Laser frequency stabilization system, method, device and readable medium in near ultraviolet band

Abstract

The application provides a near-ultraviolet-band laser frequency stabilization system, method, device and medium. The system comprises a first device and a second device. The first device comprises a first frequency conversion module and an iodine molecule modulation transfer spectrum module. The first device is configured to perform frequency conversion on received laser light through the first frequency conversion module, send the first laser light after frequency conversion to the iodine molecule modulation transfer spectrum module, and perform frequency locking on the first laser light through the iodine molecule modulation transfer spectrum module. The second device comprises a second frequency conversion module. The second device is connected with the first device and is configured to emit second laser light, lock the second laser light on the first laser light with a preset frequency difference, perform frequency locking on the second laser light, perform frequency conversion on the second laser light after frequency locking through the second frequency conversion module, and output the laser light after frequency conversion to obtain stabilized near-ultraviolet-band laser light.

Description

Technical Field

[0001] This application relates to the field of laser control technology, and in particular to a laser frequency stabilization system, method, device and readable medium in the near-ultraviolet band. Background Technology

[0002] Cold atom physics is a branch of physics that studies the properties of atoms and molecules at ultra-low temperatures. Cold atoms are atoms cooled to near absolute zero through experimental techniques. Because cold atoms move very slowly and have stable energy level structures, they possess more defined quantum states compared to hot atoms. This makes it easier to control their quantum states, such as outer electron spin and atomic magnetic moments. Furthermore, changes in the quantum states of cold atoms can, in turn, control optical signals, thus enabling information processing.

[0003] In practical applications, near-ultraviolet lasers with wavelengths in the 200-400 nm range have important uses in cold atom physics. In cold atom physics, these near-ultraviolet lasers generally need to be frequency-stabilized before use. Frequency stabilization methods can be broadly divided into two categories: one uses the center frequency of atomic spectral lines; the other uses a relative frequency reference source, such as an optical reference cavity. Based on this, the inventor's related technology has at least the following technical problems:

[0004] In related technologies, most lasers in the near-ultraviolet band with wavelengths in the range of 200-400nm are difficult to stabilize directly using the center frequency of atomic spectral lines. Therefore, they usually need to be stabilized using an external reference frequency. Specifically, this is done by locking the laser onto an optical reference cavity. However, in this method, the optical reference cavity can only provide a relative frequency standard, and it is often affected by environmental factors, resulting in long-term wavelength drift. Summary of the Invention

[0005] One objective of this application is to provide a near-ultraviolet laser frequency stabilization system, method, apparatus, and readable medium, which enables the system to output near-ultraviolet light with high stability and avoids the aforementioned long-term drift technical problem.

[0006] To achieve the above objectives, some embodiments of this application provide a near-ultraviolet laser frequency stabilization system. The system includes a first device and a second device. The first device includes a first frequency conversion module and an iodine molecule modulation transfer spectrum module. The first device is used to perform frequency conversion on a received laser beam via the first frequency conversion module, and send the frequency-converted first laser beam to the iodine molecule modulation transfer spectrum module, and lock the frequency of the first laser beam through the iodine molecule modulation transfer spectrum module. The second device includes a second frequency conversion module. The second device is connected to the first device and is used to emit a second laser beam, locking the second laser beam to the first laser beam with a preset frequency difference to lock the frequency of the second laser beam. The second frequency conversion module then performs frequency conversion on the frequency-locked second laser beam, and outputs the frequency-stabilized near-ultraviolet laser beam.

[0007] Some embodiments of this application also provide a near-ultraviolet laser frequency stabilization method, applied to the system described above. The method includes: frequency conversion of the received laser; frequency locking of the first laser after frequency conversion using the energy levels of iodine molecules; frequency locking of the second laser onto the first laser by heterodyne phase-locking with a preset frequency difference; frequency conversion of the second laser after frequency locking; and outputting the frequency-stabilized near-ultraviolet laser based on the frequency-converted laser.

[0008] Some embodiments of this application also provide a near-ultraviolet laser frequency stabilization device, the device comprising: one or more processors; and a memory storing computer program instructions, which, when executed, cause the processor to perform the method described above.

[0009] Some embodiments of this application also provide a computer-readable medium having computer program instructions stored thereon, which can be executed by a processor to implement the laser frequency stabilization method in the near-ultraviolet band.

