A single-photon detector-based extremely weak luminescence detection system and method

Abstract

The application discloses a kind of weak luminescence detection system and method based on single-photon detector, belong to optical detection field.The system includes at least one excitation light beam modulation module, common road excitation and luminescence collection module and luminescence signal detection and data processing module.Luminescence signal detection and data processing module are used to carry out single-photon counting detection to weak luminescence signal, and work with excitation light beam modulation module, according to single-photon counting result feedback adjustment excitation light intensity, realize target excitation power interval adaptive search, power-dependent luminescence response curve measurement and luminescence rise / decay kinetics analysis, to realize the automation of weak luminescence signal, high integration, adaptation and multi-mode test.The application utilizes the advantages of superconducting nanowire single-photon detector, such as high detection efficiency, low dark count and high time resolution, to realize high-sensitivity single-photon counting detection of weak luminescence signal with low photon flux.

Description

Technical Field

[0001] This invention belongs to the fields of optical detection, extremely weak emission testing, single-photon counting, and time-resolved spectroscopy, specifically relating to an extremely weak emission detection system and method based on a single-photon detector. Background Technology

[0002] Extremely weak and low-photon-flux luminescence phenomena are widely found in rare-earth-doped upconversion luminescent materials, photon avalanche luminescence systems, quantum dot materials, low-dimensional semiconductor materials, solid-state color centers, and defect-based luminescence centers. These luminescence processes are typically characterized by low signal intensity, low photon flux during the luminescence onset phase, complex dynamics, and sensitivity to excitation conditions. High-sensitivity, high-time-resolution photon counting detection of these processes is crucial for analyzing nonlinear luminescence mechanisms, luminescence center energy level dynamics, excited-state establishment processes, and luminescence lifetime characteristics.

[0003] Taking rare-earth photonic avalanche luminescence materials as an example, photonic avalanche is a high-order nonlinear luminescence phenomenon that relies on processes such as excited-state absorption and cross-relaxation. When the excitation power reaches a certain threshold, the luminescence intensity exhibits a significant nonlinear gain. However, in the early stages near the threshold and before the avalanche is fully established, the luminescence signal is usually extremely weak. Traditional photodetectors, photomultiplier tubes, or area array cameras often suffer from limited detection efficiency, high dark noise, insufficient signal-to-noise ratio, and limited temporal resolution under these conditions, making it difficult to accurately identify the key process of the transition from extremely weak luminescence to strong nonlinear luminescence.

[0004] For color centers or defect-emitting centers, their single-photon source signals are typically at low photon flux levels. Emission lifetime, power saturation behavior, decay characteristics, and luminescence stability are crucial parameters for assessing their photophysical properties. Such samples often require single-photon counting and time-correlated single-photon statistical testing under low background noise to obtain reliable luminescence intensity response and kinetic information. For quantum dot materials, low-dimensional semiconductor materials, and other extremely weakly emitting samples, their photoluminescence processes also often require comprehensive analysis combining excitation power scanning and time-resolved measurements.

[0005] Existing systems for detecting extremely weak luminescence typically set up power-dependent luminescence response testing and luminescence lifetime testing on different platforms. This requires recalibrating the optical path, resetting the sample position, and re-calibrating the excitation conditions between different testing modes. This not only makes the testing process cumbersome but also easily introduces systematic errors, making it difficult to perform correlation analysis on the luminescence intensity response and time evolution of the same test area. Furthermore, most existing systems still use manual adjustment of the excitation power, making it difficult to achieve rapid, stable, and repeatable power positioning during the extremely weak luminescence on-phase, nonlinear response range, or near the target counting range. Summary of the Invention

[0006] The purpose of this invention is to overcome the problems of insufficient detection sensitivity, high dark noise, limited time resolution, difficulty in accurately locating the target excitation power range, separation of power-dependent luminescence response testing and luminescence dynamics testing, and large system errors caused by repeated light matching in existing extremely weak luminescence testing, and to provide an automated integrated extremely weak luminescence detection system and method based on a superconducting nanowire single-photon detector.

[0007] To achieve the above objectives, this invention provides an automated integrated extremely weak emission detection system and method based on a superconducting nanowire single-photon detector. The system includes at least one excitation beam modulation module, a common-path excitation and emission collection module, and an emission signal detection and data processing module. The excitation beam modulation module generates an excitation beam and adjusts its power, which is then guided into the common-path excitation and emission collection module. In an embodiment with two excitation beam modulation modules, the system further includes an excitation beam path switching module for selectively guiding a first excitation beam and a second excitation beam into the common-path excitation and emission collection module. The common-path excitation and emission collection module collects photoexcitation and emission signals from the sample using the same objective lens. The emission signal detection and data processing module performs band selection, optical coupling, single-photon counting detection, time-correlation acquisition, and result processing and output on the extremely weak emission signal emitted by the sample. The host computer processing unit controls the excitation power based on single-photon count feedback and supports power-dependent emission response testing mode and emission dynamics testing mode. The system can also be configured with a spectral acquisition unit to meet different testing requirements.

