Optical clock with direct interaction of optical comb and atomic beam and implementation method thereof
By directly interacting an optical comb with an atomic beam, the comb tooth signal corresponding to the atomic transition frequency was obtained, solving the problems of large size and instability of optical clocks and realizing miniaturized and highly stable optical clocks.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- PEKING UNIV
- Filing Date
- 2023-02-28
- Publication Date
- 2026-06-12
AI Technical Summary
Existing optical clocks are large in size, complex in structure, and unstable in operation, which limits their performance.
By employing a method of direct interaction between an optical comb and an atomic beam, the optical comb tooth signal corresponding to the atomic transition frequency is obtained through a filter, modulated using an acousto-optic modulator, and a mirror forms a parallel laser to excite atomic transitions. An error signal is obtained by combining a photodetector and a mixer, and a servo feedback circuit locks the optical comb frequency, thus achieving frequency locking between the optical comb and the atomic transition.
A miniaturized, simple, and highly stable optical clock has been achieved, reducing the complexity of the optical clock and improving its stability.
Smart Images
Figure CN116339111B_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of optical frequency standard technology, and in particular to an optical clock and its implementation method that directly interacts with an optical comb and an atomic beam. Background Technology
[0002] With the development of atomic physics, it has been discovered that the electromagnetic waves emitted during atomic transitions have a stable and unchanging period. Using this period to define time standards can effectively improve the accuracy and stability of the time standards. By using atomic transition spectral lines as frequency references to lock the frequency of an optical comb, the optical comb can achieve accuracy and stability comparable to that of atomic transitions, thereby obtaining an optical clock with corresponding accuracy and stability, and realizing the accurate definition of the time standard.
[0003] In existing technologies, ultrastable lasers are typically used to detect atomic spectral lines, thereby locking the ultrastable laser to the atomic resonance spectral lines to form an optical frequency standard signal. Subsequently, an optical comb is locked to the optical frequency standard signal, thereby transferring the optical frequency stability to microwaves to form an optical clock.
[0004] However, the ultrastable lasers commonly used in existing technologies are generated by ultrastable lasers. Ultrastable lasers have complex structures, large volumes, and unstable operation, which leads to large optical clocks, increases the complexity and instability of optical clocks, and limits their performance. Summary of the Invention
[0005] This application provides an optical clock and its implementation method that directly interacts with an optical comb and an atomic beam, which solves the problems of large size, complex structure and unstable operation of optical clocks in the prior art.
[0006] In a first aspect, this application provides an optical clock that directly interacts with an optical comb and an atomic beam, comprising: an optical comb for emitting broadband light with a spectral width of a first spectral width; a filter for filtering the broadband light to obtain an optical comb tooth signal corresponding to an atomic transition frequency; an acousto-optic modulator for modulating the optical comb tooth signal; an atomic furnace for emitting an atomic beam; a reflector for reflecting the modulated optical comb tooth signal to form four parallel laser beams, and allowing the four parallel laser beams to pass through the atomic beam respectively to excite atomic clock transitions; a laser for emitting a probe laser; and a beam splitter for splitting the probe laser into two beams, one of which is inserted into the atomic beam before the four parallel laser beams pass through it. An atomic beam, with another beam entering the atomic beam after the four parallel laser beams pass through it, interacts with the upper or lower energy level atoms of the clock transition, generating a fluorescence signal; a photodetector is used to detect the fluorescence signal and load it into a mixer; the mixer is used to demodulate the fluorescence signal to obtain an error signal; a servo feedback circuit is used to generate a servo signal based on the error signal and feed the servo signal back to the optical comb; the optical comb is also used to process the comb tooth signal based on the servo signal to lock the frequency of the comb tooth signal at the atomic transition frequency, obtaining an output signal that includes both optical and microwave signals.
[0007] In one specific embodiment, the filter is a filter that transmits light signals with a wavelength of 657nm.
[0008] In one specific embodiment, the laser is a 423nm laser or a 431nm laser.
[0009] In one specific embodiment, when the laser is a 423nm laser and the probe laser is a 423nm laser, the beam splitter is specifically used to: split the probe laser into two beams, one of which enters the atomic beam before the four parallel laser beams pass through the atomic beam, and the other beam enters the atomic beam after the four parallel laser beams pass through the atomic beam, interacting with the lower energy level atoms of the zenith transition to generate a fluorescence signal; or when the laser is a 431nm laser and the probe laser is a 431nm laser, the probe laser does not undergo beam splitting and directly enters the atomic beam after the four parallel laser beams pass through the atomic beam, interacting with the upper energy level atoms of the zenith transition to generate a fluorescence signal.
