Microcavity enhanced single photon structure, preparation method and microcavity enhanced light quantum chip

Abstract

According to the microcavity enhanced single-photon structure, the preparation method and the microcavity enhanced light quantum chip provided by the invention, the thin-film resistor is formed near the waveguide layer, the electrodes are formed at the two ends of the thin-film resistor, and the local heating effect of the thin-film resistor is utilized to change the temperature of the corresponding quantum dot, so that the light-emitting wavelength of the quantum dot is regulated and controlled; by accurately controlling the heating power of the thin-film resistor, the light-emitting wavelength of the quantum dots can be accurately regulated and controlled, so that the light-emitting wavelength of the quantum dots can be accurately matched with the mode frequency of the micro-ring resonant cavity, the Purcell effect is maximized, the emission efficiency of photons is improved, and the light-emitting efficiency of the quantum dots is improved. The bottleneck problem that in the prior art, accurate matching of the quantum dot emission wavelength and the mode frequency of the micro-ring resonant cavity is difficult to achieve is effectively solved, and meanwhile the limitation that localized and discrete independent regulation and control cannot be conducted on a single device at a specific position in the integrated light quantum chip through an existing global regulation and control technology is overcome.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optical quantum devices and chip technology, in particular to a microcavity enhanced single photon structure, a preparation method and a microcavity enhanced optical quantum chip. BACKGROUND

[0002] High-quality factor (Q) on-chip photonic microcavities play a core role in cavity quantum electrodynamics (cQED) systems. These microcavities can significantly enhance the spontaneous emission rate of quantum dots (Purcell effect), effectively suppress noise interference, and thus realize high-performance quantum light sources, such as single photon sources. The Purcell factor is used to measure the degree of enhancement of the spontaneous emission rate of quantum dots by microcavities, and this factor depends on the characteristics of the microcavity and the degree of overlap between the quantum dot and the microcavity mode. In order to achieve optimal performance, the microcavity mode and the quantum dot emission wavelength must be precisely resonant, at which point the light field localization intensity is highest, the Purcell factor is maximized, and the light-matter interaction efficiency is optimal.

[0003] However, III-V self-assembled quantum dots grown by molecular beam epitaxy technology have inherent growth randomness, resulting in significant non-uniformity in size, shape, composition, and strain state. This non-uniformity directly causes a large broadening of the quantum dot emission spectrum. At the same time, high-quality on-chip photonic microcavities usually have a relatively narrow cavity mode linewidth. These factors make it difficult to achieve precise matching of the quantum dot emission wavelength and the microcavity mode frequency during device preparation, which is a key bottleneck problem restricting the development of on-chip high-performance quantum light sources. Therefore, there is an urgent need to develop effective post-fabrication tuning techniques to overcome the mode detuning caused by the non-uniform broadening of the quantum dot spectrum.

[0004] For the spectral tuning of on-chip integrated quantum dots, existing research has proposed various post-growth regulation strategies, such as strain regulation technology based on piezoelectric film substrates and regulation technology based on a temperature controller platform. However, these technologies belong to the global regulation category and are difficult to perform localized, discrete independent regulation on a single device at a specific location in an integrated optical quantum chip, which severely limits their application potential in large-scale, high-density integrated quantum chips. SUMMARY

[0005] In view of the above-mentioned shortcomings of the prior art, the purpose of the present application is to provide a microcavity enhanced single photon structure, a preparation method and a microcavity enhanced optical quantum chip, which are used to solve the problem of difficulty in achieving precise matching of the quantum dot emission wavelength and the microcavity mode frequency in the prior art, and the problem that existing global regulation techniques cannot perform localized, discrete independent regulation on a single device at a specific location in an integrated optical quantum chip.

[0006] To achieve the above object and other related objects, the present application provides a preparation method of a microcavity enhanced single photon structure, which comprises the following steps:

[0007] A light quantum structure is provided, which comprises, from bottom to top, a substrate, a lower cladding layer, a photonic micro-ring, and a waveguide layer containing a quantum dot light source; wherein the waveguide layer is located on the photonic micro-ring;

[0008] A thin film resistor is formed at a predetermined distance from the waveguide layer, and the thin film resistor is located outside the photonic micro-ring;

[0009] Two electrodes are formed on opposite ends of the length direction of the thin film resistor, and the electrodes form ohmic contact with the thin film resistor.

[0010] Optionally, the thin film resistor is formed by a Lift-off process, and the method for forming the thin film resistor comprises the following steps:

[0011] A first photoresist layer is formed on the lower cladding layer, covering the photonic micro-ring and the waveguide layer containing the quantum dot light source;

[0012] An ultraviolet lithography technique is used to pattern the first photoresist layer to form a first photoresist opening in the first photoresist layer;

[0013] A resistor layer is deposited on the first photoresist layer, and the resistor layer is deposited on the lower cladding layer through the first photoresist opening;

[0014] The first photoresist layer and the resistor layer formed on the first photoresist layer are removed by a Lift-off process, and the resistor layer on the lower cladding layer is retained to form the thin film resistor.