[0008] Furthermore, the excitation beam modulation module includes an excitation source unit, a wavelength filtering unit, an intensity adjustment unit, a servo drive unit, and a beam quality control unit. The excitation source unit outputs continuous excitation light, pulsed excitation light, or modulated excitation light; the wavelength filtering unit selects the excitation light band or the target spectrum; the intensity adjustment unit adjusts the excitation light power; the servo drive unit, under the control of the host computer processing unit, drives the intensity adjustment unit to automatically adjust the excitation light power; and the beam quality control unit collimates, expands, contracts, spatially filters, or shapes the excitation beam to improve the matching and stability between the excitation beam, the objective lens, and the sample under test.

[0009] Furthermore, the excitation optical path switching module includes a first optical path switching component and a second optical path switching component, used to selectively introduce single-path or dual-path excitation light, thereby meeting the testing requirements of different samples in terms of excitation wavelength, excitation mode, or excitation conditions. In an embodiment with only one excitation beam modulation module, the excitation beam can be directly introduced into the common-path excitation and emission collection module, eliminating the need for an excitation optical path switching module for selecting multiple excitation beams.

[0010] Furthermore, the common-path excitation and emission collection module includes an emission emission extraction and reflection component, an excitation-emission beam splitter, an objective lens unit, and a sample unit under test. Using the same objective lens for both excitation and emission collection reduces optical path errors during switching between different test modes and improves the consistency between power-dependent emission response testing and emission kinetic testing. For example, the excitation-emission beam splitter uses a dichroic mirror to guide the excitation light to the objective lens unit and separates and extracts the weak light signal emitted by the sample; the objective lens unit focuses the excitation light onto the sample unit under test and collects the emitted light; the emission emission extraction and reflection component introduces the extracted emitted light into the emission signal detection and data processing module.

[0011] Furthermore, the emission signal detection and data processing module includes an emission wavelength filtering component, an optical coupling unit, an optical signal transmission interface, a superconducting nanowire single-photon detection unit, a photon counting and time-correlation acquisition unit, and a host computer processing unit. The emission wavelength filtering component is used to suppress residual excitation light and background stray light, and to select the emission band to be measured; The optical coupling unit and optical signal transmission interface are used to couple and transmit the emitted signal to the superconducting nanowire single-photon detection unit. The superconducting nanowire single-photon detection unit is used to convert extremely weak luminescent signals into electrical pulse signals. The photon counting and time-correlation acquisition unit is used to count and acquire the electrical pulse signal and perform time statistical analysis. Preferably, the photon counting and time-correlation acquisition unit further includes a counting and statistics module and a time-correlation acquisition module connected to the superconducting nanowire single-photon detection unit, which are used to acquire the time-correlation single-photon statistical signal of the sample under the action of the synchronous trigger signal, and further obtain the emission rise time, emission lifetime, decay parameter or emission center dynamic parameter. The host computer processing unit is used to uniformly control, display, and output the excitation power adjustment, counting acquisition, power-dependent luminescence response curve display, and luminescence dynamics test results. For example, it outputs the real-time counting rate, integral count, and power-dependent luminescence response curve, and automatically fits, differentiates, judges thresholds, or extracts parameters from the power-dependent luminescence response curve to obtain the maximum response slope, threshold excitation power, nonlinear response parameters, or saturated luminescence range. It mainly includes a test control module, a curve generation module, a parameter extraction module, and a fitting analysis module.

[0012] During the power-dependent emission response test, the host computer processing unit acquires the single-photon count rate or integral count at the current excitation power and compares it with the preset target count interval. When the target count condition is not met, the host computer processing unit controls the servo drive unit to adjust the light intensity modulation unit until the target count condition is met. After the target count condition is met, the system scans according to the preset power step size, records the correspondence between the excitation power and the single-photon count, and generates a power-dependent emission response curve.

[0013] Furthermore, the emission signal detection and data processing module also includes an optical path distribution component and a spectral acquisition unit. The optical path distribution component guides the signal to the spectral acquisition unit and / or the superconducting nanowire single-photon detection unit. The spectral acquisition unit is a spectrometer or an integrating optical detector, used to obtain the emission spectrum, emission peak position, spectral width, or spectral integrated intensity of the sample under test. The spectral acquisition unit, as an optional testing configuration, together with power-dependent emission response testing and emission dynamics testing, constitutes the system's multi-mode testing capability.

