Double-channel frequency locking system for Rydberg atom low-frequency electric field measurement

Abstract

The invention discloses a double-channel frequency locking system for Rydberg atom low-frequency electric field measurement. Comprising a first laser, a first optical fiber beam splitter, a first optical fiber attenuator, an electro-optical modulator, a second optical fiber beam splitter, a saturated absorption spectrum light path, a first photoelectric detector, a control circuit, a second laser, a third optical fiber beam splitter, a second optical fiber attenuator, an EIT spectrum light path and a second photoelectric detector. The ultra-stable frequency locking device is simple and easy to construct, and the ultra-stable frequency locking function can be achieved while the technical cost is greatly reduced.

Description

Technical Field

[0001] The invention relates to the technical field of laser frequency locking, in particular to a dual-path frequency locking system for measuring low-frequency electric fields of Rydberg atoms. Background Art

[0002] Rydberg atoms are being explored for applications in quantum sensing, which mainly rely on electromagnetically induced transparency (EIT) and the Stark effect to obtain precise measurements of the electric field.

[0003] At present, the technical research on quantum measurement of Rydberg atoms is mainly used for the measurement of microwave electric fields. There are few methods for measuring low-frequency electric fields, and no mature technical solutions have been formed. With the development of quantum sensing technology, it is gradually being considered for application in power systems. The voltage frequency of power systems is generally 50Hz industrial frequency voltage, making quantum microwave measurement solutions no longer applicable to low-frequency or industrial frequency electric fields.

[0004] After further research, it was found that there are actually two measurement schemes in the actual measurement process of industrial frequency electric field (50Hz): one is to lock the detection light and scan the coupling light, and fit the external electric field strength through the displacement of the spectrum analysis peak obtained by frequency scanning; the other is to lock the coupling light while locking the detection light, and observe the change law of the spectrum locking value to obtain the external electric field strength. However, both schemes are in the research stage and there is no mature measurement system. This case proposes a frequency locking method for the dual locking scheme, and further optimizes and improves the vacancy of the frequency locking part of quantum measurement in the low-frequency dual locking measurement scheme.

[0005] At present, in the dual-lock electric field measurement scheme, the 852nm detection light is mainly stabilized by saturated absorption spectroscopy, modulation transfer spectroscopy or polarization spectroscopy, while the 512nm coupling light is usually stabilized by the PDH frequency stabilization method. Usually, a dual-lock electric field measurement scheme requires two methods to be used to stabilize the two lasers in different bands, and the PDH frequency stabilization method requires high-precision optical devices such as FP cavities, which is costly and difficult to implement. Summary of the invention

[0006] In view of the above-mentioned deficiencies in the prior art, the present invention provides a dual-path frequency-locked system for measuring the low-frequency electric field of Rydberg atoms, which solves the problems of high cost and low applicability of the prior art.

[0007] In order to achieve the above-mentioned invention object, the technical solution adopted by the present invention is: a dual-path frequency-locked system for measuring the low-frequency electric field of Rydberg atoms, comprising a first laser, a first optical fiber beam splitter, a first optical fiber attenuator, an electro-optic modulator, a second optical fiber beam splitter, a saturated absorption spectrum optical path, a first photodetector, a control circuit, a second laser, a third optical fiber beam splitter, a second optical fiber attenuator, an EIT spectrum optical path, and a second photodetector;

[0008] The light emitted by the second laser is the coupled light; after the coupled light passes through the third optical fiber beam splitter, a part of the coupled light is output to the outside of the system, and the other part of the coupled light passes through the second optical fiber attenuator and enters the EIT spectrum optical path;

[0009] The light emitted by the first laser is the detection light; after the detection light passes through the first optical fiber beam splitter, a part of the detection light is output to the outside of the system, and the other part of the detection light passes through the first optical fiber attenuator, the electro-optic modulator and the second optical fiber beam splitter in sequence, and is divided into two identical detection light beams A and B by the second optical fiber beam splitter. The detection light A enters the saturated absorption spectrum optical path and then enters the first photodetector, and the output of the first photodetector serves as an input of the control circuit; the detection light B enters the EIT spectrum optical path and then interacts with the coupled light and enters the second photodetector; the output of the second photodetector serves as another input of the control circuit;

[0010] The output of the control circuit is respectively used as the input of the first laser, the second laser and the electro-optic modulator.