[0015] Further, the first photoresist layer comprises a lower first photoresist layer and an upper first photoresist layer; wherein the material of the lower first photoresist layer comprises one or more of LOR5A photoresist and LOR10B photoresist; and the material of the upper first photoresist layer comprises one or more of AZ5214 photoresist and SPR photoresist.

[0016] Further, the method for patterning the first photoresist layer by an ultraviolet lithography technique comprises one or more of laser direct writing lithography and mask lithography.

[0017] Optionally, the predetermined distance is 3 μm to 10 μm.

[0018] Optionally, the electrodes are formed by a Lift-off process, and the method for forming the electrodes comprises the following steps:

[0019] forming a second photoresist layer on the lower cladding layer, the second photoresist layer covering the photonic micro-ring, the waveguide layer containing the quantum dot light source and the thin film resistor;

[0020] performing a patterned processing on the second photoresist layer by using ultraviolet lithography technology to form a second photoresist opening in the second photoresist layer;

[0021] depositing an electrode material layer on the second photoresist layer, the electrode material layer being deposited on the lower cladding layer and the opposite ends of the thin film resistor in the length direction of the thin film resistor through the second photoresist opening;

[0022] removing the second photoresist layer and the electrode material layer formed on the second photoresist layer by using a Lift-off process, and retaining the electrode material layer on the lower cladding layer and the thin film resistor to form the electrode.

[0023] Optionally, the material of the thin film resistor comprises one or more of titanium nitride, platinum, titanium and nichrome, the thickness of the thin film resistor is 80nm-140nm, and the width of the thin film resistor is 5μm-10μm.

[0024] Optionally, the material of the electrode comprises gold, and the thickness of the electrode is 150nm-300nm.

[0025] Optionally, the thin film resistor is formed by using a magnetron sputtering process, and the electrode is formed by using an electron beam evaporation process.

[0026] The application further provides a microcavity enhanced single photon structure, which comprises, from bottom to top, a substrate, a lower cladding layer, a photonic micro-ring, a waveguide layer containing a quantum dot light source and a micro-heating circuit; wherein the waveguide layer is located on the photonic micro-ring; the micro-heating circuit comprises:

[0027] a thin film resistor formed on the lower cladding layer at a preset distance from the waveguide layer, and the thin film resistor is located outside the photonic micro-ring;

[0028] an electrode arranged on the opposite ends of the thin film resistor in the length direction of the thin film resistor and forming an ohmic contact with the thin film resistor.

[0029] Optionally, the preset distance is 3μm-10μm.

[0030] Optionally, the material of the thin film resistor comprises one or more of titanium nitride, platinum, titanium and nichrome, the thickness of the thin film resistor is 80nm-140nm, and the width of the thin film resistor is 5μm-10μm.

[0031] Optionally, the material of the electrode comprises gold, and the thickness of the electrode is 150-300 nm.

[0032] The microcavity-enhanced light quantum chip comprises:

[0033] at least two microcavity-enhanced single-photon structures as described in any one of the above;

[0034] a reflector for reflecting photons to enhance the local intensity of the in-cavity photons;

[0035] a bus waveguide for coupling out the in-cavity photons;

[0036] a beam splitter for splitting the photons and realizing photon interconnection between the multiple microcavity-enhanced single-photon structures;

[0037] a grating for coupling out the split photons from the chip and into an optical fiber, wherein one end of the beam splitter is connected to the bus waveguide, and the other end is connected to the grating.

[0038] Optionally, the distance between two adjacent microcavity-enhanced single-photon structures is not less than 250 μm.

[0039] As described above, the microcavity-enhanced single-photon structure, the preparation method and the microcavity-enhanced light quantum chip of the present application have the following beneficial effects: by forming a thin-film resistor near the waveguide layer and forming electrodes at both ends of the thin-film resistor, the local heating effect of the thin-film resistor is utilized to achieve precise local regulation of the quantum dot light emission wavelength. Specifically, when a driving voltage is applied to the thin-film resistor, the heat generated by the resistor can locally change the temperature of the quantum dots, thereby regulating the light emission wavelength of the quantum dots. Since a certain preset distance is maintained between the thin-film resistor and the waveguide layer, this local heating effect only acts on the quantum dots at a specific location, and does not have a significant impact on the entire chip. By precisely controlling the heating power of the thin-film resistor, precise regulation of the light emission wavelength of the quantum dots can be achieved, so that it can be accurately matched with the mode frequency of the micro-ring resonant cavity, thereby maximizing the Purcell effect, improving the emission efficiency of the photons, effectively solving the bottleneck problem that the light emission wavelength of the quantum dots cannot be accurately matched with the mode frequency of the micro-ring resonant cavity in the prior art, and overcoming the limitation that the existing global regulation technology cannot locally and discretely regulate a single device at a specific location in an integrated light quantum chip. BRIEF DESCRIPTION OF DRAWINGS

[0040] Figure 1 A flowchart showing the preparation method of the microcavity-enhanced single-photon structure of the present application.