[0010] Compared to existing technologies, the laser frequency stabilization system in the near-ultraviolet band provided in this application includes a first device and a second device. The first device includes a first frequency conversion module and an iodine molecule modulation and transfer spectrum module. The first frequency conversion module performs frequency conversion on the received laser and sends the frequency-converted first laser to the iodine molecule modulation and transfer spectrum module. The second device includes a second frequency conversion module connected to the first device, used to emit a second laser, locking the second laser to the first laser with a preset frequency difference, thereby frequency locking the second laser. The second frequency conversion module then performs frequency conversion on the frequency-locked second laser, and outputs the laser based on the frequency-converted laser. Since the energy levels of iodine molecules are considered absolute in the art, in the laser frequency stabilization system provided in this application, the first laser emitted by the first device is frequency-converted by the first frequency conversion module and locked to the iodine molecule modulation and transfer spectrum module, resulting in a stable frequency. After the second device performs frequency locking through heterodyne phase-locking, the frequency difference between it and the first device is also a stable frequency. Therefore, the frequency of the laser output by this system is also a stable frequency. Furthermore, since iodine molecules have numerous absorption peaks in the 500-700 nm wavelength range, through the combination of iodine spectrum frequency stabilization and heterodyne phase-locking, the stable laser output from this system can almost cover the near-ultraviolet band. In addition, because the frequency difference between the energy levels of iodine molecules and the phase-locking does not experience long-term drift, the frequency of the output near-ultraviolet laser will also not experience long-term drift. Attached Figure Description

[0011] Figure 1 A schematic diagram of a near-ultraviolet laser frequency stabilization system provided in this application embodiment;

[0012] Figure 2 A schematic diagram of another near-ultraviolet laser frequency stabilization system provided in this application embodiment;

[0013] Figure 3 A schematic diagram of another near-ultraviolet laser frequency stabilization system provided in this application embodiment;

[0014] Figure 4 A schematic diagram of another near-ultraviolet laser frequency stabilization system provided in this application embodiment;

[0015] Figure 5 A schematic diagram of another near-ultraviolet laser frequency stabilization system provided in this application embodiment;

[0016] Figure 6 A schematic flowchart illustrating a near-ultraviolet laser frequency stabilization method provided in this application embodiment;

[0017] Figure 7 This is a schematic diagram of a near-ultraviolet laser frequency stabilization device provided in an embodiment of this application. Detailed Implementation

[0018] 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 obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0019] The following terms are used in this document.

[0020] Laser: The energy released when electrons in an atom absorb energy and jump from a low energy level to a high energy level, and then fall back from the high energy level to a low energy level, is emitted in the form of photons, and the optical properties of the photons are highly consistent.

[0021] Long-term drift: In this article, it specifically refers to wavelength (frequency) drift.

[0022] Modulation transfer spectroscopy, abbreviated as "MTS".

[0023] Heterodyne: Combining one electromagnetic wave frequency with another different frequency to generate a beat. The beat refers to the signal response after the interference wave is received and output. When two wave signals of different frequencies interact, the periodic changes formed, with the amplitude increasing or decreasing periodically according to the difference between the two frequencies, result in wave amplitude modulation and fluctuations.

[0024] Phase-locked loop (PLL): This technique allows the phase of a controlled oscillator to be controlled by a standard signal or an external signal. It is used to achieve phase synchronization with the external signal or to track the frequency or phase of the external signal. PLL is short for phase-locked, meaning phase synchronization between two signals. Here, the oscillator is the seed laser described in this application.

[0025] Seed light: refers to the light emitted from a light source before it is amplified or converted in frequency.

[0026] A beam splitter is an optical device that can split a beam of light into two or more beams.

[0027] Seed laser: A laser that generates seed light for an amplifier or other laser.

[0028] Absorption peak: refers to the maximum absorption value corresponding to the center wavelength on the curve of absorbance versus wavelength in an absorption spectrum. An absorption spectrum is the spectrum produced when a substance absorbs photons and transitions from a lower energy level to a higher energy level.

[0029] Frequency locking: The frequency locking in this article refers to absolute frequency locking, that is, locking the laser frequency to a certain gas absorption line.

[0030] Frequency multiplier, in electronic circuits, refers to the frequency of the output signal being an integer multiple of the input signal frequency. For example, if the input signal frequency is n, then the first multiplier is 2n, and correspondingly 3n, 4n, and so on.