[0011] Furthermore: the saturated absorption spectrum optical path includes a first high reflector, an attenuation plate, a first cesium atomic gas chamber, a first polarization beam splitter prism, a first light stopper, and a first half-wave plate; the detection light A entering the saturated absorption spectrum optical path passes through the first half-wave plate and the first polarization beam splitter prism in sequence; after passing through the first polarization beam splitter prism, a part of the detection light A reaches the first light stopper, and the other part of the detection light enters the first cesium atomic gas chamber and passes through the attenuation plate to reach the first high reflector; after reaching the first high reflector, the detection light is reflected to the attenuation plate and enters the first cesium atomic gas chamber to obtain a saturated absorption spectrum; the detection light entering the first cesium atomic gas chamber from the attenuation plate passes through the first polarization beam splitter prism and enters the first photodetector.

[0012] Furthermore: the EIT spectral optical path includes a pinhole aperture, a second half-wave plate, a second polarization beam splitter prism, a second high reflector, a third half-wave plate, a first dichroic plate, a second cesium atomic gas chamber, a second dichroic plate, a third polarization beam splitter prism, and a fourth half-wave plate; the coupled light entering the EIT spectral optical path passes through the pinhole aperture, the second half-wave plate, and the second polarization beam splitter prism in sequence; after passing through the second polarization beam splitter prism, a part of the coupled light reaches the second light stopper, and another part of the coupled light reaches the second high reflector, where the coupled light is reflected to the third half-wave plate, and is reflected by the first dichroic plate The detection light B enters the EIT spectrum optical path through the fourth half-wave plate and the third polarization beam splitter prism in sequence. After passing through the third polarization beam splitter prism, part of the detection light B reaches the second light stopper, and the other part passes through the second dichroic plate and enters the second cesium atomic gas chamber to interact with the coupled light and cesium atoms in the second cesium atomic gas chamber to obtain the EIT spectrum. The detection light entering the second cesium atomic gas chamber passes through the first dichroic plate and enters the second photodetector.

[0013] Furthermore: the first photodetector and the second photodetector convert the received detection light into an electrical signal and input it into the control circuit, and the control circuit modulates the electrical signal to obtain a modulated signal; the control circuit inputs the modulated signal into the electro-optical modulator, modulates the light passing through the electro-optical modulator, so that the control circuit finally receives the modulated electrical signal; the control circuit demodulates the received modulated electrical signal to obtain an error signal; and the controller feeds back the error signal to the first laser and the second laser to achieve dual-path frequency locking.

[0014] Furthermore: the detection light emitted by the first laser has a wavelength of 852nm.

[0015] Furthermore: the coupling light emitted by the second laser has a wavelength of 512nm.

[0016] The beneficial effects of the present invention are as follows: the present invention has a simple structure and is easy to build, and realizes dual-path frequency locking while greatly reducing the technical cost. In addition, the dual-path frequency locking system designed by the present invention uses the EOM high-frequency 10MHz modulation and demodulation method, so that the laser modulation signal only has a frequency stabilization optical path, and the laser output signal has no modulation, which further improves the stability of the laser frequency and reaches 10 -10 Order of magnitude. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A schematic diagram of the structure of a dual-path frequency-locked system for measuring the low-frequency electric field of Rydberg atoms provided by the present invention;

[0018] Figure 2It is a structural schematic diagram of the saturated absorption spectrum optical path;

[0019] Figure 3 It is a schematic diagram of the structure of the EIT spectrum optical path;