[0010] In one specific embodiment, the atomic beam is a calcium atomic beam.
[0011] Secondly, this application provides a method for realizing an optical clock through direct interaction between an optical comb and an atomic beam, comprising: triggering an optical comb to emit broadband light with a spectral width of a first spectral width; triggering a filter to filter the broadband light to obtain an optical comb tooth signal corresponding to the atomic transition frequency; triggering an acousto-optic modulator to modulate the optical comb tooth signal; triggering an atomic furnace to emit an atomic beam; triggering a reflector to reflect the modulated optical comb tooth signal to form four parallel laser beams, and causing the four parallel laser beams to pass through the atomic beam respectively to excite atomic clock transitions; triggering a laser to emit a probe laser; triggering a beam splitter to split the probe laser into two beams, one of which is inserted before the four parallel laser beams pass through the atomic beam. The atomic beam is further divided by another beam that strikes the atomic beam after the four parallel laser beams have passed through it. This beam interacts with the upper or lower energy level atoms of the clock transition, generating a fluorescence signal. A photodetector is triggered to detect the fluorescence signal and load it into a mixer. The mixer is then triggered to demodulate the fluorescence signal to obtain an error signal. A servo feedback circuit is triggered to generate a servo signal based on the error signal and feeds the servo signal back to the optical comb. The optical comb is then triggered to process the comb tooth signal based on the servo signal to lock the frequency of the comb tooth signal at the atomic transition frequency, resulting in an output signal that includes both optical and microwave signals.
[0012] In one specific embodiment, the filter is a filter that transmits light signals with a wavelength of 657nm.
[0013] In one specific embodiment, the laser is a 423nm laser or a 431nm laser.
[0014] In one specific embodiment, when the laser is a 423nm laser and the probe laser is a 423nm laser, the trigger beam splitter splits the probe laser into two beams. One beam enters the atomic beam before the four parallel laser beams pass through the atomic beam, and the other beam enters the atomic beam after the four parallel laser beams pass through the atomic beam. These beams interact with the upper or lower energy level atoms of the clock transition, generating a fluorescence signal. This includes: the trigger beam splitter splitting the probe laser into two beams, one beam entering the atomic beam before the four parallel laser beams pass through the atomic beam, and the other beam entering the atomic beam after the four parallel laser beams pass through the atomic beam. The probe laser beam interacts with the lower energy level atoms of Zhong Yueqian to generate a fluorescence signal; or when the laser is a 431nm laser and the probe laser is a 431nm laser, the trigger beam splitter splits the probe laser into two beams, one of which enters the atomic beam before the four parallel laser beams pass through the atomic beam, and the other enters the atomic beam after the four parallel laser beams pass through the atomic beam, interacting with the upper or lower energy level atoms of Zhong Yueqian to generate a fluorescence signal, including: triggering the probe laser to directly enter the atomic beam after the four parallel laser beams pass through the atomic beam, interacting with the upper energy level atoms of Zhong Yueqian to generate a fluorescence signal.
[0015] In one specific embodiment, the atomic beam is a calcium atomic beam.
[0016] This application provides an optical clock and its implementation method that directly interacts with an optical comb and an atomic beam. The optical clock includes: an optical comb for emitting broadband light with a spectral width of a first spectral width; a filter for filtering the broadband light to obtain an optical comb tooth signal corresponding to the atomic transition frequency; an acousto-optic modulator for modulating the optical comb tooth signal; an atomic furnace for emitting an atomic beam; a reflector for reflecting the modulated optical comb tooth signal to form four parallel laser beams, and allowing the four parallel laser beams to pass through the atomic beam to excite atomic clock transitions; a laser for emitting a probe laser; and a beam splitter for splitting the probe laser into two beams, one of which is separated from the four parallel laser beams. One atomic beam is injected before the first atomic beam, and another beam is injected after the four parallel laser beams pass through the first atomic beam. These beams interact with the atoms at the upper or lower energy levels of the clock transition, generating a fluorescence signal. A photodetector detects this fluorescence signal and loads it into a mixer. The mixer demodulates the fluorescence signal to obtain an error signal. A servo feedback circuit generates a servo signal based on the error signal and feeds it back to the optical comb. The optical comb further processes the comb tooth signal based on the servo signal to lock its frequency to the atomic transition frequency, resulting in an output signal that includes both optical and microwave signals. Compared to existing technologies, this application uses a filter to filter the broadband light emitted by the optical comb, obtains the optical comb tooth signal corresponding to the atomic transition frequency, and obtains a laser that can excite atomic clock transitions by modulating the optical comb tooth signal. This realizes the use of a small, simple, and highly stable optical comb to replace the ultra-stable laser as the excitation source, solving the problems of large size, complex structure, and unstable operation of optical clocks caused by ultra-stable lasers. It effectively reduces the complexity of optical clocks and realizes a miniaturized, simple, and highly stable optical clock. Attached Figure Description
[0017] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0018] Figure 1 A schematic diagram of an embodiment of an optical clock that directly interacts with an atomic beam, provided in this application;
[0019] Figure 2 This is a flowchart illustrating an embodiment of an optical clock implementation method for direct interaction between an optical comb and an atomic beam, as provided in this application. Detailed Implementation
[0020] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments made by those skilled in the art under the guidance of these embodiments are within the scope of protection of this application.
