Single photon generating device and method of manufacturing the same

Abstract

The application relates to a single-photon generating device and a preparation method thereof. The single-photon generating device comprises a center disc configured to arrange quantum emitters, a ring-shaped grating located at the periphery of the center disc and comprising a plurality of concentric ring-shaped bosses, and a first waveguide connected with a third elliptical arc boss of one of the ring-shaped bosses, wherein the first waveguide is parallel to the polarization direction of excitation laser used for exciting the quantum emitters. The radiation wavelength of the quantum emitters is L1, the center wavelength of the ring-shaped grating reflected along a first direction is L2, and the center wavelength of the ring-shaped grating reflected along a second direction is L3, wherein L1, L2 and L3 satisfy the following conditions: the difference between L1 and L2 is within a preset range, and L2 is greater than L3. The single-photon generating device and the preparation method thereof can enhance the pumping efficiency of the excitation laser, so that when the laser irradiates the quantum emitters, the brightness of the single photons emitted by the quantum emitters is improved.

Description

Technical Field

[0001] This invention relates to the field of quantum optical technology, and in particular to a single-photon generation device and its preparation method. Background Technology

[0002] Single photons can propagate over long distances in free space and optical fibers without losing coherence, making them an excellent physical carrier for qubits. Semiconductor quantum dots have emitted high-quality single photons with the best performance; however, because quantum dots are located in high-refractive-index materials, the collection and utilization of single photons are extremely difficult.

[0003] In traditional technology, single photons are radiated into free space using quantum dots and ring Bragg gratings, which need to be coupled to a chip via optical fiber. However, the intensity of single photons radiated by quantum dots is low, resulting in low brightness of a single light source. Summary of the Invention

[0004] Therefore, it is necessary to provide a single-photon generation device and its fabrication method to address the problem of low brightness in single-photon light sources.

[0005] In a first aspect, a single-photon generating device is provided, the single-photon generating device comprising:

[0006] A central disk for configuring a quantum emitter, the central disk having symmetrical first elliptical arc protrusions on both sides along a first direction and symmetrical second elliptical arc protrusions on both sides along a second direction, the first direction and the second direction intersecting;

[0007] An annular grating, located on the outer periphery of the central disk, includes multiple concentric annular protrusions, each annular protrusion having symmetrical third elliptical arc protrusions on both sides along a first direction and symmetrical fourth elliptical arc protrusions on both sides along a second direction.

[0008] A first waveguide is connected to the third elliptical arc protrusion of one of the annular protrusions, and the first waveguide is parallel to the polarization direction of the excitation laser used to excite the quantum emitter.

[0009] Wherein, the radiation wavelength of the quantum emitter is L1, the center wavelength of the reflection of the annular grating along the first direction is L2, and the center wavelength of the reflection along the second direction is L3. L1, L2 and L3 satisfy the following: the difference between L2 and L1 is within a preset range, and L2 is greater than L3.

[0010] In one embodiment, the single-photon generating device further includes a substrate, wherein the central disk, the annular grating, and the first waveguide are all located on the substrate; the refractive indices of the central disk, the annular grating, and the first waveguide are all greater than the refractive index of the substrate.

[0011] In one embodiment, the two first elliptical arc protrusions of the central disk correspond to a first ellipse, the major axis of the first ellipse being parallel to the first direction, and the two third elliptical arc protrusions of each annular boss correspond to a third ellipse, the third ellipse being concentric with the first ellipse and having a collinear major axis;

[0012] The two second elliptical arc protrusions of the central disk correspond to the second ellipse, the major axis of the second ellipse is parallel to the second direction, and the two fourth elliptical arc protrusions of each annular boss correspond to the fourth ellipse, the fourth ellipse is concentric with the second ellipse and their major axes are collinear.

[0013] In one embodiment, the major axis of the first ellipse is longer than the major axis of the second ellipse, and the difference between the two is between 5 nm and 15 nm.

[0014] In one embodiment, a second waveguide is further included, which is located on the side of the annular grating away from the first waveguide and is connected to the third elliptical arc protrusion of one of the annular bosses. The polarization direction of the second waveguide is also parallel to the polarization direction of the excitation laser.

[0015] In one embodiment, the spacing between the plurality of annular bosses, as well as the spacing between the smallest annular boss and the central disk, are all equal.

[0016] In one embodiment, the annular grating includes N annular protrusions, numbered from the 1st to the Nth in the direction away from the central disk; the first waveguide connects to the i-th to the N-th annular protrusions, where N is a positive integer, 1 < i ≤ N / 2.

[0017] Secondly, this application also provides a method for fabricating a single-photon generating device, comprising the following steps:

[0018] A substrate structure is provided, the substrate structure including a quantum emitter;

[0019] Multiple positioning marks are formed on the substrate structure;

[0020] The quantum emitter is excited, and the relative positional relationship between the quantum emitter and the positioning marker is determined by imaging.

