Pulsed light output module and single-photon detector calibration system

Abstract

The utility model relates to a pulsed light output module and a single-photon detector calibration system, and belongs to the field of quantum detection. The pulse light output module included in the single-photon detector calibration system comprises the pulse laser, the continuous laser and the waveguide with the sum frequency characteristic, and after pulse light and continuous light are input into the waveguide at the same time, the needed pulse light is output by utilizing the sum frequency characteristic of the waveguide. By adjusting the wavelength of the continuous laser and changing the matching temperature of the waveguide, the wavelength of the output required pulsed light can be changed on the premise that the pulsed light is not changed, and compared with a single-wavelength pulse laser, the pulsed light output module has the advantages that the adjustable range of the wavelength of the pulsed light output by the pulsed light output module is wider; a large number of pulse lasers can be prevented from being adopted, and output of some pulse light with the wavelength not easy to achieve in engineering can be achieved. Therefore, the cost of the single-photon detector calibration system can be remarkably reduced, and the application range is widened.

Description

Technical Field

[0001] This utility model relates to the field of quantum detection technology, and in particular to a pulsed light output module and a single-photon detector calibration system. Background Technology

[0002] Single-photon detectors are widely used in research on high-sensitivity detection, such as lidar, quantum communication, and single-photon imaging. Common single-photon detectors include superconducting nanowire single-photon detectors, indium gallium arsenide (IGaAs) single-photon detectors, and silicon single-photon detectors. Superconducting nanowire detectors have a broad response wavelength range, IGaAs single-photon detectors have a high response wavelength of 1000-1700 nm, while silicon single-photon detectors have high detection efficiency in the 500-900 nm range.

[0003] To calibrate the performance parameters (such as efficiency, dead time, afterpulse, timing accuracy, saturation count rate, etc.) of the various single-photon detectors mentioned above, it is necessary to build corresponding calibration systems for different detectors and different response wavelengths. The current conventional method for calibrating single-photon detectors is to use a pulsed laser of a specific wavelength, that is, to calibrate it using a pulsed laser of the wavelength corresponding to the single-photon detector. For example, to test the performance of silicon at 631nm, a 631nm pulsed laser is used; to test the performance of indium gallium arsenide at 1550nm, a 1550nm pulsed laser is required.

[0004] It can be seen that, using existing single-photon detector calibration methods, obtaining a complete efficiency curve for a single-photon detector requires the use of many pulsed lasers of specific wavelengths. However, pulsed lasers are expensive, which leads to excessively high calibration system costs. At the same time, certain pulsed lasers of specific wavelengths are not easy to implement in engineering, making it difficult to calibrate the performance parameters of single-photon detectors at these specific wavelengths, resulting in an incomplete applicability of the calibration system.

[0005] In other words, current calibration methods for single-photon detectors suffer from technical problems such as excessive cost and limited applicability. Utility Model Content

[0006] To address the aforementioned technical problems, this utility model provides a pulsed light output module and a single-photon detector calibration system, thereby solving the technical problems of excessively high cost and limited applicability of existing single-photon detector calibration methods.

[0007] In a first aspect, this utility model provides a pulsed light output module, comprising: a pulsed laser, a continuous laser, and a lithium niobate waveguide;

[0008] The output end of the pulsed laser is connected to the incident end of the lithium niobate waveguide, the output end of the continuous laser is connected to the incident end of the lithium niobate waveguide, and the emitting end of the lithium niobate waveguide is connected to the output end of the pulsed light output module.

[0009] Optionally, the lithium niobate waveguide is a periodically polarized lithium niobate waveguide.

[0010] Optionally, a filter is also included, wherein the output end of the periodically polarized lithium niobate waveguide is connected to the input end of the filter, and the output end of the filter is connected to the output end of the pulsed light output module.

[0011] Secondly, this utility model also provides a single-photon detector calibration system, which includes any of the above-mentioned pulsed light output modules, as well as a single-photon calibration module and a time-to-digital converter.

[0012] The output terminal of the pulsed light output module is connected to the input terminal of the single-photon calibration module, the output terminal of the single-photon calibration module is used to connect to the input terminal of the single-photon detector to be calibrated, and the input terminal of the time-to-digital converter is used to connect to the counting signal output terminal of the single-photon detector to be calibrated.

