Super-diffraction light-limiting storage read-write device based on optical antenna and preparation method of super-diffraction light-limiting storage read-write device

Abstract

The invention discloses an ultra-diffraction light-limiting storage read-write device based on an optical antenna and a preparation method, an optical antenna array of the device comprises a plurality of optical antenna structures distributed in an array, and each optical antenna structure comprises a pointed structure and a metal film layer wrapping the pointed structure. The metal film layers of any two adjacent optical antenna structures in each row are electrically connected, the metal film layers of any two adjacent optical antenna structures in each column are electrically connected, and the metal films wrapping the rows and the columns of the array are led out to electrodes at the edge of the optical antenna array through the electric connection. The input module is used for inputting driving control signals; according to the optical antenna, incident light super-diffraction limit focusing is achieved through strong electron accumulation of the optical antenna, the resolution ratio and the storage capacity of a conventional optical storage device are remarkably improved, the optical antenna has high imaging light wave collection efficiency, and the appearance design of the optical antenna gives consideration to ultralow fly height lt; and the requirement of 10nm is met.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of nano-optical antenna, and particularly relates to an ultra-diffraction-limit optical storage reading and writing device based on an optical antenna and a preparation method thereof. BACKGROUND

[0002] Optical storage technology is widely used in mass cold data storage due to its long service life, non-contact reading and writing, high security, easy disc replacement, low production cost and convenient replication and distribution. Traditional optical storage technology is based on the interaction between laser and medium, which causes the change of the properties of the medium to store information. With the advent of the digital era, the demand for information storage is growing, and it is predicted that the total amount of data generated worldwide will reach 175 zettabytes (ZB) by 2026. In order to meet the growing demand for storage, it is of great significance to improve the storage capacity of optical storage devices. Traditional optical storage technology improves the storage capacity of optical storage devices by reducing the size of the focused laser spot and the recording symbol on the medium, but it is limited by the optical diffraction limit, making it increasingly difficult to improve the capacity of optical discs using traditional optical storage technology.

[0003] In recent years, optical antenna structures obtained by micro-nano processing technology from functional materials such as semiconductor materials silicon germanium, etc., have attracted widespread attention from researchers due to their wide operating bandwidth, high stability, and easy control of surface light waves. Through the radiation excitation of a point light source, a sharp tip of the surface can achieve a strong accumulation of "surface state" electrons. Due to the relatively strong response and highly localized resonance enhancement, surface waves with characteristic frequencies can be effectively excited and transmitted along the tip surface to the apex, through continuous refraction and reflection, resulting in a resonant condensation of surface electromagnetic wave field at the tip, which can achieve resonant super-diffraction-limit enhancement of the tip light field. At the same time, when the profile and parameters of the micro-nano structure are determined, its optical properties and functions are generally also determined, making it difficult to meet the demand for dynamic adjustment of the functions of micro-nano devices in complex and variable scenarios. The optical properties of the surface of the optical antenna are greatly affected by the structure parameters and the refractive index of the surrounding medium. By coupling the surface of the optical antenna with a variable material or a variable structure, and changing the dielectric constant of the variable material or the size parameters of the variable structure through an external signal, the optical properties of the coupled device can be quantitatively controlled, which can be used for intelligent control of ultra-diffraction-limit optical storage.

[0004] The preparation of optical antennas is mostly carried out by electron beam lithography technology, which can achieve precise control of parameters such as array diameter, height and period, but electron beam lithography technology is high in cost and time-consuming, and difficult to mass-produce. In addition, low-cost optical antenna preparation methods, including nano-imprinting, etc., have great difficulty in alignment during the processing process, with low yield and small tip sharpness of the processed optical antennas, which further leads to unsatisfactory tip electron accumulation effect. SUMMARY

[0005] This invention provides a super-diffraction-limited optical storage read / write device and its fabrication method based on an optical antenna. It features high imaging light wave collection efficiency and achieves super-diffraction-limited focusing of incident light through strong electron accumulation of the optical antenna, which significantly improves the resolution and storage capacity of conventional optical storage devices.

[0006] To solve the above problems, the technical solution provided by the present invention is as follows:

[0007] This invention provides a read / write device for super-diffraction-limited optical storage based on an optical antenna, including a femtosecond laser, a rewritable optical disk to be recorded, and an optical antenna assembly located between the femtosecond laser and the rewritable optical disk. The optical antenna assembly includes a substrate and an optical antenna array disposed on the substrate. The optical antenna array includes multiple optical antenna structures arranged in an array. Each optical antenna structure includes a pointed structure and a metal film layer covering the pointed structure. The metal film layers of any two adjacent optical antenna structures in each row are electrically connected, and the metal film layers of any two adjacent optical antenna structures in each column are electrically connected. The metal film covering the array rows and columns is led out to electrodes at the edge of the optical antenna array through the above electrical connections for input of drive signals.