[0021] The terms “first,” “second,” “third,” “fourth,” etc. (if present) in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a particular order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms “comprising” and “having,” and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.
[0022] First, let me explain the terms used in this application:
[0023] Optical clock: The definition of "second" is the basis of time standards. The general definition of "second" is based on the transition of atoms in the microwave band, while "optical clock" uses the transition of atoms in the light band as its standard.
[0024] An optical comb, also known as an optical frequency comb, is a series of uniformly spaced frequency components with a coherent and stable phase relationship in the frequency spectrum. The frequency domain image of an optical comb is a series of equally spaced "teeth", with the frequency interval numerically equal to the repetition frequency of the optical comb.
[0025] In existing technologies, ultrastable lasers are typically used to detect atomic spectral lines, thereby locking the ultrastable laser to the atomic resonance spectral lines to form an optical frequency standard signal. Subsequently, an optical comb is locked to the optical frequency standard signal, thereby transferring the optical frequency stability to microwaves to form an optical clock.
[0026] However, the ultrastable lasers commonly used in existing technologies are generated by ultrastable lasers. Ultrastable lasers have complex structures, large volumes, and unstable operation, which leads to large optical clocks, increases the complexity and instability of optical clocks, and limits their performance.
[0027] Based on the above-mentioned technical problems, the inventive concept of this application is: how to realize an optical clock that is small in size, simple in structure and highly stable.
[0028] The technical solution of this application will now be described in detail through specific embodiments. It should be noted that the following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments.
[0029] Figure 1 A schematic diagram of an embodiment of an optical clock where an optical comb and an atomic beam interact directly, as provided in this application. See also... Figure 1 The optical clock includes: an optical comb 101, a filter 102, an acousto-optic modulator 103, an atomic furnace 201, a reflector 202, a laser 203, a beam splitter 204, a photodetector 105, a mixer 106, and a servo feedback circuit 107. Specifically, the optical comb 101 emits broadband light with a spectral width of a first spectral width; the filter 102 filters the broadband light to obtain a comb tooth signal corresponding to the atomic transition frequency; the acousto-optic modulator 103 modulates the comb tooth signal; the atomic furnace 201 emits an atomic beam; the reflector 202 reflects the modulated comb tooth signal to form four parallel laser beams, which then pass through the atomic beam to excite atomic clock transitions; the laser 203 emits a probe laser; and the beam splitter 204 splits the probe laser into two beams, one of which enters the atomic beam before the four parallel laser beams pass through, and the other beam... After the four parallel laser beams pass through the atomic beam, they strike the atomic beam and interact with the upper or lower energy level atoms of the clock transition, generating a fluorescence signal. The photodetector 105 detects the fluorescence signal and loads it into the mixer 106. The mixer 106 demodulates the fluorescence signal to obtain an error signal. The servo feedback circuit 107 generates a servo signal based on the error signal and feeds the servo signal back to the optical comb 101. The optical comb 101 also processes the optical comb tooth signal based on the servo signal to lock the frequency of the optical comb tooth signal at the atomic transition frequency, thereby obtaining an output signal that includes both optical and microwave signals.
[0030] In this embodiment, the optical comb 101 is used to emit broadband light with a spectral width of a first spectral width. For example, the optical comb 101 can emit broadband light of 400nm-1200nm, with the first spectral width being 800nm.