[0041] Figures 2 to 9 Structural diagrams showing the structure presented in each step of the preparation method of the microcavity-enhanced single-photon structure of the present application.

[0042] Figure 10 A schematic diagram of a microcavity-enhanced light quantum chip of the present application is shown.

[0043] Figure 11 Quantum dot photoluminescence spectra of a microcavity-enhanced light quantum chip of the present application under micro-heating circuit driving voltage are shown.

[0044] Figure 12 A plot of quantum dot emission peak center wavelength versus heating power for a microcavity-enhanced light quantum chip of the present application is shown.

[0045] Figure 13 Quantum dot photoluminescence spectra of a microcavity-enhanced light quantum chip of the present application under different detunings are shown.

[0046] Figure 14 Quantum dot fluorescence lifetimes of a microcavity-enhanced light quantum chip of the present application under different detunings are shown.

[0047] Figure 15 Spectral changes in quantum dot wavelength of two independent microcavity-enhanced single photon structures of a microcavity-enhanced light quantum chip of the present application under different driving voltages are shown.

[0048] Element Number Description

[0049] 1 microcavity-enhanced single photon structure

[0050] 2 reflector

[0051] 3 bus waveguide

[0052] 4 beam splitter

[0053] 5 grating

[0054] 10 substrate

[0055] 11 lower cladding layer

[0056] 12, 26 photonic micro-ring

[0057] 13, 27 waveguide layer

[0058] 14 quantum dot

[0059] 15 first photoresist layer

[0060] 151 lower first photoresist layer

[0061] 152 upper first photoresist layer

[0062] 16 first photoresist opening

[0063] 17 resistive layer

[0064] 18 Thin-film resistors

[0065] 19 Second photoresist layer

[0066] 191 Lower second photoresist layer

[0067] 192 Lower second photoresist layer

[0068] 20 Second photoresist opening

[0069] 21 Electrode material layer

[0070] 22 electrodes

[0071] 23 Micro heating circuit

[0072] 24 First Microcavity Enhanced Single-Photon Structure

[0073] 241 First Micro Heating Circuit

[0074] 25 Second Microcavity Enhanced Single-Photon Structure

[0075] 251 Second Micro Heating Circuit

[0076] Steps S1 to S3 Detailed Implementation

[0077] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0078] Example 1

[0079] Please see Figures 1 to 9 It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Therefore, the illustrations only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0080] This embodiment provides a method for fabricating a microcavity enhanced single-photon structure, such as... Figure 1 As shown, the preparation method includes:

[0081] S1 provides a photonic quantum structure, which, from bottom to top, comprises a substrate, a lower cladding layer, a photonic microring, and a waveguide layer containing a quantum dot light source; wherein the waveguide layer is located on the photonic microring.

[0082] S2, forming a thin film resistance at a preset distance from the waveguide layer, and the thin film resistance is located outside the photonic micro-ring;

[0083] S3, forming two electrodes on the opposite ends of the length direction of the thin film resistance, and the electrodes form ohmic contact with the thin film resistance.

[0084] The preparation method of the microcavity enhanced single photon structure of the embodiment forms a thin film resistance near the waveguide layer and forms electrodes at both ends of the thin film resistance. By using the local heating effect of the thin film resistance, precise local regulation of the quantum dot light emitting wavelength is achieved. Specifically, when a driving voltage is applied to the thin film resistance, the heat generated by the resistance can locally change the temperature of the quantum dot, thereby regulating the light emitting wavelength of the quantum dot. Since a certain preset distance is maintained between the thin film resistance and the waveguide layer, this local heating effect only acts on the quantum dots at a specific position, and does not have a significant impact on the entire chip. By precisely controlling the heating power of the thin film resistance, precise regulation of the quantum dot light emitting wavelength can be achieved, so that it can be accurately matched with the mode frequency of the micro-ring resonant cavity, thereby maximizing the Purcell effect, improving the emission efficiency of photons, and effectively solving the bottleneck problem that the quantum dot emission wavelength cannot be accurately matched with the mode frequency of the micro-ring resonant cavity in the prior art. At the same time, it overcomes the limitation that the existing global regulation technology cannot locally and discretely regulate a single device at a specific position in an integrated optical quantum chip.

[0085] The preparation method of the microcavity enhanced single photon structure of the embodiment will be described in detail below in conjunction with specific drawings.

[0086] As shown in the figure, Figure 2 First, step S1 is performed to provide an optical quantum structure, which includes, from bottom to top, a substrate 10, a lower cladding layer 11, a photonic micro-ring 12, and a waveguide layer 13 containing a quantum dot 14 light source; wherein the waveguide layer 13 is located on the photonic micro-ring 12.

[0087] As an example, the material of the substrate 10 includes but is not limited to silicon; the material of the lower cladding layer 11 includes but is not limited to silicon oxide, and can also be other low refractive index materials, which are not limited here.

[0088] As an example, the photonic micro-ring 12 and the waveguide layer 13 containing the quantum dot 14 light source can be prepared by conventional techniques in the art, which will not be described in detail here.