[0008] For a specific optical rewritable disk track to be written, a specific sub-optical antenna array is used. The sub-optical antenna array includes at least one optical antenna structure, and the projection area of ​​the sub-optical antenna array corresponding to the optical rewritable disk track on the substrate does not exceed the projection area of ​​the optical rewritable disk track on the substrate. The tip structure of each optical antenna structure points to the optical rewritable disk. The optical antenna array and the optical rewritable disk track are coupled in the near field.

[0009] The optical antenna achieves super-diffraction-limited focusing of incident light through strong electron accumulation, which significantly improves the resolution and storage capacity of conventional optical storage devices. It also features high imaging light wave collection efficiency, and its shape design takes into account the requirement of ultra-low flight height <10nm.

[0010] In a preferred embodiment of the present invention, the distance between the optical antenna assembly and the optically rewritable disk recording track is 40nm-300nm, so that the two can be coupled in the near field.

[0011] In a preferred embodiment of the present invention, the optical antenna structure includes a planar optical antenna and a vertical optical antenna, wherein the planar optical antenna is etched into the substrate to a depth of 100-800 nm, and the vertical optical antenna protrudes from the substrate surface to a height of 500-1500 nm.

[0012] In a preferred embodiment of the present invention, the lateral period of the optical antenna array is 500nm-2000nm, and the duty cycle is 50%-70%; the longitudinal period of the optical antenna array is 500nm-2000nm, and the duty cycle is 50%-70%, wherein the duty cycle = structural size / period size, the structural size is the bottom feature size of the optical antenna structure, and the bottom feature size is the diameter of the circumcircle of the pattern; the lateral period is the distance between the center lines of two optical antenna structures in the lateral direction, and the longitudinal period is the distance between the center lines of two optical antenna structures in the longitudinal direction, the lateral direction is the direction of a row, and the longitudinal direction is the direction of a column.

[0013] In a preferred embodiment of the present invention, the material of the metal film layer is selected from aluminum, chromium, copper, silver, and gold.

[0014] This invention provides a method for fabricating a super-diffraction-limited light storage read / write device based on an optical antenna, comprising the following steps:

[0015] Step 1, fabricating the optical antenna assembly, specifically includes the following sub-steps:

[0016] Step 1.1, First cleaning process: Clean the silicon wafer substrate material and dry it;

[0017] Step 1.2, Coating process: A silicon dioxide film is deposited on one surface of a cleaned substrate using plasma-enhanced chemical vapor deposition, followed by cleaning and drying.

[0018] Step 1.3, Photoresist Coating Process: Apply photoresist to the side of the silicon dioxide film away from the substrate using a spin coater, and then dry it;

[0019] Step 1.4, Electron beam lithography process: Scan the electron beam along a circular or rectangular path to expose the photoresist to light;

[0020] Step 1.5, Development process: Use developer to develop and dry the photoresist, so that the photoresist with reduced molecular weight after photosensitive denaturation can be dissolved, and the photoresist portion that needs to be retained can be preserved.

[0021] Step 1.6, First etching process: The magnetic neutral loop discharge plasma etching process is used to etch away the silicon dioxide film without photoresist coverage, so that the pattern on the silicon dioxide covered with photoresist is consistent with the pattern of the retained photoresist, thereby forming a silicon dioxide mask.

[0022] Step 1.7, Second Cleaning Process: The processed substrate is cleaned by water bath heating and then dried;

[0023] Step 1.8, Resin Removal Process: A resist removal machine is used to remove the resist to ensure that all photoresist residue on the surface of the obtained silicon dioxide mask is removed;

[0024] Step 1.9, Second Etching Process: Inductively Coupled Plasma Etching Process is adopted, and the substrate is etched using a planar ion beam: the area on the substrate not covered by the silicon dioxide mask is etched, and the etching parameters are adjusted according to the sidewall tilt angle of the desired pointed structure. The area on the substrate covered by the silicon dioxide mask is etched to obtain the pointed structure.

[0025] Step 1.10, Third cleaning process: The structure obtained in step 1.9 is ultrasonically cleaned sequentially with hydrofluoric acid, acetone, alcohol and deionized water solvent, and then dried. Hydrofluoric acid is used to remove the silicon dioxide mask.

[0026] Step 1.11, Magnetron sputtering process: Magnetron sputtering of metal is performed on each pointed structure to form a metal film. During magnetron sputtering, a mask is used to ensure that no metal film is formed on the substrate between any adjacent pointed structures. Then the substrate is cleaned and dried.