[0014] On the other hand, the present invention also provides a testing method using the aforementioned extremely weak light emission detection system, comprising the following steps: S1. Select the test mode and set the test parameters, including selecting the excitation channel, setting the initial power range, target counting interval or target power point, integration time, step size and number of scans; S2. Control the servo drive unit to drive the light intensity modulation unit and adjust the excitation light power; S3. The excitation light is applied to the sample under test through the objective lens unit. The extremely weak light emission signal emitted by the sample is collected by the same objective lens and introduced into the superconducting nanowire single photon detection unit for single photon counting and acquisition. S4. Read the count rate or integral count corresponding to the current power, and determine whether the target count condition or target power condition has been met; in the target count interval search mode, if the target count condition has not been met, return to step S2, and continue to adjust the excitation power according to the comparison result between the current count and the target count interval; if it has been met, proceed to step S5. S5. Perform power scanning according to the preset power step size, collect single photon counting data at each power point and record the power-count correspondence; S6. Generate a power-dependent emission response curve based on the data collected in step S5, and perform one or more of the following processing on the power-dependent emission response curve through the host computer processing unit: background subtraction, smoothing, normalization, curve fitting, derivative analysis or piecewise fitting, and automatically extract and output the maximum response slope, threshold excitation power, nonlinear response parameters, saturated emission range or target power point. S7. In the optional luminescence dynamics test mode, set the target power point and configure the time-related acquisition parameters to obtain the time-related single-photon statistical signal, and automatically fit the luminescence rise time and lifetime decay curve through the preset fitting model.

[0015] Furthermore, the automated integrated method for testing extremely weak luminescence provided by this invention includes test mode and parameter settings, servo drive unit adjustment of light intensity modulation unit, sample photoexcitation and single-photon counting acquisition, target condition judgment, power scanning and power-dependent luminescence response curve generation, and optional time-resolved test mode switching and time-correlated single-photon statistical analysis steps. Through this method, extremely weak luminescence signal detection, target excitation power range search, power-dependent luminescence response characterization, and luminescence dynamics analysis can be completed on the same platform.

[0016] It should be noted that, in this invention, the extremely weak emission signal refers to a low-photon flux emission signal generated by the sample under photoexcitation conditions, which requires a single-photon counting method to obtain an effective signal-to-noise ratio. The emission response intensity in the power-dependent emission response curve is preferably characterized by the single-photon count rate or the integral count within a preset integration time.

[0017] Furthermore, the luminescence response intensity in the power-dependent luminescence response curve is characterized by the single-photon count rate or the integral count within a preset integration time. The power-dependent luminescence response curve is used to characterize the luminescence on-off characteristics, power-dependent response law, nonlinear luminescence behavior, saturated luminescence behavior, or extremely weak luminescence response changes of the sample under test. The time-correlated single-photon statistical signal is used to obtain the luminescence rise time, luminescence lifetime, excited state establishment process, luminescence center relaxation process, or defect luminescence dynamics parameters of the sample under test.

[0018] Furthermore, this invention also provides applications of the above-described system and method in the characterization of extremely weakly luminescent materials, nonlinear luminescent materials, upconversion luminescent materials, color centers or defect luminescent centers, single-photon sources, quantum dot materials, and low-dimensional semiconductor materials. The samples to be tested include one or more of the following: photon avalanche luminescent materials, rare-earth-doped upconversion luminescent materials, diamond color centers, silicon carbide color centers, two-dimensional material defect luminescent centers, semiconductor quantum dots, perovskite quantum dots, low-dimensional semiconductor materials, or other low-photon flux luminescent samples. It is particularly suitable for high-sensitivity detection of low-photon flux luminescent signals, power-dependent luminescence response measurement, and luminescence dynamics research.

[0019] Compared with the prior art, the present invention has at least the following beneficial effects: Firstly, this invention utilizes the advantages of high detection efficiency, low dark count, and high temporal resolution of superconducting nanowire single-photon detectors to improve the detection sensitivity and signal-to-noise ratio of extremely weak emission signals with low photon flux, providing a reliable means to accurately identify subtle changes in light intensity during the extremely weak emission on-stage, nonlinear emission stage, or single-photon source emission stage.

[0020] Secondly, this invention improves testing efficiency, power positioning accuracy and repeatability by coordinating the excitation light intensity adjustment unit driven by a servo and the host computer processing unit, automatically adjusting the excitation power based on single photon counting feedback, and completing the preset power scan and power-dependent emission response curve acquisition after reaching the target counting condition.