[0031] Specifically, the optical comb is obtained by locking a repetition frequency and a single comb tooth using a mode-locked laser. The single comb tooth locked by the mode-locked laser can be either the initial frequency f0 or any other comb tooth. If the mode-locked laser locks the initial frequency f0, the spectral width can be hundreds of nanometers; if the mode-locked laser locks any comb tooth other than the initial frequency, the spectral width is determined by the mode-locked laser used and can range from tens of nanometers to hundreds of nanometers.
[0032] In this embodiment, the filter 102 is used to filter the broadband light to obtain the optical comb tooth signal corresponding to the atomic transition frequency.
[0033] Specifically, filter 102 filters the broadband light emitted by optical comb 101 to obtain the optical comb tooth signal corresponding to the atomic transition frequency. Different atoms have different transition frequencies. Taking calcium atoms as an example, their transition frequency corresponds to light with a wavelength of 657 nm. That is, to achieve a clock transition in calcium atoms, it is necessary to excite calcium atoms to receive 657 nm light. Therefore, filter 102 filters the broadband light emitted by optical comb 101 to obtain the optical comb tooth signal corresponding to the atomic transition frequency, that is, to obtain an optical comb tooth signal close to 657 nm.
[0034] In this embodiment, the acousto-optic modulator 103 is used to modulate the optical comb tooth signal. The optical comb tooth signal obtained after the filter 102 filters the broadband light emitted by the optical comb 101 is modulated by the acousto-optic modulator 103, shifting its frequency to the atomic transition frequency. For example, the filter 102 obtains an optical comb tooth signal close to 657nm after filtering the broadband light emitted by the optical comb 101; after modulation by the acousto-optic modulator 103, the frequency of the optical comb tooth signal is shifted to the frequency corresponding to 657nm.
[0035] Atomic furnace 201 emits an atomic beam. Reflector 202 reflects the modulated optical comb signal to form four parallel laser beams, which are then passed through the atomic beam to excite atomic clock transitions.
[0036] Laser 203 emits a probe laser. Beam splitter 204 splits the probe laser into two beams. One beam enters the atomic beam before the four parallel laser beams pass through the atomic beam, and the other beam enters the atomic beam after the four parallel laser beams pass through the atomic beam. The two beams interact with the upper or lower energy level atoms of the clock transition, generating a fluorescence signal.
[0037] In this embodiment, the photodetector 105 is used to detect the fluorescence signal and load the fluorescence signal into the mixer 106.
[0038] Specifically, the fluorescence signal can be received by the photodetector 105 and loaded into the mixer 106 for further processing.
[0039] In this embodiment, mixer 106 is used to demodulate the fluorescence signal to obtain an error signal. Servo feedback circuit 107 is used to generate a servo signal based on the error signal and feed the servo signal back to optical comb 101. Optical comb 101 is also used to process the optical comb tooth signal based on the servo signal to lock the frequency of the optical comb tooth signal at the atomic transition frequency, thereby obtaining an output signal that includes both optical and microwave signals.
[0040] Specifically, the demodulation performed by mixer 106 is the process of mixing the fluorescence signal with the demodulated signal to obtain an error signal. Ideally, this error signal should be a constant frequency signal. However, due to the existence of unstable factors, the error signal obtained here is a changing frequency signal. Therefore, the error signal, i.e., the servo signal, needs to be fed back to the optical comb 101 through the subsequent servo feedback circuit 107. The electro-optic modulator in the optical comb 101 gradually adjusts the optical comb tooth signal according to the servo signal, so that the error signal is a constant frequency signal within a certain frequency range. In other words, the frequency of the optical comb tooth signal is locked at the atomic transition frequency, thus realizing an optical clock.
[0041] In this embodiment, the optical clock that directly interacts with the atomic beam includes an optical comb for emitting broadband light with a spectral width of a first spectral width; a filter for filtering the broadband light to obtain a comb tooth signal corresponding to the atomic transition frequency; an acousto-optic modulator for modulating the comb tooth signal; a triggering atomic furnace to emit an atomic beam; a triggering mirror to reflect the modulated comb tooth signal to form four parallel laser beams, which then pass through the atomic beam to excite atomic clock transitions; a triggering laser to emit a probe laser; and a triggering beam splitter to split the probe laser into two beams, one of which enters the atomic clock before the four parallel laser beams pass through the atomic beam. The sub-beam consists of four parallel laser beams that pass through the atomic beam and then strike the atomic beam. The sub-beam interacts with the upper or lower energy level atoms of the clock transition, generating a fluorescence signal. A photodetector detects this fluorescence signal and loads it into a mixer. The mixer demodulates the fluorescence signal to obtain an error signal. A servo feedback circuit generates a servo signal based on the error signal and feeds it back to the optical comb. The optical comb further processes the comb tooth signal based on the servo signal to lock its frequency to the atomic transition frequency, resulting in an output signal that includes both optical and microwave signals. Compared to existing technologies, this application uses a filter to filter the broadband light emitted by the optical comb, obtains the optical comb tooth signal corresponding to the atomic transition frequency, and obtains a laser that can excite atomic clock transitions by modulating the optical comb tooth signal. This realizes the use of a small, simple, and highly stable optical comb to replace the ultra-stable laser as the excitation source, solving the problems of large size, complex structure, and unstable operation of optical clocks caused by ultra-stable lasers. It effectively reduces the complexity of optical clocks and realizes a miniaturized, simple, and highly stable optical clock.
