atomic oscillator

Abstract

To solve a problem in difficulty of providing an atomic oscillator having high long-term stability, while achieving miniaturization.SOLUTION: An atomic oscillator 100 includes: a light generator 101 for generating first excitation light of a designated single wavelength and generating second excitation light including two frequency components by performing frequency modulation by designated frequency modulation power from the first excitation light; an alkali metal atom gas cell 102 to which the second excitation light including two frequency components is irradiated with its frequency difference being changed; a measurement unit 103 for measuring an amount of light transmitted through an alkali metal atom gas cell; and a calculation unit 104 for calculating frequency modulation power based on a distribution of the amount of transmitted light with respect to the frequency difference between the two frequency components in the second excitation light that is measured each time the wavelength and frequency modulation power of the first excitation light are changed by the light generator.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present invention relates to an atomic oscillator, a control method, a control device, and a program. [Background technology]

[0002] An atomic oscillator is a device that measures time accurately based on the natural frequency of an atom. Compact atomic clocks mainly measure the natural frequency of an atom by using coherent population trapping (CPT), a quantum interference effect that occurs when an alkali metal atomic gas is irradiated with excitation light of two frequencies. In CPT, when the difference in the frequencies of the two excitation lights matches the transition frequency between the ground levels of the alkali metal, the amount of transmitted light increases without absorption of the excitation light. Atomic oscillators that use CPT as their operating principle sweep the difference in the frequency of the excitation lights, and the frequency difference at which the amount of transmitted light is maximized is taken as the natural frequency of the atom. Whether or not this natural frequency of the atom can be stably obtained over a long period of time (long-term stability) is one of the performance indicators of an atomic oscillator.

[0003] In atomic frequency measurements using CPT, the main factor that reduces the long-term stability is the change in the light shift over time. The light shift is a phenomenon in which the atomic frequency shifts due to the interaction between the excitation light and the atom. Specifically, changes over time in the intensity, wavelength, and intensity ratio of the two frequency components of the total excitation light induce changes in the light shift over time, reducing the long-term stability of the atomic clock.

[0004] In conventional atomic clocks, the excitation light contains multiple frequency components generated by applying frequency modulation at half the transition frequency between the ground levels of alkali metal atoms to a single frequency light, and the ±1st-order sidebands of this excitation light are used to generate and detect CPT. The intensity ratio of these ±1st-order sidebands is always approximately 1:1, which has the advantage that no intensity ratio correction is required to implement a stable atomic clock. However, the method using these ±1st-order sidebands has the disadvantage that the change in light shift relative to the change in total excitation light intensity is relatively large, resulting in reduced long-term stability.

[0005] As an example of a method to solve this disadvantage, atomic clocks have been reported that include a mechanism to suppress changes in the light shift over time by correcting for changes in the intensity of the total pump light. For example, Patent Document 1 describes an atomic clock equipped with a mechanism that corrects the total pump light intensity to a constant value by using two types of light sources. However, since it is impossible to maintain a completely constant value for the total pump light intensity, using the ±1st-order sidebands, which are also employed in the examples of this patent document, for CPT generation and detection is undesirable from the perspective of long-term stability, as they result in large changes in the light shift relative to changes in the total pump light intensity. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-72371 Summary of the Invention [Problem to be solved by the invention]

[0007] The above-mentioned problems can be solved by using pairs of -1st and 0th orders or +1st and 0th orders in the pump light, which is frequency-modulated to a single frequency equal to the ground-level transition frequency, for CPT generation and detection. When frequency-modulated to a single frequency equal to the ground-level transition frequency, the sidebands are farther apart in frequency than when frequency-modulated to half the ground-level transition frequency. Therefore, for cesium atoms, when frequency-modulated to a single frequency equal to the ground-level transition frequency, the change in light shift relative to a change in total pump light intensity is approximately one-quarter of that when frequency-modulated to half the ground-level transition frequency. Therefore, to develop an atomic clock that is stable against changes in total pump light intensity, it is desirable to use pairs of -1st and 0th orders or +1st and 0th orders in the pump light, which is frequency-modulated to a single frequency equal to the ground-level transition frequency, for CPT generation and detection. However, unlike the ±1st-order light, the intensity ratio between the -1st and 0th order light or the +1st and 0th order light depends on the frequency modulation power. Therefore, a mechanism for correcting the intensity ratio is required to implement an atomic clock with high long-term stability.

