Quantum illuminant dipole structure and orientation characterization system and method

Abstract

The invention relates to the technical field of quantum illuminant characterization, and discloses a quantum illuminant dipole structure and orientation characterization system and method. The characterization system comprises a quantum illuminant sample fixing assembly, a fluorescence excitation, fluorescence detection and fluorescence lifetime measurement assembly, a scanning near-field optical probe assembly, a scanning near-field optical probe control assembly and a data processing module. The scanning near-field optical probe assembly carries out three-dimensional space scanning around the to-be-measured sub-illuminant to obtain Purcell factor distribution, the Purcell factor distribution is compared with Purcell factor distribution obtained through numerical simulation under any dipole structure and orientation parameters, and the three-dimensional dipole structure and orientation parameters of the to-be-measured sub-illuminant are obtained through fitting. The characterization scheme provided by the invention is a near-field characterization scheme based on fluorescence lifetime information, and compared with a traditional far-field characterization scheme based on fluorescence intensity information, the near-field characterization scheme provided by the invention has better robustness and higher resolution, and can more accurately characterize three-dimensional dipole parameters of the quantum illuminant.

Description

Technical Field

[0001] The invention relates to the technical field of quantum luminescent body characterization, and specifically discloses a system and method for characterizing the dipole structure and orientation of a quantum luminescent body by using scanning near-field fluorescence lifetime imaging technology. Background Art

[0002] Quantum luminophores have a wide range of applications. For example, the efficient coupling of quantum luminophores with micro-nano optical structures can realize high-quality on-chip integrated quantum light sources. Quantum luminophores can be used as fluorescent markers for fluorescence imaging. The coupling between multiple quantum luminophores can realize quantum computing and simulation. These applications all involve the acquisition of dipole structural information of quantum luminophores and the manipulation of dipole orientation. Therefore, the accurate characterization of the dipole structure and orientation of quantum luminophores is of great significance.

[0003] In general, the dipole structure and orientation of room temperature quantum luminescent bodies can be described by a three-dimensional dipole model. The three-dimensional dipole model consists of three mutually perpendicular linear dipoles d1, d2, and d3 in an incoherent superposition. When only the relative size of the dipole moment is considered, five independent parameters (α, β, θ1, φ1, φ2, φ3) are required. rot ) to describe the three-dimensional dipole model, where and It shows the relative proportions of the three linear dipoles d1, d2, and d3. θ1 and φ1 represent the orientation of dipole d1, φ rot It represents the angle of rotation of d2 in the plane perpendicular to d1.

[0004] At present, the characterization methods of the dipole structure and orientation of quantum luminescent bodies mainly include fluorescence polarization analysis, fluorescence defocus imaging fitting, and fluorescence back focal plane imaging fitting. These methods are all based on the far-field radiation information of quantum luminescent body fluorescence, and have the following disadvantages: the far-field information is easily affected by the surrounding environment of the quantum luminescent body, for example, the substrate may change the far-field characteristics; the fluorescence information is also easily affected by the optical path and experimental device during transmission to the far field, causing the final far-field information to be distorted; at the same time, the imaging accuracy of the camera will greatly limit the quality of imaging. These factors make it difficult to accurately fit the three-dimensional dipole model of the quantum luminescent body using far-field radiation information. Therefore, in actual measurement, it is often necessary to simplify the three-dimensional dipole model of the quantum luminescent body and adopt a simpler two-dimensional dipole model or a one-dimensional dipole model, which will lead to an inaccurate description of the dipole structure. With the continuous deepening of research and the rapid development of quantum luminescent body related applications, it is becoming more and more important to accurately grasp the dipole structure and orientation of quantum luminescent bodies. Therefore, it is urgent to develop a characterization system and characterization method that can accurately characterize the three-dimensional dipole structure and orientation of quantum luminescent bodies. Summary of the invention

[0005] The technical problem of the present invention is to provide a system and method that can accurately characterize the three-dimensional dipole structure and orientation of a quantum light emitting body.