[0042] In the above Figure 1 Based on the embodiment shown, there can be multiple reflectors 202 and beam splitters 204 in the optical clock.
[0043] In this embodiment, the optical clock further includes a signal source 205 for generating a modulation signal, which is loaded into the acousto-optic modulator 103 to modulate the optical comb tooth signal. The signal source 205 is also used to generate a demodulation signal, which is loaded into the mixer 106 to demodulate the fluorescence signal and obtain an error signal.
[0044] Taking the excitation of calcium atom clock transitions to realize an optical clock as an example, the transition frequency of calcium atoms corresponds to light with a wavelength of 657 nm. An optical comb 101 emits broadband light of 400 nm to 1200 nm. Specifically, the filter 102 can be a filter that transmits light signals with a wavelength of 657 nm. The filter 102 filters the broadband light to obtain an optical comb tooth signal close to 657 nm. An acousto-optic modulator 103 modulates this optical comb tooth signal, shifting its frequency to the frequency corresponding to 657 nm.
[0045] The atomic furnace 201 emits an atomic beam. Specifically, the atomic beam can be a calcium atom beam, a strontium atom beam, a rubidium atom beam, or a cesium atom beam. Taking a calcium atom beam as an example, the reflector 202 reflects the modulated optical comb signal to form four parallel laser beams, and these four parallel laser beams pass through the atomic beam respectively to excite calcium atom clock transitions.
[0046] Laser 203 emits a probe laser. Laser 203 can be a 423nm laser or a 431nm laser. Beam splitter 204 splits the probe laser into two beams. One beam enters the calcium atom beam before the four parallel laser beams pass through it, and the other beam enters the calcium atom beam after the four parallel laser beams pass through it. Both beams interact with the upper or lower energy level atoms of the clock transition, generating a fluorescence signal.
[0047] Specifically, when the laser 203 is a 423nm laser, the probe laser it emits is a 423nm laser. The beam splitter 204 splits the probe laser into two beams. One beam enters the atomic beam before the four parallel laser beams pass through the atomic beam, and the other beam enters the atomic beam after the four parallel laser beams pass through the atomic beam. The two beams interact with the lower energy level atoms of the clock transition and generate a fluorescence signal.
[0048] When laser 203 is a 431nm laser, the probe laser it emits is a 431nm laser. This probe laser does not pass through beam splitter 204. Instead, it directly enters the atomic beam after the four parallel laser beams have passed through the atomic beam. It interacts with the upper energy level atoms of the clock transition and generates a fluorescence signal.
[0049] Photodetector 105 detects the fluorescence signal and loads it into mixer 106. Mixer 106 demodulates the fluorescence signal to obtain an error signal. Servo feedback circuit 107 generates a servo signal based on the error signal and feeds it back to optical comb 101. Optical comb 101 processes the comb tooth signal based on the servo signal to lock the frequency of the comb tooth signal to the calcium atom transition frequency, obtaining an output signal that contains both optical and microwave signals.
[0050] In this embodiment, a calcium atom furnace, a mirror, a laser, and a beam splitter are used to interact the modulated optical comb tooth signal with the calcium atom beam, exciting the calcium atoms to undergo clock transitions. The probe laser then interacts with the clock-transitioned atoms, generating a fluorescence signal. This provides the prerequisite for subsequently obtaining an error signal from the fluorescence signal and processing the optical comb tooth signal using this error signal to lock the frequency of the optical comb tooth signal to the calcium atom transition frequency, thus realizing an optical clock.
[0051] Figure 2 This is a flowchart illustrating an embodiment of an optical clock that utilizes the direct interaction between an optical comb and an atomic beam, as provided in this application. See also... Figure 2 The implementation method of this optical clock specifically includes the following steps:
[0052] Step S301: Trigger the optical comb to emit broadband light with a spectral width of the first spectral width.