[0089] As an example, the quantum dot 14-layer structure may include a first gallium arsenide (GaAs) layer, an indium gallium arsenide (InGaAs) layer disposed on the first gallium arsenide layer, and a second gallium arsenide (GaAs) layer disposed on the indium gallium arsenide layer; that is, the InGaAs layer can be embedded in the GaAs layer. The quantum dot 14-layer structure may also include a first indium phosphide (InP) layer, an indium arsenide (InAs) layer disposed on the first indium phosphide layer, and a second indium phosphide (InP) layer disposed on the indium arsenide layer; that is, the InAs layer can be embedded in the InP layer. The quantum dot 14-layer structure may also include a first aluminum gallium arsenide (AlGaAs) layer, a gallium arsenide (GaAs) layer disposed on the first aluminum gallium arsenide layer, and a second aluminum gallium arsenide (AlGaAs) layer disposed on the gallium arsenide layer; that is, the GaAs layer can be embedded in the AlGaAs layer. Furthermore, the specific materials of each layer in the quantum dot 14 layer structure can be set according to the actual application needs, and are not limited to this embodiment.

[0090] Furthermore, when the 14-layer quantum dot structure includes a first gallium arsenide (GaAs) layer, an indium gallium arsenide (InGaAs) layer disposed on the first gallium arsenide layer, and a second gallium arsenide (GaAs) layer disposed on the indium gallium arsenide layer, a GaAs waveguide layer containing an InGaAs quantum dot light source can be fabricated; when the 14-layer quantum dot structure includes a first indium phosphide (InP) layer, an indium arsenide (InAs) layer disposed on the first indium phosphide layer, and a second indium phosphide (InP) layer disposed on the indium arsenide layer, an InP waveguide layer containing an InAs quantum dot light source can be fabricated; when the 14-layer quantum dot structure includes a first aluminum gallium arsenide (AlGaAs) layer, a gallium arsenide (GaAs) layer disposed on the first aluminum gallium arsenide layer, and a second aluminum gallium arsenide (AlGaAs) layer disposed on the gallium arsenide layer, an AlGaAs waveguide layer containing a GaAs quantum dot light source can be fabricated; in practical applications, the specific materials of each layer can be set as needed, and are not limited to this embodiment.

[0091] like Figure 6 As shown, step S2 is then performed, in which a thin film resistor 18 is formed at a predetermined distance from the waveguide layer 13, and the thin film resistor 18 is located outside the photonic microring 12.

[0092] As a specific example, such as Figures 3 to 6 As shown, the thin-film resistor 18 is formed using a lift-off process. The method for forming the thin-film resistor 18 includes the following steps:

[0093] S21, as Figure 3As shown, a first photoresist layer 15 is formed on the lower cladding layer 11, which covers the photonic micro-ring 12 and the waveguide layer 13 containing the quantum dot 14 light source. Preferably, the first photoresist layer 15 includes a lower first photoresist layer 151 and an upper first photoresist layer 152, which can be spin-coated on the lower cladding layer 11 in sequence, for example. The material of the lower first photoresist layer 151 includes one or more of LOR5A photoresist and LOR10B photoresist. The material of the upper first photoresist layer 152 includes one or more of AZ5214 photoresist and SPR photoresist. The thickness and material of the lower first photoresist layer 151 and the upper first photoresist layer 152 can be selected according to actual needs, which are not limited in the embodiment.

[0094] S22, as shown, the first photoresist layer 15 is patterned by using ultraviolet lithography technology, which includes the step of washing away the first photoresist layer 15 in the exposed area by using MIF-300 developer, to form a first photoresist opening 16 in the first photoresist layer. For example, the method of patterning the first photoresist layer 15 by using ultraviolet lithography technology includes one or more of laser direct writing lithography and mask lithography, which can be selected according to needs, and is not limited here. Figure 4

[0095] S23, as shown, the resistance layer 17 is deposited on the first photoresist layer 15 by using magnetron sputtering process, for example. The resistance layer 17 is deposited on the lower cladding layer 11 through the first photoresist opening 16. In addition, the resistance layer 17 can also be deposited by using physical vapor deposition processes such as electron beam evaporation or thermal evaporation. The specific forming process can be selected according to the material of the resistance layer 17 to be compatible with existing preparation processes, which is not limited here. Figure 5

[0096] S24, as shown, the first photoresist layer 15 and the resistance layer 17 formed on the first photoresist layer 15 are removed by using Lift-off process, for example, by using a solvent such as acetone, N-methyl pyrrolidone or dimethyl sulfoxide. The resistance layer 17 on the lower cladding layer 11 is retained to form the thin film resistance 18. Figure 6

[0097] ​​​As an example, the material of the thin-film resistor 18 includes one or more of titanium nitride (TiN), platinum (Pt), titanium (Ti), and nickel-chromium alloy (NiCr), the thickness of the thin-film resistor 18 is 80 nm to 140 nm, and the width of the thin-film resistor 18 is 5 μm to 10 μm, but the material, thickness, and width of the thin-film resistor 18 are not limited thereto and can be adjusted according to actual needs, which are not limited herein.

