A method and apparatus for quantum stabilization of laser power

Abstract

The application discloses a method and device for quantum stabilization of laser power. First input laser is received, the wavelength of the first laser is resonant with the atomic clock energy level transition frequency; the output frequency of the atomic clock is measured as the first output frequency; second input laser is received, the wavelength of the second laser is the same as that of the first laser, the second laser power is known and stable; the second output frequency of the atomic clock is measured as the calibration output frequency; the difference between the first output frequency and the calibration output frequency is taken as feedback to control the power of the first laser. The method and device realize quantum stabilization control of laser power, which can not only adapt to wide range of laser power measurement, but also maintain high precision.

Description

Technical Field

[0001] This application relates to the field of optoelectronic technology, and in particular to a method and apparatus for quantum stabilization of laser signal power utilizing atomic transitions within an atomic clock. Background Technology

[0002] In research fields such as precision measurement, laser ranging, and laser interferometry, fluctuations in laser output power directly affect the accuracy of measurement and the stability of the system. Therefore, the requirements for the stability of laser output power are becoming increasingly stringent.

[0003] Currently, internationally, the measurement of laser power and the calibration of the device under test mainly utilize laser radiometers and calorimeters, along with photodetectors, to measure power. Depending on the parameters of the laser being measured, the measurement uncertainty ranges from 0.01% to 2%. In the current definition of luminous intensity in the International System of Units (SI), the measurement uncertainty is 10⁻⁶. -4 Regarding the magnitude of light emission, some research groups are already working on new definitions, such as defining the candela by counting photons. However, due to the unique nature of light emission intensity and the issues related to human eye sensitivity, progress has been limited. Current methods achieve relatively low power stability, which is insufficient to meet the needs of fields such as precision measurement.

[0004] An atomic clock consists of an atomic clock cell filled with an atomic beam, along with related optical and electrical systems. Essentially, it uses the resonant transitions between atomic energy levels to calibrate the frequency of a laser or a voltage-controlled oscillator. Theoretically, the output frequency of an atomic clock depends only on the transition frequencies of its atomic energy levels, thus exhibiting high stability and accuracy. Currently, the accuracy of realized atomic clocks has reached 10-1. -16 The order of magnitude became the most accurate basic unit of clock frequency.

[0005] For atomic energy level transitions, the transition frequency changes under the influence of external laser light, producing an optical frequency shift effect. This principle provides a theoretical basis for converting laser power measurement into frequency measurement. Furthermore, there is currently no literature researching methods for quantum stabilization of laser power. Summary of the Invention

[0006] This application proposes a method and apparatus for quantum stabilizing laser power to address the technical deficiency of low laser power stability.

[0007] This application proposes a method for quantum stabilizing laser power, comprising:

[0008] The input first laser is received, and the wavelength of the first laser resonates with the energy level transition frequency of the atomic clock.

[0009] The output frequency of the atomic clock is measured and used as the first output frequency.

[0010] The system receives a second laser input, the wavelength of which is the same as that of the first laser, and the power of the second laser is known and stable.

[0011] The second output frequency of the atomic clock is measured and used as the calibration output frequency.

[0012] The difference between the first output frequency and the calibrated output frequency is used as feedback to control the power of the first laser.

[0013] This application also proposes a quantum stabilization device for laser power, comprising a first laser, a second laser, a frequency measurement module, a feedback module, and a stabilization module.

[0014] The first laser outputs a first laser beam, the wavelength of which resonates with the energy level transition frequency of the atomic clock.

[0015] The second laser outputs a second laser, the wavelength of which is the same as that of the first laser, and the power of the second laser is known and stable.

[0016] The frequency measurement module receives the input first laser and measures the output frequency of the atomic clock as the first output frequency; it also receives the input second laser and measures the second output frequency of the atomic clock as the calibration output frequency.

[0017] The feedback module takes the difference between the first output frequency and the calibrated output frequency as feedback and outputs it to the stabilization module.

[0018] The stabilization module receives the feedback and controls the power of the first laser.

[0019] The quantum stabilization method and apparatus for laser power proposed in this application use the difference between the output frequency of the first laser after it is input into the atomic clock and the calibrated output frequency of the second laser after it is input into the atomic clock as feedback to stabilize the laser power, thereby improving the stability of the laser power. It can achieve laser power control both outside and inside the cavity, thus solving the defect of low power stability in laser power control. Attached Figure Description

[0020] 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:

[0021] Figure 1 A schematic diagram of the quantum stabilization method for laser power provided by the present invention;

[0022] Figure 2 A schematic diagram of the quantum stabilization device for laser power provided by the present invention. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0024] The technical solutions provided by the various embodiments of this application are described in detail below with reference to the accompanying drawings.

[0025] Example 1

[0026] The following is combined with Figure 1 This will illustrate the quantum stabilization method for laser power in this application.

[0027] Step 110: Receive the input first laser, the wavelength of which resonates with the energy level transition frequency of the atomic clock.

