Light clock device based on bidirectional thermal atom beam
By using a combination of bidirectional thermal atomic beam and optical frequency comb in the atomic beam photoclock system, the problem of long-term frequency stability being affected by the remaining first-order Doppler effect is solved, and a high-stability and low-complexity photoclock device is achieved.
Patent Information
- Application Number
- CN202411980319.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-31
- Publication Date
- 2025-03-14
AI Technical Summary
The existing atomic beam clock systems have constraints in long-term frequency stability, mainly due to the influence of the remaining first-order Doppler effect, and achieving high-resolution clock transition detection spectral line width requires a complex optical Ramsey optical path detection system and two optical super-stable cavity and frequency stabilization lasers.
Using an optical clock device based on a bidirectional thermal atom beam, the clock transition detection laser is output through the first stabilization module. The second stabilization module includes a frequency shifter, a beam splitter, a four-wire reflective component, a bidirectional thermal atom chamber, an optical frequency comb and a fluorescence detector to realize high-resolution spectral detection and frequency stability transmission, and lock the laser to the atom transition spectral line through the feedback control module.
The optical clock device with low cost, low structural complexity and high output signal stability is realized, which can effectively eliminate the remaining first-order Doppler effect and improve long-term frequency stability without the need for an additional optical super-stable cavity and frequency stabilization laser.
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Figure CN119620577A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of quantum precision measurement, and in particular to an optical clock device based on a bidirectional thermal atomic beam. Background Art
[0002] Frequency stability is one of the most important indicators for evaluating the performance of timekeeping clocks. Generally, attention should be paid to short-term frequency stability and long-term frequency stability. For atomic beam optical clock systems, the atomic optical clock transition detection spectrum is a key physical factor affecting its short-term frequency stability. Obtaining high-resolution optical clock transition detection spectrum width is helpful to improve the short-term frequency stability performance of optical clocks. The residual first-order Doppler effect caused by the interaction between the atomic beam and the laser is a key factor restricting the improvement of the long-term frequency stability performance of the atomic beam optical clock system. How to suppress the residual first-order Doppler effect has become the primary issue for improving the long-term stability of atomic beam optical clocks. Optical Ramsey spectroscopy detection can obtain high-resolution spectra and improve the short-term frequency stability of atomic beam optical clock systems. The bidirectional atomic beam counterattack method can suppress the residual first-order Doppler effect and improve the medium- and long-term stability of atomic beam optical clocks. The atomic beam optical clock using this solution has achieved a frequency stability index of the order of E-16, which is an ideal choice for optical frequency band timekeeping clocks. However, the current implementation of such devices requires the use of two optical ultra-stable cavity-stabilized lasers and a complex optical Ramsey light path detection system. Summary of the invention
[0003] Based on the above, the object of the present invention is to provide an optical clock device based on a bidirectional thermal atomic beam, which has low cost, low structural complexity and high output signal stability.
[0004] To achieve the above object, the present invention adopts the following technical solutions:
[0005] An optical clock device based on a bidirectional thermal atomic beam comprises a first stabilization module, a second stabilization module and a feedback control module;
[0006] The first stabilization module is used to output clock transition detection laser;
[0007] The second stabilization module comprises a frequency shifter, a first beam splitter, a four-line reflection component, a bidirectional thermal atom chamber, an optical frequency comb, a detection laser, a second beam splitter, a reflector and two fluorescence detectors. The bidirectional thermal atom chamber has two thermal atom beams ejected in opposite directions. The clock transition detection laser is frequency-shifted to the atomic transition spectrum line by the frequency shifter and then divided into a first laser beam and a second laser beam by the first beam splitter. The first laser beam forms four action laser beams in the bidirectional thermal atom chamber by the four-line reflection component. The four action laser beams are used to act on the thermal atoms in the bidirectional thermal atom chamber. The second laser The optical frequency comb transfers the frequency stability of the beam to the detection laser, the detection laser emits a third laser beam with the same frequency stability as the second laser beam, the third laser beam is divided into a fourth laser beam and a fifth laser beam via the second beam splitter; the fourth laser beam enters the bidirectional hot atom chamber to act on the hot atoms, the fifth laser beam is reflected by the reflector and enters the bidirectional hot atom chamber to act on the hot atoms; the two fluorescence detectors are used to detect the fluorescence signal in the bidirectional hot atom chamber to obtain the bidirectional atomic beam optical Ramsey spectrum, and the optical frequency comb is also used to output a light signal with a stable frequency;
[0008] The feedback control module is used to extract an error signal from the optical Ramsey spectrum and feed it back to the frequency shifter, so that the clock transition detection laser is frequency-shifted and locked to the atomic transition spectrum line via the frequency shifter.