[0031] In laser frequency stabilization methods in related technologies, when the laser frequency deviates from the standard frequency, a frequency discriminator provides an error signal. A servo system and piezoelectric elements then control the cavity length, current, and other parameters to automatically return the laser frequency to the standard frequency. However, optical reference cavities can only provide a relative frequency standard and are often affected by environmental factors, leading to long-term wavelength drift.

[0032] To address the aforementioned technical problems, this application provides a near-ultraviolet laser frequency stabilization system. The core of this application lies in the following: the system includes a first device and a second device; the first device includes a first frequency conversion module and an iodine molecule modulation transfer spectrum module; the first device is used to perform frequency conversion on the received laser through the first frequency conversion module, and send the frequency-converted first laser to the iodine molecule modulation transfer spectrum module, and lock the frequency of the first laser through the iodine molecule modulation transfer spectrum module; the second device includes a second frequency conversion module; the second device is connected to the first device and is used to emit a second laser, causing the second laser to lock to the first laser by a preset frequency difference, thereby locking the frequency of the second laser, and performing frequency conversion on the frequency-locked second laser through the second frequency conversion module, outputting the frequency-stabilized near-ultraviolet laser.

[0033] It is understood that, since the energy levels of iodine molecules can be considered absolute in this field, the laser frequency stabilization system provided in this application, with its first device emitting a first-path laser beam, locks its frequency onto the iodine molecule modulation transfer spectrum module after frequency conversion by the first frequency conversion module, resulting in a stable frequency. The second device, after frequency locking via heterodyne phase-locking, also achieves a stable frequency difference with the first device. Therefore, the frequency of the laser output by this system is also stable. Furthermore, since iodine molecules have numerous absorption peaks in the 500-700 nm wavelength range, the stable laser output by this system, through the combination of iodine spectrum frequency stabilization and heterodyne phase-locking, can almost cover the near-ultraviolet band. Additionally, since the frequency difference between the energy levels of iodine molecules and the phase-locked frequency does not drift over a long period, the frequency of the output near-ultraviolet laser will also not experience long-term drift.

[0034] In some embodiments of this application, the first device may further include a first seed laser and a first beam splitter; the second device may further include a second seed laser, a second beam splitter, and a beam combiner; the first seed laser is used to emit the first laser beam and split the first laser beam through the first beam splitter so that a preset proportion of the laser beam enters the beam combiner; the second seed laser is used to emit the second laser beam and split the second laser beam through the second beam splitter so that the preset proportion of the laser beam enters the beam combiner.

[0035] In some embodiments of this application, the first beam splitter is further configured to split the first laser beam so that the remaining laser beams, except for the laser beams of the preset ratio, enter the first frequency conversion module. The first frequency conversion module is configured to perform frequency conversion on the received laser beams and send the frequency-converted laser beams to the iodine molecule modulation transfer spectrum module.

[0036] In some embodiments of this application, the first device may further include a frequency stabilization control module; one end of the frequency stabilization control module is connected to the output end of the iodine molecule modulation transfer spectrum module, and the other end of the frequency stabilization control module is connected to the input end of the first seed laser; the frequency stabilization control module is used to perform frequency stabilization control on the first laser path.

[0037] In some embodiments of this application, the second device includes a beat frequency detector and a phase-locked module; the beat frequency detector is used to detect the beat frequency of the laser emitted by the beam combiner, and send the laser after beat frequency detection to the phase-locked module, and perform heterodyne phase-locking through the phase-locked module to lock the frequency of the second laser.

[0038] In some embodiments of this application, the second beam splitter is further configured to split the second laser beam so that the remaining laser beams, except for the laser beams of the preset ratio, enter the second frequency conversion module; the second frequency conversion module is configured to perform frequency conversion on the received laser beams to obtain the frequency-stabilized near-ultraviolet laser beams.

[0039] In some embodiments of this application, the first laser and the second laser are lasers with wavelengths differing from 1 μm by a preset range. That is, embodiments of this application may employ two laser sources with wavelengths near or longer than 1 μm.

[0040] The implementation details of the near-ultraviolet laser frequency stabilization system of this application embodiment are described below with reference to a specific application example. The following implementation details are provided for ease of understanding only and are not necessary for implementing this solution.

[0041] like Figure 1 As shown, the system includes a first device 1 and a second device 2; the first device 1 includes a first laser output module 10, a first frequency conversion module 20, an iodine molecule modulation transfer spectrum module 30 and a frequency stabilization control module 40; the second device 2 includes a second laser output module 50, a heterodyne phase-locked module 60, a beam combining module 70 and a second frequency conversion module 80.