[0021] Third, this invention integrates power-dependent luminescence response testing and luminescence dynamics testing on the same platform, and can be configured with spectral acquisition function according to testing needs to form a multi-mode testing system for extremely weak luminescence samples; it can perform unified analysis of the test sample from three dimensions: excitation power, luminescence intensity and time evolution, which helps to reduce systematic errors caused by repeated light exposure and cross-platform testing.

[0022] Fourth, this invention is not only applicable to the study of threshold behavior and nonlinear response of photon avalanche luminescent materials, but also to the power response and luminescence dynamics characterization of color centers or defect luminescent centers, quantum dot materials, low-dimensional semiconductor materials, single-photon sources and other extremely weak luminescent samples, and has strong versatility and scalability. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the overall structure of the automated integrated extremely weak emission detection system and method based on a superconducting nanowire single-photon detector in an embodiment of the present invention; Figure 2 This is a schematic diagram of the host computer control interface in an embodiment of the present invention, used to demonstrate the unified settings and display of the system for target power search, power scanning, real-time counting, response curves and luminescence dynamics test results; Figure 3 This is a schematic diagram of the automated integrated extremely weak light emission detection system in an embodiment of the present invention; Figure 4 The figures show the power-dependent luminescence response curves and nonlinear fitting results of the photonic avalanche luminescent material in this embodiment of the invention; wherein, Figure 4 (a) and (b) in the figure show the test and fitting results for different samples, respectively. Figure 5 The figure shows the luminescence dynamics test and fitting results of the photon avalanche luminescent material in the embodiments of the present invention; wherein, Figure 5 (a) shows the luminescence rise curve and the fitting result. Figure 5 (b) in the figure shows the luminescence decay lifetime curve and the fitting result. Detailed Implementation

[0024] The technical solution of the present invention will be further described below with reference to the accompanying drawings. It should be noted that the following embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the present invention. All equivalent substitutions or modifications made based on the concept of the present invention should fall within the scope of protection of the present invention.

[0025] This invention provides an automated integrated extremely weak emission detection system and method based on a superconducting nanowire single-photon detector, such as... Figure 1 As shown, the system includes an excitation beam modulation module, a light emission signal detection and data processing module 3, and a common-path excitation and light emission collection module 4. Preferably, the excitation beam modulation module includes a first excitation beam modulation module 1 and a second excitation beam modulation module 2, which are used to output a first excitation beam and a second excitation beam, respectively, and are then introduced into the common-path excitation and light emission collection module 4 via an excitation beam path switching module 5, so as to meet the testing requirements of different extremely weak light emission samples in terms of excitation band, excitation mode, or excitation conditions.

[0026] The excitation light is focused by the objective lens unit 43 onto the sample unit 44 after passing through the excitation-emission beam splitter 42. The extremely weak emission signal generated by the sample is collected by the same objective lens unit 43 and introduced into the emission signal detection and data processing module 3 via the emission emission guide reflection component 41. Thus, excitation and light collection are achieved under the same objective lens, which helps to reduce the optical error when switching between different test modes repeatedly and improves the consistency between power-dependent emission response test and emission dynamics test.

[0027] Further, the first excitation beam modulation module 1 includes a first excitation source unit 11, a first wavelength filter unit 12, a first intensity adjustment unit 13, a first servo drive unit 14, and a first beam quality control unit 15; the second excitation beam modulation module 2 includes a second excitation source unit 21, a second wavelength filter unit 22, a second intensity adjustment unit 23, a second servo drive unit 24, and a second beam quality control unit 25. The wavelength filter unit is used to select the excitation light band or select the target spectrum. The intensity adjustment unit is preferably an attenuator used to adjust the excitation light power. The servo drive unit is preferably a servo motor used to drive the intensity adjustment unit under the control of a host computer to achieve automatic adjustment of the excitation power. The beam quality control unit is used to collimate, expand, contract, or shape the excitation beam to improve the matching and stability between the excitation beam, the objective lens, and the sample under test.

[0028] With the above structure, more precise and repeatable excitation power control can be achieved in the extremely weak emission on-stage, nonlinear emission response range, or near the target counting range, providing stable conditions for subsequent detection of extremely weak emission signals, acquisition of power-dependent emission response curves, and time-resolved emission dynamics testing.

