Semiconductor quantum dot, single photon source preparation method and optical quantum signal detection system

Abstract

This invention discloses a semiconductor quantum dot, a method for preparing a single-photon source, and a quantum signal detection system. The method prepares InAs / GaAs quantum dots using molecular beam epitaxy in the Stranski-Krastanow mode, and then combines the prepared semiconductor quantum dots with a microcavity to form a single-photon source. The quantum signal detection system includes a semiconductor quantum dot single-photon source, a laser pump source, a wavelength division multiplexing (WDM) fiber, and an HBT interferometer. The input end of the WDM fiber is connected to the laser pump source, and the output end is connected to the HBT interferometer. Laser light excited by the laser pump source is perpendicularly irradiated onto the surface of the semiconductor quantum dot single-photon source through the WDM fiber, causing electrons to transition to an excited state and radiate recombination to emit photons. After emission, the quantum dot emits light, which is then collected at the end face of the same fiber. The HBT interferometer measures the output signal. This invention allows for the adjustment of the luminescence properties by doping with appropriate metal elements, enabling precise detection of the single-photon signal output from the quantum dot single-photon source.

Description

Technical Field

[0001] This invention belongs to the field of optical technology, specifically relating to a single-photon source preparation and its optical quantum signal detection system. Background Technology

[0002] Weak light measurement plays a crucial role in the field of optics, directly affecting the performance and success rate of critical missions such as space navigation, lidar detection, and communication. A weak light source outputs light intensity at the quantum level and can generate one and only one single photon within a given time interval; this is a single-photon source, and the emitted photon is deterministic.

[0003] In the process of detecting atmospheric echo signals in lidar receiving and detection systems, background light from the sky introduces noise, photodetectors suffer from dark current noise, and photon counting itself generates Poisson noise, ultimately leading to inaccurate photon counts. Because there is no weak single-photon source that can be quantitatively and accurately measured, it is currently impossible to quantitatively analyze the uncertainty of photon counts detected by lidar receiving and detection systems, nor can its detection linearity and the statistical distribution of detection results over time be quantitatively calculated. Furthermore, star sensors are currently the most accurate absolute attitude sensors. Their calibration requires a single-photon source as a standard light source, which, when used in conjunction with a high-precision star target, can simulate the generation of starlight points of different magnitudes. This, combined with a star magnitude determination standard device, completes the calibration of the star sensor. Weak light metrology is becoming increasingly important; the calibration of instruments in many fields currently relies on single-photon sources. Therefore, it is necessary to develop an ideal single-photon source and a corresponding quantum signal detection system.

[0004] To realize an ideal single-photon source and corresponding optical quantum signal detection system, it is necessary to study new on-demand single-photon sources and their detection systems, capable of effectively emitting on-demand single photons and performing high-precision detection. Traditional on-demand single-photon sources are quasi-single-photon sources that achieve single-photon sequence output based on the laser attenuation method. The laser attenuation method is currently a commonly used method in scientific research and practical engineering applications. The resulting signal is a quasi-single-photon source, where the single photons are not uniformly distributed, leading to certain errors in calibration. In addition, quasi-single-photon sources also suffer from drawbacks such as low single-photon generation efficiency and inability to precisely control photon generation. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing a single-photon source and a corresponding optical quantum signal detection system, which can effectively emit on-demand single photons and perform high-precision detection.

[0006] To achieve the objective of this invention, a method for preparing semiconductor quantum dots is provided, and the technical solution is as follows:

[0007] InAs / GaAs quantum dots were prepared using molecular beam epitaxy in the Stranski-Krastanow mode.

[0008] Furthermore, the InAs / GaAs quantum dot preparation method is as follows: the GaAs substrate temperature is controlled at 450–600℃, the arsenic source furnace temperature at 300–400℃, the gallium source furnace temperature at 800–1000℃, and the indium source furnace temperature at 900–1100℃. First, a GaAs buffer layer of 350–650 nm is prepared on the GaAs substrate, and then an AlAs layer of 70–130 nm is prepared. Based on this, a GaAs thin film of 21–39 nm is prepared. Using subcritical indium deposition technology, In is gradient-deposited on the static GaAs substrate to form InAs quantum dots. The thickness of the quantum dots is adjustable in the range of 2–10 nm. Then, a GaAs thin film of 70–130 nm is deposited to obtain self-assembled semiconductor quantum dots.