[0098] As an example, the preset distance is 3 μm to 10 μm, and preferably 3 μm, and the closer the thin-film resistor 18 is to the quantum dot 14 light source, the higher the regulation efficiency is. However, in step S22, the mask type ultraviolet lithography overlay accuracy limits the reduction of the distance, and the laser direct writing lithography technology can realize an overlay of 3 μm spacing, as shown in Figure 6 It should be noted that the preset distance is the distance W between the middle position of the horizontal direction size of the waveguide layer 13 and the thin-film resistor 18.

[0099] As shown in Figure 9 Then, step S3 is performed to form two electrodes 22 on the opposite ends of the length direction of the thin-film resistor 18, and the electrodes 22 form ohmic contact with the thin-film resistor 18.

[0100] As an example, as shown in Figures 7 to 9 The electrodes 22 are formed by using a Lift-off process, and the method for forming the electrodes 22 includes the following steps:

[0101] S31, as shown in Figure 7 A second photoresist layer 19 is formed on the lower cladding layer 11, the second photoresist layer 19 covers the photonic micro-ring 12, the waveguide layer 13 containing the quantum dot 14 light source, and the thin-film resistor 18. Preferably, the second photoresist layer 19 includes a lower second photoresist layer 191 and an upper second photoresist layer 192, and the lower second photoresist layer 191 and the upper second photoresist layer 192 can be spin-coated on the lower cladding layer 11 in sequence, for example. The material of the lower second photoresist layer 191 includes one or more of LOR5A photoresist and LOR10B photoresist, and the material of the upper second photoresist layer 192 includes one or more of AZ5214 photoresist and SPR photoresist. The thickness and material of the lower second photoresist layer 191 and the upper second photoresist layer 192 can be selected according to actual needs, which are not limited herein.

[0102] S32, as shown in Figure 8As shown, ultraviolet lithography is used to pattern the second photoresist layer 19, which includes the step of washing away the exposed area of ​​the second photoresist layer 19 with MIF-300 developer to form a second photoresist opening 20 in the second photoresist layer 19. Inventively, the patterning method for the second photoresist layer 19 using ultraviolet lithography includes one or more of laser direct-write lithography and mask lithography, which can be selected as needed and are not excessively limited here.

[0103] S33, such as Figure 8 As shown, an electrode material layer 21 is exemplarily deposited on the second photoresist layer 19 using an electron beam evaporation process. The electrode material layer 21 passes through the second photoresist opening 20 and is deposited on the lower cladding layer 11 and the two opposite ends of the thin film resistor 18 in the length direction. Alternatively, other processes can be used, such as magnetron sputtering to deposit the resistor layer 17. The specific formation process can be selected according to the material of the resistor layer 17 to be compatible with existing fabrication processes, and no excessive restrictions are imposed here.

[0104] S34, such as Figure 9 As shown, a lift-off process is used, specifically a resist remover (such as acetone, N-methylpyrrolidone or dimethyl sulfoxide) to remove the second photoresist layer 19 and the electrode material layer 21 formed on the second photoresist layer 19, while retaining the lower cladding layer 11 and the electrode material layer 21 on the thin film resistor 18 to form the electrode 22.

[0105] As an example, the material of the electrode 22 includes gold, and the thickness of the electrode 22 is 150nm to 300nm. The material and thickness of the electrode 22 are not limited to these and can be adjusted according to actual needs. No excessive restrictions are imposed here.

[0106] refer to Figure 9 It should be noted that the electrode 22 is placed on the two opposite ends of the thin film resistor 18 along its length, as described in step S33. The electrode 22 includes a portion formed on the thin film resistor 18 and a portion formed on the lower cladding layer 11, so that while the electrode 22 forms an ohmic contact with the thin film resistor 18, it can also lead out a wire through gold or aluminum wire bonding technology to connect to the driving power supply device.

[0107] Thus, as Figure 9 As shown, the thin-film resistor 18 and the electrode 22 constitute the micro-heating circuit 23 of the microcavity enhanced single-photon structure. When a driving voltage is applied to the thin-film resistor 18 of the micro-heating circuit 23, the heat generated by the resistor can locally change the temperature of the quantum dot, thereby controlling the emission wavelength of the quantum dot.

[0108] Reference Figures 2 to 9 The embodiment also provides a microcavity enhanced single photon structure, which comprises, from bottom to top, a substrate 10, a lower cladding layer 11, a photonic micro-ring 12, a waveguide layer 13 containing a quantum dot 14 light source, and a micro-heating circuit 23; wherein the waveguide layer 13 is located on the photonic micro-ring 12; the micro-heating circuit 23 comprises:

[0109] a thin film resistor 18 formed on the lower cladding layer 11 at a preset distance from the waveguide layer 13, and the thin film resistor 18 is located outside the photonic micro-ring 12;

[0110] an electrode 22 arranged on opposite ends of the thin film resistor 18 in the length direction and forming an ohmic contact with the thin film resistor 18.