[0008] However, in order to provide a mechanism for correcting the intensity ratio, it is necessary to incorporate a new device such as a Fabry-Perot interferometer to monitor the intensity ratio, which creates the problem that it is not possible to miniaturize the atomic oscillator itself.

[0009] Therefore, an object of the present invention is to solve the above-mentioned problem that it is difficult to provide an atomic oscillator that is compact and has high long-term stability. [Means for solving the problem]

[0010] An atomic oscillator according to one aspect of the present invention includes: a light generator that generates first excitation light of a specified single wavelength and generates second excitation light containing two frequency components by frequency-modulating the first excitation light with a specified frequency modulation power; an alkali metal atomic gas cell that is irradiated with the second excitation light with a changed frequency difference between the two frequency components; a measuring unit for measuring the amount of light transmitted through the alkali metal atomic gas cell; a calculation unit that calculates the frequency modulation power based on a distribution of the amount of transmitted light with respect to a frequency difference between two frequency components of the second excitation light, the distribution being measured each time the wavelength of the first excitation light and the frequency modulation power are changed by the light generator; and Equipped with The structure is as follows.

[0011] Furthermore, a control method according to one aspect of the present invention includes: a light generator that generates first excitation light of a specified single wavelength and generates second excitation light containing two frequency components by frequency-modulating the first excitation light with a specified frequency modulation power; an alkali metal atomic gas cell that is irradiated with the second excitation light with a changed frequency difference between the two frequency components; a measuring unit for measuring the amount of light transmitted through the alkali metal atomic gas cell, measuring the amount of transmitted light relative to the frequency difference between the two frequency components in the second excitation light, and calculating the frequency modulation power based on a distribution of the amount of transmitted light relative to the frequency difference between the two frequency components in the second excitation light measured each time the wavelength of the first excitation light and the frequency modulation power are changed by the light generator; The structure is as follows.

[0012] Furthermore, a control device according to one aspect of the present invention includes: a light generator that generates first excitation light of a specified single wavelength and generates second excitation light by frequency-modulating the first excitation light with a specified frequency modulation power; an alkali metal atomic gas cell that is irradiated with the second excitation light with a frequency difference between two frequency components changed; a measuring unit for measuring the amount of light transmitted through the alkali metal atomic gas cell, calculating the frequency modulation power based on a distribution of the amount of transmitted light relative to the frequency difference between two frequency components of the second excitation light, the distribution being measured each time the wavelength of the first excitation light and the frequency modulation power are changed by the light generator; The structure is as follows.

[0013] Furthermore, a program according to one aspect of the present invention includes: a light generator that generates first excitation light of a specified single wavelength and generates second excitation light by frequency-modulating the first excitation light with a specified frequency modulation power; an alkali metal atomic gas cell that is irradiated with the second excitation light with a frequency difference between two frequency components changed; a control device for controlling an atomic oscillator having a measuring unit for measuring the amount of light transmitted through the alkali metal atomic gas cell, calculating the frequency modulation power based on a distribution of the amount of transmitted light relative to the frequency difference between two frequency components of the second excitation light, the distribution being measured each time the wavelength of the first excitation light and the frequency modulation power are changed by the light generator; Execute the process, The structure is as follows. [Effects of the Invention]

[0014] With the above-described configuration, the present invention can provide an atomic oscillator that is compact and has high long-term stability. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a block diagram showing an outline of the configuration of an atomic oscillator according to a first embodiment of the present invention. [Figure 2]2 is a flowchart showing an algorithm for calculating frequency modulation power by the atomic oscillator disclosed in FIG. 1. [Figure 3] FIG. 1 is a block diagram showing the configuration of an atomic oscillator used in a verification experiment of a first embodiment of the present invention. [Figure 4] FIG. 4 is a diagram showing how data processing of measurement values ​​by the atomic oscillator disclosed in FIG. 3 is performed. [Figure 5] FIG. 4 is a diagram showing how data processing of measurement values ​​by the atomic oscillator disclosed in FIG. 3 is performed. [Figure 6] FIG. 4 is a diagram showing how data processing of measurement values ​​by the atomic oscillator disclosed in FIG. 3 is performed. [Figure 7] FIG. 4 is a diagram showing how data processing of measurement values ​​by the atomic oscillator disclosed in FIG. 3 is performed. [Figure 8] FIG. 10 is a block diagram showing the configuration of an atomic oscillator according to a second embodiment of the present invention. [Figure 9] 10 is a flowchart showing the operation of the atomic oscillator according to the second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0016] <Embodiment 1> A first embodiment of the present invention will be described with reference to FIGS.

