the λ2 light, and the A0 and C0 components will not react with the λ2 light. The specific writing process of the B0 layer is the same as that of the A0 layer data writing, and will not be described in detail; then the laser wavelength is modulated to λ3, so that the λ3 light is focused and irradiated to the surface of the material, and only the C0 component in the material will be converted into C1 material after being irradiated by the λ3 light, and the A0 and B0 components will not react with the λ3 light. The specific writing process of the C0 layer is the same as that of the A0 layer data writing, and will not be described in detail. In summary, the use of frequency-tunable lasers can achieve the writing of super-resolution optical information data.

[0050] If the recording data corresponding to the optical storage medium layers A1, B1, and C1 are set to "1", and the recording data corresponding to the optical storage medium layers A0, B0, and C0 are set to "0", the situation where three sets of data "11010", "10111", and "01011", 15 bytes, are written in sequence using the super-diffraction limit resolution optical storage medium disclosed in the solution of the present invention is as follows: Fig. 9As shown. In contrast, if the existing optical storage medium is used, only 5 bytes of data can be written under the same size, such as Fig.10 shown.

[0051] When reading data, the frequency-tunable laser wavelength is modulated to λ4. The λ4 laser beam does not react with the optical storage medium layers A0, A1, B0, B1, C0, and C1. However, the reflectivity of the optical storage medium layer A1 to the λ4 wavelength is significantly higher than that of other optical storage medium layers. Therefore, the optical information data recorded in the optical storage medium layer A1 can be accurately read out using the λ4 light. After the A1 series data is scanned and read, the frequency-tunable laser wavelength is modulated to λ5. The λ5 light does not react with the components of the optical storage medium layers A0, A1, B0, B1, C0, and C1. However, the optical storage medium layer B1 has a reflectivity to the λ5 wavelength. The reflectivity is significantly higher than that of other optical storage medium layers. Therefore, the optical information data recorded in the optical storage medium layer B1 can be accurately read out using λ5 light. After the B1 series data scanning and reading is completed, the wavelength of the frequency-adjustable laser is modulated to λ6. The λ6 light does not react with the optical storage medium layers A0, A1, B0, B1, C0, and C1. However, the reflectivity of the optical storage medium layer C1 to the λ6 wavelength is significantly higher than that of other optical storage medium layers. Therefore, the optical information data recorded in the optical storage medium layer C1 can be accurately read out using λ6 light. In summary, the reading of super-resolution optical information data is achieved using a frequency-adjustable laser.

[0052] If the data recorded on the optical storage medium layers A1, B1, and C1 is set to "1", and the data recorded on the optical storage medium layers A0, B0, and C0 is set to "0", the situation of reading three sets of data "11010", "10111", and "01011" (15 bytes) in sequence using the super-resolution optical storage medium disclosed in the present invention is as follows: Fig.11 shown.

[0053] In addition, the scheme of the present invention uses a frequency-adjustable laser as a multi-wavelength output light source. In fact, a wide-band light source can also be used in conjunction with a narrow-band filter color wheel 16 to achieve the purpose of adjusting the output light source wavelength, and the effect achieved is consistent with the frequency-adjustable laser mentioned in the scheme of the present invention.

[0054] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A super-diffraction-limited resolution optical storage medium, characterized in that: It comprises a plurality of optical storage medium layers which are periodically stacked, the wavelengths of the read / write laser beams of any two adjacent optical storage medium layers are different, and the thickness of any one of the optical storage medium layers is less than the diffraction limited spot diameter d1 of the minimum wavelength laser beam in the read / write laser beam, and the total thickness D of the optical storage medium layers in each period is ≥ the diffraction limited spot diameter d2 of the maximum wavelength laser beam in the read / write laser beam; the stacking surface of the optical storage medium layer is the read / write surface.

2. The super-diffraction-limited resolution optical storage medium according to claim 1, characterized in that: The number of optical storage medium layers n in each period is greater than or equal to 2, and the wavelengths of the reading and writing laser beams of any optical storage medium layer in each period are different.

3. The super-diffraction-limited resolution optical storage medium according to claim 1 or 2, characterized in that: The thickness of each optical storage medium layer is equal.

4. The super-diffraction-limited resolution optical storage medium according to claim 3, characterized in that: The thickness of each optical storage medium layer is 50-100 nm.

5. The super-diffraction-limited resolution optical storage medium according to claim 1, characterized in that: The optical storage medium layer is made of photochromic material.

6. A method for preparing a super-diffraction-limited resolution optical storage medium according to any one of claims 1 to 5, characterized in that: The following steps are involved: An alternating composite process is used to periodically stack different optical storage medium layer materials in sequence to form a multi-layer optical storage medium layer. The wavelengths of the read / write laser beams of any two adjacent optical storage medium layers are different, and the thickness of any one of the optical storage medium layers is less than the diffraction-limited spot diameter d1 of the minimum wavelength laser beam in the read / write laser beam. The total thickness D of the optical storage medium layer in each period is ≥ the diffraction-limited spot diameter d2 of the maximum wavelength laser beam in the read / write laser beam. The stacked surface of the optical storage medium layer is the read / write surface.

7. The method for preparing a super-diffraction-limited resolution optical storage medium according to claim 6, characterized in that: It also includes cutting multiple optical storage medium layers along a direction perpendicular to the stacking direction to form a sheet-like optical storage medium.

8. The method for preparing a super-diffraction-limited resolution optical storage medium according to claim 6 or 7, characterized in that: The alternating composite process is a coating process.

9. A method for reading and writing data using the super-diffraction-limited resolution optical storage medium according to any one of claims 1 to 5, characterized in that: Including data writing method and data reading method; The steps of the data writing method are as follows: Selecting a laser beam with a wavelength corresponding to a certain optical storage medium layer in a period of the multi-layer optical storage medium layer as a writing laser beam in sequence, and completing data writing to all optical storage medium layers corresponding to the writing laser beam in the multi-layer optical storage medium layer by using the writing laser beam; The steps of the data reading method are as follows: A laser beam with a wavelength corresponding to a certain optical storage medium layer in a period of the multi-layer optical storage medium layer is selected in sequence as a reading laser beam, and data reading of all optical storage medium layers corresponding to the reading laser beam in the multi-layer optical storage medium layer is completed through the reading laser beam.

10. The method for reading and writing data of an optical storage medium with a resolution beyond the diffraction limit according to claim 9, characterized in that: The data reading and writing light source adopts frequency-tunable laser.

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