[0111] For example, the material of the thin film resistor 18 includes one or more of titanium nitride (TiN), platinum (Pt), titanium (Ti), and nickel-chromium alloy (NiCr), the thickness of the thin film resistor 18 is 80-140 nm, and the width of the thin film resistor 18 is 5-10 μm, but the material, thickness, and width of the thin film resistor 18 are not limited to this, and can be adjusted according to actual needs, which is not limited here.

[0112] For example, the preset distance is 3-10 μm, and preferably 3 μm, and the closer the thin film resistor 18 is to the quantum dot 14 light source, the higher the regulation efficiency. It should be noted that the preset distance is the distance W between the middle position of the horizontal direction size of the waveguide layer 13 and the thin film resistor 18 (see Figure 6 ).

[0113] For example, the material of the electrode 22 includes gold, and the thickness of the electrode 22 is 150-300 nm, but the material and thickness of the electrode 22 are not limited to this, and can be adjusted according to actual needs, which is not limited here.

[0114] The microcavity enhanced single photon structure can be prepared by the above-mentioned preparation method of the microcavity enhanced single photon structure, but is not limited to this, and other preparation methods can also be used, and the beneficial effects that can be achieved can be referred to the specific description in the preparation method, which is not described here.

[0115] Embodiment two

[0116] Please refer to Figure 10It is to be noted that the diagram provided in the embodiment only schematically illustrates the basic concept of the present application, and only the components related to the present application are shown in the diagram, rather than the number, shape and size of the components when actually implemented. The shape, number and ratio of the components when actually implemented can be arbitrarily changed, and the layout of the components can be more complex.

[0117] The embodiment provides a microcavity enhanced optical quantum chip, which comprises at least two microcavity enhanced single-photon structures 1. Figure 10

[0118] A reflector 2 is configured to reflect photons to enhance the local intensity of the photons in the cavity.

[0119] A bus waveguide 3 is configured to couple out the photons in the cavity.

[0120] A beam splitter 4 is configured to split the photons and realize photon interconnection between the plurality of microcavity enhanced single-photon structures 1.

[0121] A grating 5 is configured to couple the split photons out of the chip and into an optical fiber, wherein one end of the beam splitter 4 is connected to the bus waveguide 3, and the other end of the beam splitter 4 is connected to the grating 5.

[0122] Specifically, as shown in the figure, the microcavity enhanced single-photon structure 1 comprises an optical quantum structure, and the optical quantum structure comprises a photonic micro-ring 26 and a waveguide layer 27 comprising a quantum dot light source. Figure 10

[0123] Specifically, the material of the reflector 2 comprises silicon carbide (SiC), the material of the bus waveguide 3 comprises silicon carbide (SiC), the material of the beam splitter 4 comprises silicon carbide (SiC), and the material of the photonic micro-ring 26 comprises silicon carbide (SiC). In actual application, the specific materials of each layer can be set according to the needs, and the embodiment is not limited.

[0124] Specifically, as an example, the beam splitter 4 comprises one or more of a direct coupling beam splitter and a multimode interference beam splitter.

[0125] ​​Furthermore, this embodiment uses the gallium arsenide (GaAs) waveguide and silicon carbide (SiC) photonic microring resonator containing a III-V group self-assembled quantum dot single-photon source as an example for illustration. In this embodiment, the microcavity-enhanced photonic quantum chip is placed in a 6K cryostat, and the quantum dots are excited by a laser. The photon signal emitted at the SiC grating 5 is collected through an objective lens (or optical fiber). When only a single GaAs / 4H-SiC hybrid waveguide microring resonator is excited, the micro-heating circuit (reference) is continuously adjusted. Figure 10 The driving voltage of the first micro-heating circuit 241 and the second micro-heating circuit 251 in the image is measured, and the spectrum at the corresponding SiC grating is measured, such as... Figure 11 As shown, the spectral range is 912 nm to 920 nm. Fluorescence quenching occurs when the temperature of the quantum dots is too high, therefore the spectral tuning range based on the micro-heating circuit is limited. Figure 11 This indicates that before quenching, as the driving voltage of the micro-heating circuit increases, the quantum dot emission peak redshifts by more than 3.5 nm, covering the entire free spectral range (FSR) of the hybrid waveguide microring resonator. This demonstrates that the microcavity-enhanced photonic quantum chip of this embodiment can achieve the tuning of any quantum dot to resonate with the mode of the hybrid waveguide microring resonator.