[0053] Step S302: Trigger the filter to filter the broadband light and obtain the optical comb tooth signal corresponding to the atomic transition frequency.
[0054] Step S303: Trigger the acousto-optic modulator to modulate the signal of the optical comb teeth.
[0055] Step S304: Trigger the atomic furnace to emit an atomic beam.
[0056] Step S305: The trigger mirror reflects the modulated optical comb tooth signal to form four parallel laser beams, and the four parallel laser beams pass through the atomic beam to excite the atomic clock transition.
[0057] Step S306: Trigger the laser to emit a detection laser.
[0058] Step S307: The beam splitter is triggered to split the probe laser into two beams. One beam enters the atomic beam before the four parallel laser beams pass through the atomic beam, and the other beam enters the atomic beam after the four parallel laser beams pass through the atomic beam. The two beams interact with the upper or lower energy level atoms of the clock transition to generate a fluorescence signal.
[0059] Step S308: Trigger the photodetector to detect the fluorescence signal and load the fluorescence signal into the mixer.
[0060] Step S309: Trigger the mixer to demodulate the fluorescence signal to obtain the error signal.
[0061] Step S310: Trigger the servo feedback circuit to generate a servo signal based on the error signal, and feed the servo signal back to the optical comb.
[0062] Step S311: Trigger the optical comb to process the optical comb tooth signal according to the servo signal, so as to lock the frequency of the optical comb tooth signal at the atomic transition frequency, and obtain an output signal that contains both optical signal and microwave signal.
[0063] In this embodiment, the trigger optical comb 101 emits broadband light with a spectral width of a first spectral width. Exemplarily, the first spectral width can be 400nm-1200nm. The trigger filter 102 filters this broadband light to obtain an optical comb tooth signal corresponding to the atomic transition frequency. Taking calcium atoms as an example, their transition frequency corresponds to light with a wavelength of 657nm. The trigger filter 102 can filter the broadband light emitted by the optical comb 101 to obtain an optical comb tooth signal close to 657nm.
[0064] The acousto-optic modulator 103 is triggered to modulate the optical comb tooth signal. For example, the acousto-optic modulator is triggered to modulate the optical comb tooth signal, shifting the frequency of the optical comb tooth signal to the frequency corresponding to 657nm.
[0065] The atomic furnace 201 is triggered to emit an atomic beam. Specifically, the atomic beam can be a calcium atomic beam, a strontium atomic beam, a rubidium atomic beam, or a cesium atomic beam. Taking a calcium atomic beam as an example, the trigger mirror 202 reflects the modulated optical comb signal to form four parallel laser beams, and these four parallel laser beams pass through the atomic beam respectively to excite the atomic clock to transition.
[0066] Trigger laser 203 emits a probe laser. Trigger beam splitter 204 splits the probe laser into two beams. One beam enters the atomic beam before the four parallel laser beams pass through the atomic beam, and the other beam enters the atomic beam after the four parallel laser beams pass through the atomic beam. The two beams interact with the upper or lower energy level atoms of the clock transition, generating a fluorescence signal.
[0067] The photodetector 105 is triggered to detect the fluorescence signal and the fluorescence signal is loaded into the mixer 106.
[0068] The trigger mixer 106 demodulates the fluorescence signal to obtain an error signal. The trigger servo feedback circuit 107 generates a servo signal based on the error signal and feeds the servo signal back to the optical comb 101. The trigger optical comb 101 processes the optical comb tooth signal based on the servo signal to lock the frequency of the optical comb tooth signal at the atomic transition frequency, thereby obtaining an output signal that contains both optical and microwave signals.
[0069] In this embodiment, a trigger mirror reflects the modulated optical comb tooth signal to form four parallel laser beams. These four parallel laser beams are then passed through an atomic beam to excite an atomic clock transition, thus obtaining a Ramsey spectrum. Alternatively, the method can involve obtaining the clock transition signal through a saturation spectrum, a modulation transfer spectrum, or a Doppler spectrum.
[0070] In this embodiment, the broadband light emitted by the optical comb is filtered by a trigger filter to obtain the optical comb tooth signal corresponding to the atomic transition frequency. The optical comb tooth signal is then modulated by an acousto-optic modulator to obtain a laser that can excite atomic clock transitions. This realizes the use of a small, simple, and highly stable optical comb to replace the ultrastable laser as the excitation source, solving the problems of large size, complex structure, and unstable operation of the optical clock caused by the ultrastable laser. It effectively reduces the complexity of the optical clock and realizes a miniaturized, simple, and highly stable optical clock.
