Apparatus for generating continuous wave vacuum ultraviolet laser based on four-wave mixing of cadmium vapor

Abstract

The application particularly relates to a device for generating continuous wave vacuum ultraviolet laser based on four-wave mixing of cadmium vapor, which comprises a light source system, an optical focusing system, a cadmium atom vapor chamber and a light splitting system, wherein the light source system is used for emitting multiple beams of incident light meeting a preset wavelength range; the optical focusing system is used for focusing the multiple beams of incident light meeting the preset wavelength range to a target area in the cadmium atom vapor chamber to obtain vacuum ultraviolet light; and the light splitting system is used for separating the vacuum ultraviolet light from the multiple beams of incident light meeting the preset wavelength range. Thus, the problem that the continuous wave vacuum ultraviolet laser cannot be efficiently generated is solved, and an ideal laser source directly driving nuclear transition is provided for a nuclear optical clock.

Description

Technical Field

[0001] This application relates to the field of nonlinear optics and nuclear physics, and in particular to a device for generating continuous-wave vacuum ultraviolet laser based on cadmium vapor four-wave mixing. Background Technology

[0002] As the core carrier of the next-generation time and frequency standard, the nuclear optical clock's performance breakthrough relies on the unique advantage of nuclear transitions rather than traditional atomic electronic transitions. Th-229 3+ The nuclear isotropic transition (energy 8.4 eV, corresponding wavelength 148.4 nm) can improve the stability of atomic clocks to 10 due to its extremely narrow linewidth (expected <1 mHz) and strong robustness to environmental disturbances. -19 Magnitude.

[0003] Among related technologies, VUV (Vacuum Ultraviolet Light) laser generation technologies mainly include gas medium four-wave mixing technology, high-order harmonic generation (HHG) technology, and nonlinear crystal frequency conversion technology. Specifically, for xenon gas systems, gas medium four-wave mixing technology typically uses fundamental frequency light with wavelengths of 249.6 nm and 784.8 nm to generate a pulsed 148.4 nm laser through a four-wave mixing process. For mercury vapor systems, it typically uses 257 nm, 399 nm, and 545 nm (or 313 nm and 545 nm) and generates a 121 nm continuous wave laser through four-wave mixing. HHG generates an ultraviolet beam by interacting a mode-locked femtosecond pulsed laser (with a center frequency continuously tunable in the range of 1040 nm to 1070 nm and a pulse width <150 fs) with xenon gas. Its seventh harmonic spectrum covers 148.5 nm to 152.9 nm, and the average power per tooth is typically <10 nW. Nonlinear crystal frequency doubling technology typically uses periodically polarized barium magnesium fluoride (PPLN) or potassium beryllium fluoroborate (KBBF) crystals for deep ultraviolet frequency doubling. The former is currently difficult to fabricate using conventional methods to create a periodically polarized structure suitable for vacuum ultraviolet output, while the latter's minimum continuous wave output wavelength currently cuts off at 191 nm.

[0004] However, the core technological challenge of nuclear optical clocks lies in integrating Th-229... 3+The nuclear transition (148.4 nm, narrow linewidth) transforms into a controllable quantum system, requiring the driving laser to possess stringent characteristics such as precise wavelength locking, continuous-wave operation, μW-level power, and 1kHz-level linewidth. In related technologies, pulsed four-wave mixing schemes (xenon gas media) result in spectral linewidths broadened to the GHz level, exceeding the broad linewidth of nuclear transitions by more than 10 orders of magnitude, and the average power is limited by the repetition frequency, making it difficult to break the μW threshold. Vacuum ultraviolet frequency comb technology's single-mode power is limited to the nW level by the comb structure, failing to meet the signal-to-noise ratio requirements for nuclear transition excitation. Continuous-wave four-wave mixing schemes based on mercury vapor media are limited by the medium's energy level structure, making them unsuitable for generating high-power continuous-wave lasers with a wavelength of 148.4 nm. Nonlinear crystals currently lack the ability to directly generate lasers with wavelengths as short as 148.4 nm. Therefore, the media systems in related technologies cannot simultaneously satisfy the conditions of high nonlinear efficiency, broad spectral transparency, and continuous-wave phase matching in the 148.4 nm band, a problem that urgently needs to be solved. Summary of the Invention

[0005] This application provides a device and method for generating continuous-wave vacuum ultraviolet laser based on cadmium vapor four-wave mixing, to solve the problem of inefficient generation of continuous-wave vacuum ultraviolet laser, and to provide an ideal laser source for nuclear optical clocks that can directly drive nuclear transitions.