[0009] As a preferred solution of an optical clock device based on a bidirectional thermal atomic beam, it also includes a frequency stabilization output module, which is used to receive the optical signal output by the optical frequency comb and output a microwave signal with a stable frequency.
[0010] As a preferred solution of an optical clock device based on a bidirectional thermal atom beam, two calcium atom furnaces are respectively arranged at the opposite ends of the bidirectional thermal atom chamber, and the injection ports of the two calcium atom furnaces are arranged opposite to each other. The two calcium atom furnaces are used to heat calcium atoms and to inject two opposite beams of thermal calcium atom beams into the bidirectional thermal atom chamber; the fourth laser beam and the fifth laser beam are respectively located on both sides of the four action laser beams, one of the fluorescence detectors is adjacent to one of the calcium atom furnaces relative to the four-line reflection component, and the other of the fluorescence detectors is adjacent to another of the calcium atom furnaces relative to the four-line reflection component.
[0011] As a preferred solution of an optical clock device based on a bidirectional thermal atom beam, the four-line reflection component includes two roof prisms relatively arranged on the outside of the bidirectional thermal atom chamber, and the first laser beam split by the first beam splitter is reflected multiple times between the two roof prisms to form the four-line action laser beam.
[0012] As a preferred solution of an optical clock device based on a bidirectional thermal atomic beam, the first stabilization module includes an optical reference cavity and a clock transition detection laser locked in the optical reference cavity, and the clock transition detection laser is used to output the clock transition detection laser.
[0013] As a preferred solution for an optical clock device based on a bidirectional thermal atomic beam, the feedback control module includes an error signal extraction module, a servo control module and a radio frequency signal output module. The error signal extraction module is used to extract an error signal from the optical Ramsey spectrum, and the servo control module is used to control the radio frequency signal output by the radio frequency signal output module according to the error signal, and the radio frequency signal is fed back to the frequency shifter.
[0014] As a preferred solution for an optical clock device based on a bidirectional thermal atomic beam, the first beam splitter is a 1:9 energy beam splitter for splitting the clock transition detection laser into a second laser beam with an energy of 1:9 and the first laser beam.
[0015] As a preferred solution of an optical clock device based on a bidirectional thermal atomic beam, the second beam splitter is an equal-proportional energy beam splitter.
[0016] As a preferred solution of an optical clock device based on a bidirectional thermal atomic beam, the reflector is a high reflectivity lens.
[0017] As a preferred solution of the optical clock device based on bidirectional thermal atomic beam, the fluorescence detector includes a photomultiplier tube.
[0018] The beneficial effects of the present invention are:
[0019] The present invention provides an optical clock device based on a bidirectional thermal atomic beam, wherein a first laser beam separated by a clock transition detection laser through a first beam splitter passes through a four-line reflection component to form four action laser beams in a bidirectional thermal atomic chamber clock to excite the transition of thermal atoms from a ground state to an excited state, and the structural complexity is relatively small; and the frequency stability transmission of the clock transition detection laser to the third laser beam is realized through an optical frequency comb, without the need to additionally adopt an optical ultra-stable cavity frequency-stabilizing laser; and then the transfer detection of the bidirectional atomic beam is realized through partition detection of two fluorescent detectors, and the bidirectional atomic beam optical Ramsey spectrum is obtained, so that the error signal can be extracted from the optical Ramsey spectrum through a feedback control module and then fed back to a frequency shifter, so that the clock transition detection laser is frequency-shifted and locked to the atomic transition spectrum line through the frequency shifter, and finally a stable frequency optical signal is provided through an optical frequency comb, so as to realize the high stability of the optical clock device. Among them, the bidirectional atomic beam is provided through a bidirectional atomic chamber, which can effectively eliminate the residual first-order Doppler effect, thereby facilitating the long-term stability of the optical clock device. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the contents of the embodiments of the present invention and these drawings without paying any creative work.