[0020] Figure 4 This is a schematic diagram of the results of measuring the maximum frequency value of a 1025nm light source;

[0021] Figure 5 This is a schematic diagram of the results of measuring the minimum frequency value of a 1025nm light source;

[0022] Figure 6 This is a schematic diagram of the results of measuring the maximum frequency value of the 852nm light source;

[0023] Figure 7 This is a schematic diagram of the results of measuring the minimum frequency value of the 852nm light source. DETAILED DESCRIPTION

[0024] The specific implementation modes of the present invention are described below so that those skilled in the art can understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific implementation modes. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations utilizing the concept of the present invention are protected.

[0025] like Figure 1 As shown, a dual-path frequency-locked system for measuring the low-frequency electric field of Rydberg atoms provided by the present invention includes a first laser, a first optical fiber beam splitter, a first optical fiber attenuator, an electro-optic modulator, a second optical fiber beam splitter, a saturated absorption spectrum optical path, a first photodetector, a control circuit, a second laser, a third optical fiber beam splitter, a second optical fiber attenuator, an EIT spectrum optical path, and a second photodetector.

[0026] The light emitted by the second laser is coupled light; after the coupled light passes through the third optical fiber beam splitter, a part of the coupled light is output to the outside of the system, and the other part of the coupled light passes through the second optical fiber attenuator and enters the EIT spectrum optical path.

[0027] The light emitted by the first laser is the detection light; after the detection light passes through the first optical fiber beam splitter, a part of the detection light is output to the outside of the system, and the other part of the detection light passes through the first optical fiber attenuator, the electro-optic modulator and the second optical fiber beam splitter in sequence, and is divided into two completely identical detection lights A and B by the second optical fiber beam splitter. The detection light A enters the saturated absorption spectrum optical path and then enters the first photodetector, and the output of the first photodetector serves as an input of the control circuit; the detection light B enters the EIT spectrum optical path and then interacts with the coupled light and then enters the second photodetector; the output of the second photodetector serves as another input of the control circuit; the output of the control circuit serves as the input of the first laser, the second laser and the electro-optic modulator respectively.

[0028] The first photodetector and the second photodetector convert the received detection light into an electrical signal and input it into the control circuit, which modulates the electrical signal to obtain a modulated signal; the control circuit inputs the modulated signal into the electro-optical modulator, modulates the light passing through the electro-optical modulator, so that the control circuit finally receives the modulated electrical signal; the control circuit demodulates the received modulated electrical signal to obtain an error signal; the controller feeds back the error signal to the first laser and the second laser to achieve dual-path frequency locking.

[0029] like Figure 2 As shown, the saturated absorption spectrum optical path includes a first high reflector, an attenuation plate, a first cesium atomic gas chamber, a first polarization beam splitter prism, a first stopper, and a first half-wave plate; the detection light A entering the saturated absorption spectrum optical path is polarized by the first half-wave plate and then adjusted by the first polarization beam splitter prism to adjust the light beam component; after passing through the first polarization beam splitter prism, a part of the detection light A reaches the first stopper, and the other part of the detection light enters the first cesium atomic gas chamber and passes through the attenuation plate to reach the first high reflector; after reaching the first high reflector, the detection light is reflected to the attenuation plate and re-enters the first cesium atomic gas chamber with low power to obtain a saturated absorption spectrum, thereby obtaining a reference frequency of the detection light; finally, the detection light entering the first cesium atomic gas chamber from the attenuation plate passes through the first polarization beam splitter prism and enters the first photodetector.