[0009] According to another aspect of the present invention, the present invention provides a method for preparing a semiconductor quantum dot single-photon source, the technical solution of which is as follows:

[0010] Semiconductor quantum dots are prepared based on the above-mentioned semiconductor quantum dot preparation method, and then the prepared semiconductor quantum dots are combined with micro-cylinder cavities to form a single-photon source.

[0011] According to another aspect of the present invention, a photonic quantum signal detection system based on a semiconductor quantum dot single-photon source is provided, and the technical solution is as follows:

[0012] The optical quantum signal detection system includes a semiconductor quantum dot single-photon source, a laser pump source, a wavelength division multiplexing fiber, and an HBT interferometer.

[0013] The semiconductor quantum dot single-photon source is prepared based on the semiconductor quantum dot single-photon source preparation method described above;

[0014] The input end of the wavelength division multiplexing fiber is connected to the laser pump source, and the output end is connected to the HBT interferometer. The laser excited by the laser pump source is perpendicularly irradiated onto the surface of the semiconductor quantum dot single photon source through the wavelength division multiplexing fiber, causing electrons to transition to the excited state and emit photons through recombination. After the quantum dot emits light, it exits from its surface and is collected at the end face of the same fiber. The HBT interferometer measures its output signal.

[0015] Furthermore, the semiconductor quantum dot single-photon source is placed in a cryogenic chamber.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0017] Based on practical needs, this invention uses a novel semiconductor quantum dot system to prepare a single-photon source. By doping with appropriate metal elements, its luminescence properties can be adjusted. Combined with a single-photon counter and a low-temperature platform, the precise detection of single-photon signals output by the quantum dot single-photon source is achieved, realizing efficient single-photon emission and transmission. This lays the technological foundation for fields such as quantum guidance, lidar, and star sensors. Attached Figure Description

[0018] The accompanying drawings, which form part of this specification, are provided to further illustrate embodiments of the invention and, together with the textual description, explain the principles of the invention. It is obvious that the drawings described below are merely some embodiments of the invention, and those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0019] Figure 1 This is a schematic diagram of a photonic quantum signal detection system based on a semiconductor quantum dot single-photon source, provided as an embodiment of the present invention. Detailed Implementation

[0020] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Semiconductor quantum dots are a new type of quantum dot. The semiconductor quantum dot preparation method provided in this invention adopts the following technical solution:

[0022] Semiconductor quantum dots are prepared using molecular beam epitaxy, as detailed below:

[0023] Molecular beam epitaxy (MBE) was used to prepare InAs / GaAs quantum dots in the Stranski-Krastanow (SK) mode. By precisely controlling the GaAs substrate temperature at 450–600 °C, the arsenic source furnace temperature at approximately 300–400 °C, the gallium source furnace temperature at approximately 800–1000 °C, and the indium source furnace temperature at approximately 900–1100 °C, a 350–650 nm GaAs buffer layer was first prepared on the GaAs substrate, followed by a 70–130 nm AlAs layer. On this basis, a 21–39 nm GaAs thin film was prepared. Using subcritical indium deposition technology, In was gradient-deposited on the static GaAs substrate to form InAs quantum dots. The thickness of the quantum dots was adjustable in the range of 2–10 nm. Then, a 70–130 nm GaAs thin film was deposited to obtain self-assembled semiconductor quantum dots.

[0024] Depending on the application requirements, the thickness and composition of each layer can be appropriately adjusted and doped within the above range.