[0042] One output branch of the first laser output module 10 is connected to the input terminal of the first frequency conversion module 20, the output terminal of the first frequency conversion module 20 is connected to the input terminal of the iodine molecule modulation transfer spectrum module 30, the output terminal of the iodine molecule modulation transfer spectrum module 30 is connected to the input terminal of the frequency stabilization control module 40, and the output terminal of the frequency stabilization control module 40 is connected to the input terminal of the first laser output module 10; wherein, the other output branch of the first laser output module 10 is connected to the input terminal of the beam combining module 70.

[0043] The output of the beam combining module 70 is connected to the input of the heterodyne phase-locked module 60, the output of the heterodyne phase-locked module 60 is connected to the input of the second laser output module 50, and the output of the second laser output module 50 is connected to the input of the second frequency conversion module 80. In this way, the output of the second frequency conversion module 80 can output a near-ultraviolet laser with a stable frequency.

[0044] Specifically, this application embodiment utilizes different laser frequency conversions to achieve laser frequency stabilization. Most of the laser emitted from the first laser output module 10 of the first device 1 undergoes frequency conversion by the first frequency conversion module 20 and can directly enter the iodine molecule modulation transfer spectrum module 30 to generate an error signal. Then, the frequency stabilization control module 40 stabilizes the laser emitted from the first laser output module 10. A small portion of the laser emitted from the first laser output module 10 enters the beam combining module 70 of the second device 2. A small portion of the laser emitted from the second laser output module 50 also enters the beam combining module 70, where it is combined with a small portion of the laser emitted from the first laser output module 10 and then enters the heterodyne phase-locked loop module 60. The heterodyne phase-locked loop module 60 stabilizes the frequency of the laser emitted from the second laser output module 50. Most of the laser emitted from the second laser output module 50 enters the second frequency conversion module 80, where it undergoes frequency conversion to output a near-ultraviolet laser with a stable frequency.

[0045] In this embodiment, the laser output from the first laser output module 10, after frequency conversion by the first frequency conversion module 20, can directly enter the iodine molecule modulation transfer spectrum module 30, thereby utilizing the rich energy levels of iodine molecules in the 500-700nm wavelength range for frequency locking. The laser output from the second laser output module 50 is locked to the laser output from the first laser output module 10 with a certain frequency difference through heterodyne phase-locked loop. Then, the second frequency conversion module 80 can convert and output the laser in the near-ultraviolet band. Therefore, in this embodiment, the laser frequency can be precisely located to the laser frequency required for cold atom physics or quantum information experiments by flexibly utilizing frequency conversion and heterodyne phase-locked loop.

[0046] In some examples, the second frequency conversion module 80 can perform frequency conversion using a triple or quadruple frequency conversion method.

[0047] It is not difficult to see that, compared with the prior art, the embodiments of this application, since the energy levels of iodine molecules can be considered absolute in the art, utilize the near-ultraviolet laser frequency stabilization system provided in this application. The first laser emitted by the first device is frequency-converted by the first frequency conversion module and then locked onto the iodine molecule modulation transfer spectrum module. After the second device performs frequency locking through heterodyne phase-locking, its frequency difference with the first device is also a stable frequency. Therefore, the frequency of the laser output by this system is also a stable frequency. Furthermore, since iodine molecules have numerous absorption peaks in the 500-700nm band, through the combination of iodine spectrum frequency stabilization and heterodyne phase-locking, the stable laser output by this system can almost cover the near-ultraviolet band. In addition, since the frequency of the laser locked onto the iodine spectrum will not drift due to environmental factors and the frequency difference of the phase-locked signal will not drift over time, the frequency of the output near-ultraviolet laser will also not drift over time.

[0048] In some embodiments of this application, such as Figure 2 As shown, the first laser output module 10 may include a first seed laser 110 and a first beam splitter 120, with the output end of the first seed laser 110 connected to the input end of the first beam splitter 120; the output end of the frequency stabilization control module 40 is connected to the input end of the first seed laser 110, the output end of the first beam splitter 120 is connected to the input end of the first frequency conversion module 20, and the output end of the first frequency conversion module 20 is connected to the input end of the iodine molecule modulation transfer spectrum module 30.

[0049] Specifically, in some examples, most of the laser emitted by the first laser output module 10 of the first device 1 can be frequency-converted by the first frequency conversion module 20. The frequency-converted laser then passes through the iodine molecule modulation transfer spectrum module 30 to generate an error signal, and then the laser emitted by the first laser output module 10 is frequency-stabilized by the frequency stabilization control module 40.