[0027] Step 2, integrating the optical antenna assembly and photosensitive array, specifically includes the following sub-steps:

[0028] Step 2.1, Optical alignment process between optical antenna assembly and optical rewritable disk: Align each sub-optical antenna array in the optical antenna array with the optical rewritable disk recording track in the optical rewritable disk, and make the optical antenna assembly and the optical rewritable disk recording track generate near-field coupling;

[0029] Step 2.2, Packaging process: Lead out the conductive lines of a row of optical antenna structures at the edge of the optical antenna array to connect the drive control signal and to generate near-field coupling between the optical antenna array and the optical rewritable disk recording track.

[0030] In a preferred embodiment of the present invention, the thickness of the substrate in step 1.1 is 100nm-300nm.

[0031] In a preferred embodiment of the present invention, the thickness of the metal film layer in step 1.11 is 30nm-50nm.

[0032] Compared with the prior art, the embodiments of the present invention provide a super-diffraction-limited light storage read / write device and its preparation method based on an optical antenna, which has the following beneficial effects:

[0033] (1) Near-field coupling is required between the optical antenna array and the optical rewritable disk, which allows the surface "roaming" electrons to be strongly accumulated at the tip of the optical antenna and form a local strong electric field at the tip of the optical antenna structure. This electric field is an evanescent field, that is, the field strength decreases with the -2 power of the distance, thereby realizing high gain amplification of the incident light of the optical antenna structure.

[0034] (2) Due to the tip effect, a large number of surface states filled with free electrons are generated at the tip of the optical antenna structure, resulting in a high surface distribution density of free electrons at the tip. Simultaneously, when the excited surface wave propagates to the tip of the optical antenna structure, the tip boundary guides the surface wave towards the optical antenna, ultimately achieving nano-focusing of the incident electromagnetic radiation. For electromagnetic waves like light, the optical antenna structure can effectively perform optical wave modulation, achieving super-diffraction-limited focusing of the incident light and improving system resolution. Furthermore, by forming a localized focused light field on the tip surface of the optical antenna array, a grating electric field is induced, enabling pixel-level in-situ high-sensitivity measurement and output control and dynamic adjustment of the photoinduced electrical signal, thereby increasing the optical storage capacity.

[0035] (3) High gain amplification of incident light in optical antenna structure: The optical storage device based on optical antenna array of the present invention has the characteristics of controlling the strong accumulation of electrons at the tip of the optical antenna structure through visible or infrared light, and controlling the excitation and nano-convergence of surface waves on the surface of the optical antenna structure to amplify the intensity of the incident light wave and reduce the recording energy consumption.

[0036] (4) Electrically adjustable optical antenna light wave collection gain: By using the electromagnetic wave convergence of the surface of the optical antenna structure and the coupling correlation of the enhanced surface plasmons, the electron distribution density of the surface "roaming state" is controlled, the nano-convergence intensity of the surface electromagnetic wave beam is adjusted, and thus the recording resolution is adjusted.

[0037] (5) Intelligent drive and control: The surface wave excitation and nano-convergence of the optical antenna structure are easily constrained, enhanced or guided by external drive and control signals such as bias electric field, and have intelligent characteristics.

[0038] (6) Low cost: The main body of the optical storage device based on the optical antenna array of the present invention is an optical antenna array and an optical rewritable disk encapsulated in a shell, which is easy to process and has a high yield.

[0039] The incident beam exits from the femtosecond laser, inducing surface charges to form nanofocus (strong charge accumulation) at the tip of the optical antenna, thereby creating a locally enhanced electromagnetic field. In the near-field region (40nm-3000nm), resonant super-diffraction-limited enhancement of the tip's optical field can be achieved, with intensity jumps exceeding five orders of magnitude. The advantages lie in the super-diffraction-limited focusing of the recorded beam and the significant enhancement of light intensity. Attached Figure Description

[0040] To more clearly illustrate the technical solutions in the embodiments or prior art, the drawings used in the description of the embodiments or prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0041] Figure 1 This is a schematic diagram of a super-diffraction-limited light storage read / write device based on an optical antenna, provided in an embodiment of this application.

[0042] Figure 2 This is a schematic diagram of a multi-configuration optical antenna unit provided in an embodiment of this application.

[0043] Figure 3 This is a schematic diagram of the ultraviolet-visible-infrared optical characteristics of the optical antenna and substrate provided in the embodiments of this application.

[0044] Figure 4 The measured image of the optical antenna exceeding the diffraction limit provided in the embodiments of this application is shown. Detailed Implementation

[0045] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application. The terms "upper," "lower," "front," "rear," "left," and "right," etc., used when describing the installation position or direction of the structure or components in this embodiment are based on the orientation shown in the accompanying drawings. They are merely for convenience of description, used to distinguish the relative positions of various components or directions, and do not represent the orientation of the device or functional component in this embodiment during use.