[0017] [Configuration and operation] 1 is a block diagram showing an outline of the configuration of an atomic oscillator according to this embodiment. The atomic oscillator according to this embodiment includes a light generator 1, an alkali metal atomic gas cell 2, a photodetector 3, and a calculator 4. The light generator 1 includes a frequency modulation unit 11, an intensity control unit 12, and a wavelength control unit 13. The calculator 4 includes a distortion parameter calculation unit 41, a frequency modulation setting value calculation unit 42, an intensity control setting value calculation unit 43, and a wavelength control setting value calculation unit 44. The calculator 4 is configured as an information processing device (control device) equipped with an arithmetic unit and a storage device, and the units 41 to 44 of the calculator 4 are realized by executing a program on the arithmetic unit.

[0018] The light generator 1 generates pump light of a single wavelength and generates two pump lights by frequency-modulating the single-wavelength pump light, and irradiates the alkali metal atomic gas cell 2 with these. Specifically, the light generator 1 generates pump light of a single wavelength in the range of 894.5770 to 894.5820 nm from the wavelength control unit 13 based on the setting values ​​specified by the wavelength control setting value calculation unit 44 of the calculator 4. This single-wavelength pump light (first pump light) is sent to the frequency modulation unit 11, where it is frequency-modulated with a modulation frequency of around 9.2 GHz, which corresponds to the transition frequency between the ground levels of cesium atoms, specified by the frequency modulation setting value calculation unit 42 of the calculator 4, and a frequency modulation power of 5 to 18 dBm, thereby modulating it into pump light (second pump light) containing zeroth-order and -1st-order sidebands. Next, this pump light is sent to the intensity control unit 12, where it is attenuated to an intensity of 1 to 0.1 times the intensity specified by the intensity control setting value calculation unit 43 of the calculator 4. This excitation light is converted into circularly polarized light by a λ / 2 plate and a λ / 4 plate, and then irradiated onto the cesium atomic gas cell 2 .

[0019] In this way, the wavelength of the single-wavelength excitation light, the modulation frequency and frequency modulation power during frequency modulation, and the intensity of the total excitation light are set at any time by the calculator 4, and the light generator 1 irradiates the generated excitation light onto the alkali metal atomic gas cell 2 while changing, i.e., sweeping, these set values.

[0020] The alkali metal atom gas cell 2 is filled with alkali metal atoms such as cesium atoms, rubidium atoms, sodium atoms, and potassium atoms. In the first embodiment, cesium atoms are filled in the gas cell. The alkali metal atom gas cell 2 is installed in a space to which a magnetic field is applied, and as described above, excitation light from the light generator 1 is incident on the alkali metal atom gas cell 2, with a portion of the light being transmitted through the cell.

[0021] The photodetector 3 (measurement unit) detects the transmitted light that has passed through the alkali metal atomic gas cell 2 and measures the amount of transmitted light. At this time, the excitation light is irradiated while changing the setting values ​​of the wavelength of the single wavelength excitation light, the modulation frequency and frequency modulation power during frequency modulation, and the intensity of the total excitation light. Therefore, the measured amount of transmitted light is passed to the calculator 4 in association with each changed setting value.

[0022] The calculator 4 (calculation unit) determines the setting values ​​for correcting the frequency modulation power using the algorithm shown in Fig. 2, using the units 41 to 44 shown in Fig. 1. First, the wavelength control setting value calculation unit 44, frequency modulation setting value calculation unit 42, and intensity control setting value calculation unit 43 of the calculator 4 respectively set the start value, increase value, and sweep range of the setting values ​​for the wavelength of the single-wavelength excitation light, the modulation frequency and frequency modulation power during frequency modulation, and the intensity of the excitation light, and also set the excitation light intensity and control the light generator 1 to generate excitation light at these setting values ​​(step S1). As a result, excitation light from the light generator 1 is irradiated onto the alkali metal atomic gas cell 2, and the transmitted light is measured by the photodetector 3 (step S2).