[0050] It should be noted that the frequency conversion method of the first frequency conversion module 20 provided in this application embodiment is not the same as the frequency conversion method of the second frequency conversion module 80 in the following embodiments. For example, the first frequency conversion module 20 can use a double frequency conversion method, while the second frequency conversion module 80 can use a triple or quadruple frequency conversion method.

[0051] Specifically, after the laser emitted by the first seed laser 110 in the first laser output module 10 passes through the first beam splitter 120, most of the laser is converted by the first frequency conversion module 20 and can directly enter the iodine molecule modulation transfer spectrum module 30 to generate an error signal. Then, the laser emitted by the first seed laser 110 is stabilized by the frequency stabilization control module 40, and a small portion of the laser output by the first beam splitter 120 enters the beam combining module 70 of the second device 2.

[0052] In some examples, most of the laser beam may be split at 90% power, while a small portion may be split at 10% power. Of course, this is merely an illustrative example, and the actual phenomenon in practical applications should prevail. This application does not impose any specific limitations on this aspect.

[0053] In some embodiments of this application, the laser emitted by the first seed laser 110 is a laser with a wavelength that differs from 1 μm by a wavelength within a first preset range. The laser with a wavelength within the first preset range may be a laser in the 1000nm-1200nm band.

[0054] In some embodiments of this application, the frequency stabilization control module 40 may be a servo controller.

[0055] In some embodiments of this application, such as Figure 3 As shown, the second laser output module 50 includes a second seed laser 510 and a second beam splitter 520, with the output terminal of the second seed laser 510 connected to the input terminal of the second beam splitter 520; the output terminal of the heterodyne phase-locked module 60 is connected to the input terminal of the second seed laser 510, and the output terminal of the second beam splitter 520 is connected to the input terminal of the second frequency conversion module 80.

[0056] Specifically, in the second laser output module 50, the laser emitted by the second seed laser 510 passes through the second beam splitter 520, and a small portion of the laser also enters the beam combining module 70. This beam is combined with a small portion of the laser emitted by the first seed laser 110 after passing through the first beam splitter 120 and then enters the heterodyne phase-locked loop module 60. The heterodyne phase-locked loop module 60 stabilizes the frequency of the laser emitted by the second seed laser 510. Most of the laser from the second beam splitter 520 enters the second frequency conversion module 80. After frequency conversion by the second frequency conversion module 80, a near-ultraviolet laser with a stable frequency can be output.

[0057] In some examples, most of the laser beam may be split at 90% power, while a small portion may be split at 10% power. Of course, this is merely an illustrative example, and the actual phenomenon in practical applications should prevail. This application does not impose any specific limitations on this aspect.

[0058] In addition, it should be noted that the embodiments of this application may also be improvements made based on the first and other arbitrary embodiments provided.

[0059] In some embodiments of this application, the laser emitted by the second seed laser 510 is a laser with a wavelength that differs from 1 μm by a second preset range. That is, embodiments of this application may employ two laser sources with wavelengths near or longer than 1 μm.

[0060] In practical applications, the second preset range here should be roughly the same as the first preset range mentioned in the above embodiments. Its specific value can be set according to actual needs. This application embodiment does not make specific limitations on this.

[0061] In some embodiments of this application, such as Figure 4 As shown, the heterodyne phase-locked module 60 may include a beat frequency detector 610 and a phase-locked submodule 620. The output terminal of the beat frequency detector 610 is connected to the input terminal of the phase-locked submodule 620. The output terminal of the beam combining module 70 is connected to the input terminal of the beat frequency detector 610, and the output terminal of the phase-locked submodule 620 is connected to the input terminal of the second seed laser 510.

[0062] Specifically, after the laser emitted by the second seed laser 510 in the second laser output module 50 passes through the second beam splitter 520, a small portion of the laser also enters the beam combining module 70. This beam is combined with a small portion of the laser emitted by the first seed laser 110 after passing through the first beam splitter 120 and then enters the beat frequency detector 610. Finally, heterodyne phase locking is performed through the phase-locked loop submodule 620 to stabilize the frequency of the laser emitted by the second seed laser 510.

[0063] In some embodiments of this application, the beam combining module 70 may be a beam combiner.

[0064] The implementation details of the near-ultraviolet laser frequency stabilization system of this application embodiment are described below with reference to another specific application example. The following implementation details are provided for ease of understanding only and are not necessary for implementing this solution.