[0046] like Figure 1 and Figure 2As shown, this embodiment of the invention provides a super-diffraction-limited light storage read / write device based on an optical antenna, including a femtosecond laser 1, a rewritable optical disk 3 to be recorded, and an optical antenna assembly 2 located between the femtosecond laser 1 and the rewritable optical disk 3. The term "rewritable optical disk" refers to any medium that can be rewritten by a focused laser, including but not limited to recording disks coated with magnetic materials, phase-change materials, etc. The optical antenna assembly 2 includes a substrate and an optical antenna array disposed on the substrate. The optical antenna array includes multiple optical antenna structures arranged in an array. Each optical antenna structure includes a pointed structure and a metal film layer surrounding the pointed structure. Any two adjacent optical antenna structures in each row are electrically connected via conductive lines, and any two adjacent optical antenna structures in each column are also electrically connected via conductive lines. Each metal film layer of a row of optical antenna structures located at the edge of the optical antenna array is connected to an outgoing wire for connecting control signals.

[0047] Figure 2 In (a), a star-shaped tip structure 2-2 is etched on the substrate 2-1. The star-shaped tip structure 2-2 is a type of planar optical antenna. Figure 2 (b) A triangular structure 2-3 is etched on the substrate 2-1. The triangular structure 2-3 is a type of planar optical antenna. Figure 2 In (c), a strip-shaped structure 2-4 is etched on the substrate 2-1. The strip-shaped structure 2-4 is a type of planar optical antenna. Figure 2 The (d) substrate 2-1 has a protruding conical structure 2-5, which is a type of upright optical antenna. Figure 2 (e) A pyramidal structure 2-6 protrudes from the substrate 2-1. The pyramidal structure 2-6 is a type of upright optical antenna. Figure 2 The substrate 2-1 in (f) has a protruding boss structure 2-7, which is a type of upright optical antenna. The material of the metal film layer is selected from aluminum, chromium, copper, silver, and gold.

[0048] For a specific optical rewritable disk track to be written, a specific sub-optical antenna array is used. The sub-optical antenna array includes at least one optical antenna structure, and the projection area of ​​the sub-optical antenna array corresponding to the optical rewritable disk track on the substrate does not exceed the projection area of ​​the optical rewritable disk track on the substrate. The tip structure of each optical antenna structure points to the optical rewritable disk. The optical antenna array and the optical rewritable disk track generate near-field coupling.

[0049] In this embodiment, a specific track on the optically rewritable disk to be written refers to the target track currently being written. Its "specificity" is reflected in two dimensions: ① Time dimension: The writing process is performed "track-by-track." When it is necessary to record a certain portion of data, the system selects an "unwritten / to-be-updated" track as the current operation target, and then switches to the next track after completion; ② Spatial matching dimension: It is strongly bound to the "sub-optical antenna array" in this invention. The "optical antenna array" designed in this invention is partitioned (i.e., "sub-optical antenna array"), with each sub-array corresponding to only one "specific track" (rather than covering all tracks), ensuring that the "effective range" of the sub-optical antenna array accurately covers the target track, avoiding energy waste or interference from adjacent tracks.

[0050] The optical antenna achieves super-diffraction-limited focusing of incident light through strong electron accumulation, which significantly improves the resolution and storage capacity of conventional optical storage devices. It also features high imaging light wave collection efficiency, and its shape design takes into account the requirement of ultra-low flight height <10 nm.

[0051] The spacing between the optical antenna components and the optically rewritable disk's recording tracks is 40nm-300nm to enable near-field coupling. The optical antenna structure includes planar and vertical optical antennas. The planar optical antenna is etched into the substrate to a depth of 100-800nm, while the vertical optical antenna protrudes from the substrate surface by 500-1500nm. The lateral period of the optical antenna array is 500nm-2000nm, with a duty cycle of 50%-70%. The longitudinal period of the optical antenna array is also 500nm-2000nm, with a duty cycle of 50%-70%. The duty cycle is calculated as the ratio of the structural dimension to the period dimension. The structural dimension is the bottom feature dimension of the optical antenna structure, which is the diameter of the circumcircle of the pattern. The lateral period is the spacing between the center lines of two horizontally aligned optical antenna structures, and the longitudinal period is the spacing between the center lines of two vertically aligned optical antenna structures. The lateral period represents a row, and the longitudinal period represents a column.

[0052] This invention provides a method for fabricating a super-diffraction-limited light storage read / write device based on an optical antenna, comprising the following steps:

[0053] Step 1, fabricating the optical antenna assembly, specifically includes the following sub-steps:

[0054] Step 1.1, First cleaning process: The substrate is ultrasonically cleaned sequentially with acetone, alcohol and deionized water, and then dried. The substrate material is a silicon wafer. Preferably, the thickness of the substrate in step 1.1 is 100 nm-300 nm.