[0028] The energy level transition frequencies of the atomic beam in an atomic clock exhibit frequency shift characteristics under the influence of an external light field, causing the output frequency of the atomic clock to change relative to its output frequency without the influence of a light field. In this embodiment, under the premise that the wavelength of the first laser resonates with the energy level transition frequency of the atomic clock, the first laser is introduced into the atomic clock, and the output frequency of the atomic clock will change with the power of the first laser.

[0029] Furthermore, the first laser beam is parallel to the direction of the atomic beam in the atomic clock. In this embodiment, the resonance effect is better when the direction of the atomic beam is parallel to the direction of the first laser beam.

[0030] Step 120: Measure the output frequency of the atomic clock and use it as the first output frequency.

[0031] Step 130: Receive the input of a second laser, the wavelength of which is the same as that of the first laser, and the power of the second laser is known and stable.

[0032] In an atomic clock, the energy level transition frequencies of the atomic beam exhibit frequency shift characteristics under the influence of an external light field, causing the atomic clock's output frequency to change relative to its output frequency without the influence of a light field. In this embodiment, when the wavelengths of the first and second lasers are the same and both resonate with the energy level transition frequencies of the atomic clock, the change in the atomic clock's output frequency is determined by the magnitude of the laser power. With the power of the second laser known and stable, the output frequency of the atomic clock is also stable.

[0033] Furthermore, the second laser beam is parallel to the direction of the atomic beam in the atomic clock. In this embodiment, the resonance effect is better when the direction of the atomic beam is parallel to the direction of the second laser beam.

[0034] Step 140: Measure the second output frequency of the atomic clock as the calibration output frequency.

[0035] The wavelength and power of the second laser are fixed, and the output frequency of the atomic clock is stable. It serves as the calibration output frequency for benchmarking other laser signals with uncertain power.

[0036] Step 150: Use the difference between the first output frequency and the calibrated output frequency as feedback to control the power of the first laser.

[0037] The difference between the first output frequency and the calibrated output frequency can be greater than 0, less than 0, or equal to 0.

[0038] If the difference between the first output frequency and the calibrated output frequency is greater than 0, then the power of the first laser is greater than the power of the second laser.

[0039] If the difference between the first output frequency and the calibrated output frequency is less than 0, then the power of the first laser is less than the power of the second laser.

[0040] If the difference between the first output frequency and the calibrated output frequency is equal to 0, then the power of the first laser is equal to the power of the second laser.

[0041] Furthermore, the control includes using the difference between the first output frequency and the calibrated output frequency as the input signal for servo control, and outputting a laser power control quantity.

[0042] If the difference between the first output frequency and the calibrated output frequency is greater than 0, then the power of the first laser is reduced.

[0043] If the difference between the first output frequency and the calibrated output frequency is less than 0, then the power of the first laser is increased.

[0044] If the difference between the first output frequency and the calibrated output frequency is equal to 0, then the power of the first laser is kept constant.

[0045] In this embodiment, the power of the first laser is controlled according to the laser power control amount.

[0046] In this embodiment, the method for controlling the power of the first laser includes controlling the diffraction efficiency of the first laser when it passes through an acousto-optic modulator using an external modulation device such as an acousto-optic modulator, thereby controlling the power of the first laser.

[0047] Optionally, the method for controlling the power of the first laser includes controlling the power of the first laser by adjusting parameters such as the cavity length and temperature of the laser.

[0048] This method utilizes the high output frequency accuracy of atomic clocks and the optical frequency shift characteristics of atomic clock energy level transitions. Compared with existing laser power stabilization methods, the quantum stabilization method for laser power described in this embodiment can surpass the accuracy limitations of traditional photosensitive probes, thermal probes, and other measurement methods. It can adapt to a wide range of laser power measurements, from microwatts (uW) to petawatts, while significantly improving laser power stability and reducing the uncertainty of laser power measurement.

[0049] Example 2

[0050] Figure 2 A schematic diagram of a quantum stabilization device for laser power is shown, including a first laser 210, a second laser 220, a frequency measurement module 230, a feedback module 240, and a stabilization module 250, as detailed below:

[0051] The first laser 210 outputs a first laser, the wavelength of which resonates with the energy level transition frequency of the atomic clock.

[0052] In this embodiment, the first laser wavelength is 795nm and the power is approximately 1mW.

[0053] The second laser 220 outputs a second laser, the wavelength of which is the same as that of the first laser, and the power of the second laser is known and stable.

[0054] In this embodiment, the second laser wavelength is 795nm and the power is constant at 1mW.

[0055] The frequency measurement module 230 receives the input first laser and measures the output frequency of the atomic clock as the first output frequency; it also receives the input second laser and measures the second output frequency of the atomic clock as the calibration output frequency.

[0056] In this embodiment, the frequency measurement module 230 includes an atomic clock, specifically a 10MHz rubidium atomic clock. After the second laser is input to the frequency measurement module, the output frequency of the rubidium atomic clock increases by 0.13Hz, resulting in a frequency shift of 1.3E-8 (@10MHz). After the first laser is input to the frequency measurement module, the output frequency of the rubidium atomic clock changes by 0.10 to 0.16Hz.