[0023] The distortion parameter calculation unit 41 plots the amount of transmitted light versus the frequency difference between the swept 0th-order and −1st-order sidebands from the amount of transmitted light measured by the photodetector 3. That is, it generates a distribution of the amount of transmitted light versus the frequency difference between the two pump lights. Then, the distortion parameter calculation unit 41 calculates a distortion parameter q (distribution characteristic value) that represents the characteristics of this distribution by fitting this plot using the least squares method with equation 1. Then, the distortion parameter q is recorded together with the setting values ​​of the single-wavelength pump light and frequency modulation power at that time (step S3).

[0024]

number

[0025] It is known that the transmitted light distribution in a typical CPT resonance can be fitted using equation 1. The distortion parameter q represents the ratio of the asymmetric to symmetric components in the transmitted light distribution. Specifically, when the coefficient of the symmetric Lorentz component is S and the coefficient of the antisymmetric Lorentz component is A, q can be written as A / S. Therefore, the smaller the value (degree) of the distortion parameter q, the smaller the ratio of the asymmetric component to the symmetric component, resulting in a transmitted light distribution with symmetrical characteristics. An example of fitting the transmitted light distribution and the distortion parameter q is shown in Figure 4, which will be discussed later.

[0026] Next, according to the algorithm shown in FIG. 2, the calculator 4 repeats the above measurement while sweeping the wavelength setting value of the single-wavelength pump light in the range of 894.5770 to 894.5820 nm and the frequency modulation power setting value in the range of 5 to 18 dBm (No in step S4, step S6). This generates a data set of the wavelength of the single-wavelength pump light, the frequency modulation power, and the distortion parameter q. Then, for this data set, the calculator 4 calculates, for example, the variance of q with respect to the frequency modulation power value, and determines the frequency modulation power value that minimizes the variance of q. The frequency modulation setting value calculation unit 42 of the calculator 4 then updates the determined frequency modulation power as the new setting value of the frequency modulation unit 11 of the light generator 1 (step S5).

[0027] As described above, the atomic oscillator according to the first embodiment of the present invention is provided with a mechanism for fixing the set value of the frequency modulation power of the frequency modulation unit 11 to a constant value based on the transmitted light amount distribution measured by the photodetector 3. This eliminates the need to introduce a new device for directly monitoring the intensity ratio, and makes it possible to provide an atomic oscillator that is compact, has little change in light shift over time, and has high long-term stability.

[0028] [Verification experiment] Next, we will explain the results of a verification experiment using the atomic oscillator shown in Figure 3, which embodies the configuration of the atomic oscillator shown in Figure 1. In the atomic oscillator shown in Figure 3, first, excitation light is generated from a wavelength-controllable laser 13. Next, this excitation light is frequency-modulated by a signal generator and optical frequency modulator 11, and the intensity of the frequency-modulated excitation light is controlled by an optical attenuator 12. Then, the excitation light modulated to the intensity set by the optical attenuator 12 is converted into circularly polarized light by a λ / 2 plate and a λ / 4 plate.

[0029] Next, excitation light is irradiated from the light generator 1 onto a cesium atomic gas cell 2, which is placed at a position where the frequency-modulated and intensity-modulated excitation light passes through. The cesium atomic gas cell is installed in the space where the magnetic field is applied. Then, a photodetector 3 is placed at a position where it detects the light that has passed through the cesium atomic gas cell, and the amount of transmitted light recorded by the photodetector 3 is received by a computer 4. The computer 4 then calculates the distortion parameter q using the measured amount of transmitted light, and determines a new frequency modulation power.

[0030] Figure 4 shows the results of fitting the transmitted light amount against the frequency difference between the 0th-order and -1st-order sidebands in the distortion parameter calculation unit 41 of the computer 4 using the atomic oscillator shown in Figure 3, using equation 1. As shown in Figure 4, it can be confirmed that the transmitted light amount distribution is successfully fitted by equation 1. Therefore, it has been demonstrated that the above-mentioned method can calculate the resonance frequency and distortion parameter q for a specific 0th-order light wavelength, frequency modulation power, and excitation light intensity.