[0021] Based on the relative positional relationship, a single-photon generating device is formed on the substrate structure. The single-photon generating device includes: a central disk for arranging a quantum emitter, the central disk having symmetrical first elliptical arc protrusions on both sides along a first direction and symmetrical second elliptical arc protrusions on both sides along a second direction, the first direction and the second direction intersecting; an annular grating located on the outer periphery of the central disk, including multiple concentric annular protrusions, each annular protrusion having symmetrical third elliptical arc protrusions on both sides along the first direction and symmetrical fourth elliptical arc protrusions on both sides along the second direction; a first waveguide connected to the third elliptical arc protrusion of one of the annular protrusions, the first waveguide being parallel to the polarization direction of the excitation laser used to excite the quantum emitter; wherein, the radiation wavelength of the quantum emitter is L1, the center wavelength reflected by the annular grating along the first direction is L2, and the center wavelength reflected along the second direction is L3, L1, L2, and L3 satisfying: the difference between L2 and L1 is within a preset range, and L2 is greater than L3.

[0022] In one embodiment, the fabrication process of the substrate structure includes:

[0023] A stacked structure is provided, the stacked structure including a sacrificial layer, and a first device layer and a second device layer located on both sides of the sacrificial layer;

[0024] A substrate layer and a conductive layer are sequentially formed on the second device layer to obtain an intermediate structure;

[0025] An adhesive layer is formed on the intermediate structure, and the structure is bonded to the base plate through the adhesive layer;

[0026] The first device layer and the sacrificial layer are removed to obtain the substrate structure.

[0027] In one embodiment, exciting the quantum emitter and determining the relative positional relationship between the quantum emitter and the positioning marker by imaging includes:

[0028] The quantum emitter is excited, causing it to emit light.

[0029] Provide a light source to illuminate each of the positioning marks;

[0030] A positioning image is acquired, the positioning image being obtained through visible light imaging, and the positioning image including the quantum emitter and the positioning marker;

[0031] The relative positional relationship between the quantum emitter and the positioning mark is determined based on the first luminous region from the quantum emitter and the second luminous region from the positioning mark on the positioning image.

[0032] The aforementioned single-photon generation device includes a central disk, a ring grating, and a first waveguide. A quantum emitter is disposed within the central disk. When an excitation laser is incident on the central disk, the quantum emitter is excited and releases a single photon with wavelength L1. This single photon couples with the first waveguide and is emitted, achieving radiation of the single photon into free space. The ring grating includes multiple concentric ring protrusions. Each ring protrusion has elliptical arc protrusions on both sides along a first direction and on both sides along a second direction, such that the center wavelength of reflection in the first direction is L2, and the center wavelength of reflection in the second direction is L3. L2 is equal to L1, or the difference between L1 and L2 is within a preset range, and L2 is greater than L3. This ensures that the reflection curve of the ring grating in the second direction still has a certain intensity at the L1 wavelength position. This enhances the pumping efficiency of the excitation laser, increasing the intensity of the single photon emitted by the quantum emitter when the laser irradiates it, thereby increasing the intensity of the single photon coupled to the first waveguide and improving the brightness of the single photon received in free space. In order to enable the degeneracy of orthogonal cavity modes, the length of a traditional single elliptical grating in the short axis direction is limited, resulting in limited pumping efficiency. Therefore, the single photon generation device provided in this application can improve the brightness of single photons compared with traditional technology. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of a single-photon generation device in one embodiment;

[0034] Figure 2 This is a graph showing the radiation wavelength of the quantum emitter and the wavelength intensity curves of the reflection from the annular grating in the first and second directions, in one embodiment.

[0035] Figure 3 This is an enlarged view of the structure of the central disk in one embodiment;

[0036] Figure 4a This is an enlarged view of the annular boss structure in one embodiment;

[0037] Figure 4b This is a schematic diagram of an embodiment where the annular boss is composed of elliptical rings;

[0038] Figure 5a This is a schematic diagram showing the positional relationship between the first elliptical arc protrusion and the third elliptical arc protrusion in one embodiment;

[0039] Figure 5b This is a schematic diagram showing the positional relationship between the second and fourth elliptical arc protrusions in one embodiment;

[0040] Figure 6 This is a flowchart of a method for fabricating a single-photon generation device in one embodiment;

[0041] Figures 7a-7hThis is a flowchart illustrating the process steps for fabricating a single-photon generation device in one embodiment.