[0029] Furthermore, the emission signal detection and data processing module 3 includes an emission wavelength filter component 31, an optical coupling unit 32, an optical signal transmission interface 33, a superconducting nanowire single-photon detection unit 34, a photon counting and time-correlation acquisition unit 35, and a host computer processing unit 36. The sample emission signal exported from the common-path excitation and emission collection module 4 is first filtered by the emission wavelength filter component 31 to suppress residual excitation light and background stray light, and then introduced into the superconducting nanowire single-photon detection unit 34 via the optical coupling unit 32 and the optical signal transmission interface 33. The superconducting nanowire single-photon detection unit 34 is used to convert the extremely weak emission signal into an electrical pulse signal. The photon counting and time-correlation acquisition unit 35 is used to count and acquire the electrical pulse signal and perform time statistical analysis. The host computer processing unit 36 ​​is used to receive test data and complete power search, power-dependent emission response curve generation, emission dynamics statistics, result display, and data storage. By employing a superconducting nanowire single-photon detector, its high detection efficiency, low dark count, and high temporal resolution can be leveraged to improve the detection sensitivity and signal-to-noise ratio of extremely weak emission signals with low photon flux, thereby facilitating the accurate identification of micro-weak emission response changes. Preferably, the host computer processing unit 36 ​​sends control commands to the servo drive units (e.g., the first servo drive unit 14 and the second servo drive unit 24) based on the single-photon count feedback. The servo drive units then drive the corresponding intensity adjustment units (e.g., the first intensity adjustment unit 13 and the second intensity adjustment unit 23) to change the position or attenuation degree of the attenuator, thereby achieving automatic adjustment of the excitation light power.

[0030] Furthermore, such as Figure 2 As shown, the host computer control interface 6 includes an automatic search control area 61, a manual adjustment area 62, a scan parameter setting area 63, a real-time count rate display area 64, a lifetime statistics display area 65, and a power-dependent luminescence response curve display area 66. The automatic search control area 61 is used to start or stop the target power range search process; the manual adjustment area 62 is used to fine-tune the excitation power position when needed; the scan parameter setting area 63 is used to set the integration time, number of scans, scan step size, and related test parameters; the real-time count rate display area 64 is used to display the single-photon count response of the sample under the current excitation conditions; the lifetime statistics display area 65 is used to display time-correlated single-photon statistical results or lifetime decay data; and the power-dependent luminescence response curve display area 66 is used to display the relationship between the sample's luminescence response intensity under different excitation light powers. The host computer processing unit 36 ​​receives test data from the superconducting nanowire single-photon detection unit 34 and the photon counting and time-correlated acquisition unit 35, and performs unified control and output for power search, count display, power-dependent luminescence response curve plotting, lifetime testing, and result saving. Figure 2 It embodies the centralized setting and display of relevant parameters, processes and results of power response testing and luminescence dynamics testing, and is a human-computer interaction interface for automated integrated multi-mode testing.

[0031] Furthermore, such as Figure 3 As shown, the automated integrated extremely weak luminescence detection system and method of the present invention includes test mode and parameter settings, servo drive unit adjustment of light intensity tuning unit, sample excitation and single-photon counting acquisition, target condition judgment, power scanning and power-dependent luminescence response data acquisition, and an optional lifetime test mode. The system first sets parameters such as excitation channel, initial power range, target counting interval, integration time, and number of scans. Then, it controls the servo drive unit to drive the light intensity tuning unit to change the excitation power. The sample under test is excited under the same objective lens and generates an extremely weak luminescence signal. After detection by the superconducting nanowire single-photon detection unit, the current count rate or integrated count is output. When the target counting condition or target power condition is reached, the system performs a power scan and records the correspondence between the excitation power and the luminescence response intensity, further generating a power-dependent luminescence response curve and outputting the test results. In lifetime test mode, the system further acquires time-correlated single-photon statistical signals, constructs a lifetime decay curve, and fits it to obtain the luminescence rise time and / or luminescence lifetime parameters. By integrating power-dependent luminescence response testing and luminescence dynamics testing on the same platform, the present invention can uniformly characterize the extremely weak luminescence process from three dimensions: excitation power, luminescence intensity, and time evolution. Figure 3 This demonstrates the workflow from single-photon counting and acquisition, feedback adjustment, to power scanning and multi-mode testing.

[0032] In another specific embodiment, the emission signal detection and data processing module 3 further includes an optical path distribution component and a spectral acquisition unit. The optical path distribution component guides the signal to the spectral acquisition unit and / or the superconducting nanowire single-photon detection unit 34. The spectral acquisition unit is a spectrometer or an integrating optical detector, used to obtain the emission spectrum, emission peak position, spectral width, or spectral integrated intensity of the sample under test. The superconducting nanowire single-photon detection unit 34 is used to obtain real-time or near-real-time single-photon count rate, power-dependent emission response curve, and time-correlated single-photon statistical signal under low photon flux conditions. The spectral acquisition unit is an optional test configuration, enabling the system to select the appropriate signal acquisition method according to the sample and test purpose.