[0006] In order to solve the above problems, the present invention first provides a characterization system for the dipole structure and orientation of a quantum luminescent body, comprising:

[0007] A quantum luminescent body sample fixing component, used to fix the quantum luminescent body sample to be measured;

[0008] Fluorescence excitation, fluorescence detection and fluorescence lifetime measurement components, used to excite the quantum luminescent body to be measured, detect the fluorescence of the quantum luminescent body and analyze the fluorescence lifetime of the quantum luminescent body;

[0009] A scanning near-field optical probe assembly is used to perform three-dimensional spatial scanning around the sub-luminescent body to be measured, change the fluorescence lifetime of the sub-luminescent body to be measured through the Purcell effect, record the corresponding fluorescence lifetime at each scanning spatial position point, and obtain the fluorescence lifetime distribution;

[0010] A scanning near-field optical probe control component, used to control the scanning near-field optical probe component to move in three-dimensional space around the sub-luminous body sample to be measured;

[0011] The data processing module plays the following roles: processing the fluorescence lifetime distribution data obtained from the experiment to obtain the Purcell factor distribution; numerically simulating the Purcell factor distribution when the luminescent body to be measured has any dipole structure and orientation parameters; determining the dipole structure and orientation parameters by fitting, so that the Purcell factor distribution simulated by the numerical simulation is most consistent with the Purcell factor distribution measured experimentally.

[0012] Optionally, the scanning near-field optical probe assembly includes a dielectric nanoneedle tip and a metal nanostructure located on the tip surface of the dielectric nanoneedle tip.

[0013] Optionally, the dielectric nano-needle tip is a tapered optical fiber tip or an atomic force microscope probe.

[0014] Optionally, the end face diameter of the tapered optical fiber tip is 50 to 500 nanometers.

[0015] Optionally, the metal nanostructure located on the tip surface of the dielectric nanoneedle is metal nanoparticles, and the metal nanoparticles are loaded onto the tip surface of the dielectric nanoneedle via a chemical adhesive.

[0016] Optionally, the metal nanoparticles are spherical gold nanoparticles.

[0017] Optionally, the spherical gold nanoparticles have a radius of 20 to 50 nanometers.

[0018] Optionally, the quantum luminescent body sample fixing assembly includes a transparent substrate and silica nanospheres, the silica nanospheres are fixed on the surface of the transparent substrate, and the quantum luminescent body to be measured is encapsulated in the silica nanospheres.

[0019] Optionally, the radius of the silica nanosphere is 10 to 30 nanometers.

[0020] Optionally, the silicon dioxide nanospheres are fixed to the surface of the transparent substrate via an organic polymer film, and the thickness of the organic polymer film is 4 to 8 nanometers.

[0021] The present invention also provides a method for characterizing the dipole structure and orientation of a quantum luminescent body based on the above characterization system, comprising the following steps:

[0022] Fix the quantum luminescent body to be measured by using the quantum luminescent body sample fixing component;

[0023] Using fluorescence excitation, fluorescence detection and fluorescence lifetime measurement components to excite the quantum luminescent body to be measured, detect the fluorescence of the quantum luminescent body and analyze the fluorescence lifetime of the quantum luminescent body;

[0024] The scanning near-field optical probe control component controls the scanning near-field optical probe component to perform three-dimensional space scanning around the quantum light emitter to be measured; the scanning near-field optical probe component changes the fluorescence lifetime of the quantum light emitter to be measured through the Purcell effect, records the fluorescence lifetime of the quantum light emitter corresponding to each scanning space position point, and obtains the fluorescence lifetime distribution;

[0025] The data processing module is used to process the experimental data to obtain the Purcell factor distribution; the data processing module is used to numerically simulate the Purcell factor distribution when the sub-luminescent body to be measured has any dipole structure and orientation parameters; the data processing module is used to fit and determine the dipole structure and orientation parameters so that the Purcell factor distribution simulated by the numerical simulation is most consistent with the Purcell factor distribution measured experimentally, that is, the three-dimensional dipole structure and orientation of the sub-luminescent body to be measured are obtained.

