Spectrometer based on single-pixel single-channel single-photon detector and detection method

Abstract

The invention provides a spectrometer based on a single-pixel single-channel single-photon detector and a detection method, and the spectrometer comprises a dispersion module which broadens a to-be-detected broadband light beam in space; the light beam path control module is used for controlling the light beam after space broadening to perform one-dimensional movement on the surface of the single-photon detector so as to ensure that light with different wavelengths is sequentially irradiated on the single-photon detector; the single-photon detector is used for detecting components with different wavelengths, realizing horizontal detection of a single photon and outputting a detection signal to the time-to-digital converter; the time-to-digital converter is used for recording and converting photon signal time information into digital signals; and the control system is connected with the light beam path control module and the time-to-digital converter, establishes single-channel communication with the single-photon detector, and is used for controlling the motion state of the light beam in the whole detection process and recording the photon count of each wavelength so as to obtain the wavelength-intensity corresponding relation of the light beam to be detected. The invention has the advantages of high detection sensitivity, high resolution, simple system and low cost.

Description

Technical Field

[0001] This application belongs to the field of ultrafast lasers and spectral measurement, and specifically relates to spectral detection technology based on a single-pixel single-channel single-photon detector. Background Technology

[0002] Spectrometers are essential tools for spectral analysis, widely used in fields such as biomedicine, materials analysis, quality control, and ultrafast optics. Traditional spectrometers use linear CCD arrays as their detection devices, possessing thousands of pixels on a one-dimensional scale, enabling the measurement of spatially stretched light beams. However, due to the large number of pixels, linear CCD arrays have low sampling rates. Increasing the sampling rate requires adding more channels, significantly increasing costs. Furthermore, traditional spectrometers cannot perform weak light measurements and have low sensitivity, severely limiting their application range.

[0003] Currently, single-pixel single-photon detectors, such as avalanche photodiode single-photon detectors, are technologically mature. The time jitter of silicon avalanche photodiode single-photon detectors reaches 56 ps at half maximum width and height [Acta Physica Sinica, 69(7), 074204(2020)], and the quantum efficiency reaches 70% [Acta Physica Sinica, 67(22),221401(2018)]. They can achieve weak light detection of a single photon, reaching the quantum limit, and are small in size and highly integrated.

[0004] For weak light spectral detection required in quantum physics experiments, traditional photodetectors, such as linear CCD arrays, cannot detect at the level of a single photon. If cumulative measurement is performed, there are problems with large environmental noise and thermal noise.

[0005] Using a single-photon detector array would significantly increase costs and also suffer from low sampling rates. For example, the spectral measurement system based on a single-photon detector array disclosed in patent document CN114166765A employs a virtual image phase array and two-dimensional dispersion of reflection diffraction, utilizing a single-photon detector array for detection to improve wavelength resolution and expand the detection range. However, its detection requires a single-photon detector array, which is extremely expensive.

[0006] Using multi-channel detection increases the complexity of subsequent signal and control system design. For example, patent document CN116608949A discloses a single-photon spectrometer based on fiber dispersion. It uses optical fiber as the light transmission device. Its advantage lies in the fact that due to group velocity dispersion, different wavelengths of light have different refractive indices in the optical fiber, so different wavelengths of light travel at different speeds in the optical fiber and arrive at the detector in a certain order. The intensity of different wavelengths is measured through this temporal separation. However, for time-stretched pulses, using only one detector to measure the stretched pulse requires chopper-like or other frequency-dividing methods. Furthermore, the final detector is often a silicon-based single-photon detector with a wavelength range of 400-1000 nm, but optical fiber has a narrow bandwidth, and the optical fiber system is greatly affected by temperature.

[0007] These disadvantages increase the cost and complexity of spectrometers, resulting in significant shortcomings in improving sampling rates, reducing costs, enhancing integration, and achieving high-sensitivity detection under low-light conditions. Therefore, a new technological solution is urgently needed to address these technical problems and achieve high-sensitivity, high-sampling-rate, low-cost, and highly integrated spectral detection. Summary of the Invention

[0008] To address the aforementioned issues, this application provides a spectrometer based on a single-pixel, single-channel, single-photon detector. This spectrometer achieves spatial broadening through a dispersion module, enabling the separation of different wavelengths in space. By using a single-pixel, single-channel, single-photon detector and employing mechanical scanning, it achieves the same effect as linear or area array detectors, offering advantages such as high detection sensitivity, high resolution, system simplicity, and low cost.