[0025] To address the need for uncertainty and detection linearity analysis in single-photon detectors of lidar receiving and detection systems, in one embodiment of this invention, semiconductor quantum dots are prepared using molecular beam epitaxy (MBE), as follows:

[0026] Molecular beam epitaxy (MBE) was used to prepare InAs / GaAs quantum dots in the Stranski-Krastanow (SK) mode. By precisely controlling the GaAs substrate temperature at 450–600 °C, the arsenic source furnace temperature at approximately 300–400 °C, the gallium source furnace temperature at approximately 800–1000 °C, and the indium source furnace temperature at approximately 900–1100 °C, a 500 nm GaAs buffer layer was first prepared on the substrate, followed by a 100 nm AlAs layer. On this basis, a 30 nm GaAs thin film was prepared. In was then deposited in a gradient on the static GaAs substrate using subcritical indium deposition technology to form InAs quantum dots. The thickness of the quantum dots was adjustable in the range of 2–10 nm. Finally, a 100 nm GaAs thin film was deposited to obtain self-assembled semiconductor quantum dots.

[0027] For applications requiring star sensor calibration, in one embodiment of this invention, semiconductor quantum dots are prepared using molecular beam epitaxy (MBE), as follows:

[0028] Molecular beam epitaxy (MBE) was used to prepare InAs / GaAs quantum dots in the Stranski-Krastanow (SK) mode. By precisely controlling the GaAs substrate temperature at 450–600 °C, the arsenic source furnace temperature at approximately 300–400 °C, the gallium source furnace temperature at approximately 800–1000 °C, and the indium source furnace temperature at approximately 900–1100 °C, a 400 nm GaAs buffer layer was first prepared on the substrate, followed by a 110 nm AlAs layer. On this basis, a 25 nm GaAs thin film was prepared. In was then deposited in a gradient on the static GaAs substrate using subcritical indium deposition technology to form InAs quantum dots. The thickness of the quantum dots was adjustable in the range of 2–10 nm. Finally, a 110 nm GaAs thin film was deposited to obtain self-assembled semiconductor quantum dots.

[0029] According to another aspect of the present invention, based on the aforementioned semiconductor quantum dot fabrication method, the present invention provides a method for fabricating a semiconductor quantum dot single-photon source, the technical solution of which is as follows:

[0030] Semiconductor quantum dots are prepared using the aforementioned semiconductor quantum dot preparation method, and then the prepared semiconductor quantum dots are combined with a microcavity to form a single-photon source. This single-photon source can generate single-photon signals through pulsed laser excitation or continuous laser excitation. This single-photon source is small in size and light in weight, and can be compatible with a variety of different types of optical systems and devices.

[0031] According to another aspect of the present invention, based on the semiconductor quantum dot single-photon source preparation method, an optical quantum signal detection system based on a semiconductor quantum dot single-photon source is provided, including a semiconductor quantum dot single-photon source, a laser pump source, a cryogenic chamber, a wavelength division multiplexing fiber, a beam splitter, a spectrometer, a single-photon counter, a single-photon detector, etc.

[0032] A semiconductor quantum dot single-photon source is placed in a cryogenic chamber and connected by a wavelength division multiplexing (WDM) fiber. The input end of the fiber is connected to a laser pump source, and the output end is connected to a beam splitter, a single-photon detector, and a single-photon counter. The laser excited by the laser pump source is perpendicularly incident on the surface of the quantum dot through the WDM fiber, causing electrons to transition to an excited state and emit photons through recombination. The emitted photons are then collected from the surface of the quantum dot and collected at the end face of the same fiber. The entire excitation and emission process of the semiconductor quantum dot single-photon source is carried out in the cryogenic chamber, which better utilizes the luminescence performance of the quantum dots. Furthermore, the output signal of the semiconductor quantum dot single-photon source needs to be connected to an HBT interferometer for effective measurement. Single-photon purity is mainly measured experimentally using HBT interferometry. The HBT interferometer consists of a beam splitter, two single-photon detectors, and electronic equipment for repetition counting and readout. Single-photon purity is characterized by measuring the overlap count caused by photons at zero time delay. The above-mentioned quantum signal detection system can effectively test the quantum signal of the semiconductor quantum dot single-photon source, such as... Figure 1 As shown.

[0033] The features described and / or illustrated above with respect to one embodiment may be used in the same or similar manner in one or more other embodiments, and / or in combination with or in lieu of features in other embodiments.

[0034] It should be emphasized that the term "including / comprises" as used herein refers to the presence of a feature, whole, step, or component, but does not exclude the presence or addition of one or more other features, wholes, steps, components, or combinations thereof.