[0026] Optionally, the quantum light emitter sample fixing component fixes the quantum light emitter to be measured in the following manner: the quantum light emitter sample fixing component includes a transparent substrate and silica nanospheres, the quantum light emitter to be measured is coated at the center of the silica nanospheres, and the silica nanospheres are fixed to the surface of the transparent substrate through an organic polymer film.

[0027] Preferably, the scanning near-field optical probe assembly performs a three-dimensional spatial scan around the sub-light emitter to be measured, in the following manner: the scanning near-field optical probe assembly includes a dielectric nano-needle tip and a spherical gold nanoparticle located on the tip surface of the dielectric nano-needle tip, the sub-light emitter to be measured is coated in the center of a silica nano-sphere, and when the scanning near-field optical probe assembly performs a three-dimensional spatial scan around the sub-light emitter to be measured, the spherical gold nano-particle runs close to the surface of the silica nano-sphere.

[0028] Compared with the prior art, the present invention has the following advantages:

[0029] 1. The present invention uses the fluorescence lifetime change information of the quantum light emitter to characterize the dipole structure and orientation of the quantum light emitter. Compared with the traditional method of using fluorescence intensity distribution information, it has better robustness and will not be affected by factors such as optical path, experimental device and camera resolution.

[0030] 2. The near-field scanning characterization method proposed in the present invention is based on near-field information, is not affected by the optical diffraction limit, and has higher resolution.

[0031] 3. The present invention does not require prior knowledge of the dipole model of the quantum luminescent sample to be measured, but directly adopts a universal three-dimensional dipole model for description, and is therefore suitable for accurate characterization of various dipole structures. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 The present invention is a schematic diagram of a specific quantum luminescent body dipole structure and orientation characterization system. In the figure: 1 is a spherical gold nanoparticle; 2 is a silica nanosphere; 3 is a quantum luminescent body to be measured coated in the silica nanosphere; 4 is an organic polymer film; 5 is a transparent substrate; 6 is a tapered optical fiber; 7 is a quartz tuning fork; 8 is a preamplifier; 9 is an inverted microscope; 10 is a dichroic mirror; 11 is an input laser; 12 is the quantum luminescent body fluorescence collected by the inverted microscope; 13 is a reflector; 14 is a pulsed laser; 15 is a single photon detector; 16 is a time-correlated single photon counter; 17 is a synchronization signal input channel of the time-correlated single photon counter; 18 is a photon signal input channel of the time-correlated single photon counter.

[0033] Figure 2 Schematic diagram of the method for adhering a gold nanoparticle to the end face of a tapered optical fiber. Figure 2 (a) shows the tapered fiber probe being positioned directly above a target gold nanoparticle and then lowered. Figure 2 (b) shows the contact between the tapered fiber probe and the target gold nanoparticles. Figure 2 (c) shows that the tapered fiber probe is lifted, and the target gold nanoparticles are adsorbed on the end surface of the probe.

[0034] Figure 3 This is a scanning electron microscope image of a tapered fiber probe with a spherical gold nanoparticle adsorbed on it.

[0035] Figure 4 This is a transmission electron microscope image of a quantum dot sample encapsulated in a silica sphere.

[0036] Figure 5 This is a schematic diagram of scanning a quantum light-emitting body sample using a scanning near-field optical probe, in which: 19 is a laser incident at a total reflection angle; 20 is a scanning trajectory.

[0037] Figure 6 This is the distribution diagram of the experimental measurement raw data of a quantum dot sample, where: Figure 6 (a) is the distribution diagram of probe height z(x,y); Figure 6 (b) is the distribution diagram of Purcell factor F(x,y).