[0006] The first aspect of this application provides a device for generating continuous-wave vacuum ultraviolet laser based on cadmium vapor four-wave mixing, comprising: a light source system, an optical focusing system, a cadmium atomic vapor chamber, and a beam splitting system, wherein... The light source system is used to emit multiple beams of incident light that meet a preset wavelength range; The optical focusing system is used to focus the multiple beams of incident light that meet the preset wavelength range onto the target area in the cadmium atom vapor chamber to obtain vacuum ultraviolet light; The beam splitting system is used to separate the vacuum ultraviolet light from the multiple incident beams that meet the preset wavelength range; Optionally, the vacuum ultraviolet light detection system is used to detect the vacuum ultraviolet light and determine whether the vacuum ultraviolet light meets the preset output power condition and the preset output linewidth condition based on the detection result.

[0007] Optionally, the cadmium atomic vapor chamber includes cadmium atomic vapor.

[0008] Optionally, based on the window protection of the cadmium atomic vapor chamber and the phase matching requirements of cadmium vapor four-wave mixing, one or more protective gases are stored in the cadmium atomic vapor chamber.

[0009] Optionally, the cadmium atomic vapor chamber includes: A temperature control unit is used to adjust the temperature of the cadmium atomic vapor based on the number density requirements of the cadmium atomic vapor.

[0010] Optionally, the cadmium atomic vapor chamber includes: An airflow control device for adjusting the gas flow rate and gas flow volume of one or more protective gases based on the gas partial pressure requirements of one or more protective gases.

[0011] Optionally, the light source system includes: A first laser source device, used to emit the first incident laser; The second laser source device is used to emit the second incident laser.

[0012] Optionally, the light source system further includes: The third laser source device is used to emit the third incident laser.

[0013] Optionally, the optical focusing system includes: a first waveplate, a first laser beam expander, a second waveplate, a second laser beam expander, a long-pass dichroic mirror, and a focusing assembly, wherein... The first waveplate is used to adjust the polarization of the incident first laser beam. The first laser beam expander is used to expand the first incident laser beam after it has been adjusted by the first waveplate to obtain the first expanded laser beam. The second waveplate is used to adjust the polarization of the incident second laser beam; The second laser beam expander is used to expand the second incident laser beam after it has been adjusted by the second waveplate to obtain a second expanded laser beam; The long-pass dichroic mirror is used to combine the first expanded laser beam and the second expanded laser beam to obtain a combined laser beam. The focusing component is used to focus the combined laser beam onto the target area within the cadmium atom vapor chamber to obtain vacuum ultraviolet light.

[0014] Optionally, the deviation of the confocal parameters of the first incident laser and the second incident laser is within a first preset range; The deviation between the focal positions of the first incident laser and the second incident laser is within a second preset range.

[0015] Optionally, the vacuum ultraviolet light detection system includes: A spectral filter is used to filter the vacuum ultraviolet light to obtain filtered vacuum ultraviolet light; The power detection module is used to identify the output power of the filtered vacuum ultraviolet light and determine whether the vacuum ultraviolet light meets the preset output power condition based on the first identification result. The linewidth detection module is used to identify the linewidth of the filtered vacuum ultraviolet light and determine whether the vacuum ultraviolet light meets the preset output linewidth condition based on the second identification result.

[0016] A second aspect of this application provides a method for generating continuous-wave vacuum ultraviolet laser, employing the apparatus for generating continuous-wave vacuum ultraviolet laser based on cadmium vapor four-wave mixing as described in any of the preceding claims, comprising the following steps: The light source system emits multiple beams of incident light that meet a preset wavelength range; The optical focusing system is used to focus the multiple beams of incident light that meet the preset wavelength range onto the target area in the cadmium atom vapor chamber to obtain vacuum ultraviolet light; The vacuum ultraviolet light is separated from the multiple incident light beams that meet the preset wavelength range using the aforementioned beam splitting system.