[0031] Figure 5 shows the results of investigating the light shift when sweeping the zeroth-order light wavelength and frequency modulation power. As a result of this experiment, it was confirmed that the resonance frequency shifts depending on the frequency modulation power. Therefore, it was shown that by adding a mechanism to fix the frequency modulation power at a constant value, it is possible to suppress the shift change and improve long-term stability.

[0032] Figure 6 shows the results of linear fitting the plot of the distortion parameter q and frequency modulation power for each wavelength. The frequency modulation power at which the dispersion of q relative to wavelength variation is minimized was calculated to be 15.10 dBm.

[0033] Figure 7 shows the results of an experiment similar to that shown in Figure 6, in which the total pump light intensity was varied. The variance of the distortion parameter q with respect to the frequency modulation power for each wavelength of the pump light of a single wavelength was calculated, and the frequency modulation power that minimized this variance is shown in the figure. As a result of the experiment, the strong frequency modulation power that minimizes the variance was 15.01 ± 0.05 (standard deviation) dBm, independent of the total pump light intensity. From this result, by providing a feedback mechanism that searches for and fixes the frequency modulation power that minimizes the variance of the distortion parameter q when the atomic oscillator is first used, it is possible to provide an atomic oscillator that maintains a constant total pump light intensity, has little change in light shift over time, and has high long-term stability.

[0034] As described above, the atomic oscillator according to the present invention can be utilized in the following fields. First, the Global Positioning System (GPS) performs stable and highly accurate positioning based on time data from atomic clocks installed on satellites. If inexpensive, highly accurate small atomic clocks were to be put into practical use, they could be used in a variety of devices, including automobiles, smartphones, small satellites, and mobile phone base stations. Furthermore, by installing high-precision small atomic clocks in sensors used in locations where GPS cannot be reached, such as inside buildings, under the sea, or in tunnels, it is expected that high-precision measurements and efficient remote operation of sensors can be realized through time synchronization between multiple sensors. Furthermore, installing high-precision small atomic clocks in moving objects such as automobiles and aircraft is expected to enable stable and highly accurate positioning, thereby realizing autonomous driving technology.

[0035] <Embodiment 2> Next, a second embodiment of the present invention will be described with reference to Fig. 8 and Fig. 9. Fig. 8 is a block diagram showing the configuration of an atomic oscillator in embodiment 2, and Fig. 9 is a flowchart showing the operation of the atomic oscillator. Note that this embodiment shows an outline of the configuration of the atomic oscillator and the control method described in the above embodiments.

[0036] As shown in FIG. 8, the atomic oscillator 100 in this embodiment is configured to include a light generator 101 that generates first excitation light of a specified single wavelength and generates second excitation light containing two frequency components by frequency-modulating the first excitation light with a specified frequency modulation power; an alkali metal atomic gas cell 102 that is irradiated with the second excitation light while changing the frequency difference between the two frequency components in the two second excitation lights; a measurement unit 103 that measures the amount of light transmitted through the alkali metal atomic gas cell; and a calculation unit 104 that calculates the frequency modulation power based on the distribution of the amount of transmitted light relative to the frequency difference between the two frequency components in the second excitation light, which is measured by the light generator every time the wavelength of the first excitation light and the frequency modulation power are changed.

[0037] 9, the calculation unit 104 (control device) having the above configuration measures the amount of transmitted light with respect to the frequency difference between the two frequency components in the second excitation light (step S101), and calculates the frequency modulation power based on the distribution of the amount of transmitted light with respect to the frequency difference between the two frequency components in the second excitation light measured each time the wavelength of the first excitation light and the frequency modulation power are changed by the light generator (step S102), thereby executing processing. Note that the processing by the calculation unit 104 is realized by an arithmetic device constituting the calculation unit 104 executing a program.