[0013] Optionally, the single-photon calibration module includes: a first adjustable attenuator, a beam splitter, and an optical power meter;

[0014] The input terminal of the first adjustable attenuator is connected to the input terminal of the single-photon calibration module, the output terminal of the first adjustable attenuator is connected to the input terminal of the beam splitter, the first output terminal of the beam splitter is connected to the input terminal of the optical power meter, and the second output terminal of the beam splitter is connected to the output terminal of the single-photon calibration module.

[0015] Optionally, the single-photon calibration module further includes a second adjustable attenuator;

[0016] The second output terminal of the beam splitter is connected to the input terminal of the second adjustable attenuator, and the output terminal of the second adjustable attenuator is connected to the output terminal of the single-photon calibration module.

[0017] Optionally, the attenuation value of the beam splitter and the second adjustable attenuator is 50 dB.

[0018] The above scheme has the following beneficial effects:

[0019] The pulsed light output module included in the single-photon detector calibration system of this invention comprises a pulsed laser, a continuous laser, and a waveguide with sum-frequency characteristics. After simultaneously inputting pulsed light and continuous light into the waveguide, it outputs the desired pulsed light using the sum-frequency characteristics of the waveguide. Furthermore, by adjusting the wavelength of the continuous laser and changing the matching temperature of the waveguide, the wavelength of the output pulsed light can be changed without changing the pulsed light itself. Compared to a single-wavelength pulsed laser, the pulsed light output module of this invention has a wider adjustable wavelength range, avoiding the need for a large number of pulsed lasers and enabling the output of pulsed light at wavelengths that are difficult to achieve in engineering. Attached Figure Description

[0020] Figure 1 This is a structural block diagram of the pulsed light output module provided in Embodiment 1 of this utility model;

[0021] Figure 2 This is a structural block diagram of the single-photon detector calibration system provided in Embodiment 2 of this utility model;

[0022] Figure 3 This is a structural block diagram of the single-photon calibration module provided in Embodiment 2 of this utility model. Detailed Implementation

[0023] To make the technical problems, technical solutions and beneficial effects solved by this utility model clearer, the following detailed description of this utility model is provided in conjunction with the accompanying drawings and embodiments.

[0024] It should be understood that the embodiments described below represent essential information to enable those skilled in the art to implement the embodiments and to illustrate the best mode of implementation. Upon reading the following description in conjunction with the accompanying drawings, those skilled in the art will understand the concepts of this disclosure and recognize the applications of these concepts not specifically mentioned herein. It should be understood that these concepts and applications fall within the scope of this disclosure and the appended claims.

[0025] It should also be understood that although the terms first, second, etc., may be used herein to describe various elements, these elements should not be limited by these terms. These terms are used only to distinguish one element from another. For example, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element, without departing from the scope of this disclosure. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0026] It should also be understood that when a component is referred to as "connected" or "coupled" to another component, it can be directly connected or coupled to the other component, or there may be intermediate components. Conversely, when an element is referred to as "directly connected" or "directly coupled" to another element, there are no intermediate components.

[0027] It should also be understood that the terms “upper,” “lower,” “left,” “right,” “front,” “back,” “bottom,” “middle,” “center,” “top,” etc., may be used herein to describe various elements, indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. They are used only for the convenience of describing the present invention and to simplify the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, these elements should not be limited by these terms.

[0028] These terms are used only to distinguish one element from another. For example, a first element may be referred to as the “upper” element, and similarly, a second element may be referred to as the “upper” element depending on the relative orientation of these elements, without departing from the scope of this disclosure.

[0029] To be further understood, the terms “comprising,” “including,” “including,” and / or “include” as used herein specify the presence of the said feature, integer, step, operation, element, and / or component, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0030] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. It will be further understood that the terms used herein should be interpreted as having the same meaning as they mean in the context of this specification and related art, and will not be interpreted in an idealized or overly formal sense unless expressly defined herein.

[0031] In Embodiment 1, a method is provided as follows: Figure 1 The pulsed light output module shown includes: a pulsed laser, a continuous laser, and a lithium niobate waveguide;

[0032] The output end of the pulsed laser is connected to the incident end of the lithium niobate waveguide, the output end of the continuous laser is connected to the incident end of the lithium niobate waveguide, and the emitting end of the lithium niobate waveguide is connected to the output end of the pulsed light output module.