[0038] Figure 7 Schematic diagram of the scanning trajectory of the center of a spherical gold nanoparticle: Figure 7 (a) Schematic diagram of the relationship between the scanning trajectory parameters and the parameters such as the radius of spherical gold nanoparticles, the radius of silica nanospheres, and the thickness of polymer films; Figure 7 (b) is an ideal scanning trajectory diagram of the center of a spherical gold nanoparticle, where 21 is the plane portion of the scanning trajectory diagram and 22 is the spherical portion of the scanning trajectory diagram.

[0039] Figure 8 The experimentally measured Purcell factor distribution is plotted on a sphere.

[0040] Fig. 9 It is a three-dimensional dipole model of quantum dots obtained by fitting the experimentally measured Purcell factor distribution.

[0041] Fig.10 To plot the measured Purcell factor distribution on a 3D surface: Fig.10 (a) is the experimentally measured Purcell factor distribution diagram; Fig.10 (b) is the Purcell factor distribution diagram obtained by simulating the fitted three-dimensional dipole model. DETAILED DESCRIPTION

[0042] For better understanding, embodiments of the present invention will now be described by way of non-limiting examples with reference to the accompanying drawings. It should be noted that those skilled in the art should understand that reasonable modifications to the system and method of the present invention still fall within the scope of protection of the present invention. It should also be noted that the optical elements in the accompanying drawings do not constitute an equal-scale demonstration.

[0043] Combination Figure 1The figure shows a specific quantum luminescent body radiation dipole structure and orientation characterization system of the invention, including a quantum luminescent body sample fixing component, a fluorescence excitation, fluorescence detection and fluorescence lifetime measurement component, a scanning near-field optical probe component, a scanning near-field optical probe control component and a data processing module. Among them,

[0044] The quantum luminescent body sample fixing assembly includes a silicon dioxide nanosphere 2, a quantum luminescent body sample 3 to be measured is coated in the silicon dioxide nanosphere 2, and is fixed on a transparent substrate 5 through an organic polymer film 4, the radius of the silicon dioxide nanosphere is 10 to 30 nanometers, and the thickness of the organic polymer film is 4 to 8 nanometers. Optimally, the quantum luminescent body sample 3 to be measured is coated in the center of the silicon dioxide nanosphere 2.

[0045] Fluorescence excitation, fluorescence detection and fluorescence lifetime measurement components, including a pulse laser, an inverted optical microscope, a single-photon detector, and a time-correlated single-photon counter; the pulse laser is used to emit laser pulses to excite the quantum luminescent body sample to be measured, and generate a synchronous electronic pulse signal to the time-correlated single-photon counter; the inverted optical microscope is used to guide the laser emitted by the pulse laser to the quantum luminescent body sample to be measured to excite the quantum luminescent body sample to emit fluorescence, and is also used to collect the fluorescence emitted by the quantum luminescent body sample and transmit the fluorescence to the single-photon detector for detection; the single-photon detector is used to detect the fluorescence photons emitted by the quantum luminescent body, and after detecting the fluorescence photons, it generates an electrical pulse signal and sends it to the time-correlated single-photon counter; the time-correlated single-photon counter receives the synchronous electronic pulse signal of the pulse laser and the electrical pulse signal of the single-photon detector, analyzes the time difference of the pulse signals, and thus obtains the fluorescence lifetime of the quantum luminescent body. Combined with Figure 1 As shown, the pulse laser 11 emitted by the pulse laser 14 is reflected by the dichroic mirror 10 and converged onto the sample through the inverted microscope objective 9 to excite the quantum light-emitting body sample 3 on the transparent substrate 5. The fluorescence radiated by the quantum light-emitting body sample is collected by the inverted microscope objective 9, passes through the dichroic mirror 10, and then reflected by the reflector 13 to be detected by the single photon detector 15. The single photon detection electrical pulse signal of the single photon detector 15 is connected to the photon signal input channel 18 of the time-correlated single photon counter 16. The synchronous electrical pulse signal of the pulse laser 14 is connected to the synchronous signal input channel 17 of the time-correlated single photon counter 16. The fluorescence lifetime of the quantum light-emitting body is obtained by statistical analysis of the pulse arrival time difference between the photon signal channel 18 and the synchronous signal channel 17.