[0030] like Figure 3As shown, the EIT spectrum optical path includes a pinhole aperture, a second half-wave plate, a second polarization beam splitter prism, a second high reflector, a third half-wave plate, a first dichroic plate, a second cesium atomic gas chamber, a second dichroic plate, a third polarization beam splitter prism, and a fourth half-wave plate; the coupled light entering the EIT spectrum optical path is adjusted to have a halo by the pinhole aperture, and the optical power of the coupled light is adjusted by the second half-wave plate in combination with the second polarization beam splitter prism; after passing through the second polarization beam splitter prism, a part of the coupled light reaches the second light stopper, and another part of the coupled light reaches the second high reflector, where the coupled light is reflected to the third half-wave plate, and is reflected to the fourth half-wave plate by the first dichroic plate. The detection light B enters the second cesium atomic gas chamber and reaches the second dichroic plate, and reaches the light stop after the propagation direction is changed by the second dichroic plate; at the same time, the detection light B entering the EIT spectrum optical path passes through the fourth half-wave plate and the third polarization beam splitter prism for power adjustment, and after passing through the third polarization beam splitter prism, part of the detection light B reaches the second light stop, and the other part of the detection light passes through the second dichroic plate, enters the second cesium atomic gas chamber, and interacts with the coupled light in the second cesium atomic gas chamber and the cesium atoms to obtain the EIT spectrum, thereby obtaining the reference frequency of the coupled light; the detection light entering the second cesium atomic gas chamber passes through the first dichroic plate and enters the second photodetector.

[0031] In order to verify the frequency locking effect of the dual-path frequency locking system for measuring the low-frequency electric field of Rydberg atoms proposed in the present invention, the following frequency stability test was performed on the system proposed in the present invention.

[0032] The frequency stability S of the laser is defined as:

[0033]

[0034] Where Δf = f max -f min , f avg =[f max +f min ] / 2, f max is the maximum frequency, f min is the minimum frequency.

[0035] Since the power of 512nm laser is required to reach 300mW when locked, which exceeds the maximum power value that the wavelength meter can receive, the power of 512nm laser cannot be measured directly. In addition, 512nm laser is obtained by frequency doubling of 1025nm seed source, and the frequency stability of 1025nm light source is the same as that of 512nm light source, so the frequency stability of 1025nm seed source is used here to represent the frequency stability of 512nm laser, that is:

[0036] S(512nm)=S(1025nm)

[0037] like Figure 4As shown, the maximum frequency value f of the 1025nm light source is measured max =292.3877676THz; Figure 5 As shown, the minimum frequency value f of the 1025nm light source is measured min =292.3877671THz. Calculation yields:

[0038] Δf=0.0000005THz

[0039] f avg =292.3877674THz

[0040] Finally available

[0041] S(512nm)=±8.55×10 -10 .

[0042] like Figure 6 As shown, the maximum frequency value f of the 852nm light source is measured max =351.7219225THz; Figure 7 As shown, the minimum frequency value f of the 852nm light source is measured min =351.7219218. Calculation yields:

[0043] Δf=0.0000007THz

[0044] f avg =351.7219222THz

[0045] Finally available

[0046] S(852nm)=±9.95×10 -10 .

[0047] In summary, in the system proposed by the present invention, the frequency stability of the laser can reach 10 -10 This high stability is crucial for application scenarios that require precise frequency control (such as quantum optics and atomic physics) and can meet the needs of high-precision frequency control.

Claims

1. A dual-path frequency-locked system for measuring the low-frequency electric field of Rydberg atoms, characterized in that: It includes a first laser, a first optical fiber beam splitter, a first optical fiber attenuator, an electro-optic modulator, a second optical fiber beam splitter, a saturated absorption spectrum optical path, a first photodetector, a control circuit, a second laser, a third optical fiber beam splitter, a second optical fiber attenuator, an EIT spectrum optical path, and a second photodetector; The light emitted by the second laser is the coupled light; after the coupled light passes through the third optical fiber beam splitter, a part of the coupled light is output to the outside of the system, and the other part of the coupled light passes through the second optical fiber attenuator and enters the EIT spectrum optical path; The light emitted by the first laser is the detection light; after the detection light passes through the first optical fiber beam splitter, a part of the detection light is output to the outside of the system, and the other part of the detection light passes through the first optical fiber attenuator, the electro-optic modulator and the second optical fiber beam splitter in sequence, and is divided into two identical detection light beams A and B by the second optical fiber beam splitter. The detection light A enters the saturated absorption spectrum optical path and then enters the first photodetector, and the output of the first photodetector is used as an input of the control circuit; the detection light B enters the EIT spectrum optical path and then interacts with the coupling light and enters the second photodetector; The output of the second photodetector serves as another input to the control circuit; The output of the control circuit is respectively used as the input of the first laser, the second laser and the electro-optic modulator.