[0042] Explanation of reference numerals in the attached figures:

[0043] 100. Single-photon generating device; 10. Central disk; 11. First elliptical arc protrusion; 111. First ellipse; 12. Second elliptical arc protrusion; 121. Second ellipse; 20. Annular grating; 21. Annular boss; 211. Third elliptical arc protrusion; 2111. First elliptical ring; 2112. Third ellipse; 212. Fourth elliptical arc protrusion; 2121. Second elliptical ring; 2122. Fourth ellipse; 31. First waveguide; 32. Second waveguide; 71. First device layer; 72. Sacrificial layer; 73. Second device layer; 74. Substrate layer; 75. Conductive layer; 76. Adhesive layer; 77. Base plate; 78. Positioning mark; 79. Quantum emitter; X, First direction; Y, Second direction. Detailed Implementation

[0044] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0045] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0046] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0047] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0048] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0049] It should be noted that when an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0050] See Figure 1 , Figure 1 A schematic diagram of a single-photon generation device according to one embodiment of the present invention is shown. The single-photon generation device provided in one embodiment includes a central disk 10, a ring grating 20, and a first waveguide 31. A quantum emitter is disposed within the central disk 10. When an excitation laser is incident on the central disk 10, the quantum emitter is excited and releases a single photon. The single photon couples with the first waveguide 31 and is emitted, realizing the radiation of the single photon into free space. The central disk 10 and the ring grating 20 constitute a microcavity structure and are coupled to the first waveguide 31.

[0051] Specifically, the central disk 10 is used to configure the quantum emitter. The central disk 10 has symmetrical first elliptical arc protrusions 11 on both sides along the first direction X, and symmetrical second elliptical arc protrusions 12 on both sides along the second direction Y. The first direction X and the second direction Y intersect, as shown below. Figure 1 As shown, the first elliptical arc protrusion 11 and the second elliptical arc protrusion 12 are both protrusions that radiate outward along the central disk 10.

[0052] The annular grating 20 is located on the outer periphery of the central disk 10 and includes multiple concentric annular protrusions 21, with intervals between each annular protrusion 21. Each annular protrusion 21 has symmetrical third elliptical arc protrusions 211 on both sides along the first direction X, and symmetrical fourth elliptical arc protrusions 212 on both sides along the second direction Y. Figure 1 As shown, the third elliptical arc protrusion 211 and the fourth elliptical arc protrusion 212 are both protrusions that radiate outward along the central disk 10. In some embodiments, the spacing between the plurality of annular protrusions 21 and the spacing between the smallest annular protrusion 21 and the central disk 10 are equal. Thus, the first elliptical arc protrusion 11 of the central disk 10 and the third elliptical arc protrusion 211 of the annular protrusion 21 form a grating along the first direction X, and the second elliptical arc protrusion 12 of the central disk 10 and the fourth elliptical arc protrusion 212 of the annular protrusion 21 form a grating along the second direction Y.

[0053] It is understood that an elliptical arc protrusion refers to a protrusion whose shape is an ellipse, such as a section of the edge or curve of an ellipse. Optionally, the first elliptical arc protrusion 11, the second elliptical arc protrusion 12, the third elliptical arc protrusion 211, and the fourth elliptical arc protrusion 212 are the ends of the ellipse along its major axis.

[0054] The first waveguide 31 is connected to the third elliptical arc protrusion 211 of one of the annular protrusions 21. The first waveguide 31 is parallel to the polarization direction of the excitation laser used to excite the quantum emitter. Since the polarization mode of the first waveguide 31 does not match the polarization mode of the excitation laser, the excitation source cannot be coupled into the first waveguide 31. When the first waveguide 31 couples a single photon, the purity of the single photon is guaranteed.

[0055] Furthermore, the single-photon generating device may also include a second waveguide 32. When the single-photon generating device includes a second waveguide 32, the second waveguide 32 is located on the side of the annular grating 20 away from the first waveguide 31 and is connected to the third elliptical arc protrusion 211 of one of the annular protrusions 21. The polarization direction of the second waveguide 32 is also parallel to the polarization direction of the excitation laser.

[0056] At this point, the first waveguide 31 and the second waveguide 32 are located on opposite sides of the central disk 10 and both extend along the first direction X. The first waveguide 31 and the second waveguide 32 are respectively connected to the third elliptical arc protrusion 211 of one of the annular protrusions 21, so that the single photon emitted by the quantum emitter can be coupled to the first waveguide 31 and / or the second waveguide 32. The first waveguide 31 and the second waveguide 32 can use waveguides to couple out the single photon emitted by the quantum emitter, realizing the transfer of single photons from the microcavity to the waveguide network, and improving the single photon radiation efficiency.

[0057] For example, the straight line containing the first waveguide 31 and the second waveguide 32 coincides with the straight line containing the major axis of the first elliptical arc protrusion and / or the third elliptical arc protrusion. The first waveguide 31 and the second waveguide 32 extend along the first direction X to form an elongated structure, which is convenient for insertion into the annular grating 20 and connection with one of the annular protrusions 21.