[0057] Preferably, a timer switch is used to switch the first laser and the second laser into the frequency measurement module 230. For example, the first laser is switched into the frequency measurement module every minute for 50 seconds, and then the second laser is switched into the measurement module for 10 seconds. This method and device reduce the systematic error in the output frequency measurement and improve the accuracy of the measurement.

[0058] The feedback module 240 takes the difference between the first output frequency and the calibrated output frequency as feedback and outputs it to the stabilization module 250.

[0059] In this embodiment,

[0060] The stabilization module 250 receives the feedback and controls the power of the first laser.

[0061] Furthermore, the stabilization module 250 receives feedback and controls the power of the first laser, including:

[0062] If the difference between the first output frequency and the calibrated output frequency is greater than 0, then the power of the first laser is greater than the power of the second laser, and the power of the first laser is controlled to decrease.

[0063] If the difference between the first output frequency and the calibrated output frequency is less than 0, then the power of the first laser is less than the power of the second laser, and the power of the first laser is controlled to increase.

[0064] If the difference between the first output frequency and the calibrated output frequency is equal to 0, then the power of the first laser is equal to the power of the second laser, and the power of the first laser is kept constant.

[0065] Furthermore, after controlling the power of the first laser to decrease or increase, the laser output from the first laser is input into the frequency measurement module 230 to obtain the output frequency of the first laser. The feedback module 240 uses the difference between the output frequency of the first laser and the calibrated output frequency as feedback input to the stabilization module 250 to control the power of the first laser.

[0066] In this embodiment, the output frequency of the rubidium atomic clock increases by 0.13 Hz after the calibration laser is applied, resulting in a frequency shift of 1.3E-8 (@10MHz). Using the rubidium clock's second stability of 3E-12 as a reference, the laser's second-level relative power at 1mW can be stabilized to the order of 1E-4.

[0067] The device described in this application achieves quantum stability of laser power, significantly improving laser power stability.

[0068] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0069] The above description is merely an 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 spirit and principle of this application should be included within the scope of the claims of this application.

Claims

1. A method for quantum stabilizing laser power, characterized in that, include: The first laser and the second laser are switched to enter the frequency measurement module by a timer switch device. The first laser and the second laser have the same wavelength and resonate with the energy level transition frequency of the atomic clock. The system receives the input first laser, measures the output frequency of the atomic clock, and obtains the first output frequency generated by the atomic clock based on the influence of the power of the first laser on the output frequency of the atomic clock through the optical frequency shift effect. The second laser input is received. The power of the second laser is known and stable. The second laser is input into the atomic clock to obtain a second output frequency generated by the atomic clock that corresponds to the known and stable power. This second output frequency is used as the calibration output frequency. The difference between the first output frequency and the calibrated output frequency is used as feedback and input to the servo control loop; Based on the deviation of the feedback signal from the zero point, a laser power control quantity is generated to control the power of the first laser, so that the difference between the first output frequency and the calibrated output frequency approaches zero, and the laser relative power at 1mW is stabilized at the second level to the 1E-4 level. Specifically, if the difference between the first output frequency and the calibrated output frequency is greater than 0, the power of the first laser is controlled to decrease; if the difference between the first output frequency and the calibrated output frequency is less than 0, the power of the first laser is controlled to increase; if the difference between the first output frequency and the calibrated output frequency is equal to 0, the power of the first laser is controlled to remain unchanged. The method of switching the first laser and the second laser into the frequency measurement module by means of a timed switch includes: switching the first laser into the frequency measurement module every 1 minute for 50 seconds, and then switching the second laser into the measurement module for 10 seconds; at least one of the first laser and the second laser is parallel to the direction of the atomic beam in the atomic clock.

2. The method for quantum stabilizing laser power according to claim 1, characterized in that, The method for controlling the power of the first laser includes controlling the diffraction efficiency of the first laser as it passes through the acousto-optic modulator using an external modulation device, thereby adjusting the power of the first laser.

3. The method for quantum stabilizing laser power according to claim 1, characterized in that, Methods for controlling the power of the first laser include adjusting the power of the first laser by adjusting the cavity length and / or temperature parameters of the laser.

4. A quantum stabilizing device for laser power, used to implement the method according to any one of claims 1 to 3, characterized in that, It includes a first laser, a second laser, a frequency measurement module, a feedback module, and a stabilization module. The first laser outputs a first laser beam, the wavelength of which resonates with the energy level transition frequency of the atomic clock. The second laser outputs a second laser, the wavelength of which is the same as that of the first laser, and the power of the second laser is known and stable. The frequency measurement module receives the input first laser and measures the output frequency of the atomic clock as the first output frequency; it also receives the input second laser and measures the second output frequency of the atomic clock as the calibration output frequency. The feedback module takes the difference between the first output frequency and the calibrated output frequency as feedback and outputs it to the stabilization module. The stabilization module receives the feedback and controls the power of the first laser.

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