[0033] In this embodiment, pulsed light generated by a commonly used pulsed laser and continuous light generated by a continuous laser are input into a lithium niobate waveguide with sum-frequency characteristics. By adjusting the wavelength of the continuous light generated by the continuous laser and adjusting the waveguide matching temperature, the desired pulsed light output at a specific wavelength is achieved.

[0034] In this embodiment, to achieve better sum-frequency characteristics of the waveguide, periodically polarized lithium niobate (PPLN) waveguides are preferred. Utilizing the sum-frequency characteristics of PPLNs, different wavelengths of desired pulsed light can be generated by changing the wavelengths of the pulsed light used as the signal light and the continuous light used as the pump light. While the wavelength of a pulsed laser is generally not adjustable in a specific scenario, the wavelength of the desired pulsed light output by the pulsed light output module can be adjusted by changing the wavelength of the pump laser. This allows for a wider range of pulsed light output compared to a single pulsed laser.

[0035] It is important to note that due to the temperature characteristics of PPLN, the matching temperature is different for different wavelengths of pulsed light to be generated. Therefore, the matching temperature of PPLN needs to be adjusted according to the actual wavelength of the output pulsed light.

[0036] Furthermore, in order to better calibrate the performance parameters of a single-photon detector at a specific wavelength, it is necessary to ensure, to the greatest extent possible, that the pulse light input to the single-photon detector does not contain light of other wavelengths. Therefore, in this embodiment, it is further preferred to add a filter after the PPLN waveguide. The purpose of this filter is to filter out noise light generated during the PPLN waveguide and frequency conversion process, as well as pump light that is not fully converted.

[0037] For example, to test the performance of a silicon single-photon detector at 631nm, a common 1550nm pulsed laser can be used as the signal light, and a 1064nm continuous-wave laser as the pump laser. The output pulse light is then up-converted and frequency-controlled via a PPLN waveguide, and noise is filtered out to produce the desired 631nm pulsed light for testing. The wavelength of the output pulsed light can be changed by fine-tuning the pump laser wavelength—the wavelength of the 1064nm continuous-wave laser. Simultaneously, the PPLN waveguide temperature needs to be adjusted accordingly to achieve optimal output. To test the performance of a silicon single-photon detector at 863nm, a common 1550nm pulsed laser can be used as the signal light, and a 1950nm continuous-wave laser as the pump light. The output pulsed light is then up-converted and frequency-controlled via a PPLN waveguide, and noise is filtered out to produce the desired 863nm pulsed light.

[0038] This embodiment of the pulsed light output module can achieve pulsed light output within a certain wavelength range based on a single pulsed laser and a single continuous laser. It can also achieve pulsed light output of specific wavelengths that are not easy to achieve in engineering. Compared with the solution of using a series of pulsed lasers, the cost is much lower and it is easier to achieve wide wavelength calibration.

[0039] Based on the pulsed light output module of Embodiment 1 above, Embodiment 2 provides a... Figure 2The single-photon detector calibration system shown includes the pulsed light output module in Embodiment 1 above, as well as a single-photon calibration module and a time-to-digital converter. It should be noted that, although... Figure 2 The system includes a single-photon detector, but the single-photon detector calibration system in this embodiment does not include a single-photon detector. It is only used here to illustrate the specific connection method between the single-photon detector calibration system and the single-photon detector to be calibrated.

[0040] The output terminal of the pulsed light output module is connected to the input terminal of the single-photon calibration module, the output terminal of the single-photon calibration module is used to connect to the input terminal of the single-photon detector to be calibrated, and the input terminal of the time-to-digital converter is used to connect to the counting signal output terminal of the single-photon detector to be calibrated.

[0041] In this embodiment, after obtaining the required pulse light through the pulse light output module, the obtained pulse light is input into the single-photon detector through the single-photon calibration module. The single-photon detector counting signal is then input into the time-to-digital converter (TDC) for data processing, thereby obtaining the performance parameters of the single-photon detector such as efficiency, dead time, afterpulse, and time accuracy, and completing its calibration.

[0042] Among them, the single-photon calibration module is as follows Figure 3 As shown, it includes: a first adjustable attenuator, a beam splitter, and an optical power meter.