[0065] See also Figure 5 As shown, the first device 1 includes a first seed laser 110, a first beam splitter 120, a first frequency conversion module 20, an iodine molecule modulation transfer spectrum module 30, and a frequency stabilization control module 40; the second device 2 includes a second seed laser 510, a second beam splitter 520, a second frequency conversion module 80, a beam combiner module 70, a beat frequency detector 610, and a phase-locked loop submodule 620. The frequency stabilization control module 40 is a servo controller, and the beam combiner module 70 is a beam combiner.

[0066] The output of the first seed laser 110 is connected to the input of the first beam splitter 120. One branch of the first beam splitter 120 is connected to the input of the first frequency conversion module 20. The output of the first frequency conversion module 20 is connected to the input of the iodine molecule modulation transfer spectrum module 30. The output of the iodine molecule modulation transfer spectrum module 30 is connected to the input of the servo controller. The output of the servo controller is also connected to the input of the first seed laser 110. The other branch of the first beam splitter 120 is connected to the input of the beam combiner.

[0067] The output of the beam combiner is connected to the input of the beat frequency detector 610. The output of the beat frequency detector 610 is connected to the input of the phase-locked module 620. The output of the phase-locked module 620 is connected to the input of the second seed laser 510. The output of the second seed laser 510 is connected to the input of the second beam splitter 520. The output of the second beam splitter 520 is connected to the second frequency conversion module 80. Another branch of the second beam splitter 520 is connected to the input of the beam combiner.

[0068] Specifically, the laser emitted by the first seed laser 110 in the first laser output module 10 passes through the first beam splitter 120. Most of the laser then passes through the first frequency conversion module 20 and enters the iodine molecule modulation transfer spectrum module 30, generating an error signal. The frequency of the laser emitted by the first seed laser 110 is then stabilized by the frequency stabilization control module 40. A small portion of the laser output from the first beam splitter 120 enters the beam combining module 70 of the second device 2. Similarly, the laser emitted by the second seed laser 510 in the second laser output module 50 passes through the second beam splitter 520, and a small portion of the laser also enters the beam combining module 70. This beam is combined with the small portion of the laser emitted by the first seed laser 110 after passing through the first beam splitter 120 and then enters the heterodyne phase-locked loop module 60. The heterodyne phase-locked loop module 60 stabilizes the frequency of the laser emitted by the second seed laser 510. Most of the laser from the second beam splitter 520 enters the second frequency conversion module 80. After frequency conversion by the second frequency conversion module 80, a near-ultraviolet laser with a stable frequency is output.

[0069] For example, the first 1108nm laser is frequency-doubled to 554nm and locked using iodine spectroscopy. The second 1108nm laser is heterodyne-locked to the first laser and then triharmonicized to 369nm. This laser can be used as cooling light for ytterbium ions. Therefore, in this embodiment, the laser frequency can be precisely positioned to the frequency required for cold atom physics or quantum information experiments by flexibly utilizing frequency conversion and heterodyne phase-locking.

[0070] In summary, this application provides a near-ultraviolet laser frequency stabilization system. The core of this application lies in the following: the system includes a first device and a second device. The first device includes an iodine molecule modulation transfer spectrum module. The first device is used to perform frequency conversion on the received laser through the first frequency conversion module, and send the frequency-converted first laser to the iodine molecule modulation transfer spectrum module, and lock the frequency of the first laser through the iodine molecule modulation transfer spectrum module. The second device includes a second frequency conversion module. The second device is connected to the first device and is used to emit a second laser, locking the second laser to the first laser with a preset frequency difference, thereby locking the frequency of the second laser. The second frequency conversion module performs frequency conversion on the frequency-locked second laser, and outputs the frequency-stabilized near-ultraviolet laser based on the frequency-converted laser. It is understood that, since the energy levels of iodine molecules can be considered absolute in this field, the laser frequency stabilization system provided in this application, with its first device emitting a first-path laser beam, locks its frequency onto the iodine molecule modulation transfer spectrum module after frequency conversion by the first frequency conversion module, resulting in a stable frequency. The second device, after frequency locking via heterodyne phase-locking, also achieves a stable frequency difference with the first device. Therefore, the frequency of the laser output by this system is also stable. Furthermore, since iodine molecules have numerous absorption peaks in the 500-700 nm wavelength range, the stable laser output by this system, through the combination of iodine spectrum frequency stabilization and heterodyne phase-locking, can almost cover the near-ultraviolet band. Additionally, since the frequency difference between the energy levels of iodine molecules and the phase-locked frequency does not drift over a long period, the frequency of the output near-ultraviolet laser will also not experience long-term drift.