[0126] The high-resistance thin-film resistor used to generate the thermal field in the micro-heating circuit provided in Embodiment 1 of the present invention has a typical resistance value of 23.8 kΩ, which can be adjusted between 1 kΩ and 100 kΩ as needed. Its driving voltage range is 0–30 V. Based on the typical resistance value of the thin-film resistor, the thermal field power range can be calculated to be 0–37.8 mW. Within this range, the following can be achieved: Figure 12 The spectral tuning exceeds 3.5 nm. At this point, the spectra of the quantum dot exciton X resonating and detuning with the resonant cavity mode C1 under different driving voltages are extracted, as shown... Figure 13 As shown, when the quantum dot exciton X resonates with the resonant cavity mode C1, the signal intensity is significantly enhanced, and gradually weakens until it is submerged by background noise when detuned. The fluorescence lifetime of the quantum dot exciton X under these different driving voltages is then extracted, as shown... Figure 14 As shown, the fluorescence lifetime of the quantum dots at far detuning (detuning > 1.2 nm) is τ0 = 2.550 ± 0.030 ns, and the fluorescence lifetime of the quantum dots at resonance (detuning = 0 nm) is τ0 = 2.550 ± 0.030 ns. c =0.499±0.010ns. According to the Purcell factor estimation formula (1), F can be calculated. p =4.9, where ζ PL The photon emission ratio of the zero phonon line of the quantum dot is 90% in this invention.

[0127]

[0128] The quantum dot fluorescence lifetime of different detunings conforms to the Lorentz curve fitting, which is consistent with the coupling degree of quantum dot emission photons and cavity mode, and conforms to the Purcell effect model of quantum dots as formula (2).

[0129] Further, the microcavity enhanced optical quantum chip of the embodiment is described by taking two microcavity enhanced single photon structures 1 as an example, and specifically, as shown in the figure, Figure 10 The two microcavity enhanced single photon structures 1 are a first microcavity enhanced single photon structure 24 and a second microcavity enhanced single photon structure 25, respectively, the first microcavity enhanced single photon structure 24 includes a first micro-heating circuit 241, and the second microcavity enhanced single photon structure 25 includes a second micro-heating circuit 251. The number of microcavity enhanced single photon structures 1 can be set according to actual needs, which is not limited by the embodiment.

[0130] As an example, the distance between two adjacent microcavity enhanced single photon structures 1 (referring to the first microcavity enhanced single photon structure 24 and the second microcavity enhanced single photon structure 25 of the figure) Figure 10 ) is not less than 250 μm, two independent GaAs / 4H-SiC hybrid waveguide micro-ring resonators are tuned by using two micro-heating circuits (the first micro-heating circuit 241 and the second micro-heating circuit 251) with a distance of 250 μm or more, after the two independent GaAs / 4H-SiC hybrid waveguide micro-ring resonators are excited, the photons are guided along the bus waveguide 3 to the SiC beam splitter 4, after the beam splitter 4 is combined, the signal photons are emitted through one of the output gratings 5, and the optical spectrum under different driving voltages is as shown in the figure Figure 15 When the first micro-heating circuit 241 of the first microcavity enhanced single photon structure 24 is applied with a driving voltage of 0-2V, the corresponding quantum dot emission photon wavelength appears obvious red shift, and the quantum dot emission photon wavelength of the second microcavity enhanced single photon structure 25 does not change. On the other hand, when the second micro-heating circuit 251 of the second microcavity enhanced single photon structure 25 is applied with a driving voltage of 0-2V, the corresponding quantum dot emission photon wavelength of the second microcavity enhanced single photon structure 25 appears obvious red shift, and the quantum dot emission photon wavelength of the first microcavity enhanced single photon structure 24 does not change, which verifies that the microcavity enhanced optical quantum chip of the embodiment can realize independent regulation and control of devices with a distance of 250 μm or more.

[0131] In summary, the present application provides a microcavity enhanced single-photon structure, a preparation method and a microcavity enhanced optical quantum chip, by forming a thin film resistor near the waveguide layer and forming electrodes at both ends of the thin film resistor, the local heating effect of the thin film resistor is used to change the temperature of the corresponding quantum dot, and then the luminescence wavelength of the quantum dot is regulated, by accurately controlling the heating power of the thin film resistor, the precise regulation of the luminescence wavelength of the quantum dot can be realized, so that it can be accurately matched with the mode frequency of the micro-ring resonant cavity, thereby maximizing the Purcell effect, improving the emission efficiency of the photon, effectively solving the bottleneck problem that the luminescence wavelength of the quantum dot is difficult to accurately match with the mode frequency of the micro-ring resonant cavity in the prior art, and overcoming the limitation that the existing global regulation technology cannot locally and discretely regulate a single device at a specific position in the integrated optical quantum chip. Therefore, the present application effectively overcomes various shortcomings in the prior art and has high industrial utilization value.

[0132] The above embodiments only exemplarily illustrate the principles and effects of the present application, and are not used to limit the present application. Any person skilled in the art can modify or change the above embodiments without departing from the spirit and scope of the present application. Therefore, all equivalent modifications or changes completed by those skilled in the art without departing from the spirit and technical thought disclosed by the present application should be covered by the claims of the present application.