[0038] As described above, in the present invention, the frequency modulation power is calculated based on the distribution of the transmitted light amount relative to the frequency difference between two frequency components in the second excitation light, which is measured each time the wavelength of the first excitation light and the frequency modulation power are changed. By setting and fixing this frequency modulation power, it is possible to minimize the change in the light shift over time, and to provide an atomic oscillator that is compact and has high long-term stability.

[0039] Although the present invention has been described above with reference to the above-mentioned embodiments, the present invention is not limited to the above-mentioned embodiments. Various modifications that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention.

[0040] <Additional Notes> A part or all of the above-described embodiments can be described as follows: The following provides an overview of the configurations of the atomic oscillator, control method, control device, and program according to the present invention. However, the present invention is not limited to the following configurations. (Appendix 1) a light generator that generates first excitation light of a specified single wavelength and generates second excitation light containing two frequency components by frequency-modulating the first excitation light with a specified frequency modulation power; an alkali metal atomic gas cell to which the second excitation light containing two frequency components is irradiated with the second excitation light having its frequency difference changed; a measuring unit for measuring the amount of light transmitted through the alkali metal atomic gas cell; a calculation unit that calculates the frequency modulation power based on a distribution of the amount of transmitted light with respect to a frequency difference between two frequency components of the second excitation light, the distribution being measured each time the wavelength of the first excitation light and the frequency modulation power are changed by the light generator; and Equipped with Atomic oscillator. (Appendix 2) 2. The atomic oscillator according to claim 1, the calculation unit specifies, for the light generator, varying the wavelength of the first excitation light and the frequency modulation power, and calculates the frequency modulation power based on a distribution of the amount of transmitted light with respect to a frequency difference between two frequency components in the second excitation light measured each time the wavelength of the first excitation light and the frequency modulation power are changed. Atomic oscillator. (Appendix 3) 10. The atomic oscillator according to claim 2, the calculation unit calculates a distribution characteristic value that indicates a degree to which a distribution of the amount of transmitted light with respect to a change in the frequency difference between two frequency components of the second excitation light conforms to a predetermined characteristic, and calculates the frequency modulation power based on the distribution characteristic value. Atomic oscillator. (Appendix 4) 4. The atomic oscillator according to claim 3, the calculation unit calculates the distribution characteristic value representing the degree to which the distribution of the amount of transmitted light with respect to a change in the frequency difference between the two frequency components of the second excitation light is symmetrical, and calculates the frequency modulation power based on the distribution characteristic value. Atomic oscillator. (Appendix 5) 5. The atomic oscillator according to claim 3 or 4, the calculation unit specifies the frequency modulation power based on the distribution characteristic value for the frequency modulation power for each wavelength of the first excitation light that has been changed, and assigns the specified frequency modulation power to the light generator. Atomic oscillator. (Appendix 6) 6. The atomic oscillator according to claim 5, the calculation unit specifies the frequency modulation power at which the variance of the distribution characteristic value is minimum, based on the distribution characteristic value with respect to the frequency modulation power for each wavelength of the changed first excitation light, and specifies the specified frequency modulation power to the light generator. Atomic oscillator. (Appendix 7) a light generator that generates a first excitation light having a specified single wavelength and generates two second excitation lights by frequency modulating the first excitation light with a specified frequency modulation power; an alkali metal atomic gas cell to which the second excitation light containing two frequency components is irradiated with the second excitation light having its frequency difference changed; a measuring unit for measuring the amount of light transmitted through the alkali metal atomic gas cell, measuring the amount of transmitted light with respect to the frequency difference between the two frequency components in the second excitation light, and calculating the frequency modulation power based on a distribution of the amount of transmitted light with respect to the frequency difference between the two frequency components in the second excitation light measured each time the wavelength of the first excitation light and the frequency modulation power are changed by the light generator; Control method. (Appendix 7.1) 8. The control method of claim 7, further comprising: specifying the wavelength of the first excitation light and the frequency modulation power to the light generator while varying them, and calculating the frequency modulation power based on the distribution of the transmitted light amount with respect to the frequency difference between two frequency components in the second excitation light measured each time the wavelength of the first excitation light and the frequency modulation power are changed; Control method. (Appendix 7.2) 7.1, a control method according to claim 7.1, comprising: calculating a distribution characteristic value that indicates the degree to which a distribution of the amount of transmitted light with respect to a frequency difference between two frequency components of the second excitation light conforms to a predetermined characteristic, and calculating the frequency modulation power based on the distribution characteristic value; Control method. (Appendix 7.3) 7.2, comprising: calculating the distribution characteristic value representing the degree to which a distribution of the amount of transmitted light with respect to a frequency difference between two frequency components in the second excitation light is symmetrical with respect to a resonance frequency, and calculating the frequency modulation power based on the distribution characteristic value; Control method. (Appendix 7.4) 7.2 or 7.3, comprising: specifying the frequency modulation power based on the distribution characteristic value for the frequency modulation power for each wavelength of the first excitation light that has been changed, and assigning the specified frequency modulation power to the light generator. Control method. (Appendix 7.5) 7.4, comprising: identifying the frequency modulation power at which the variance of the distribution characteristic value is minimum based on the distribution characteristic value for the frequency modulation power for each wavelength of the first excitation light that has been changed, and specifying the identified frequency modulation power to the light generator. Control method. (Appendix 8) an optical generator that generates first excitation light of a specified single wavelength and generates second excitation light containing two frequency components by frequency-modulating the first excitation light with a specified frequency modulation power; an alkali metal atomic gas cell to which the second excitation light containing two frequency components is irradiated with the second excitation light having its frequency difference changed; a measuring unit for measuring the amount of light transmitted through the alkali metal atomic gas cell, calculating the frequency modulation power based on a distribution of the amount of transmitted light with respect to a change in the frequency difference of the second excitation light, the distribution being measured each time the wavelength of the first excitation light and the frequency modulation power are changed by the light generator; Control device. (Appendix 9) an optical generator that generates first excitation light of a specified single wavelength and generates second excitation light containing two frequency components by frequency-modulating the first excitation light with a specified frequency modulation power; an alkali metal atomic gas cell to which the second excitation light containing two frequency components is irradiated with the second excitation light having its frequency difference changed; a control device for controlling an atomic oscillator having a measuring unit for measuring the amount of light transmitted through the alkali metal atomic gas cell, calculating the frequency modulation power based on a distribution of the amount of transmitted light relative to the frequency difference between two frequency components of the second excitation light, the distribution being measured each time the wavelength of the first excitation light and the frequency modulation power are changed by the light generator; A program for executing a process. [Explanation of symbols]