[0055] Step 1.2, Coating process: A silicon dioxide film is deposited on one surface of a cleaned substrate using plasma-enhanced chemical vapor deposition, followed by cleaning and drying.

[0056] Step 1.3, Photoresist Coating Process: Apply photoresist to the side of the silicon dioxide film away from the substrate using a spin coater, and then dry it;

[0057] Step 1.4, Electron beam lithography process: Scan the electron beam along a circular or rectangular path to expose the photoresist to light;

[0058] Step 1.5, Development process: Use developer to develop and dry the photoresist, so that the photoresist with reduced molecular weight after photosensitive denaturation can be dissolved, and the photoresist portion that needs to be retained can be preserved.

[0059] Step 1.6, First etching process: The magnetic neutral loop discharge plasma etching process is used to etch away the silicon dioxide film without photoresist coverage, so that the pattern on the silicon dioxide covered with photoresist is consistent with the pattern of the retained photoresist, thereby forming a silicon dioxide mask.

[0060] Step 1.7, Second cleaning process: The substrate is sequentially cleaned with NMP solution and isopropyl ketone solvent using a water bath and then dried;

[0061] Step 1.8, Resin Removal Process: A resist removal machine is used to remove the resist to ensure that all photoresist residue on the surface of the obtained silicon dioxide mask is removed;

[0062] Step 1.9, Second Etching Process: Inductively Coupled Plasma Etching Process is adopted, and the substrate is etched using a planar ion beam: the area on the substrate not covered by the silicon dioxide mask is etched, and the etching parameters are adjusted according to the sidewall tilt angle of the desired pointed structure. The area on the substrate covered by the silicon dioxide mask is etched to obtain the pointed structure.

[0063] Step 1.10, Third cleaning process: The structure obtained in step 1.9 is ultrasonically cleaned sequentially with hydrofluoric acid, acetone, alcohol and deionized water solvent, and then dried. Hydrofluoric acid is used to remove the silicon dioxide mask.

[0064] Step 1.11, Magnetron sputtering process: Magnetron sputtering of metal is performed on each pointed structure to form a metal film layer. During magnetron sputtering, a mask is used to ensure that no metal film layer is formed on the substrate between any adjacent pointed structures. Then, the substrate is cleaned and dried. Preferably, the thickness of the metal film layer in step 1.11 is 30nm-50nm.

[0065] Step 2, integrating the optical antenna assembly and photosensitive array, specifically includes the following sub-steps:

[0066] Step 2.1, Optical alignment process between optical antenna assembly and optical rewritable disk: Align each sub-optical antenna array in the optical antenna array with the optical rewritable disk recording track in the optical rewritable disk, and make the optical antenna assembly and the optical rewritable disk recording track generate near-field coupling;

[0067] Step 2.2, Packaging process: Lead out the conductive lines of a row of optical antenna structures at the edge of the optical antenna array to connect the drive control signal and to generate near-field coupling between the optical antenna array and the optical rewritable disk recording track.

[0068] The sharp electron aggregation effectively reduces far-field transmittance and reflectance, significantly improves absorption, and releases a large amount of near-field light waves. Moreover, the spot size exceeds the traditional optical diffraction limit, enabling effective super-diffraction limit optical storage read and write. Figure 3 The optical characteristics of the optical antenna and substrate in the ultraviolet-visible-infrared band are presented. The reflectivity of the optical antenna is significantly lower than that of the substrate in the ultraviolet-visible-infrared broadband band, and its transmittance is significantly lower than that of the substrate in the infrared band. According to the formula "absorption rate = 1 - reflectivity - transmittance", the absorptivity of the optical antenna is significantly higher than that of the substrate in the ultraviolet-visible-infrared broadband band, indicating that more incident light is absorbed by the optical antenna structure and released in the near field.

[0069] Figure 4 The near-field light spot obtained by scanning near-field optical microscopy (SNOM) has a diameter of ~0.1 μm, exceeding the traditional optical diffraction limit. During optical disc reading and writing, the reduced spot size effectively decreases the bit spacing between sites and the track spacing between recording tracks, improving read / write resolution and optical disc storage capacity. Therefore, introducing an optical antenna can effectively achieve super-diffraction-limit optical storage reading and writing.

[0070] The optical antenna array of the present invention needs to be coupled in the near field with the optical rewritable disk, which allows the surface "roaming" electrons to be strongly accumulated at the tip of the optical antenna in a controlled manner, and a local strong electric field is formed at the tip of the optical antenna structure. This electric field is an evanescent field, that is, the field strength decreases with the -2 power of the distance, thereby realizing high gain amplification of the incident light of the optical antenna structure.