[0046] The scanning near-field optical probe assembly is composed of a tapered optical fiber 6 with a tip diameter of 50 to 500 nanometers and a spherical gold nanoparticle 1 located on its end surface, and the radius of the spherical gold nanoparticle is 20 to 50 nanometers. Those skilled in the art will know that the tapered optical fiber 6 can also be replaced by an atomic force microscope probe.

[0047] A scanning near-field optical probe control component comprises a piezoelectric ceramic tube (not shown), a piezoelectric ceramic tube controller (not shown), a quartz tuning fork 7, a tuning fork welding circuit board (not shown), a pre-signal amplification circuit board (not shown), a tuning fork control system (not shown), and a feedback control system (not shown). The tapered optical fiber probe 6 of the scanning near-field optical probe component is adhered to a quartz tuning fork 7 with a resonance frequency of 40 kHz. The quartz tuning fork is welded on the tuning fork welding circuit board. The tuning fork welding circuit board is fixed to the pre-signal amplification circuit board with screws. The pre-signal amplification circuit board is connected to the tuning fork control system with a wire. The pre-signal amplification circuit board is fixed to one end of the piezoelectric ceramic tube. The piezoelectric ceramic tube controller controls the piezoelectric ceramic tube to move in three dimensions so that the scanning near-field optical probe performs three-dimensional scanning. During the scanning process, the interaction between the scanning near-field optical probe and the physical surface causes the amplitude of the quartz tuning fork to change. The amplitude change signal of the quartz tuning fork is fed back to the piezoelectric ceramic tube controller through the feedback control system so that the scanning near-field optical probe maintains a constant distance from the physical surface.

[0048] A specific method for preparing a scanning near-field optical probe assembly is as follows Figure 2 As shown: The spherical gold nanoparticle colloidal solution is spin-coated on the surface of a transparent substrate to form a single-particle dispersed spherical gold nanoparticle sample. The radius R of the spherical gold nanoparticle is AuNS Then, the tapered optical fiber probe 6 immersed in the poly-lysine solution is moved to the top of one of the target gold nanoparticles 1, as shown in the schematic diagram. Figure 2 (a); then the probe is lowered to make it contact with the target gold nanoparticle 1, as shown in Figure 2 (b); then lift the probe, and the gold nanoparticles 1 can be adsorbed onto the end face of the tapered optical fiber probe, as shown in Figure 2 (c) as shown. Figure 3 A scanning electron microscope image showing a tapered fiber-optic probe with a spherical gold nanoparticle adsorbed on it.

[0049] In this embodiment, the quantum luminescent body sample to be measured is colloidal quantum dots. First, the colloidal quantum dots are coated in silica nanospheres. A specific method for coating colloidal quantum dots in silica nanospheres is as follows: first, prepare a reaction container and add 1 ml of ethanol solution of tetraethyl orthosilicate with a concentration of 3 mM; then, continue to add 110 microliters of quantum dot colloidal aqueous solution with a concentration of 80 nM to the reaction container under vigorous stirring; then, inject 5 microliters of sodium hydroxide aqueous solution with a concentration of 0.1 M as a catalyst for the hydrolysis reaction of tetraethyl orthosilicate to start the coating process of silica; finally, at room temperature and in the dark, the reaction mixture is stirred vigorously for 24 hours to obtain a colloidal solution of quantum dots coated in silica nanospheres. Figure 4 The transmission electron microscope image of quantum dots encapsulated in silica nanospheres. The quantum dot colloid solution encapsulated in silica nanospheres is diluted and spin-coated onto a transparent substrate, thereby forming a monodispersed quantum dot sample encapsulated in silica nanospheres on the substrate. Then, a certain mass fraction of organic polymer solution (such as Zeonex toluene solution) is spin-coated onto the substrate to form an organic polymer film to fix the quantum dot sample.