2. A dual-path frequency-locked system for measuring low-frequency electric fields of Rydberg atoms according to claim 1, characterized in that: The saturation absorption spectrum optical path includes a first high reflector, an attenuation plate, a first cesium atomic gas chamber, a first polarization beam splitter prism, a first light stopper, and a first half-wave plate; the detection light A entering the saturation absorption spectrum optical path passes through the first half-wave plate and the first polarization beam splitter prism in sequence; after passing through the first polarization beam splitter prism, a part of the detection light A reaches the first light stopper, and the other part of the detection light enters the first cesium atomic gas chamber and passes through the attenuation plate to reach the first high reflector; after reaching the first high reflector, the detection light is reflected to the attenuation plate and enters the first cesium atomic gas chamber to obtain a saturation absorption spectrum; The detection light entering the first cesium atomic gas cell through the attenuation plate passes through the first polarization beam splitter prism and enters the first photodetector.

3. A dual-path frequency-locked system for measuring low-frequency electric fields of Rydberg atoms according to claim 1, characterized in that: The EIT spectral optical path includes a pinhole aperture, a second half-wave plate, a second polarization beam splitter prism, a second high reflector, a third half-wave plate, a first dichroic plate, a second cesium atomic gas chamber, a second dichroic plate, a third polarization beam splitter prism, and a fourth half-wave plate; the coupled light entering the EIT spectral optical path passes through the pinhole aperture, the second half-wave plate, and the second polarization beam splitter prism in sequence; after passing through the second polarization beam splitter prism, a part of the coupled light reaches the second light stopper, and the other part of the coupled light reaches the second high reflector, where the coupled light is reflected to the third half-wave plate, and is reflected to the first dichroic plate through the first dichroic plate. The second cesium atomic gas chamber reaches the second dichroic plate, and the propagation direction is changed by the second dichroic plate before reaching the light stopper; at the same time, the detection light B entering the EIT spectrum optical path passes through the fourth half-wave plate and the third polarization beam splitter prism in sequence, and after passing through the third polarization beam splitter prism, part of the detection light B reaches the second light stopper, and the other part of the detection light passes through the second dichroic plate, enters the second cesium atomic gas chamber, and interacts with the coupled light in the second cesium atomic gas chamber and the cesium atoms to obtain the EIT spectrum; the detection light entering the second cesium atomic gas chamber passes through the first dichroic plate and enters the second photodetector.

4. A dual-path frequency-locked system for measuring low-frequency electric fields of Rydberg atoms according to claim 1, characterized in that: The first photodetector and the second photodetector convert the received detection light into an electrical signal and input it into the control circuit, and the control circuit modulates the electrical signal to obtain a modulated signal; the control circuit inputs the modulated signal into the electro-optical modulator to modulate the light passing through the electro-optical modulator, so that the control circuit finally receives the modulated electrical signal; the control circuit demodulates the received modulated electrical signal to obtain an error signal; The controller feeds back the error signal to the first laser and the second laser to achieve dual-path frequency locking.

5. A dual-path frequency-locked system for measuring low-frequency electric fields of Rydberg atoms according to claim 1, characterized in that: The detection light emitted by the first laser has a wavelength of 852nm.

6. A dual-path frequency-locked system for measuring low-frequency electric fields of Rydberg atoms according to claim 1, characterized in that: The coupling light emitted by the second laser has a wavelength of 512nm.

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