[0071] Due to the tip effect, a large number of surface states filled with free electrons are generated at the tip of the optical antenna structure, resulting in a high surface electron density at the tip. Simultaneously, when the excited surface wave propagates to the tip, the tip boundary guides the surface wave towards the optical antenna, ultimately achieving nano-focusing of the incident electromagnetic radiation. For electromagnetic waves like light, the optical antenna structure can effectively perform optical wave modulation, achieving super-diffraction-limited focusing of the incident light and improving system resolution. Furthermore, by forming a localized focused light field on the tip surface of the optical antenna array, a grating electric field is induced, enabling pixel-level in-situ high-sensitivity measurement and output control and dynamic adjustment of the photoinduced electrical signal, thereby increasing optical storage capacity.

[0072] High-gain amplification of incident light from optical antenna structure: The optical storage device based on optical antenna array of the present invention has the characteristics of controlling the strong accumulation of electrons at the tip of the optical antenna structure through visible or infrared light, and controlling the excitation and nano-convergence of surface waves on the surface of the optical antenna structure to amplify the intensity of the incident light wave and reduce the recording energy consumption.

[0073] Electrically adjustable optical antenna light wave collection gain: By leveraging the coupling correlation between electromagnetic wave convergence on the surface of the optical antenna structure and enhanced surface plasmon resonance, the surface "roaming state" electron distribution density is controlled, adjusting the nano-convergence intensity of the surface electromagnetic wave beam, thereby adjusting the recording resolution. Intelligent drive control: The surface wave excitation and nano-convergence of the optical antenna structure are easily constrained, enhanced, or guided by external drive signals such as bias electric fields, exhibiting intelligent characteristics. Low cost: The main body of the optical storage device based on the optical antenna array of this invention consists of an optical antenna array and an optically rewritable disk encapsulated in a housing, making it easy to manufacture and achieving a high yield.

[0074] The incident beam exits from a femtosecond laser, inducing surface charges to form nanofocus (strong charge accumulation) at the tip of the optical antenna, thereby creating a locally enhanced electromagnetic field. In the near-field region (40 nm ~ 3000 nm), resonant super-diffraction-limited enhancement of the tip's optical field can be achieved, with intensity jumps exceeding five orders of magnitude. The advantages lie in the super-diffraction-limited focusing of the recorded beam and the significant enhancement of light intensity.

[0075] The above addresses the "diffraction limit" bottleneck of traditional optical storage: Traditional optical storage technology relies on the interaction between laser and medium to record data. Its storage capacity improvement depends on "reducing the size of the focused laser spot." However, it is limited by the optical diffraction limit, meaning that the wave nature of light prevents the focused spot from being infinitely reduced. Under conventional techniques, the spot diameter is usually no less than half the wavelength of the incident light (for example, the spot diameter in the visible light band is often in the hundreds of nanometers range). This bottleneck makes it difficult for traditional optical storage capacity to meet the demands of massive data storage. The "super-diffraction-limit optical storage read / write" invention is precisely designed to overcome this bottleneck.

[0076] The core technology of this invention is to achieve super-diffraction limit based on optical antennas. The core carrier for "super-diffraction limit optical storage read / write" is an optical antenna array, which breaks through the diffraction limit through a dual mechanism of "strong electron accumulation + near-field coupling". The specific process adopts three key technical steps:

[0077] (1) Structural basis of optical antennas: The optical antenna array is composed of multiple pointed structures (planar / vertical) and metal film layers that wrap around the pointed structures. The metal film layers of adjacent antennas are electrically connected (allowing for the introduction of control signals). The core function of this structure is:

[0078] Sharp structures (such as star-shaped / triangular structures etched on a plane, and upright cone-shaped / pyramidal structures) utilize the "point effect" to create an extremely high surface distribution density of free electrons at the tip; the metal film provides a channel for electron flow and accumulation, while enhancing the interaction between the light field and electrons through the surface plasmon resonance effect.

[0079] (2) Strong electron accumulation and local strong electric field formation: The optical antenna achieves super-diffraction limit focusing through strong electron accumulation: When the incident light emitted from the femtosecond laser irradiates the optical antenna, it induces the surface "roaming" electrons in the metal film to move towards the tip of the pointed structure and accumulate strongly; the accumulated electrons form a local strong electric field at the tip, and the spatial distribution of the electric field is strictly limited to a very small amplitude region near the tip (far smaller than the wavelength of the incident light), thereby breaking through the diffraction limit of traditional laser focusing.