[0033] In one specific embodiment, the sample to be tested is a high-order nonlinear luminescent material. Figure 4 (a) shows the power curve for 25% Tm-doped NaYF4 nanoparticles. Figure 4 (b) shows the power curve of 15% Tm-doped NaLuF4 nanoparticles. The automated integrated extremely weak luminescence detection system of this invention can be used to perform power-dependent luminescence response testing on this material. By adjusting the intensity modulation unit through a servo drive unit, the excitation light power applied to the sample is gradually changed, and the luminescence response intensity under different power conditions is collected using a superconducting nanowire single-photon detection unit, thereby obtaining the power-dependent luminescence response curve and nonlinear fitting results as shown in the figure. Figure 4 As shown. The power-dependent luminescence response curve can be used to determine the luminescence threshold, nonlinear order, and other characteristics of the material. Figure 4 The output results of the power-dependent luminescence response test mode are shown, and the curves can be used to determine the luminescence threshold, nonlinear order, and other characteristics of the material.

[0034] Furthermore, the automated integrated extremely weak luminescence detection system of this invention can also be used to perform luminescence dynamics tests on high-order nonlinear luminescent materials under selected excitation power conditions. The time-correlated single-photon statistical signal of the sample is obtained through a photon counting and time-correlation acquisition unit, and a luminescence rise curve and a luminescence decay lifetime curve are constructed. Further fitting yields the luminescence rise time and / or luminescence lifetime parameters, such as... Figure 5 As shown. It should be noted that, Figure 4 and Figure 5 Using high-order nonlinear luminescent materials as an example, the purpose is to illustrate the application of the present invention in the testing of extremely weak luminescence and nonlinear luminescence, and does not constitute a limitation on the type of sample to be tested.

[0035] In another specific embodiment, the sample to be tested is a color center or a defect emission center. The color center or defect emission center can be a diamond color center, a silicon carbide color center, a two-dimensional material defect emission center, or other solid-state single-photon sources. Combined with... Figure 1 The first excitation beam modulation module 1 or the second excitation beam modulation module 2 provides continuous excitation light or pulsed excitation light, which is then introduced into the common excitation and emission collection module 4 via the excitation beam switching module 5, and focused onto the sample under test by the objective lens unit 43. The color center emission or defect emission signals generated by the sample are collected by the same objective lens, and after the target emission band is selected by the emission wavelength filter component 31, they are introduced into the superconducting nanowire single photon detection unit 34 through the optical coupling unit 32 and the optical signal transmission interface 33.

[0036] By adjusting the excitation light power, the power-dependent counting response curve of the color center or defect luminescence center can be obtained, which can be used to characterize the low-power extremely weak luminescence response, saturated luminescence behavior, or photostability. In pulsed excitation mode, the photon counting and time-correlated acquisition unit 35 acquires the time-correlated single-photon statistical signal and fits it to obtain the luminescence lifetime, rise time, or decay parameters, which can then be used to characterize the luminescence dynamics of the color center or defect luminescence center. Since the luminescence signal of the color center or defect luminescence center is usually weak, using the superconducting nanowire single-photon detection unit 34 is beneficial to improving the detection sensitivity and time resolution.

[0037] In yet another specific embodiment, the sample to be tested is a quantum dot material, perovskite quantum dot material, low-dimensional semiconductor material, or other sample with extremely weak photoluminescence. Combined with Figure 1 The first excitation beam modulation module 1 or the second excitation beam modulation module 2 outputs excitation light that matches the absorption band of the sample under test. This light is then applied to the sample via the common excitation and emission collection module 4. The photoluminescence signal generated by the sample is collected by the same objective lens and enters the emission signal detection and data processing module 3. By automatically scanning the excitation power, the power-dependent photoluminescence response of the sample under test can be obtained. Through time-correlated single-photon statistical testing, the emission lifetime, decay parameters, or excited-state relaxation process can be obtained. This embodiment demonstrates that the present invention is not only applicable to high-order nonlinear luminescent materials with strong nonlinear responses, but also to high-sensitivity testing and luminescence dynamics analysis of low-photon-flux photoluminescent samples.