[0071] In the above Figure 2 Based on the illustrated embodiment, an optical clock is implemented by exciting the clock transitions of calcium atoms. The transition frequency of calcium atoms corresponds to light with a wavelength of 657 nm. The specific implementation method of the optical clock is as follows:
[0072] The trigger optical comb 101 emits broadband light in the 400nm-1200nm range. The trigger filter 102 filters the broadband light; specifically, the filter 102 can be a filter that transmits light signals with a wavelength of 657nm, to obtain an optical comb tooth signal close to 657nm. The trigger acousto-optic modulator 103 modulates this optical comb tooth signal, shifting its frequency to the frequency corresponding to 657nm.
[0073] The atomic furnace 201 is triggered to emit a beam of calcium atoms. The trigger mirror 202 reflects the modulated optical comb signal to form four parallel laser beams, which are then passed through the atomic beam to excite calcium atom clock transitions.
[0074] The trigger laser 203 emits a probe laser. The laser 203 can be a 423nm laser or a 431nm laser. The trigger beam splitter 204 splits the probe laser into two beams. One beam enters the calcium atom beam before the four parallel laser beams pass through it, and the other beam enters the calcium atom beam after the four parallel laser beams pass through it. Both beams interact with the upper or lower energy level atoms of the clock transition, generating a fluorescence signal.
[0075] Specifically, when the laser 203 is a 423nm laser, the probe laser it emits is a 423nm laser, which triggers the beam splitter 204 to split the probe laser into two beams. One beam enters the atomic beam before the four parallel laser beams pass through the atomic beam, and the other beam enters the atomic beam after the four parallel laser beams pass through the atomic beam. The two beams interact with the lower energy level atoms of the clock transition and generate a fluorescence signal.
[0076] When laser 203 is a 431nm laser, the probe laser it emits is a 431nm laser. This probe laser is triggered to directly enter the atomic beam after the four parallel laser beams pass through the atomic beam, and interact with the upper energy level atoms of the clock transition to generate a fluorescence signal.
[0077] A photodetector 105 is triggered to detect the fluorescence signal and load it into a mixer 106. The mixer 106 demodulates the fluorescence signal to obtain an error signal. A servo feedback circuit 107 generates a servo signal based on the error signal and feeds it back to the optical comb 101. The optical comb 101 processes the comb tooth signal based on the servo signal to lock its frequency at the calcium atom transition frequency, resulting in an output signal that includes both optical and microwave signals. In this embodiment, by triggering the calcium atom furnace, mirror, laser, and beam splitter, the modulated optical comb tooth signal interacts with the calcium atom beam, exciting the calcium atoms to undergo clock transitions. The detection laser interacts with the clock-transitioned atoms to generate a fluorescence signal. This provides the prerequisite for subsequently obtaining the error signal through the fluorescence signal and processing the optical comb tooth signal using the error signal to lock its frequency at the atomic transition frequency to achieve an optical clock.
[0078] Those skilled in the art will understand that all or part of the steps of the above-described method embodiments can be implemented by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium. When executed, the program performs the steps of the above-described method embodiments; and the aforementioned storage medium includes various media capable of storing program code, such as ROM, RAM, magnetic disks, or optical disks.
[0079] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.
Claims
1. An optical clock that directly interacts with an optical comb and an atomic beam, characterized in that, include: An optical comb is used to emit broadband light with a spectral width of the first spectral width. A filter is used to filter the broadband light and directly obtain the comb tooth signal corresponding to the atomic transition frequency from the broadband light of the optical comb. An acousto-optic modulator is used to modulate the optical comb tooth signal, shifting the frequency of the comb tooth signal to the atomic transition frequency. Atomic furnaces are used to emit atomic beams; A reflector is used to reflect the modulated optical comb tooth signal to form four parallel laser beams, and to make the four parallel laser beams pass through the atomic beam to excite the atomic clock transition. Laser, used to emit detection laser light; A beam splitter is used to split the detection laser into two beams. One beam enters the atomic beam before the four parallel laser beams pass through the atomic beam, and the other beam enters the atomic beam after the four parallel laser beams pass through the atomic beam. The beam interacts with the upper or lower energy level atoms of the clock transition to generate a fluorescence signal. A photodetector is used to detect the fluorescence signal and load the fluorescence signal into a mixer; The mixer is used to demodulate the fluorescence signal to obtain an error signal; A servo feedback circuit is used to generate a servo signal based on the error signal and directly feed the servo signal back to the optical comb; The optical comb, as the excitation source for the atomic transition, is also used to process the optical comb tooth signal according to the servo signal, so as to lock the frequency of the optical comb tooth signal at the atomic transition frequency, thereby obtaining an output signal that contains both optical and microwave signals.