[0050] The scanning near-field optical probe assembly is used to perform scanning near-field fluorescence lifetime imaging of quantum dot samples. Figure 5 As shown, laser 19 is incident obliquely at a total reflection angle to excite the quantum dot sample. When the near-field optical probe is scanned for space scanning, the spherical gold nanoparticles on the probe always run close to the sample surface, close to the surface of the organic polymer film where there are no silica nanospheres, and close to the surface of the silica nanospheres where there are silica nanospheres, that is, it runs along the scanning trajectory indicated by the dotted line 20. The fluorescence lifetime of the quantum light emitter to be measured is changed through the Purcell effect. During the scanning process, the height information z(x,y) of the probe and the fluorescence lifetime information τ(x,y) of the quantum dots measured by the fluorescence lifetime measurement component are recorded, wherein (x,y) is the plane coordinate position of the probe. Figure 6 (a) is the experimentally measured probe height distribution z(x,y), Figure 6 (b) is the experimentally measured fluorescence lifetime shortening factor F(x,y)=τ0 / τ(x,y), that is, the distribution of the Purcell factor, where the benchmark fluorescence lifetime τ0 is the fluorescence lifetime when the quantum dot is far away from the gold nanoparticles.

[0051] Then the data processing module is used to process the data, so as to determine the three-dimensional dipole structure and orientation of the quantum emitter to be measured, that is, to determine the three-dimensional dipole model parameters (α, β, θ1, φ1, φ rot Data processing includes: processing the experimental data to obtain the relationship between the Purcell factor and the orientation of the spherical gold nanoparticles F(θ,φ); performing numerical simulation to obtain the parameters of the arbitrary dipole model (α,β,θ1,φ1,n rot ) and the relationship between the Purcell factor and the orientation of spherical gold nanoparticles 仿真 (θ, φ); find the value that makes F 仿真 (θ, φ) is closest to the three-dimensional dipole model parameters (α, β, θ1, φ1, φ rot ), that is, determine the three-dimensional dipole structure and orientation of the quantum luminous body to be measured. The specific process of the above data processing is as follows:

[0052] according to Figure 6(a) The centroid of the height distribution can be used to obtain the coordinate position (x0, y0) corresponding to the center of the silica nanosphere. Figure 6 The maximum height of (a) can determine the height difference ΔH between the top of the silica nanosphere and the surface of the organic polymer film. The thickness H of the organic polymer film film The radius of the silica nanosphere can be determined by scratching the film with a metal needle tip and then performing atomic force microscopy imaging.

[0053] like Figure 7 (a) is a schematic diagram of the scanning trajectory of the spherical gold nanoparticles. During scanning, the scanning trajectory of the spherical gold nanoparticles close to the surface of the polymer film is a plane, such as Figure 7 As shown in plane 21 in (b), the trajectory of the spherical gold nanoparticle close to the silica surface is a radius of A part of the sphere, such as Figure 7 As shown in the spherical surface 22 in (b), the half angle θ of the spherical surface 22 is max =arccos(H tri / R scan ),in The projection of the sphere 22 on the xy plane is a circle with a center at (x0, y0) and a radius of R. contact =

[0054] R scan sinθ max ,like Figure 6 (a) and Figure 6 (b) is a circular area bounded by a dotted circle. The position coordinates (x, y) within the circular area can be mapped one-to-one to the azimuth coordinates (θ, φ) on the spherical surface 22. Therefore, Figure 6 (b) The data F(x, y) within the dotted circle (i.e., the data obtained by scanning the spherical gold nanoparticles close to the silica nanospheres) can be plotted on the spherical surface 22, thus obtaining F(θ, φ), as shown in Figure 8 As shown. F(θ,φ) will be compared with the numerical simulation results F 仿真 (θ, φ) and find the value that makes F 仿真 The three-dimensional dipole model parameters (α, β, θ1, φ1, φ) that are closest to the experimental data F(θ, φ) rot ), this group of parameters is the measurement result of the dipole structure and orientation parameters of the sub-point sample to be measured. Figure 8 The F(θ,φ) data shown in the figure are fitted to obtain the three-dimensional dipole model parameters (α, β, θ1, φ1, φ rot )=(0.79,0.36,67,319°,97°), the corresponding three-dimensional dipole model is as follows Fig. 9 shown.