[0038] In summary, this invention integrates highly sensitive counting detection of extremely weak emission signals, automatic target power range search, power-dependent emission response curve acquisition, and emission dynamics testing through multi-excitation beam modulation, excitation optical path switching, common-path excitation and emission collection, superconducting nanowire single-photon detection, and automated processing by a host computer. The system integrates single-photon counting feedback power adjustment, power-dependent emission response testing, and emission dynamics testing onto a single platform, and can be configured with spectral acquisition functions according to testing requirements, demonstrating the system's characteristics of automation, integration, and multi-mode testing. The system has a clear structure, strong compatibility with testing modes, and a wide range of applicable objects, providing a unified, efficient, and highly sensitive testing platform for the study of emission mechanisms in systems such as extremely weak luminescent materials, nonlinear luminescent materials, color centers or defect emission centers, and single-photon sources. Through a modular architecture for excitation modulation, optical path collection, signal detection, and data processing, it achieves the integration and automatic switching of multiple testing modes without relying on customized dedicated hardware, offering advantages such as strong equipment compatibility, flexible system deployment, high testing efficiency, and high data measurement accuracy.

[0039] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, various modifications, equivalent substitutions, or variations can be made to the present invention without departing from the concept of the present invention, and all such modifications, equivalent substitutions, or variations should fall within the protection scope defined by the claims of the present invention.

Claims

1. A system for detecting extremely weak light emission based on a single-photon detector, characterized in that, It includes a common-path excitation and emission collection module (4), an emission signal detection and data processing module (3), and at least one excitation beam modulation module; The excitation beam modulation module is used to generate an excitation beam and adjust the excitation light power; the excitation beam modulation module includes an intensity adjustment unit for adjusting the excitation light power and a servo drive unit for driving the intensity adjustment unit; The common-path excitation and emission collection module (4) is used to focus the excitation light onto the surface of the sample under test through the same objective lens, and to collect the extremely weak emission signal emitted by the sample under test using the same objective lens; The luminescence signal detection and data processing module (3) includes a superconducting nanowire single-photon detection unit (34), a photon counting and time-correlation acquisition unit (35), and a host computer processing unit (36). The host computer processing unit (36) is communicatively connected to the photon counting and time-correlation acquisition unit (35) and the servo drive unit of the excitation beam modulation module. In the power-dependent luminescence response test mode, the host computer processing unit (36) acquires the single-photon count rate under the current excitation power or the integral count within a preset integral time, compares it with the preset target count interval, and controls the servo drive unit to adjust the excitation power according to the comparison result. After the target count condition is reached, the control system performs a power scan according to the preset power step size, records the single-photon count data corresponding to different excitation powers, and generates a power-dependent luminescence response curve. In the luminescence dynamics test mode, the photon counting and time-correlation acquisition unit (35) acquires the time-correlation single-photon statistical signal to obtain the luminescence dynamics parameters of the sample to be tested.

2. The extremely weak luminescence detection system according to claim 1, characterized in that, It includes a first excitation beam modulation module (1) and a second excitation beam modulation module (2); The first excitation beam modulation module (1) includes a first excitation light source unit (11), a first wavelength filter unit (12), a first light intensity modulation unit (13), a first servo drive unit (14), and a first beam quality control unit (15). The second excitation beam modulation module (2) includes a second excitation light source unit (21), a second wavelength filter unit (22), a second light intensity modulation unit (23), a second servo drive unit (24), and a second beam quality control unit (25). The first excitation light source unit (11) and the second excitation light source unit (21) are used to provide continuous excitation light, pulsed excitation light or modulated excitation light required for the extremely weak light emission test of the sample under test; The first wavelength filter unit (12) and the second wavelength filter unit (22) are used to select the excitation light band or select the target spectrum; The first light intensity modulation unit (13) and the second light intensity modulation unit (23) use attenuators to adjust the excitation light power; The first servo drive unit (14) and the second servo drive unit (24) are used to drive the light intensity modulation unit to achieve automatic power adjustment; The first beam quality control unit (15) and the second beam quality control unit (25) are used to collimate, expand, shrink and shape the excitation beam.

3. The extremely weak luminescence detection system according to claim 2, characterized in that, The excitation light path switching module (5) includes a first light path switching component (51) and a second light path switching component (52). The first light path switching component (51) and the second light path switching component (52) adopt one or more of the following: a flip mirror, a dichroic mirror, a beam splitter, or an optical switch, for selectively introducing a single excitation light or a dual excitation light.

4. The extremely weak luminescence detection system according to claim 1, characterized in that, The common-path excitation and emission collection module (4) includes an emission emission and reflection component (41), an excitation-emission beam splitter component (42), an objective lens unit (43), and a sample unit (44). The excitation-emission beam splitter (42) uses a dichroic mirror to guide the excitation light to the objective lens unit (43) and separates and extracts the weak light signal emitted by the sample; The objective lens unit (43) is used to focus the excitation light onto the sample unit (44) and collect the emitted light from the sample; The light emission output and reflection component (41) is used to introduce the emitted light into the light emission signal detection and data processing module (3).