[0021] Figure 1 is a schematic structural diagram of an optical clock device based on a bidirectional thermal atomic beam provided in an embodiment of the present invention;
[0022] Figure 2 This is a light path diagram of an optical clock device based on a bidirectional thermal atomic beam provided by an embodiment of the present invention.
[0023] In the figure:
[0024] 100, first stabilization module; 200, second stabilization module; 300, feedback control module; 400, frequency stabilization output module;
[0025] 1. Clock transition detection laser; 2. Frequency shifter; 3. First beam splitter; 4. Roof prism; 5. Bidirectional hot atom chamber; 6. Calcium atomic furnace; 7. Fluorescence detector; 8. Optical frequency comb; 9. Detection laser; 10. Second beam splitter; 11. Reflector; 12. Error signal extraction module; 13. Servo control module; 14. RF signal output module. DETAILED DESCRIPTION
[0026] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.
[0027] In the description of the present invention, unless otherwise clearly specified and limited, the terms "connected", "connected", and "fixed" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.
[0028] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.
[0029] In the description of the present embodiment, the terms "upper", "lower", "left", "right" and other directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of description and simplification of operation, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation of the present invention. In the description of the present invention, unless otherwise specified, the meaning of "plurality" is two or more. In addition, the terms "first" and "second" are only used to distinguish in the description and have no special meaning.
[0030] like Figure 1 and Figure 2As shown, this embodiment provides an optical clock device based on a bidirectional thermal atom beam, which includes a first stabilization module 100, a second stabilization module 200 and a feedback control module 300. The first stabilization module 100 is used to output a clock transition detection laser; the second stabilization module 200 includes a frequency shifter 2, a first beam splitter 3, a four-line reflection component, a bidirectional thermal atom chamber 5, an optical frequency comb 8, a detection laser 9, a second beam splitter 10, a reflector 11 and two fluorescence detectors 7. The bidirectional thermal atom chamber 5 has two thermal atom beams ejected in opposite directions; the clock transition detection laser is frequency-shifted to the atomic transition spectrum line by the frequency shifter 2, and then divided into a first laser beam and a second laser beam by the first beam splitter 3; the first laser beam forms four action laser beams in the bidirectional thermal atom chamber 5 via the four-line reflection component, and the four action laser beams are used to communicate with the bidirectional thermal atom chamber 5. The second laser beam transfers the frequency stability to the detection laser 9 via the optical frequency comb 8, and the detection laser 9 emits a third laser beam with the same frequency stability as the second laser beam, and the third laser beam is divided into a fourth laser beam and a fifth laser beam via the second beam splitter 10; the fourth laser beam enters the bidirectional hot atom chamber 5 to act on the hot atoms, and the fifth laser beam is reflected by the reflector 11 and enters the bidirectional hot atom chamber 5 to act on the hot atoms; two fluorescence detectors 7 are used to detect the fluorescence signal in the bidirectional hot atom chamber 5 to obtain the bidirectional atomic beam optical Ramsey spectrum, and the optical frequency comb 8 is also used to output a light signal with a stable frequency; the feedback control module 300 is used to extract the error signal from the optical Ramsey spectrum and feed it back to the frequency shifter 2, so that the clock transition detection laser is locked to the atomic transition spectrum line via the frequency shifter 2.
[0031] The optical clock device forms four action laser beams in the bidirectional hot atom chamber 5 through the first laser beam split by the first beam splitter 3 through the four-line reflection component to stimulate the transition of hot atoms from the ground state to the excited state, and the structural complexity is relatively small; and the frequency stability transmission of the clock transition detection laser to the third laser beam is realized through the optical frequency comb 8, without the need to use an optical ultra-stable cavity frequency-stabilizing laser; and then the transfer detection of the bidirectional atomic beam is realized through the partition detection of two fluorescence detectors 7, and the bidirectional atomic beam optical Ramsey spectrum is obtained, so that the error signal can be extracted from the optical Ramsey spectrum through the feedback control module 300 and the error signal is fed back to the frequency shifter 2, so that the clock transition detection laser is frequency-shifted and locked to the atomic transition spectrum line through the frequency shifter 2, and finally the optical frequency comb 8 provides a stable frequency optical signal to achieve the high stability of the optical clock device. Among them, the bidirectional atomic beam is provided by the bidirectional atomic chamber, which can effectively eliminate the residual first-order Doppler effect, thereby helping to improve the long-term stability of the optical clock device.