[0055] In the above parameter fitting, it is necessary to efficiently obtain any dipole model parameters (α, β, θ1, φ1, φ rot ) 仿真 The specific method is as follows. The unit dipole p is simulated and calculated when the spherical gold nanoparticle is close to the silica nanosphere and located at the orientation (θ, φ). x ,p y ,p z The electric field at the dipole under excitation Thus, the dyadic Green tensor of this position is obtained

[0056]

[0057] Where ω0 is the frequency of the dipole and μ is the magnetic permeability at the location of the dipole. The simulation calculates the unit dipole p when the spherical gold nanoparticles do not exist. x ,p y ,p z The electric field at the dipole under excitation Thus, the dyadic Green tensor of this position is obtained

[0058]

[0059] For an arbitrary parameter (α,β,θ1,φ1,φ rot ) of the three-dimensional dipole d 3D , which is composed of three mutually perpendicular linear dipoles d1, d2, and d3 incoherently superposed, and its Purcell factor can be expressed as F 仿真 in When the spherical gold nanoparticle is close to the silica nanosphere and located at the orientation (θ, φ) s i The local photon state density projection in the direction, is the case when spherical gold nanoparticles do not exist i Projection of the local photon state density in the direction.

[0060] In order to make the Purcell factor distribution diagram more intuitive, the Purcell factor distribution is plotted on a surface, and the size of the Purcell factor is expressed simultaneously by color and the distance from the point on the surface to the center: Fig.10 (a) is the experimentally measured Purcell factor distribution; Fig.10 (b) is the Purcell factor distribution obtained by simulation based on the fitted three-dimensional dipole model. It can be seen that the shape of the experimentally measured Purcell factor distribution graph is very similar to the shape of the simulated Purcell factor distribution graph. This shows that the fitting result can accurately describe the radiation dipole model and orientation of the quantum dot.

[0061] Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A system for characterizing the dipole structure and orientation of a quantum luminescent body, characterized in that: include: A quantum luminescent body sample fixing component, used to fix the quantum luminescent body sample to be measured; Fluorescence excitation, fluorescence detection and fluorescence lifetime measurement components, used to excite the quantum luminescent body to be measured, detect the fluorescence of the quantum luminescent body and analyze the fluorescence lifetime of the quantum luminescent body; The scanning near-field optical probe assembly is used to perform three-dimensional spatial scanning around the quantum luminescent body, change the fluorescence lifetime of the quantum luminescent body to be measured through the Purcell effect, record the corresponding fluorescence lifetime at each scanning spatial position point, and obtain the fluorescence lifetime distribution; A scanning near-field optical probe control component, used to control the scanning near-field optical probe component to move in three-dimensional space around the sub-luminous body sample to be measured; The data processing module plays the following roles: processing the fluorescence lifetime distribution data obtained from the experiment to obtain the Purcell factor distribution; numerical simulation of the Purcell factor distribution when the measured luminescent body has any dipole structure and orientation parameters; The dipole structure and orientation parameters are determined by fitting, so that the Purcell factor distribution simulated by numerical simulation is most consistent with the Purcell factor distribution measured experimentally.

2. The characterization system for the dipole structure and orientation of a quantum luminescent body according to claim 1, characterized in that: The scanning near-field optical probe assembly comprises a dielectric nano-needle tip and a metal nano-structure located on the tip surface of the dielectric nano-needle tip.