[0080] (3) Near-field coupling enhances the super-diffraction limit effect: The optical antenna assembly and the optical rewritable disk recording track need to maintain a distance of 40nm-300nm to achieve near-field coupling: Under near-field coupling, the local strong electric field at the tip of the optical antenna can directly act on the recording medium of the optical rewritable disk (such as magnetic / phase change material), avoiding the diffusion and loss of the light field in far-field propagation; at the same time, “tip light field resonant super-diffraction limit enhancement” can be achieved in the near-field region (40nm-3000nm). The document points out that its intensity jump has exceeded five orders of magnitude, further reducing the effective spot size (the measured diameter of a single near-field spot is about 0.1μm, which is much smaller than the traditional diffraction limit spot).

[0081] Super-diffraction limit implementation of "read / write" functionality: "Super-diffraction limit" is not only reflected in "writing" but also covers "reading". The specific implementation of this functionality depends on the following design:

[0082] (1) Super-diffraction limit writing: Smaller records and higher orbital density:

[0083] During writing, the local strong electric field at the tip of the optical antenna acts on the optically rewritable disk track, inducing local state changes in the medium (such as crystalline / amorphous switching in phase change materials and domain flipping in magnetic materials). The size of the resulting "record" is determined by the amplitude of the local electric field (much smaller than the traditional laser spot). At the same time, it is required that "the projection of a specific sub-optical antenna array does not exceed the projection of the corresponding track", ensuring that each sub-array acts on only a single track, avoiding interference between adjacent tracks, and significantly reducing the track spacing. Both of these factors together achieve a significant increase in storage capacity.

[0084] (2) Super-diffraction limit readout: High sensitivity to collect near-field light signals: The optical antenna has "high imaging light wave collection efficiency": During readout, the recorders (medium regions in different states) on the optical rewritable disk will reflect or scatter light signals. The pointed structure of the optical antenna can efficiently collect these light signals that are limited to the near field. The collected light signals are converted into electrical signals by the electronic movement of the metal film layer, and then controlled and output by the drive signal drawn out by the edge electrode. Since the light signals come from tiny recorders that are super-diffraction limit, the readout resolution also breaks through the limitations of traditional technology.

[0085] The technological advantages of this invention are as follows: Super-diffraction limit is a breakthrough. Compared with traditional technologies, super-diffraction limit optical storage read / write has three core advantages: Leap in capacity and resolution: The ultra-small record size and track spacing directly increase the storage density of optically rewritable disks; Low energy consumption and high efficiency: The high energy density of the local strong electric field reduces the laser power required for writing, while the high light wave collection efficiency improves the reading sensitivity; Adjustable and intelligent electronic control: The driving control signal (such as the bias electric field) derived from the metal film layer can be used to adjust the electron accumulation intensity and local electric field distribution, realizing dynamic adjustment of read / write resolution to meet the needs of different scenarios.

[0086] The "super-diffraction-limited optical storage read / write" of this invention essentially uses an optical antenna design of "pointed structure + metal film layer" to break through the diffraction limit of traditional optical storage by utilizing the dual mechanisms of "strong electron accumulation to form a local strong electric field" and "near-field coupling", thereby achieving smaller record bits and higher density optical data writing and reading, and ultimately solving the capacity bottleneck in massive data storage scenarios.

[0087] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A read / write device for super-diffraction-limited light storage based on an optical antenna, characterized in that, The device includes a femtosecond laser, a rewritable optical disk to be recorded, and an optical antenna assembly located between the femtosecond laser and the rewritable optical disk. The optical antenna assembly includes a substrate and an optical antenna array disposed on the substrate. The optical antenna array includes multiple optical antenna structures arranged in an array. Each optical antenna structure includes a pointed structure and a metal film layer covering the pointed structure. The metal film layers of any two adjacent optical antenna structures in each row are electrically connected, and the metal film layers of any two adjacent optical antenna structures in each column are electrically connected. The metal film covering the rows and columns of the array is led out to electrodes at the edge of the optical antenna array through the above electrical connections for input of drive signals. For a specific optical rewritable disk track to be written, a specific sub-optical antenna array is used. The sub-optical antenna array includes at least one optical antenna structure, and the projection area of ​​the sub-optical antenna array corresponding to the optical rewritable disk track on the substrate does not exceed the projection area of ​​the optical rewritable disk track on the substrate. The tip structure of each optical antenna structure points to the optical rewritable disk. The optical antenna array and the optical rewritable disk track are coupled in the near field. The optical antenna achieves super-diffraction-limited focusing of incident light through strong electron accumulation, which significantly improves the resolution and storage capacity of conventional optical storage devices. It also has high imaging light wave collection efficiency, and its shape design takes into account the requirement of ultra-low flight height <10 nm.