[0017] Optionally, after separating the vacuum ultraviolet light from the multiple incident beams satisfying a preset wavelength range using the beam splitting system, the method further includes: The vacuum ultraviolet light is detected using a vacuum ultraviolet light detection system, and the detection results are used to determine whether the vacuum ultraviolet light meets the preset output power conditions and preset output linewidth conditions.

[0018] Therefore, the light source system of this application embodiment is used to emit multiple beams of incident light that meet a preset wavelength range; the optical focusing system is used to focus the multiple beams of incident light that meet the preset wavelength range onto the target area in the cadmium atomic vapor chamber to obtain vacuum ultraviolet light; and the beam splitting system is used to separate the vacuum ultraviolet light from the multiple beams of incident light that meet the preset wavelength range. This solves the problem of inefficient generation of continuous-wave vacuum ultraviolet lasers and provides an ideal laser source for nuclear optical clocks that can directly drive nuclear transitions.

[0019] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0020] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein: Figure 1 This is a schematic diagram of a device for generating continuous-wave vacuum ultraviolet laser based on cadmium vapor four-wave mixing, according to an embodiment of this application. Figure 2 This is a schematic diagram of an apparatus for generating continuous-wave vacuum ultraviolet laser based on cadmium vapor four-wave mixing, according to an embodiment of this application. Figure 3This is a schematic diagram of the optical path of an apparatus for generating continuous-wave vacuum ultraviolet laser based on cadmium vapor four-wave mixing, according to an embodiment of this application. Figure 4 This is a schematic diagram illustrating the output power performance of a device for generating continuous-wave vacuum ultraviolet laser based on cadmium vapor four-wave mixing according to an embodiment of this application, with the laser wavelength ranging from 147.0 nm to 153.7 nm. Figure 5 This is an interference diagram of a 148.4 nm laser from a device for generating continuous-wave vacuum ultraviolet laser based on cadmium vapor four-wave mixing, according to an embodiment of this application. Figure 6 This is a schematic diagram illustrating the quadratic relationship of VUV light power with respect to 375 nm light and the linear relationship with respect to 710 nm light in a device for generating continuous-wave vacuum ultraviolet laser based on cadmium vapor four-wave mixing according to an embodiment of this application. Figure 7 A schematic line diagram of VUV two-photon resonance of a device for generating continuous-wave vacuum ultraviolet laser based on cadmium vapor four-wave mixing according to an embodiment of this application; Figure 8 This is a flowchart of a method for generating continuous wave vacuum ultraviolet laser according to an embodiment of this application. Detailed Implementation

[0021] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application.

[0022] The following description, with reference to the accompanying drawings, describes an apparatus for generating continuous-wave vacuum ultraviolet lasers based on cadmium vapor four-wave mixing according to embodiments of this application. Addressing the problem of inefficient generation of continuous-wave vacuum ultraviolet lasers mentioned in the background art, this application provides an apparatus for generating continuous-wave vacuum ultraviolet lasers based on cadmium vapor four-wave mixing. In this embodiment, the light source system emits multiple beams of incident light satisfying a preset wavelength range; the optical focusing system focuses the multiple beams of incident light satisfying the preset wavelength range onto a target region within a cadmium atomic vapor chamber to obtain vacuum ultraviolet light; and the beam splitting system separates the vacuum ultraviolet light from the multiple beams of incident light satisfying the preset wavelength range. This solves the problem of inefficient generation of continuous-wave vacuum ultraviolet lasers and provides an ideal laser source for nuclear optical clocks that can directly drive nuclear transitions.

[0023] Specifically, Figure 1 This is a schematic diagram of an apparatus for generating continuous-wave vacuum ultraviolet laser based on cadmium vapor four-wave mixing, provided as an embodiment of this application.