5. The extremely weak luminescence detection system according to claim 1, characterized in that, The light emission signal detection and data processing module (3) also includes a light emission wavelength filter component (31), an optical coupling unit (32), and an optical signal transmission interface (33). The host computer processing unit (36) includes a test control module, a curve generation module, a parameter extraction module and a fitting analysis module, which are used to control the excitation power adjustment based on the comparison result between the single photon count rate or integral count and the preset target count interval, and are used for power scan control, power-dependent luminescence response curve generation and analysis, luminescence dynamics test control and test result processing. The superconducting nanowire single-photon detection unit (34) is used to convert extremely weak light emission signals into electrical pulse signals; The photon counting and time-correlation acquisition unit (35) is used to perform counting acquisition, time marking and time-correlation statistical analysis on the electrical pulse signal; The host computer processing unit (36) is used to output the real-time counting rate, integral count, and power-dependent emission response curve, and to automatically fit, differentiate, determine the threshold, or extract parameters of the power-dependent emission response curve to obtain the maximum response slope, threshold excitation power, nonlinear response parameters, or saturated emission range.

6. The extremely weak luminescence detection system according to claim 5, characterized in that, The photon counting and time-correlation acquisition unit (35) includes a counting and statistics module and a time-correlation acquisition module connected to the superconducting nanowire single-photon detection unit (34). It is used to acquire the time-correlation single-photon statistical signal of the sample under the action of the synchronous trigger signal, and further obtain the emission rise time, emission lifetime, decay parameter or emission center dynamic parameter.

7. The extremely weak luminescence detection system according to claim 5 or 6, characterized in that, The light emission signal detection and data processing module (3) also includes an optical path distribution component and a spectrum acquisition unit. The optical path distribution component imports the signal into the spectrum acquisition unit and / or the superconducting nanowire single photon detection unit (34). The spectral acquisition unit is a spectrometer or an integrating optical detector, used to obtain the emission spectrum, emission peak position, spectral width, or spectral integrated intensity of the sample to be tested.

8. A testing method using the extremely weak luminescence detection system according to any one of claims 1-7, characterized in that, Includes the following steps: S1. Select the test mode and set the test parameters, including selecting the excitation channel, setting the initial power range, target counting interval or target power point, integration time, step size and number of scans; S2. Control the servo drive unit to drive the light intensity modulation unit and adjust the excitation light power; S3. The excitation light is applied to the sample under test through the objective lens unit. The extremely weak light emission signal emitted by the sample is collected by the same objective lens and introduced into the superconducting nanowire single photon detection unit for single photon counting and acquisition. S4. Read the count rate or integral count corresponding to the current power, and determine whether the target count condition or target power condition has been met; in the target count interval search mode, if the target count condition has not been met, return to step S2, and continue to adjust the excitation power according to the comparison result between the current count and the target count interval; if it has been met, proceed to step S5. S5. Perform power scanning according to the preset power step size, collect single photon counting data at each power point and record the power-count correspondence; S6. Generate a power-dependent emission response curve based on the data collected in step S5, and perform one or more of the following processing on the power-dependent emission response curve through the host computer processing unit: background subtraction, smoothing, normalization, curve fitting, derivative analysis or piecewise fitting, and automatically extract and output the maximum response slope, threshold excitation power, nonlinear response parameters, saturated emission range or target power point. S7. In the optional luminescence dynamics test mode, set the target power point and configure the time-related acquisition parameters to obtain the time-related single-photon statistical signal, and automatically fit the luminescence rise time and lifetime decay curve through the preset fitting model.

9. The test method according to claim 8, characterized in that, The luminescence response intensity in the power-dependent luminescence response curve is characterized by the single-photon count rate or the integral count within a preset integration time. The power-dependent luminescence response curve is used to characterize the luminescence on-off characteristics, power-dependent response law, nonlinear luminescence behavior, saturated luminescence behavior, or extremely weak luminescence response changes of the sample under test. The time-correlated single-photon statistical signal is used to obtain the emission rise time, emission lifetime, excited state establishment process, emission center relaxation process, or defect emission dynamics parameters of the sample under test.

10. The test method according to claim 8, characterized in that, Used for characterizing the luminescence intensity response and luminescence dynamics of extremely weak luminescent materials, nonlinear luminescent materials, upconversion luminescent materials, color centers or defect luminescent centers, single-photon sources, quantum dot materials or low-dimensional semiconductor materials; The sample to be tested includes one or more of the following: photon avalanche luminescent materials, rare earth-doped upconversion luminescent materials, diamond color centers, silicon carbide color centers, two-dimensional material defect luminescent centers, semiconductor quantum dots, perovskite quantum dots, low-dimensional semiconductor materials, or other low photon flux luminescent samples.

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