[0009] The technical solution of this application is as follows: This application provides a spectrometer based on a single-pixel, single-channel, single-photon detector, comprising a dispersion module, a beam path control module, a single-photon detector, a time-to-digital converter, and a control system, wherein: The dispersion module is used to spatially broaden the broadband beam to be measured. The beam path control module is connected to the dispersion module and is used to control the spatially broadened beam to move in one dimension on the surface of the single-photon detector, so as to ensure that light of different wavelengths shines on the single-photon detector in sequence. The single-photon detector is connected to the beam path control module to detect the components of a one-dimensional moving beam at different wavelengths and output the detection signal to the time-to-digital converter. The time-to-digital converter is used to record the time when the single-photon detector detects the photon signal and convert it into a digital signal to be fed back to the control system. The control system connects the beam path control module and the time-to-digital converter, and establishes a single-channel communication connection with the single-photon detector. It is used to control the motion state of the beam throughout the detection process and record the photon counts at each wavelength, i.e., the light intensity information.

[0010] Preferably, the dispersion module includes a prism or a grating; the prism is specifically a Powell prism, and the grating is specifically a blazed grating, used to enhance the spatial broadening effect of the light beam.

[0011] Preferably, the beam path control module includes a one-dimensional galvanometer or a MEMS galvanometer; the one-dimensional galvanometer has small-angle oscillation characteristics, and the MEMS galvanometer has high-speed response characteristics, so as to improve the accuracy of the beam movement on the surface of the single-photon detector.

[0012] Preferably, the single-photon detector is a single-pixel avalanche photodiode single-photon detector operating in continuous detection mode, which continuously detects photons with wavelengths between 400nm and 1100nm.

[0013] Preferably, the control system is an FPGA development board or a host computer that communicates with the single-photon detector through a single channel.

[0014] Preferably, the distance between the single-photon detector and the beam path control module, and the distance between the one-dimensional galvanometer and the dispersion module are preferably set to 100 mm, and the target width of the single-photon detector is preferably set to 100 μm, in order to achieve high spectral resolution.

[0015] This application also provides a spectral detection method based on a single-pixel, single-channel, single-photon detector, the method comprising: First, the broadband beam to be measured is spatially broadened using a dispersion module, so that light of different wavelengths can be separated in physical space. Next, the beam path control module controls the movement of the broadened beam in one dimension to ensure that each spectral component in the beam can sequentially illuminate the single-photon detector in a predetermined order. A single-photon detector detects photons in a broadened beam and transmits the detected photon signal to a time-to-digital converter via a single-channel communication method. Finally, the time-to-digital converter converts the received photon signal time information into a digital signal for subsequent data processing and analysis.

[0016] Throughout the detection process, the control system establishes a single-channel communication with the beam path control module, single-photon detector, and time-to-digital converter to ensure the coordination and consistency of the entire spectral detection process, accurately record and process the photon counts corresponding to each wavelength, thereby obtaining high-resolution spectral information.

[0017] The spectrometer and detection method based on a single-pixel, single-channel, single-photon detector provided in this application have the following advantages:

[0018] 1. Spectral detection of weak light was achieved using a single-pixel single-photon detector.

[0019] 2. For light that has spatially broadened after passing through a dispersive element, a mechanical scanning method can be used to illuminate light with different spectral components after spatial broadening onto a single-pixel single-photon detector, achieving full-spectrum detection. This overcomes the problem that existing technologies require the use of area array single-photon detectors, which are expensive.

[0020] 3. Because a single-pixel detector is used, only a single channel is needed in the circuit to achieve detection, which greatly reduces the complexity of the circuit and improves stability.

[0021] Overall, this application can effectively overcome the cost problems, sampling rate limitations, and insufficient detection capabilities under low light conditions caused by the use of linear CCD or single-photon detector arrays in the prior art, and achieve the goals of maximizing cost-effectiveness, improving detection speed, and high-sensitivity detection in low light environments. It is particularly suitable for scientific research and industrial applications that require precise spectral analysis. Attached Figure Description

[0022] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a schematic diagram of the spectrometer based on a single-pixel, single-channel, single-photon detector in this application.