[0032] In this embodiment, the hot atom beam in the bidirectional hot atom chamber 5 is a calcium hot atom beam, and two calcium atom furnaces 6 are respectively arranged at opposite ends of the bidirectional hot atom chamber 5, and the injection ports of the two calcium atom furnaces 6 are arranged oppositely. The two calcium atom furnaces 6 are used to heat calcium atoms and to inject two opposite hot calcium atom beams into the bidirectional hot atom chamber 5; the fourth laser beam and the fifth laser beam are respectively located on both sides of the four action laser beams, a fluorescence detector 7 is adjacent to one calcium atom furnace relative to the four-line reflection component, and another fluorescence detector 7 is adjacent to another calcium atom furnace 6 relative to the four-line reflection component. Combined with the partitioned detection of the two fluorescence detectors 7, the residual first-order Doppler effect can be eliminated, thereby improving the signal output stability of the optical clock device.
[0033] The fluorescence detector 7 is a photomultiplier tube, which can detect fluorescence signals in the 423nm or 431nm band.
[0034] Specifically, the first stabilization module 100 includes an optical reference cavity and a clock transition detection laser 1 locked in the optical reference cavity, and the clock transition detection laser 1 is used to output a clock transition detection laser. By locking the clock transition detection laser 1 into the optical reference cavity, the line width is narrowed, so that the line width of the clock transition detection laser is narrow. Among them, the optical reference cavity is an ultra-stable optical reference cavity in the 657nm band, and the cavity finesse is generally greater than 20W; the clock transition detection laser 1 is, for example, a 657nm laser; the detection laser 9 is, for example, a 431nm laser or a 423nm laser; the optical frequency comb 8 outputs optical band components including a 657nm laser band, and an 846nm or 862nm laser band. The frequency stability of the clock transition detection laser is transferred to the third laser beam through the optical frequency comb 8, so that the third laser beam has both narrow line width and high frequency stability characteristics. The third laser beam is output by detecting the beat frequency of the laser 9 and the optical frequency comb 8. The third laser beam is divided into a fourth laser beam and a fifth laser beam by the second beam splitter 10 and enters the bidirectional thermal atom chamber for 5 minutes, which can stimulate a greater fluorescence signal intensity, which is beneficial to improving the signal-to-noise ratio of the atomic transition spectrum.
[0035] Among them, the first beam splitter 3 is a 1:9 energy beam splitter, which is used to split the clock transition detection laser into a second laser beam and a first laser beam with an energy of 1:9, that is, the energy of the second laser beam entering the optical frequency comb 8 is smaller to avoid energy waste.
[0036] Among them, the second beam splitter 10 is an equal-proportional energy beam splitter, and the reflector 11 is a high-reflectivity lens, preferably a high-reflectivity lens in the 423nm or 431nm band, that is, the third laser beam is divided into the fourth laser beam and the fifth laser beam by the second beam splitter 10 with equal energy, so that the detection result of the fluorescence detector 7 has a higher accuracy, which is beneficial to improving the accuracy of error signal extraction.
[0037] Furthermore, the four-line reflection component includes two roof prisms 4 relatively arranged outside the bidirectional thermal atom chamber 5, and the first laser beam split by the first beam splitter 3 is reflected multiple times between the two roof prisms 4 to form a four-line laser beam. That is, the generation of a four-line laser beam can be achieved by arranging two roof prisms 4, so that the structure of the optical clock device is more compact. Among them, the size of the roof prism 4, which is farther away from the first beam splitter 3, is larger so that it can smoothly receive the first laser beam split from the first beam splitter 3. Among them, the roof prism 4 is a high reflectivity mirror in the 657nm band.
[0038] Furthermore, the feedback control module 300 includes an error signal extraction module 12, a servo control module 13 and a RF signal output module 14. The error signal extraction module 12 is used to extract the error signal from the optical Ramsey spectrum. The servo control module 13 is used to control the RF signal output by the RF signal output module 14 according to the error signal. The RF signal is fed back to the frequency shifter 2 to achieve precise locking of the clock transition detection laser to the atomic transition spectrum line.
[0039] In this embodiment, the optical clock device further includes a frequency stabilization output module 400, which is used to receive the optical signal output by the optical frequency comb 8 and output a microwave signal with a stable frequency. The repetitive frequency signal of the optical frequency comb 8 is extracted by the frequency stabilization output module 400 to obtain an ultra-stable microwave signal output, which is used as the ultra-stable signal output of the optical clock device.