Claims

1. A method of fabricating a microcavity enhanced single photon structure, comprising: The preparation method comprises: ​ providing a light quantum structure, which comprises, from bottom to top, a substrate, a lower cladding layer, a photonic micro-ring, and a waveguide layer containing a quantum dot light source; wherein the waveguide layer is located on the photonic micro-ring; forming a thin film resistor at a preset distance from the waveguide layer, and the thin film resistor is located outside the photonic micro-ring; forming two electrodes on opposite ends of the length direction of the thin film resistor, and the electrodes form ohmic contact with the thin film resistor.

2. The method for fabricating a microcavity-enhanced single-photon structure according to claim 1, characterized in that, The thin film resistor is formed by using a Lift-off process, and the method for forming the thin film resistor comprises the following steps: forming a first photoresist layer on the lower cladding layer, and the first photoresist layer covers the photonic micro-ring and the waveguide layer containing the quantum dot light source; performing patterned processing on the first photoresist layer by using ultraviolet lithography technology to form a first photoresist opening in the first photoresist layer; depositing a resistor layer on the first photoresist layer, and the resistor layer is deposited on the lower cladding layer through the first photoresist opening; removing the first photoresist layer and the resistor layer formed on the first photoresist layer by using a Lift-off process, and the resistor layer on the lower cladding layer constitutes the thin film resistor.

3. The method of claim 2, wherein: The first photoresist layer comprises a lower first photoresist layer and an upper first photoresist layer; wherein the material of the lower first photoresist layer comprises one or more of LOR5A photoresist and LOR10B photoresist; and the material of the upper first photoresist layer comprises one or more of AZ5214 photoresist and SPR photoresist.

4. The method of claim 2, wherein: The method for performing patterned processing on the first photoresist layer by using ultraviolet lithography technology comprises one or more of laser direct writing lithography and mask lithography.

5. The method of claim 1, wherein: The preset distance is 3 μm to 10 μm.

6. The method for fabricating a microcavity-enhanced single-photon structure according to claim 1, characterized in that, The electrodes are formed by using a Lift-off process, and the method for forming the electrodes comprises the following steps: forming a second photoresist layer on the lower cladding layer, and the second photoresist layer covers the photonic micro-ring, the waveguide layer containing the quantum dot light source, and the thin film resistor; performing patterned processing on the second photoresist layer by using ultraviolet lithography technology to form a second photoresist opening in the second photoresist layer; depositing an electrode material layer on the second photoresist layer, and the electrode material layer is deposited on opposite ends of the length direction of the lower cladding layer and the thin film resistor through the second photoresist opening; removing the second photoresist layer and the electrode material layer formed on the second photoresist layer by using a Lift-off process, and the electrode material layer on the lower cladding layer and the thin film resistor constitutes the electrodes.

7. The method of fabricating a microcavity enhanced single photon structure of claim 1, wherein: The material of the thin film resistor comprises one or more of titanium nitride, platinum, titanium, and nichrome, the thickness of the thin film resistor is 80 nm to 140 nm, and the width of the thin film resistor is 5 μm to 10 μm.

8. The method of claim 1, wherein: The material of the electrodes comprises gold, and the thickness of the electrodes is 150 nm to 300 nm.

9. The method of fabricating a microcavity enhanced single photon structure of claim 1, wherein: The thin film resistor is formed by using a magnetron sputtering process, and the electrodes are formed by using an electron beam evaporation process.

10. A microcavity enhanced single photon structure, characterized in that, The microcavity-enhanced single-photon structure comprises, from bottom to top, a substrate, a lower cladding layer, a photonic micro-ring, a waveguide layer containing a quantum dot light source, and a micro-heating circuit; the waveguide layer is located on the photonic micro-ring; the micro-heating circuit comprises: a thin-film resistor formed on the lower cladding layer at a preset distance from the waveguide layer, and the thin-film resistor is located outside the photonic micro-ring; electrodes arranged on opposite ends of the thin-film resistor in the length direction and forming ohmic contact with the thin-film resistor.

11. The microcavity enhanced single photon structure of claim 10, wherein: The preset distance is 3-10 μm.

12. The microcavity enhanced single photon structure of claim 10, wherein: The material of the thin-film resistor comprises one or more of titanium nitride, platinum, titanium, and nichrome, the thickness of the thin-film resistor is 80-140 nm, and the width of the thin-film resistor is 5-10 μm.

13. The microcavity enhanced single photon structure of claim 10, wherein: The material of the electrodes comprises gold, and the thickness of the electrodes is 150-300 nm.

14. A microcavity enhanced optical quantum chip, comprising: The microcavity-enhanced photonic quantum chip comprises: at least two microcavity-enhanced single-photon structures as claimed in any one of claims 10-13; a reflector for reflecting photons to enhance the local intensity of photons in the cavity; a bus waveguide for coupling out the photons in the cavity; a beam splitter for splitting the photons and realizing photon interconnection between the multiple microcavity-enhanced single-photon structures; a grating for coupling out the split photons from the chip and into an optical fiber, wherein one end of the beam splitter is connected to the bus waveguide, and the other end is connected to the grating.

15. The microcavity enhanced light quantum chip of claim 14, wherein: The distance between adjacent two microcavity-enhanced single-photon structures is not less than 250 μm.

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