[0023] Figure 2 This is the optical path diagram of the spectrometer based on a single-pixel single-channel single-photon detector in this application. Detailed Implementation

[0024] The following description, with reference to the accompanying drawings and preferred embodiments, illustrates the implementation of the technical solution of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. This application can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be understood that the preferred embodiments are merely illustrative of this application and not intended to limit the scope of protection of this application.

[0025] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of this application. Therefore, the drawings only show the components related to this application and are not drawn according to the number, shape and size of the components in actual implementation. In actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0026] This embodiment relates to a spectrometer based on a single-pixel, single-channel single-photon detector. Using a single-pixel avalanche photodiode single-photon detector as the detection device, it can achieve weak light detection at the single-photon level and communicate with the control system via a single channel. Simultaneously, the control system is connected to a beam control system, allowing the spatially broadened laser beam to move across the surface of the single-photon detector. The single-photon detector detects light intensities at different wavelengths and outputs the detection signal to a time-to-digital converter, which converts the detected time signal into a digital signal, which is then output to the control system. Ultimately, this achieves high-sensitivity, high-resolution measurement of the 400-1100nm spectrum.

[0027] For details, please refer to the following structure. Figure 1 The spectrometer includes a dispersion module, a beam path control module, a single-photon detector, a time-to-digital converter, and a control system. Among these: The dispersion module is used to spatially broaden the broadband beam to be measured.

[0028] The beam path control module, connected to the dispersion module, controls the spatially broadened beam to move one-dimensionally on the surface of the single-photon detector, ensuring that light of different wavelengths illuminates the single-photon detector sequentially.

[0029] A single-photon detector, connected to a beam path control module, is used to detect the components of a one-dimensional moving beam at different wavelengths and outputs the detection signal to a time-to-digital converter.

[0030] A time-to-digital converter is used to record the time when a single-photon detector detects a photon signal and convert it into a digital signal to be fed back to the control system.

[0031] The control system connects the beam path control module and the time-to-digital converter, and establishes a single-channel communication connection with the single-photon detector. It is used to control the motion state of the beam throughout the detection process and record the photon counts at each wavelength, i.e., the light intensity information.

[0032] In this embodiment, the dispersion module spatially broadens the broadband beam to be measured, separating light of different wavelengths in space. The beam path control module controls the movement of the broadened beam in a one-dimensional direction, ensuring that light of different wavelengths sequentially illuminates the single-photon detector of a single pixel. The single-photon detector operates in continuous detection mode, capable of detecting photons between 400nm and 1100nm. When a photon signal is detected, it outputs the signal to a time-to-digital converter. The time-to-digital converter records the time of the photon signal and converts it into a digital signal, feeding it back to the control system. The control system establishes single-channel communication with the single-photon detector, controlling the beam path control module to record the photon count for each wavelength. By combining mechanical scanning and a single-pixel detector, the high cost and low detection sensitivity problems caused by using multi-pixel or multi-channel detectors in traditional spectrometers are overcome, achieving high-sensitivity measurement across the entire spectrum with high spectral resolution, suitable for spectral detection under low-light conditions.

[0033] In a further embodiment, the dispersion module is preferably a Powell prism or a blazed grating. These two dispersive elements significantly enhance the spatial broadening effect of the beam, allowing for clearer spatial separation of light of different wavelengths. When a Powell prism is used, its divergence angle (full angle) is 60 degrees, effectively broadening the beam perpendicular to the incident direction. A blazed grating, through precise angle design, generates efficient dispersion of light within a specific wavelength range. Both prisms and gratings can work in conjunction with the scanning action of a one-dimensional galvanometer or MEMS galvanometer to achieve point-by-point detection of the spatially broadened beam. By controlling the small-angle oscillation of the beam path control module, the broadened beam is precisely guided to the surface of a single-pixel single-photon detector for one-dimensional movement, ensuring that the spectral information at each point is accurately captured. This design not only reduces system complexity but also greatly improves the sensitivity and resolution of spectral measurements, especially in the 400-1100nm wavelength range. Even in low-light environments at the single-photon level, effective spectral detection can be performed, achieving the goal of high-precision measurement.