[0058] Among them, such as Figure 2 As shown, Figure 2 The diagrams shown illustrate the radiation wavelength of the quantum emitter and the reflection curves of the annular grating 20 in the first direction X and the second direction Y, according to some embodiments. The radiation wavelength of the quantum emitter is L1, the center wavelength of the reflection of the annular grating 20 along the first direction X is L2, and the center wavelength of the reflection along the second direction Y is L3. L1, L2, and L3 satisfy the following conditions: the difference between L1 and L2 is within a preset range, and L2 is greater than L3. L2 can be equal to L1.

[0059] Understandable, Figure 2 The alignment of L1 and L2 in the diagram is for illustrative purposes only. In practice, L1 and L2 can be offset, as long as the single photon emitted by the quantum emitter can be coupled by the first waveguide 31 and / or the second waveguide 32. If L1 and L2 are exactly equal, the wavelength of the single photon emitted by the quantum emitter perfectly matches the reflection wavelength of the ring grating 20 in the first direction X, resulting in the highest reflection efficiency. At this time, the intensity of the single photon coupled by the first waveguide 31 and the second waveguide 32 is the highest. If there is an offset between L2 and L1, the single photon is not at the center wavelength position of the reflection of the ring grating 20, and the reflection efficiency decreases. However, it is still acceptable as long as the intensity of the single photon received by the first waveguide 31 and the second waveguide 32 meets the requirements.

[0060] Specifically, L1 is the wavelength of the single-photon light emitted by the quantum emitter (e.g., a quantum dot) after being excited. When the first-direction X-reflection wavelength L2 of the annular grating 20 and the radiation wavelength L1 of the quantum emitter are within a preset range, the grating structure can effectively couple or resonate with the quantum emitter, thereby enhancing the single-photon radiation efficiency. When L2 is greater than L3, see [reference needed]. Figure 2 At wavelength L1, the second-direction Y-reflection curve still has a certain intensity (e.g., Figure 2 (The intensity indicated by D in the diagram) Thus, the reflection of the annular grating 20 in the second direction Y can enhance the pumping efficiency of the excited laser, so that when the laser irradiates the quantum emitter, it increases the intensity of the single photon emitted by the quantum emitter, thereby increasing the intensity of the single photon coupled by the first waveguide 31 and the second waveguide 32, and thus increasing the brightness of the single photon received in free space.

[0061] The aforementioned single-photon generation device includes a central disk 10, an annular grating 20, and a first waveguide 31. A quantum emitter is disposed within the central disk 10. When an excitation laser is incident on the central disk 10, the quantum emitter is excited and releases a single photon with a wavelength of L1. The single photon couples with the first waveguide 31 and is emitted, realizing the radiation of the single photon into free space. The annular grating 20 includes multiple concentric annular protrusions 21. Each annular protrusion 21 has elliptical arc protrusions on both sides along the first direction X and on both sides along the second direction Y, such that the central wavelength reflected by the annular grating 20 in the first direction X is L2, and the central wavelength reflected along the second direction Y is L3. The difference between L1 and L2 is within a preset range, and L2 is greater than L3, ensuring that the reflection curve of the annular grating 20 in the second direction Y still has a certain intensity at the L1 wavelength position. This enhances the pumping efficiency of the excitation laser, increasing the intensity of the single photons emitted by the quantum emitter when the laser irradiates it, thereby increasing the intensity of the single photons coupled by the first waveguide 31 and improving the brightness of the single photons received in free space. In contrast, traditional single elliptical gratings have limited length along their minor axis to achieve degeneracy of orthogonal cavity modes, resulting in limited pumping efficiency. Therefore, the single photon generation device provided in this application can improve the brightness of single photons compared to traditional technologies.

[0062] like Figure 3 As shown, to further illustrate the structure of the central disk 10, Figure 3 An enlarged view of the structure of the central disk 10 is shown. Two first elliptical arc protrusions 11 along the first direction X are located on opposite sides of the central disk 10. Each of the two first elliptical arc protrusions 11 can serve as two ends on the same major axis side of an ellipse, such as two ends along the major axis direction of a first ellipse 111. For example, two second elliptical arc protrusions 12 along the second direction Y of the central disk 10 are located on opposite sides of the central disk 10. Each of the two second elliptical arc protrusions 12 can serve as two ends on the same major axis side of an ellipse, such as two ends along the major axis direction of a second ellipse 121. Thus, as... Figure 3 As shown, the central disk 10 is formed by the overlapping of two concentric ellipses 111 and 121 with their major axes intersecting.