[0041] 1 light generator 2. Alkali metal atomic gas cell 3 Photodetector 4 calculator 11 Frequency modulation section, optical frequency modulator 12 Intensity control section, optical attenuator 13 Wavelength control section, laser 41 Distortion parameter calculation unit 42 Frequency modulation setting value calculation section, signal generator setting value calculation section 43 Intensity control setting value calculation unit, optical attenuator voltage setting value calculation unit 44 Wavelength control unit setting value calculation unit, laser voltage setting value calculation unit 100 Atomic Oscillator 101 Light Generator 102 Alkali metal atomic gas cell 103 Measuring part 104 Calculation section

Claims

1. a light generator that generates first excitation light of a specified single wavelength and generates second excitation light including two frequency components by frequency-modulating the first excitation light with a specified frequency modulation power; an alkali metal atomic gas cell onto which the second excitation light containing two frequency components is irradiated with the second excitation light having its frequency difference changed; a measuring unit for measuring the amount of light transmitted through the alkali metal atomic gas cell; a calculation unit that calculates the frequency modulation power based on a distribution of the amount of transmitted light with respect to a frequency difference between two frequency components of the second excitation light, the distribution being measured each time the wavelength of the first excitation light and the frequency modulation power are changed by the light generator; and Equipped with The calculation unit specifying the wavelength of the first excitation light and the frequency modulation power to the light generator while varying them, calculating a distribution characteristic value that indicates the degree to which a distribution of the amount of transmitted light with respect to a frequency difference between two frequency components in the second excitation light, measured each time the wavelength of the first excitation light and the frequency modulation power are changed, conforms to a predetermined characteristic, and calculating the frequency modulation power based on the distribution characteristic value; further specifying the frequency modulation power at which the variance of the distribution characteristic value is minimum based on the distribution characteristic value for the frequency modulation power for each wavelength of the first excitation light that has been changed, and assigning the specified frequency modulation power to the light generator. Atomic oscillator.