[0035] Many features and advantages of these embodiments are apparent from this detailed description, and therefore the appended claims are intended to cover all such features and advantages of these embodiments that fall within their true spirit and scope. Furthermore, since many modifications and alterations will readily occur to those skilled in the art, the embodiments of the invention are not intended to be limited to the precise structures and operations illustrated and described, but rather to encompass all suitable modifications and equivalents falling within their scope.

[0036] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0037] The parts of this invention not described in detail are techniques known to those skilled in the art.

Claims

1. A method for preparing semiconductor quantum dots, characterized by, InAs / GaAs quantum dots were prepared using molecular beam epitaxy in the Stranski-Krastanow mode.

2. The method for preparing semiconductor quantum dots according to claim 1, characterized in that, By controlling the GaAs substrate temperature at 450–600℃, the arsenic source furnace temperature at 300–400℃, the gallium source furnace temperature at 800–1000℃, and the indium source furnace temperature at 900–1100℃, a 350–650 nm GaAs buffer layer is first prepared on the GaAs substrate, followed by a 70–130 nm AlAs layer. Based on this, a 21–39 nm GaAs thin film is prepared. Using subcritical indium deposition technology, In is gradient-deposited on the static GaAs substrate to form InAs quantum dots. The thickness of the quantum dots is adjustable in the range of 2–10 nm. Then, a 70–130 nm GaAs thin film is deposited to obtain self-assembled semiconductor quantum dots.

3. The method for preparing semiconductor quantum dots according to claim 1, characterized in that, The InAs / GaAs quantum dot preparation method is as follows: The GaAs substrate temperature is controlled at 450–600℃, the arsenic source furnace temperature at approximately 300–400℃, the gallium source furnace temperature at approximately 800–1000℃, and the indium source furnace temperature at approximately 900–1100℃. First, a 500nm GaAs buffer layer is prepared on the substrate, followed by a 100nm AlAs layer. On this basis, a 30nm GaAs thin film is prepared. Using subcritical indium deposition technology, In is gradient-deposited on the static GaAs substrate to form InAs quantum dots. The thickness of the quantum dots is adjustable in the range of 2–10nm. Then, a 100nm GaAs thin film is deposited to obtain self-assembled semiconductor quantum dots.

4. The method of claim 1, wherein the semiconductor quantum dot is prepared by a method comprising: The InAs / GaAs quantum dot preparation method is as follows: The GaAs substrate temperature is controlled at 450–600℃, the arsenic source furnace temperature at approximately 300–400℃, the gallium source furnace temperature at approximately 800–1000℃, and the indium source furnace temperature at approximately 900–1100℃. First, a 400nm GaAs buffer layer is prepared on the substrate, and then a 110nm AlAs layer is prepared. Based on this, a 25nm GaAs thin film is prepared. Using subcritical indium deposition technology, In is gradient-deposited on the static GaAs substrate to form InAs quantum dots. The thickness of the quantum dots is adjustable in the range of 2–10nm. Then, a 110nm GaAs thin film is deposited to obtain self-assembled semiconductor quantum dots. ​ 5. The single-photon source production method based on the semiconductor quantum dot production method according to any one of claims 1 to 4, characterized by, The prepared semiconductor quantum dots are combined with micro-cylinder cavities to form a single-photon source.

6. A photonic quantum signal detection system based on the single-photon source preparation method according to claim 5, characterized in that, This includes semiconductor quantum dot single-photon sources, laser pump sources, wavelength division multiplexing optical fibers, and HBT interferometers. The input end of the wavelength division multiplexing fiber is connected to the laser pump source, and the output end is connected to the HBT interferometer. The laser excited by the laser pump source is perpendicularly irradiated onto the surface of the semiconductor quantum dot single photon source through the wavelength division multiplexing fiber, causing electrons to transition to the excited state and emit photons through recombination. After the quantum dot emits light, it exits from its surface and is collected at the end face of the same fiber. The HBT interferometer measures its output signal.

7. The optical quantum signal detection system of claim 6, wherein, The semiconductor quantum dot single-photon source was placed in a cryogenic chamber.

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