[0063] like Figure 4a and Figure 4b As shown, to further illustrate the structure of the annular boss 21, Figure 4 shows an enlarged view of one of the annular bosses 21. Figure 4b A schematic diagram of an embodiment is shown, showing that the annular boss 21 is composed of an elliptical ring. Figure 4aIn the annular boss 21, the two third elliptical arc protrusions 211 along the first direction X are located on opposite sides of the annular boss 21. The two third elliptical arc protrusions 211 can be respectively used as two ends on the same major axis of the ellipse, such as as Figure 4b The two ends of the first elliptical ring 2111 in the major axis direction. Exemplarily, the fourth elliptical arc protrusions 212 along the second direction Y of the annular boss 21 are located on opposite sides of the annular boss 21. The two fourth elliptical arc protrusions 212 can respectively serve as two ends on the same elliptical major axis side, such as as... Figure 4b The two ends of the second elliptical ring 2121 along its major axis. Thus, as... Figure 4b As shown, Figure 4b A schematic diagram of the annular boss 21, which is composed of elliptical rings, is shown. The annular boss 21 is equivalent to being formed by connecting two concentric elliptical rings 2111 and 2121 with their major axes intersecting.

[0064] See Figure 5a , Figure 5a A schematic diagram illustrating the positional relationship between the first elliptical arc protrusion 11 and the third elliptical arc protrusion 211 in one embodiment is shown. The two first elliptical arc protrusions 11 of the central disk 10 correspond to the first ellipse 111, serving as the two ends of the major axis of the first ellipse 111, which is parallel to the first direction X. The two third elliptical arc protrusions 211 of each annular boss 21 correspond to the third ellipse 2112, serving as the two ends of the major axis of the third ellipse 2112, which is concentric with the first ellipse 111 and whose major axes are collinear. Figure 5a The third ellipse 2112 and the first ellipse 111 share the same center P, and their major axes coincide on the straight line S1. Thus, the first elliptical arc protrusion 11 of the central disk 10 and the two third elliptical arc protrusions 211 of each annular protrusion 21 form a grating with a reflective center wavelength of L2 in the first direction X.

[0065] See Figure 5b , Figure 5b A schematic diagram illustrating the positional relationship between the second elliptical arc protrusion 12 and the fourth elliptical arc protrusion 212 in one embodiment is shown. The two second elliptical arc protrusions 12 of the central disk 10 correspond to the second ellipse 121, serving as the two ends of the major axis of the second ellipse 121, whose major axis is parallel to the second direction Y. The two fourth elliptical arc protrusions 212 of each annular boss 21 correspond to the fourth ellipse 2122, serving as the two ends of the major axis of the fourth ellipse 2122, whose fourth ellipse 2122 is concentric with the second ellipse 121 and whose major axis is collinear. Figure 5bThe fourth ellipse 2122 and the second ellipse 121 share a common center P, and their major axes coincide on the straight line S2. Thus, the second elliptical arc protrusion 12 of the central disk 10 and the two fourth elliptical arc protrusions 212 of each annular protrusion 21 form a grating with a reflective center wavelength of L3 in the second direction Y.

[0066] In the above embodiments, the central disk 10 and the annular boss 21 are both configured to be obtained by superimposing ellipses, rather than using a perfect circle structure. This can open the orthogonal polarization degeneracy of the microcavity, that is, by stretching or compressing the central circular cavity into an elliptical cavity, the cavity lengths of the two orthogonal polarization cavity modes are changed, so that their resonant wavelengths are separated.

[0067] In traditional cavities, if the cavity geometry is symmetrical (such as a circular or spherical cavity), it can lead to different polarization modes having the same frequency; this phenomenon is called degeneracy. For optical microcavities, this degeneracy is generally undesirable because it can cause competition or interference between different polarization states. By designing the central disk 10 and the annular boss 21 as elliptical, the cavity symmetry is broken, thus effectively altering the mode distribution within the cavity, especially the frequencies and cavity lengths of different polarization modes. The elliptical cavity no longer possesses the axial symmetry of a circular cavity, allowing the resonant wavelengths of two orthogonal polarization modes to be separated, thereby avoiding their frequency degeneracy, improving the independence of the cavity modes, and preventing unnecessary mode crossing.

[0068] In some embodiments, the major axis length of the first ellipse 111 is greater than the major axis length of the second ellipse 121, and the difference between the two is between 5 nm and 15 nm. The major axis length of the first ellipse 111 affects the magnitude of the center wavelength L2 of the reflected light in the first direction X, and the major axis length of the second ellipse 121 affects the magnitude of the center wavelength L3 of the reflected light in the second direction Y.

[0069] In this embodiment, the difference between the major axis length of the first ellipse 111 and the major axis length of the second ellipse 121 is between 5nm and 15nm. If the difference is too small, the central disk 10 is close to a perfect circle, and the degeneracy is high. If the difference is too large, L2 and L3 are too different, resulting in the intensity of the second direction Y reflection curve at the L1 position being too small, which does not significantly improve the pumping efficiency.