2. The super-diffraction-limited light storage read / write device based on an optical antenna according to claim 1, characterized in that, The distance between the optical antenna assembly and the optically rewritable disk recording track is 40nm-300nm to enable near-field coupling between the two.

3. The super-diffraction-limited light storage read / write device based on an optical antenna according to claim 1, characterized in that, The optical antenna structure includes a planar optical antenna and a vertical optical antenna. The planar optical antenna is etched into the substrate to a depth of 100-800 nm, and the vertical optical antenna protrudes from the substrate surface to a height of 500-1500 nm.

4. The super-diffraction-limited light storage read / write device based on an optical antenna according to claim 1, characterized in that, The optical antenna array has a lateral period of 500nm-2000nm and a duty cycle of 50%-70%. The optical antenna array has a longitudinal period of 500nm-2000nm and a duty cycle of 50%-70%, where the duty cycle = structural size / period size, the structural size is the bottom feature size of the optical antenna structure, and the bottom feature size is the diameter of the circumcircle of the pattern; the lateral period is the distance between the center lines of two optical antenna structures in the lateral direction, and the longitudinal period is the distance between the center lines of two optical antenna structures in the longitudinal direction, the lateral direction is the direction of a row, and the longitudinal direction is the direction of a column.

5. The super-diffraction-limited light storage read / write device based on an optical antenna according to claim 1, characterized in that, The material of the metal film layer is selected from one of aluminum, chromium, copper, silver, and gold.

6. A method for fabricating a super-diffraction-limited light storage read / write device based on an optical antenna, characterized in that, Includes the following steps: Step 1, fabricating the optical antenna assembly, specifically includes the following sub-steps: Step 1.1, First cleaning process: Clean the silicon wafer substrate material and dry it; Step 1.2, Coating process: A silicon dioxide film is deposited on one surface of a cleaned substrate using plasma-enhanced chemical vapor deposition, followed by cleaning and drying. Step 1.3, Photoresist Coating Process: Apply photoresist to the side of the silicon dioxide film away from the substrate using a spin coater, and then dry it; Step 1.4, Electron beam lithography process: Scan the electron beam along a circular or rectangular path to expose the photoresist to light; Step 1.5, Development process: Use developer to develop and dry the photoresist, so that the photoresist with reduced molecular weight after photosensitive denaturation can be dissolved, and the photoresist portion that needs to be retained can be preserved. Step 1.6, First etching process: The magnetic neutral loop discharge plasma etching process is used to etch away the silicon dioxide film without photoresist coverage, so that the pattern on the silicon dioxide covered with photoresist is consistent with the pattern of the retained photoresist, thereby forming a silicon dioxide mask. Step 1.7, Second Cleaning Process: The processed substrate is cleaned by water bath heating and then dried; Step 1.8, Resin Removal Process: A resist removal machine is used to remove the resist to ensure that all photoresist residue on the surface of the obtained silicon dioxide mask is removed; Step 1.9, Second Etching Process: Inductively Coupled Plasma Etching Process is adopted, and the substrate is etched using a planar ion beam: the area on the substrate not covered by the silicon dioxide mask is etched, and the etching parameters are adjusted according to the sidewall tilt angle of the desired pointed structure. The area on the substrate covered by the silicon dioxide mask is etched to obtain the pointed structure. Step 1.10, Third cleaning process: The structure obtained in step 1.9 is ultrasonically cleaned sequentially with hydrofluoric acid, acetone, alcohol and deionized water solvent, and then dried. Hydrofluoric acid is used to remove the silicon dioxide mask. Step 1.11, Magnetron sputtering process: Magnetron sputtering of metal is performed on each pointed structure to form a metal film. During magnetron sputtering, a mask is used to ensure that no metal film is formed on the substrate between any adjacent pointed structures. Then the substrate is cleaned and dried. Step 2, integrating the optical antenna assembly and photosensitive array, specifically includes the following sub-steps: Step 2.1, Optical alignment process between optical antenna assembly and optical rewritable disk: Align each sub-optical antenna array in the optical antenna array with the optical rewritable disk recording track in the optical rewritable disk, and make the optical antenna assembly and the optical rewritable disk recording track generate near-field coupling; Step 2.2, Packaging process: Lead out the conductive lines of a row of optical antenna structures at the edge of the optical antenna array to connect the drive control signal and to generate near-field coupling between the optical antenna array and the optical rewritable disk recording track.

7. The method for fabricating a super-diffraction-limited light storage read / write device based on an optical antenna according to claim 6, characterized in that, The thickness of the substrate in step 1.1 is 100nm-300nm.

8. The method for fabricating a super-diffraction-limited light storage read / write device based on an optical antenna according to claim 6, characterized in that, The thickness of the metal film in step 1.11 is 30nm-50nm.

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