[0071] Figure 6 A laser frequency stabilization method in the near-ultraviolet band is shown, which can be applied to the system described in any one or more of the above embodiments. The method may include the following steps:

[0072] Step S101: Frequency conversion is performed on the received laser.

[0073] Step S102: Frequency locking of the first laser beam after frequency conversion is performed using the energy levels of iodine molecules.

[0074] Step S103: Lock the second laser onto the first laser at a preset frequency difference using heterodyne phase-locking, thereby frequency locking the second laser.

[0075] Step S104: The second laser after frequency locking is frequency converted, and the laser after frequency conversion is output to obtain a near-ultraviolet laser after frequency stabilization.

[0076] It is not difficult to see that the embodiments of this application are method embodiments corresponding to the system embodiments. The implementation details of the embodiments of this application have been described in the system embodiments, and will not be repeated here to avoid repetition.

[0077] Furthermore, this application also provides a near-ultraviolet laser frequency stabilization device, the structure of which is as follows: Figure 7 As shown, the device includes a memory 90 for storing computer-readable instructions and a processor 100 for executing the computer-readable instructions, wherein when the computer-readable instructions are executed by the processor, the processor is triggered to execute the virtual content distribution method.

[0078] The methods and / or embodiments in this application can be implemented as computer software programs. For example, embodiments of this disclosure include a computer program product comprising a computer program carried on a computer-readable medium, the computer program containing program code for performing the methods shown in the flowchart. When the computer program is executed by a processing unit, it performs the functions defined in the methods of this application.

[0079] It should be noted that the computer-readable medium described in this application can be a computer-readable signal medium or a computer-readable storage medium, or any combination thereof. A computer-readable medium can be, for example,—but not limited to—an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples of a computer-readable storage medium may include, but are not limited to: an electrical connection having one or more wires, a portable computer disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage device, magnetic storage device, or any suitable combination thereof. In this application, a computer-readable medium can be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, apparatus, or device.

[0080] In this application, a computer-readable signal medium may include a data signal propagated in baseband or as part of a carrier wave, carrying computer-readable program code. Such propagated data signals may take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. The computer-readable signal medium may also be any computer-readable medium other than a computer-readable storage medium, capable of transmitting, propagating, or transmitting a program for use by or in connection with an instruction execution system, apparatus, or device. The program code contained on the computer-readable medium may be transmitted using any suitable medium, including but not limited to: wireless, wireline, optical fiber, RF, etc., or any suitable combination thereof.

[0081] Computer program code for performing the operations of this application can be written in one or more programming languages ​​or a combination thereof, including object-oriented programming languages ​​such as Java, Smalltalk, and C++, and conventional procedural programming languages ​​such as the "C" language or similar programming languages. The program code can be executed entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving remote computers, the remote computer can be connected to the user's computer via any type of network—including a local area network (LAN) or a wide area network (WAN)—or can be connected to an external computer (e.g., via the Internet using an Internet service provider).

[0082] The flowcharts or block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of devices, methods, and computer program products according to various embodiments of this application. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can be implemented using a dedicated hardware-specific system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0083] In another aspect, embodiments of this application also provide a computer-readable medium, which may be included in the device described in the above embodiments; or it may exist independently and not assembled into the device. The aforementioned computer-readable medium carries one or more computer-readable instructions, which may be executed by a processor to implement the steps of the methods and / or technical solutions of the various embodiments of this application.

[0084] In a typical configuration of this application, the terminal and the service network devices each include one or more processors (CPUs), input / output interfaces, network interfaces, and memory.

[0085] Memory may include non-persistent storage in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM. Memory is an example of computer-readable media.

[0086] Computer-readable media include both permanent and non-permanent, removable and non-removable media, which can store information using any method or technology. Information can be computer-readable instructions, data structures, modules of programs, or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, read-only optical disc (CD-ROM), digital versatile optical disc (DVD) or other optical storage, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other non-transfer medium that can be used to store information accessible by a computing device.

[0087] Furthermore, this application also provides a computer program stored in a computer device, which causes the computer device to execute the method for executing the control code.