[0070] In some embodiments, the single-photon generating device further includes a substrate, on which the central disk 10, the annular grating 20, the first waveguide 31, and the second waveguide 32 are all located; the refractive indices of the central disk 10, the annular grating 20, the first waveguide 31, and the second waveguide 32 are all greater than the refractive index of the substrate. By configuring the refractive indices of the central disk 10, the annular grating 20, the first waveguide 31, and the second waveguide 32 to be different from the substrate material, the mechanical fragility of the suspended structure is overcome by using a substrate made of a low-refractive-index material. In some feasible implementations, the central disk 10, the annular grating 20, the first waveguide 31, and the second waveguide 32 can be made of GaAs material, and the substrate can be SiO2.

[0071] like Figure 1 As shown, in this embodiment, the first waveguide 31 and the second waveguide 32 are two elongated planar waveguides inserted into the annular grating 20. The waveguides can couple polarized single photons located in the microcavity, and can also directly couple single photons localized within the microcavity to the on-chip waveguide network, greatly improving the on-chip single photon radiation efficiency. It can be understood that when the quantum emitter is excited to form a single photon, the excitation laser is set as polarized Gaussian light, with its polarization direction parallel to the first waveguide 31 and the second waveguide 32. The excitation light, polarized parallel to the first and second planar waveguides, is incident vertically from above onto the central disk 10, exciting the quantum emitter located in the central disk 10. After being excited, the quantum emitter emits a single photon, which is then coupled into the first waveguide 31 and the second waveguide 32.

[0072] In some embodiments, such as Figure 1 As shown, the annular grating 20 includes N annular protrusions 21, numbered from the 1st to the Nth in the direction away from the central disk 10. A first waveguide 31 connects the i-th to the N-th annular protrusions 21, where N is a positive integer, 1 < i ≤ N / 2. When the single-photon generation device also includes a second waveguide 32, the second waveguide 32 connects the i-th to the N-th annular protrusions 21. If the annular protrusions 21 connected to the first waveguide 31 and the second waveguide 32 are too close to the central disk 10, the single-photon recombination rate is low and unstable. If the annular protrusions 21 connected to the first waveguide 31 and the second waveguide 32 are too far from the central disk 10, the single-photon intensity is low, and the brightness is low.

[0073] For example, such as Figure 1 In the structure shown, the annular grating 20 includes 9 annular protrusions 21, so N is 9. In the direction away from the central disk 10, they are the 1st, 2nd, 3rd...9th in sequence. The first waveguide 31 and the second waveguide 32 are both connected to the 9th to the 3rd annular protrusions 21, that is, i equals 3.

[0074] like Figure 6 As shown, Figure 6The following steps are shown as a method for fabricating a single-photon generating device 100 in some embodiments:

[0075] S61 provides a substrate structure, which includes a quantum emitter 79.

[0076] For example, the substrate structure may be a substrate.

[0077] For example, the substrate structure can also be a multilayer structure with a substrate as the top, in which the central disk 10, the annular grating 20 and the first waveguide 31 can be formed directly on the substrate. For example, the substrate can be attached to the base plate by an adhesive.

[0078] S62, forming multiple positioning marks 78 on the base structure.

[0079] For example, the positioning marks 78 can be made of metal. The specific process is as follows: First, a layer of photoresist is uniformly coated on the substrate structure, which will serve as a carrier for subsequent pattern transfer. Then, the photoresist is exposed using a mask. The mask has a preset pattern, and by irradiating it with ultraviolet light or other suitable light sources, the exposed areas of the photoresist undergo chemical changes. After exposure, multiple precise trenches are formed on the photoresist. Subsequently, a deposition process is used to deposit a metal marking material (such as aluminum, copper, gold, etc.) into the formed trenches. The deposition process includes evaporation deposition, sputtering deposition, chemical vapor deposition (CVD), etc. After deposition, the photoresist is removed using chemical or mechanical methods, thereby obtaining regularly arranged metal positioning marks 78 on the substrate structure.

[0080] S63, excite the quantum emitter 79, and determine the relative positional relationship between the quantum emitter 79 and the positioning marker 78 by imaging.