[0040] Note that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.
Claims
1. An optical clock device based on a bidirectional thermal atomic beam, characterized in that: It includes a first stabilization module, a second stabilization module and a feedback control module; The first stabilization module is used to output clock transition detection laser; The second stabilization module comprises a frequency shifter, a first beam splitter, a four-line reflection component, a bidirectional thermal atom chamber, an optical frequency comb, a detection laser, a second beam splitter, a reflector and two fluorescence detectors. The bidirectional thermal atom chamber has two thermal atom beams ejected in opposite directions. The clock transition detection laser is frequency-shifted to the atomic transition spectrum line by the frequency shifter and then divided into a first laser beam and a second laser beam by the first beam splitter. The first laser beam forms four action laser beams in the bidirectional thermal atom chamber by the four-line reflection component. The four action laser beams are used to act on the thermal atoms in the bidirectional thermal atom chamber. The second laser The optical frequency comb transfers the frequency stability of the beam to the detection laser, the detection laser emits a third laser beam with the same frequency stability as the second laser beam, the third laser beam is divided into a fourth laser beam and a fifth laser beam via the second beam splitter; the fourth laser beam enters the bidirectional hot atom chamber to act on the hot atoms, the fifth laser beam is reflected by the reflector and enters the bidirectional hot atom chamber to act on the hot atoms; the two fluorescence detectors are used to detect the fluorescence signal in the bidirectional hot atom chamber to obtain the bidirectional atomic beam optical Ramsey spectrum, and the optical frequency comb is also used to output a light signal with a stable frequency; The feedback control module is used to extract an error signal from the optical Ramsey spectrum and feed it back to the frequency shifter, so that the clock transition detection laser is frequency-shifted and locked to the atomic transition spectrum line via the frequency shifter.
2. The optical clock device based on bidirectional thermal atomic beam according to claim 1, characterized in that: It also includes a frequency stabilization output module, which is used to receive the optical signal output by the optical frequency comb and output a microwave signal with a stable frequency.
3. The optical clock device based on bidirectional thermal atomic beam according to claim 1, characterized in that: Two calcium atom furnaces are respectively arranged at the opposite ends of the bidirectional thermal atom chamber, and the injection ports of the two calcium atom furnaces are arranged opposite to each other. The two calcium atom furnaces are used to heat calcium atoms and to inject two opposite beams of hot calcium atoms into the bidirectional thermal atom chamber; the fourth laser beam and the fifth laser beam are respectively located on both sides of the four action laser beams, one of the fluorescence detectors is adjacent to one of the calcium atom furnaces relative to the four-line reflection component, and the other fluorescence detector is adjacent to another of the calcium atom furnaces relative to the four-line reflection component.
4. The optical clock device based on bidirectional thermal atomic beam according to claim 1, characterized in that: The four-line reflection component includes two roof prisms arranged opposite to each other outside the bidirectional thermal atom chamber. The first laser beam split by the first beam splitter is reflected multiple times between the two roof prisms to form the four-line action laser beam.
5. The optical clock device based on bidirectional thermal atomic beam according to claim 1, characterized in that: The first stabilization module includes an optical reference cavity and a clock transition detection laser locked in the optical reference cavity, and the clock transition detection laser is used to output the clock transition detection laser.
6. The optical clock device based on bidirectional thermal atomic beam according to claim 1, characterized in that: The feedback control module includes an error signal extraction module, a servo control module and a radio frequency signal output module. The error signal extraction module is used to extract an error signal from the optical Ramsey spectrum. The servo control module is used to control the radio frequency signal output by the radio frequency signal output module according to the error signal. The radio frequency signal is fed back to the frequency shifter.
7. The optical clock device based on bidirectional thermal atomic beam according to claim 1, characterized in that: The first beam splitter is a 1:9 energy beam splitter, which is used to split the clock transition detection laser into a second laser beam with an energy of 1:9 and the first laser beam.
8. The optical clock device based on bidirectional thermal atomic beam according to claim 1, characterized in that: The second beam splitter is an equal-proportional energy beam splitter.
9. The optical clock device based on bidirectional thermal atomic beam according to claim 1, characterized in that: The reflector is a high reflectivity lens.
10. The optical clock device based on bidirectional thermal atomic beam according to claim 1, characterized in that: The fluorescence detector includes a photomultiplier tube.