[0034] In a further embodiment, the beam path control module employs either a one-dimensional galvanometer or a MEMS galvanometer. The one-dimensional galvanometer, with its unique small-angle oscillation capability, precisely controls the trajectory of the beam on the surface of the single-photon detector, while the MEMS galvanometer, with its high-speed response characteristics, significantly improves the efficiency and accuracy of beam scanning. This choice not only meets the requirements of beam path control but also effectively improves the dynamic performance of the entire spectrometer. In specific applications, the precise scanning of the spatially broadened beam on the surface of the single-photon detector is achieved through the minute oscillation of the one-dimensional galvanometer or the rapid response of the MEMS galvanometer, ensuring the sequential detection of different wavelength components and thus enhancing the accuracy and reliability of spectral measurements. Especially in applications requiring high-precision beam positioning and rapid scanning, the use of MEMS galvanometers can further improve the performance indicators of the spectrometer and meet more stringent measurement requirements.

[0035] In a further embodiment, the single-photon detector is a single-pixel avalanche photodiode single-photon detector operating in continuous detection mode, continuously detecting photons with wavelengths between 400 nm and 1100 nm. This design cleverly utilizes the high sensitivity and fast response characteristics of the single-pixel avalanche photodiode single-photon detector, enabling it to effectively detect photon signals under low light intensity conditions. Through continuous detection mode, the detector can monitor the arrival of photons in the beam in real time without additional signal accumulation, thus significantly improving the accuracy and speed of spectral measurements. In practical applications, the single-photon detector works in conjunction with a time-to-digital converter and a control system to ensure that even extremely weak light signals can be accurately captured and analyzed, providing a more sensitive and efficient solution for the field of spectral measurement.

[0036] In this embodiment, the control system is preferably an FPGA development board or a host computer. As the core control component of the spectrometer, it is responsible not only for single-channel communication with the single-photon detector and receiving and processing time information fed back by the time-to-digital converter, but also for controlling the movement of the beam path control module to achieve one-dimensional scanning of the beam on the surface of the single-photon detector. By precisely controlling the swing angle and frequency of the one-dimensional galvanometer, the control system can achieve precise control of the beam path, ensuring that each spectral component accurately and sequentially illuminates the single-photon detector. This design greatly simplifies circuit complexity and improves system stability.

[0037] In a further embodiment, the distance between the single-photon detector and the beam path control module, and the distance between the one-dimensional galvanometer and the dispersion module, are preferably set to 100 mm, and the target width of the single-photon detector is preferably set to 100 μm. This significantly improves the spectral resolution of the entire spectral detection system. This design not only simplifies the complexity of the optical and circuit systems and reduces costs, but also achieves a high spectral resolution of 0.14 nm, demonstrating high sensitivity and high precision in spectral detection.

[0038] In a further embodiment, a spectral detection method based on a single-pixel, single-channel single-photon detector is provided. A dispersion module spatially broadens the broadband beam to be measured, allowing light of different wavelengths to be physically separated. A beam path control module then controls the movement of the broadened beam in a one-dimensional direction, ensuring that each spectral component of the beam sequentially illuminates the single-photon detector in a predetermined order. The single-photon detector detects photons in the broadened beam and transmits the detected photon signals to a time-to-digital converter via single-channel communication. Finally, the time-to-digital converter converts the received photon signal timing information into a digital signal for subsequent data processing and analysis. This method achieves high-sensitivity and high-resolution full-spectrum detection using a single-pixel single-photon detector, overcoming the limitations of traditional detectors that cannot operate effectively in low-light conditions. It also avoids the high cost and complex system design problems associated with using multi-pixel or array-type single-photon detectors, significantly improving the performance and cost-effectiveness of spectral detection.