[0043] The input terminal of the first adjustable attenuator is connected to the input terminal of the single-photon calibration module, the output terminal of the first adjustable attenuator is connected to the input terminal of the beam splitter, the first output terminal of the beam splitter is connected to the input terminal of the optical power meter, and the second output terminal of the beam splitter is connected to the output terminal of the single-photon calibration module.

[0044] To calibrate the performance of a single-photon detector, the light source needs to be attenuated to a single-photon state. This is because the conventional optical power meter used at the monitoring end lacks the accuracy to directly measure single-photon levels; therefore, calibration can only be achieved through indirect measurement. This embodiment employs a combination of a first adjustable attenuator and a beam splitter to attenuate the pulsed light to the single-photon level before inputting it to the single-photon detector. The first adjustable attenuator is... Figure 3 The adjustable attenuator A1 is used, ensuring that the optical power level at the monitoring end is within the measurable range of the optical power meter. Single-photon level calibration can be achieved by adjusting the adjustable attenuator A1 and monitoring the optical power at the monitoring end.

[0045] Furthermore, to improve the sensitivity of attenuation control of the desired pulse light by adjusting the adjustable attenuator A1, i.e., the first adjustable attenuator, it is preferable to also employ... Figure 3The adjustable attenuator A2 shown serves as the second adjustable attenuator, and the attenuation value of both the beam splitter and the adjustable attenuator A2 is set to a fixed value, preferably 50 dB. This improves the operational flexibility of the single-photon detector calibration system.

[0046] This invention proposes a calibration system based on a waveguide with sum-frequency characteristics, particularly a periodically polarized lithium niobate (PPLN) waveguide, to achieve pulsed laser output within a certain wavelength range using a single pulsed laser and a single continuous laser. It can also achieve pulsed laser outputs that are difficult to implement in engineering. Since pulsed lasers are much more expensive than continuous lasers, compared to existing methods that require a series of pulsed lasers to generate pulsed lasers within the aforementioned wavelength range, this calibration system offers a much lower cost and a more comprehensive range of applications for single-photon detector calibration.

[0047] The above-described embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this utility model, and should all be included within the protection scope of this utility model.

Claims

1. A pulsed light output module, characterized in that, include: Pulsed lasers, continuous lasers, and lithium niobate waveguides; The output end of the pulsed laser is connected to the incident end of the lithium niobate waveguide, the output end of the continuous laser is connected to the incident end of the lithium niobate waveguide, and the emitting end of the lithium niobate waveguide is connected to the output end of the pulsed light output module.

2. The pulsed light output module according to claim 1, characterized in that, The lithium niobate waveguide is a periodically polarized lithium niobate waveguide.

3. The pulsed light output module according to claim 2, characterized in that, It also includes a filter, with the output end of the periodically polarized lithium niobate waveguide connected to the input end of the filter, and the output end of the filter connected to the output end of the pulsed light output module.

4. A single-photon detector calibration system, characterized in that, The system includes the pulsed light output module as described in any one of claims 1 to 3, and further includes a single-photon calibration module and a time-to-digital converter; The output terminal of the pulsed light output module is connected to the input terminal of the single-photon calibration module, the output terminal of the single-photon calibration module is used to connect to the input terminal of the single-photon detector to be calibrated, and the input terminal of the time-to-digital converter is used to connect to the counting signal output terminal of the single-photon detector to be calibrated.

5. The single-photon detector calibration system according to claim 4, characterized in that, The single-photon calibration module includes: a first adjustable attenuator, a beam splitter, and an optical power meter; The input terminal of the first adjustable attenuator is connected to the input terminal of the single-photon calibration module, the output terminal of the first adjustable attenuator is connected to the input terminal of the beam splitter, the first output terminal of the beam splitter is connected to the input terminal of the optical power meter, and the second output terminal of the beam splitter is connected to the output terminal of the single-photon calibration module.

6. The single-photon detector calibration system according to claim 5, characterized in that, The single-photon calibration module also includes a second adjustable attenuator; The second output terminal of the beam splitter is connected to the input terminal of the second adjustable attenuator, and the output terminal of the second adjustable attenuator is connected to the output terminal of the single-photon calibration module.

7. The single-photon detector calibration system according to claim 6, characterized in that, The attenuation value of the beam splitter and the second adjustable attenuator is 50 dB.

Images