[0024] like Figure 1 As shown, the device 10 for generating continuous-wave vacuum ultraviolet laser based on cadmium vapor four-wave mixing includes: a light source system 100, an optical focusing system 200, a cadmium atomic vapor chamber 300, and a beam splitting system 400. The light source system 100 is used to emit multiple beams of incident light that meet a preset wavelength range; The optical focusing system 200 is used to focus multiple beams of incident light that meet the preset wavelength range onto the target area in the cadmium atomic vapor chamber to obtain vacuum ultraviolet light; The spectral separation system 400 is used to separate vacuum ultraviolet light from multiple incident beams that meet a preset wavelength range.

[0025] The preset wavelength range can be a value set by the user, a value obtained through a limited number of experiments, or a value obtained through a limited number of computer simulations; no specific limitation is made here.

[0026] Understandably, the light source system 100 provides continuous-wave (CW) lasers with wavelengths of 375 nm and 710 nm as incident light within a preset wavelength range, serving as the fundamental frequency light initiating the four-wave mixing (FWM) process in cadmium (Cd) atomic vapor. The optical focusing system 200 focuses the incident light within the preset wavelength range onto the target region within the cadmium atomic vapor chamber to achieve effective beam convergence and phase matching. The beam splitting system 400 utilizes the dispersion of a Brewster prism (which has Brewster angles for both incident and exit angles of p-polarized vacuum ultraviolet light, thus reducing surface reflection losses) to separate the incident light within the preset wavelength range from the vacuum ultraviolet light, while simultaneously minimizing the power loss of the vacuum ultraviolet light.

[0027] Optionally, in some embodiments, the system further includes: a vacuum ultraviolet light detection system for detecting vacuum ultraviolet light and determining whether the vacuum ultraviolet light meets preset output power conditions and preset output linewidth conditions based on the detection results.

[0028] It is understandable that the preset output power condition refers to the vacuum ultraviolet laser output power threshold set in advance to achieve a specific application goal during the detection of vacuum ultraviolet light; the preset output linewidth condition refers to the spectral linewidth threshold set in advance to achieve a specific application goal during the detection of vacuum ultraviolet light; the vacuum ultraviolet light detection system detects vacuum ultraviolet light to achieve low background noise and high sensitivity vacuum ultraviolet light power measurement.

[0029] Optionally, in some embodiments, the light source system 100 includes: a first laser light source device for emitting a first incident laser; and a second laser light source device for emitting a second incident laser.

[0030] Optionally, in some embodiments, the light source system 100 further includes a third laser light source device for emitting a third incident laser.

[0031] Understandably, the first and second laser source devices are used to generate continuous-wave lasers with wavelengths of 375 nm (first incident laser) and 710 nm (second incident laser), respectively. Both devices are highly stable continuous-wave lasers; the first incident laser is generated by frequency doubling of a highly stable continuous-wave laser, and the second incident laser is directly provided by another highly stable continuous-wave laser. The power of the first incident laser is 2 W, and the power of the second incident laser is between 1 W and 6 W. The first and second laser source devices perform precise beam collimation and mode control on the laser sources to ensure that the quality and stability of the laser beam meet the experimental requirements.

[0032] Optionally, in some embodiments, the cadmium atomic vapor chamber 300 includes cadmium atomic vapor.

[0033] Optionally, in some embodiments, the cadmium atomic vapor chamber 300 stores one and / or more protective gases.

[0034] Optionally, in some embodiments, the cadmium atomic vapor chamber 300 includes a temperature control unit for adjusting the temperature of the cadmium atomic vapor based on the number density requirement of the cadmium atomic vapor.

[0035] Optionally, in some embodiments, the cadmium atomic vapor chamber 300 includes: an airflow control device for adjusting the gas flow rate and gas flow volume of one or more protective gases based on the gas partial pressure requirements of one or more protective gases.