[0088] It should be noted that this application can be implemented in software and / or a combination of software and hardware, for example, using an application-specific integrated circuit (ASIC), a general-purpose computer, or any other similar hardware device. In some embodiments, the software program of this application can be executed by a processor to implement the steps or functions described above. Similarly, the software program of this application (including related data structures) can be stored in a computer-readable recording medium, such as RAM memory, magnetic or optical drives, floppy disks, and similar devices. Furthermore, some steps or functions of this application can be implemented in hardware, for example, as circuitry that cooperates with a processor to perform the various steps or functions.

[0089] It will be apparent to those skilled in the art that this application is not limited to the details of the exemplary embodiments described above, and that this application can be implemented in other specific forms without departing from the spirit or essential characteristics of this application. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of this application is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be embraced within this application. No reference numerals in the claims should be construed as limiting the scope of the claims. Furthermore, it is clear that the word "comprising" does not exclude other units or steps, and the singular does not exclude the plural. Multiple units or devices recited in the apparatus claims may also be implemented by a single unit or device in software or hardware. The terms "first," "second," etc., are used to indicate names and do not indicate any particular order.

Claims

1. A laser frequency stabilization system in the near-ultraviolet band, characterized in that, The system includes a first device and a second device; The first device includes a first frequency conversion module and an iodine molecule modulation transfer spectrum module; The first device is used to convert the frequency of the received laser through the first frequency conversion module, send the first laser after frequency conversion to the iodine molecule modulation transfer spectrum module, and lock the frequency of the first laser based on the absorption peak of iodine molecules in the 500-700nm band through the iodine molecule modulation transfer spectrum module. The second device includes a second frequency conversion module; The second device is connected to the first device and is used to emit a second laser beam, which locks the second laser beam to the first laser beam with a preset frequency difference, thereby frequency locking the second laser beam. The second frequency conversion module performs frequency conversion on the frequency-locked second laser beam and outputs the laser beam after frequency conversion to obtain a frequency-stabilized near-ultraviolet laser. The first device further includes a first seed laser and a first beam splitter; the second device further includes a second seed laser, a second beam splitter, and a beam combiner; the first seed laser is used to emit the first laser beam and split the first laser beam through the first beam splitter so that a preset proportion of the laser beam enters the beam combiner; the second seed laser is used to emit the second laser beam and split the second laser beam through the second beam splitter so that the preset proportion of the laser beam enters the beam combiner.

2. The system according to claim 1, characterized in that, The first beam splitter is also used to split the first laser beam so that the remaining laser beams, except for the laser beams of the preset ratio, enter the first frequency conversion module.

3. The system according to claim 1, characterized in that, The first device also includes a frequency stabilization control module; One end of the frequency stabilization control module is connected to the output end of the iodine molecule modulation transfer spectrum module, and the other end of the frequency stabilization control module is connected to the input end of the first seed laser. The frequency stabilization control module is used to perform frequency stabilization control on the first laser path.

4. The system according to claim 1, characterized in that, The second device includes a beat frequency detector and a phase-locked loop (PLL) submodule; The beat frequency detector is used to detect the beat frequency of the laser emitted by the beam combiner, and send the laser after beat frequency detection to the phase-locked module. The phase-locked module performs heterodyne phase-locking to lock the frequency of the second laser.

5. The system according to claim 1, characterized in that, The second beam splitter is also used to split the second laser beam so that the remaining laser beams, except for the preset ratio laser beam, enter the second frequency conversion module.

6. The system according to claim 1, characterized in that, The second frequency conversion module specifically uses a triple or quadruple frequency conversion method for frequency conversion.

7. The system according to any one of claims 1 to 6, characterized in that, The first laser and the second laser are lasers with wavelengths that differ from 1 μm within a preset range.

8. A laser frequency stabilization method in the near-ultraviolet band, characterized in that, Applied to the system according to any one of claims 1-7, the method comprises: Frequency conversion is performed on the received laser light; The energy levels of iodine molecules are used to lock the frequency of the first laser beam after frequency conversion. The second laser is locked to the first laser by a preset frequency difference using heterodyne phase-locking, thereby frequency locking of the second laser. The second laser, after frequency locking, is frequency-converted, and the output is based on the frequency-converted laser to obtain a frequency-stabilized near-ultraviolet laser.

9. A laser frequency stabilization device in the near-ultraviolet band, characterized in that, The device includes: One or more processors; and A memory storing computer program instructions, which, when executed, cause the processor to perform the method as described in claim 8.

10. A computer-readable medium having stored thereon computer program instructions that can be executed by a processor to implement the method of claim 8.

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