[0081] S64, based on relative positional relationships, a single-photon generating device 100 is formed on a substrate structure. The single-photon generating device includes: a central disk 10 for arranging quantum emitters 79, the central disk 10 having symmetrical first elliptical arc protrusions 11 on both sides along a first direction X, and symmetrical second elliptical arc protrusions 12 on both sides along a second direction Y, the first direction X and the second direction Y intersecting; and an annular grating 20, located on the outer periphery of the central disk 10, including multiple concentric annular protrusions 21, each annular protrusion 21 having symmetrical third elliptical arc protrusions 12 on both sides along the first direction X. The circular arc protrusion 211 has symmetrical fourth elliptical arc protrusions 212 on both sides along the second direction Y; the first waveguide 31 is connected to the third elliptical arc protrusion 211 of one of the annular protrusions 21, and the first waveguide 31 is parallel to the polarization direction of the excitation laser used to excite the quantum emitter 79; wherein, the radiation wavelength of the quantum emitter 79 is L1, the center wavelength of the reflection of the annular grating 20 along the first direction X is L2, and the center wavelength of the reflection along the second direction Y is L3, and L1, L2, and L3 satisfy: the difference between L2 and L1 is within a preset range, and L2 is greater than L3. It can be understood that the single photon generating device 1100 provided in this embodiment can be any of the single photon generating devices 100 provided in the above embodiments.

[0082] In the above-mentioned method for preparing the single-photon generating device 100, the position of the quantum emitter 79 is first located on the substrate structure, and then the single-photon generating device 100 is prepared on the substrate structure so that the quantum emitter 79 is located at the position of the central disk 10.

[0083] In some embodiments, such as Figures 7a-7e The preparation process of the substrate structure includes:

[0084] S611, such as Figure 7a As shown, a stacked structure is provided, which includes a sacrificial layer 72, and a first device layer 71 and a second device layer 73 located on both sides of the sacrificial layer 72.

[0085] S612, such as Figure 7b As shown, a substrate layer 74 and a conductive layer 75 are sequentially formed on the second device layer 73 to obtain an intermediate structure.

[0086] S613, such as Figure 7c As shown, an adhesive layer 76 is formed on the intermediate structure, and the adhesive layer 76 is bonded to the base plate 77.

[0087] S614, such as Figure 7d and 7e As shown, the first device layer 71 and the sacrificial layer 72 are removed to obtain the substrate structure.

[0088] Among them, such as Figure 7cAs shown, adhesive layer 76 is formed on conductive layer 75, and base plate 77 is formed on adhesive layer 76. Then as... Figure 7d As shown, the obtained structure is flipped so that the base plate 77 is at the bottom, which facilitates the removal of the first device layer 71 and the sacrificial layer 72.

[0089] See after Figure 7f Multiple positioning markers 78 are formed on the substrate structure. After exciting the quantum emitter 79 to emit light, the position of the quantum emitter 79 relative to the positioning markers 78 can be determined by acquiring an image. Figure 7g It shows Figure 7f A magnified view of region A in the image, such as Figure 7h As shown, a single-photon generating device 100 can be prepared with the quantum emitter 79 as the center, wherein the single-photon generating device 100 can be the structure shown in any of the above embodiments.

[0090] In some embodiments, step S63, which excites the quantum emitter 79 and determines the relative positional relationship between the quantum emitter 79 and the positioning marker 78 by imaging, includes:

[0091] S631 excites quantum emitter 79, causing quantum emitter 79 to emit light.

[0092] For example, the quantum emitter 79 is excited by an external energy source, such as electric current, light, or other forms of excitation. After excitation, the electrons of the quantum emitter 79 transition from the ground state (low energy state) to the excited state (high energy state). When the electrons return to the lower energy level, they manifest as light.

[0093] S632 provides a light source to illuminate each positioning mark 78.

[0094] For example, the light source can be visible light, which illuminates the positioning mark 78 to make it emit light. When the positioning mark 78 is metallic, it is easier for it to emit light.

[0095] S633, acquire the positioning image, which is obtained by visible light imaging, and the positioning image includes a quantum emitter 79 and a positioning marker 78.

[0096] For example, the location image can be obtained by taking a picture with a camera or other means.

[0097] S634, based on the first luminous region from the quantum emitter 79 and the second luminous region from the positioning mark 78 on the positioning image, determine the relative positional relationship between the quantum emitter 79 and the positioning mark 78.

[0098] For example, after acquiring the positioning image, an image processing algorithm is used to obtain the absolute positions of the quantum dot and the metal marker on the photograph, and then the position of the quantum dot relative to the metal marker is obtained.

[0099] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0100] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A single-photon generating device, characterized in that, The single-photon generating device includes: A central disk for configuring a quantum emitter, the central disk having symmetrical first elliptical arc protrusions on both sides along a first direction and symmetrical second elliptical arc protrusions on both sides along a second direction, the first direction and the second direction intersecting; An annular grating, located on the outer periphery of the central disk, includes N concentric annular protrusions, numbered from the 1st to the Nth in the direction away from the central disk, where N is a positive integer; each annular protrusion has a symmetrical third elliptical arc protrusion on both sides along a first direction and a symmetrical fourth elliptical arc protrusion on both sides along a second direction. The first waveguide is connected to the third elliptical arc protrusion of the i-th to N-th annular protrusion on one side of the first direction. The first waveguide is parallel to the polarization direction of the excitation laser used to excite the quantum emitter, 1 < i ≤ N / 2. Wherein, the radiation wavelength of the quantum emitter is L1, the center wavelength of the reflection of the annular grating along the first direction is L2, and the center wavelength of the reflection along the second direction is L3. L1, L2, and L3 satisfy the following: the difference between L2 and L1 is within a preset range, and L2 is greater than L3; the central disk and the annular grating form a microcavity structure and are coupled to the first waveguide, and the shape of the elliptical arc protrusion is a portion of an ellipse.