3. The characterization system of quantum luminescent body dipole structure and orientation according to claim 2, characterized in that: The dielectric nano needle tip is a tapered optical fiber tip or an atomic force microscope probe.

4. The characterization system for the dipole structure and orientation of a quantum luminescent body according to claim 3, characterized in that: The end face diameter of the tapered optical fiber tip is 50 to 500 nanometers.

5. The characterization system for the dipole structure and orientation of a quantum luminescent body according to claim 2, characterized in that: The metal nanostructure located on the tip surface of the dielectric nanoneedle is metal nanoparticles, and the metal nanoparticles are loaded onto the tip surface of the dielectric nanoneedle through a chemical adhesive.

6. The characterization system for the dipole structure and orientation of a quantum luminescent body according to claim 5, characterized in that: The metal nanoparticles are spherical gold nanoparticles.

7. The characterization system of quantum luminescent body dipole structure and orientation according to claim 1, characterized in that: The quantum luminescent body sample fixing component comprises a transparent substrate and silicon dioxide nanospheres, wherein the silicon dioxide nanospheres are fixed on the surface of the transparent substrate, and the quantum luminescent body to be measured is encapsulated in the silicon dioxide nanospheres, and the radius of the silicon dioxide nanospheres is 10 to 30 nanometers.

8. The characterization system for the dipole structure and orientation of a quantum luminescent body according to claim 7, characterized in that: The silicon dioxide nanospheres are fixed on the surface of the transparent substrate through an organic polymer film, and the thickness of the organic polymer film is 4 to 8 nanometers.

9. A method for characterizing the dipole structure and orientation of a quantum luminescent body based on the characterization system of claim 1, characterized in that: The following steps are involved: Fix the quantum luminescent body to be measured by using the quantum luminescent body sample fixing component; Using fluorescence excitation, fluorescence detection and fluorescence lifetime measurement components to excite the quantum luminescent body to be measured, detect the fluorescence of the quantum luminescent body and analyze the fluorescence lifetime of the quantum luminescent body; The scanning near-field optical probe control component controls the scanning near-field optical probe component to perform three-dimensional space scanning around the sub-luminescent body to be measured; the scanning near-field optical probe component changes the fluorescence lifetime of the sub-luminescent body to be measured through the Purcell effect, records the corresponding fluorescence lifetime at each scanning space position point, and obtains the fluorescence lifetime distribution; The data processing module is used to process the experimental data to obtain the Purcell factor distribution; the data processing module is used to numerically simulate the Purcell factor distribution when the sub-luminescent body to be measured has any dipole structure and orientation parameters; the data processing module is used to fit and determine the dipole structure and orientation parameters so that the Purcell factor distribution simulated by the numerical simulation is most consistent with the Purcell factor distribution measured experimentally, that is, the three-dimensional dipole structure and orientation of the sub-luminescent body to be measured are obtained.

10. The method for characterizing the dipole structure and orientation of a quantum luminescent body according to claim 9, characterized in that: The quantum luminescent body sample fixing component fixes the quantum luminescent body to be measured in the following manner: the quantum luminescent body sample fixing component includes a transparent substrate and silica nanospheres, the quantum luminescent body to be measured is coated in the center of the silica nanospheres, and the silica nanospheres are fixed on the surface of the transparent substrate through an organic polymer film.

11. The method for characterizing the dipole structure and orientation of a quantum luminescent body according to claim 9, characterized in that: The scanning near-field optical probe assembly performs a three-dimensional spatial scan around the sub-light emitter to be measured, and the method is as follows: the scanning near-field optical probe assembly includes a dielectric nano-needle tip and a spherical gold nanoparticle located on the tip surface of the dielectric nano-needle tip, and the sub-light emitter to be measured is coated in the center of a silica nano-sphere. When the scanning near-field optical probe assembly performs a three-dimensional spatial scan around the sub-light emitter to be measured, the spherical gold nano-particle runs closely against the surface of the silica nano-sphere.

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