2. 2. The atomic oscillator according to claim 1, the calculation unit calculates the distribution characteristic value representing the degree to which a distribution of the amount of transmitted light with respect to a frequency difference between two frequency components in the second excitation light is symmetrical with respect to a resonance frequency, and calculates the frequency modulation power based on the distribution characteristic value. Atomic oscillator.

3. a light generator that generates first excitation light of a specified single wavelength and generates second excitation light including two frequency components by frequency-modulating the first excitation light with a specified frequency modulation power; an alkali metal atomic gas cell onto which the second excitation light containing two frequency components is irradiated with the second excitation light having its frequency difference changed; a measuring unit for measuring the amount of light transmitted through the alkali metal atomic gas cell, measuring the amount of transmitted light with respect to a change in the frequency difference between two frequency components in the second excitation light, and calculating the frequency modulation power based on a distribution of the amount of transmitted light with respect to the frequency difference between two frequency components in the second excitation light measured each time the wavelength of the first excitation light and the frequency modulation power are changed by the light generator; specifying the wavelength of the first excitation light and the frequency modulation power to the light generator while varying them, calculating a distribution characteristic value that indicates the degree to which a distribution of the amount of transmitted light with respect to a frequency difference between two frequency components in the second excitation light, measured each time the wavelength of the first excitation light and the frequency modulation power are changed, conforms to a predetermined characteristic, and calculating the frequency modulation power based on the distribution characteristic value; further specifying the frequency modulation power at which the variance of the distribution characteristic value is minimum based on the distribution characteristic value for the frequency modulation power for each wavelength of the first excitation light that has been changed, and assigning the specified frequency modulation power to the light generator. Control method.

4. a light generator that generates first excitation light of a specified single wavelength and generates second excitation light including two frequency components by frequency-modulating the first excitation light with a specified frequency modulation power; an alkali metal atomic gas cell onto which the second excitation light containing two frequency components is irradiated with the second excitation light having its frequency difference changed; a measuring unit for measuring the amount of light transmitted through the alkali metal atomic gas cell, when calculating the frequency modulation power based on the distribution of the amount of transmitted light with respect to the frequency difference between two frequency components of the second excitation light, which is measured every time the wavelength of the first excitation light and the frequency modulation power are changed by the light generator, specifying the wavelength of the first excitation light and the frequency modulation power to the light generator while varying them, calculating a distribution characteristic value that indicates the degree to which a distribution of the amount of transmitted light with respect to a frequency difference between two frequency components in the second excitation light, measured each time the wavelength of the first excitation light and the frequency modulation power are changed, conforms to a predetermined characteristic, and calculating the frequency modulation power based on the distribution characteristic value; further specifying the frequency modulation power at which the variance of the distribution characteristic value is minimum based on the distribution characteristic value for the frequency modulation power for each wavelength of the first excitation light that has been changed, and assigning the specified frequency modulation power to the light generator. Control device.

5. a light generator that generates a first excitation light having a specified single wavelength and generates two second excitation lights by frequency modulating the first excitation light with specified frequency modulation power; an alkali metal atomic gas cell onto which the two second excitation lights are irradiated with the second excitation lights having their frequency difference changed; a control device for controlling an atomic oscillator having a measuring unit for measuring the amount of light transmitted through the alkali metal atomic gas cell, when calculating the frequency modulation power based on the distribution of the amount of transmitted light with respect to the frequency difference between two frequency components of the second excitation light, which is measured every time the wavelength of the first excitation light and the frequency modulation power are changed by the light generator, specifying the wavelength of the first excitation light and the frequency modulation power to the light generator while varying them, calculating a distribution characteristic value that indicates the degree to which a distribution of the amount of transmitted light with respect to a frequency difference between two frequency components in the second excitation light, measured each time the wavelength of the first excitation light and the frequency modulation power are changed, conforms to a predetermined characteristic, and calculating the frequency modulation power based on the distribution characteristic value; further specifying the frequency modulation power at which the variance of the distribution characteristic value is minimum based on the distribution characteristic value for the frequency modulation power for each wavelength of the first excitation light that has been changed, and assigning the specified frequency modulation power to the light generator. A program for executing a process.

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