2. The single-photon generating device according to claim 1, characterized in that, The single-photon generating device further includes a substrate, and the central disk, the annular grating, and the first waveguide are all located on the substrate; the refractive indices of the central disk, the annular grating, and the first waveguide are all greater than the refractive index of the substrate.

3. The single-photon generating device according to claim 1, characterized in that, The two first elliptical arc protrusions of the central disk correspond to the first ellipse, the major axis of the first ellipse is parallel to the first direction, and the two third elliptical arc protrusions of each annular boss correspond to the third ellipse, the third ellipse is concentric with the first ellipse and the major axis is collinear; The two second elliptical arc protrusions of the central disk correspond to the second ellipse, the major axis of the second ellipse is parallel to the second direction, and the two fourth elliptical arc protrusions of each annular boss correspond to the fourth ellipse, the fourth ellipse is concentric with the second ellipse and their major axes are collinear.

4. The single-photon generating device according to claim 3, characterized in that, The major axis of the first ellipse is longer than that of the second ellipse, and the difference between the two is between 5nm and 15nm.

5. The single-photon generating device according to claim 1, characterized in that, It also includes a second waveguide, which is located on the side of the annular grating away from the first waveguide and is connected to the third elliptical arc protrusion of the i-th to N-th annular protrusions on the other side of the first direction. The polarization direction of the second waveguide is also parallel to the polarization direction of the excitation laser.

6. The single-photon generating device according to claim 1, characterized in that, The spacing between the plurality of annular bosses, as well as the spacing between the smallest annular boss and the central disk, are all equal.

7. A method for fabricating a single-photon generating device, characterized in that, Includes the following steps: A substrate structure is provided, the substrate structure including a quantum emitter; Multiple positioning marks are formed on the substrate structure; The quantum emitter is excited, and the relative positional relationship between the quantum emitter and the positioning marker is determined by imaging. Based on the relative positional relationship, a single-photon generating device is formed on the substrate structure. The single-photon generating device includes: a central disk for arranging a quantum emitter; the central disk has symmetrical first elliptical arc protrusions on both sides along a first direction and symmetrical second elliptical arc protrusions on both sides along a second direction, the first direction and the second direction intersecting; an annular grating located on the outer periphery of the central disk, including N concentric annular protrusions, numbered from the 1st to the Nth in the direction away from the central disk, where N is a positive integer; each annular protrusion has symmetrical third elliptical arc protrusions on both sides along the first direction and symmetrical fourth elliptical arc protrusions on both sides along the second direction. The device comprises an arc-shaped protrusion; a first waveguide, which is connected to the third elliptical arc protrusion of the i-th to N-th annular protrusions on one side of the first direction, the first waveguide being parallel to the polarization direction of the excitation laser used to excite the quantum emitter; wherein the radiation wavelength of the quantum emitter is L1, the center wavelength of the reflection of the annular grating along the first direction is L2, and the center wavelength of the reflection along the second direction is L3, and L1, L2, and L3 satisfy: the difference between L2 and L1 is within a preset range, and L2 is greater than L3; the central disk and the annular grating form a microcavity structure and are coupled to the first waveguide, and the shape of the elliptical arc protrusion is a portion of an ellipse, 1 < i ≤ N / 2.

8. The method for fabricating the single-photon generating device according to claim 7, characterized in that, The fabrication process of the substrate structure includes: A stacked structure is provided, the stacked structure including a sacrificial layer, and a first device layer and a second device layer respectively located on both sides of the sacrificial layer; A substrate layer and a conductive layer are sequentially formed on the second device layer to obtain an intermediate structure; An adhesive layer is formed on the intermediate structure, and the structure is bonded to the base plate through the adhesive layer; The first device layer and the sacrificial layer are removed to obtain the substrate structure.

9. The method for fabricating a single-photon generating device according to claim 8, characterized in that, The process of exciting the quantum emitter and determining the relative positional relationship between the quantum emitter and the positioning marker through imaging includes: The quantum emitter is excited, causing it to emit light. Provide a light source to illuminate each of the positioning marks; A positioning image is acquired, the positioning image being obtained through visible light imaging, and the positioning image including the quantum emitter and the positioning marker; The relative positional relationship between the quantum emitter and the positioning mark is determined based on the first luminous region from the quantum emitter and the second luminous region from the positioning mark on the positioning image.

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