2. The optical clock according to claim 1, characterized in that, The filter is a filter that transmits light signals with a wavelength of 657nm.
3. The optical clock according to claim 1, characterized in that, The laser is a 423nm laser or a 431nm laser.
4. The optical clock according to claim 3, characterized in that, When the laser is a 423nm laser and the probe laser is a 423nm laser, the beam splitter is specifically used to: split the probe laser into two beams, one of which enters the atomic beam before the four parallel laser beams pass through the atomic beam, and the other of which enters the atomic beam after the four parallel laser beams pass through the atomic beam, and interacts with the lower energy level atoms of the clock transition to generate a fluorescence signal; or When the laser is a 431nm laser and the probe laser is a 431nm laser, the probe laser does not undergo beam splitting. Instead, it directly strikes the atomic beam after the four parallel laser beams have passed through it, interacting with the upper energy level atoms of the clock transition to generate a fluorescence signal.
5. The optical clock according to claim 1, characterized in that, The atomic beam is a calcium atomic beam.
6. A method for realizing an optical clock through direct interaction between an optical comb and an atomic beam, characterized in that, include: The trigger optical comb emits broadband light with a spectral width equal to the first spectral width; The trigger filter filters the broadband light, and the comb tooth signal corresponding to the atomic transition frequency is directly obtained from the broadband light of the optical comb; The acousto-optic modulator is triggered to modulate the optical comb tooth signal, shifting the frequency of the comb tooth signal to the atomic transition frequency; Triggering the nuclear reactor to emit an atomic beam; The trigger mirror reflects the modulated optical comb tooth signal to form four parallel laser beams, and the four parallel laser beams pass through the atomic beam to excite the atomic clock to transition. Trigger the laser to emit a probe laser; The trigger beam splitter splits the probe laser into two beams. One beam enters the atomic beam before the four parallel laser beams pass through the atomic beam, and the other beam enters the atomic beam after the four parallel laser beams pass through the atomic beam. The two beams interact with the upper or lower energy level atoms of the clock transition to generate a fluorescence signal. The photodetector is triggered to detect the fluorescence signal, and the fluorescence signal is loaded into the mixer; The mixer is triggered to demodulate the fluorescence signal to obtain an error signal; The servo feedback circuit is triggered to generate a servo signal based on the error signal, and the servo signal is directly fed back to the optical comb; The optical comb, which serves as the excitation source for the atomic transition, processes the comb tooth signal according to the servo signal to lock the frequency of the comb tooth signal at the atomic transition frequency, thereby obtaining an output signal that contains both optical and microwave signals.
7. The method according to claim 6, characterized in that, The filter is a filter that transmits light signals with a wavelength of 657nm.
8. The method according to claim 6, characterized in that, The laser is a 423nm laser or a 431nm laser.
9. The method according to claim 8, characterized in that, When the laser is a 423nm laser and the probe laser is a 423nm laser, the trigger beam splitter splits the probe laser into two beams. One beam enters the atomic beam before the four parallel laser beams pass through the atomic beam, and the other beam enters the atomic beam after the four parallel laser beams pass through the atomic beam. These beams interact with the upper or lower energy level atoms of the clock transition, generating a fluorescence signal, including: The trigger beam splitter splits the probe laser into two beams. One beam enters the atomic beam before the four parallel laser beams pass through the atomic beam, and the other beam enters the atomic beam after the four parallel laser beams pass through the atomic beam. The two beams interact with the lower energy level atoms of the clock transition and generate a fluorescence signal. or When the laser is a 431nm laser and the probe laser is a 431nm laser, the trigger beam splitter splits the probe laser into two beams. One beam enters the atomic beam before the four parallel laser beams pass through the atomic beam, and the other beam enters the atomic beam after the four parallel laser beams pass through the atomic beam. These beams interact with the upper or lower energy level atoms of the clock transition, generating a fluorescence signal, including: The triggering laser directly enters the atomic beam after the four parallel laser beams pass through the atomic beam, interacting with the upper energy level atoms of the clock transition to generate a fluorescence signal.
10. The method according to claim 6, characterized in that, The atomic beam is a calcium atomic beam.