[0039] Furthermore, as a parameter for resolution verification, such as Figure 2 As shown, the incident broadband beam size is 0.8 mm, with a wavelength range of 400-1100 nm. The dispersion module uses a Powell prism with a divergence angle (full angle) of 60 degrees, and the beam path control module uses a one-dimensional galvanometer, which is located at a distance from the dispersion module. l 1. A one-dimensional galvanometer mirror, at a 45-degree angle β to the center of the spatially broadened beam, oscillates at a small angle, controlling the beam to move one-dimensionally on the surface of the single-photon detector. The distance between the single-photon detector and the one-dimensional galvanometer mirror is... l 2. The target width of the single-photon detector is d . d The corresponding spatial beam wavelength is the resolution of the spectrometer. When l 1 = 100mm l 2 = 100mm, d =100μm, the spectral resolution of the spectrometer based on a single-pixel single-channel single-photon detector proposed in this application reaches 0.14nm.

[0040] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the principles of this application should be included within the protection scope of this application.

[0041] The foregoing has shown and described the basic principles, main features, and advantages of this application. Those skilled in the art should understand that this application is not limited to the above embodiments. The embodiments and descriptions in the specification are merely the principles of this application. Various changes and modifications can be made to this application without departing from the spirit and scope thereof, and all such changes and modifications fall within the scope of the claims. The scope of protection claimed by this application is defined by the appended claims and their equivalents.

Claims

1. A spectrometer based on a single-pixel, single-channel, single-photon detector, characterized in that, It includes a dispersion module, a beam path control module, a single-photon detector, a time-to-digital converter, and a control system; The dispersion module is used to spatially broaden the broadband beam to be measured. The beam path control module is connected to the dispersion module and is used to control the spatially broadened beam to move in one dimension on the surface of the single-photon detector, so as to ensure that light of different wavelengths shines on the single-photon detector in sequence. The single-photon detector is connected to the beam path control module to detect the components of a one-dimensional moving beam at different wavelengths and output the detection signal to the time-to-digital converter. The time-to-digital converter is used to record the time when the single-photon detector detects the photon signal and convert it into a digital signal to be fed back to the control system. The control system connects the beam path control module and the time-to-digital converter, and establishes a single-channel communication connection with the single-photon detector. It is used to control the motion state of the beam throughout the detection process and record the photon counts at each wavelength, i.e., the light intensity information.

2. The spectrometer based on a single-pixel, single-channel, single-photon detector according to claim 1, characterized in that, The dispersion module includes a prism or a grating; the prism is a Powell prism, and the grating is a blazed grating, used to enhance the spatial broadening effect of the beam.

3. The spectrometer based on a single-pixel, single-channel, single-photon detector according to claim 1, characterized in that, The beam path control module includes a one-dimensional galvanometer or a MEMS galvanometer.

4. The spectrometer based on a single-pixel, single-channel, single-photon detector according to claim 1, characterized in that, The single-photon detector is a single-pixel avalanche photodiode single-photon detector operating in continuous detection mode, which continuously detects photons with wavelengths between 400nm and 1100nm.

5. The spectrometer based on a single-pixel, single-channel, single-photon detector according to claim 1, characterized in that, The control system is an FPGA development board or a host computer.

6. The spectrometer based on a single-pixel, single-channel, single-photon detector according to any one of claims 1-5, characterized in that, The distance between the single-photon detector and the beam path control module, and the distance between the one-dimensional galvanometer and the dispersion module, are preferably set to 100 mm, and the target width of the single-photon detector is preferably set to 100 μm.

7. A spectral detection method based on a single-pixel, single-channel, single-photon detector, characterized in that the method... include: First, the broadband beam to be measured is spatially broadened using a dispersion module, so that light of different wavelengths can be separated in physical space. Next, the beam path control module controls the movement of the broadened beam in one dimension to ensure that each spectral component in the beam can sequentially illuminate the single-photon detector in a predetermined order. A single-photon detector detects photons in a broadened beam and transmits the detected photon signal to a time-to-digital converter via a single-channel communication method. Finally, the time-to-digital converter converts the received photon signal time information into a digital signal for subsequent data processing and analysis. Throughout the detection process, the control system establishes a single-channel communication with the beam path control module, single-photon detector, and time-to-digital converter to ensure the coordination and consistency of the entire spectral detection process, accurately record and process the photon counts corresponding to each wavelength, thereby obtaining high-resolution spectral information.

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