[0036] It is understandable that, such as Figure 2 As shown, Figure 2This is a schematic diagram of an apparatus for generating continuous-wave vacuum ultraviolet laser based on cadmium vapor four-wave mixing according to an embodiment of this application. A cadmium atom vapor chamber 300 is used to contain cadmium atom vapor as a nonlinear medium for the four-wave mixing process. The cadmium atom vapor chamber 300 can be configured with a temperature control unit and an airflow control device to precisely regulate its temperature. It has rare gas inlets and outlets at both ends to dynamically adjust the rare gas pressure, thereby optimizing the number density of cadmium atoms, the partial pressure of the rare gas, and the phase matching conditions of the four-wave mixing process, thus optimizing the efficiency of the four-wave mixing process. A 148.4 nm mixed light is generated in the cadmium atom vapor chamber 300 through a four-wave mixing nonlinear optical process. In this process, the high nonlinear polarizability of cadmium atoms and the optimized phase matching conditions are utilized to achieve efficient energy conversion and laser generation, thereby significantly improving the conversion efficiency and output stability of the vacuum ultraviolet laser.

[0037] Optionally, in some embodiments, the deviation value of the confocal parameters of the first incident laser and the second incident laser is within a first preset range; the deviation value of the focal positions of the first incident laser and the second incident laser is within a second preset range.

[0038] The first preset range and the second preset range can be thresholds preset by the user, thresholds obtained through a limited number of experiments, or thresholds obtained through a limited number of computer simulations; no specific limitations are made here.

[0039] It is understandable that the 148.4 nm vacuum ultraviolet light obtained after four-wave mixing has the same confocal parameters and focal position as the two fundamental frequency beams at 375 nm (i.e., the first incident laser) and 710 nm (i.e., the second incident laser), with a confocal parameter of approximately 6 mm. This confocal parameter enhances the efficiency of nonlinear interaction during the four-wave mixing process and optimizes the phase-matching conditions.

[0040] Optionally, in some embodiments, the optical focusing system 200 includes: a first waveplate, a first laser beam expander, a second waveplate, a second laser beam expander, a long-pass dichroic mirror, and a focusing assembly. The first waveplate is used to polarize an incident first laser beam; the first laser beam expander is used to expand the first incident laser beam after polarization by the first waveplate to obtain a first expanded laser beam; the second waveplate is used to polarize an incident second laser beam; the second laser beam expander is used to expand the second incident laser beam after polarization by the second waveplate to obtain a second expanded laser beam; the long-pass dichroic mirror is used to combine the first and second expanded laser beams to obtain a combined laser beam; and the focusing assembly is used to focus the combined laser beam onto a target region within the cadmium vapor chamber 300 to obtain vacuum ultraviolet light.

[0041] It is understandable that, such as Figure 3 As shown, Figure 3This is a schematic diagram of the optical path of a device for generating continuous-wave vacuum ultraviolet laser based on cadmium vapor four-wave mixing according to an embodiment of this application. In this device, L1 is a mode-matching lens, CL1 is a cylindrical lens, WP1 is a first waveplate (quarter-wave plate and half-wave plate), TL1 is a first laser beam expander, WP2 is a second waveplate, TL2 is a second laser beam expander, DM is a long-pass dichroic mirror, L2 is an achromatic double lens with f = 300 mm, L3 is a MgF2 lens with f = 400 mm, BP is a Brewster prism, L4 is a MgF2 lens, and SF is a spectral filter. The 375 nm laser (i.e., the first incident laser) and the 710 nm laser (i.e., the second incident laser) are respectively passed through the first laser beam expander (i.e.,... Figure 3 TL1) and the second laser beam expander (i.e. Figure 3 The beam is expanded to 5 mm and 7 mm diameter using TL2, and the first and second waveplates (i.e., Figure 3 WP1 and WP2 in the image are adjusted to horizontal polarization (p polarization); then they pass through a long-pass dichroic mirror (i.e., Figure 3 The DM beam in the image is combined and simultaneously passed through an achromatic lens (i.e., a focusing component, such as...) Figure 3 The L2 in the laser is focused into the cadmium atom vapor chamber 300 to precisely control the focal position and confocal parameters of the incident laser.

[0042] Optionally, in some embodiments, the vacuum ultraviolet light detection system includes: a spectral filter for filtering vacuum ultraviolet light to obtain filtered vacuum ultraviolet light; a power detection module for identifying the output power of the filtered vacuum ultraviolet light and determining whether the vacuum ultraviolet light meets a preset output power condition based on a first identification result; and a linewidth detection module for identifying the linewidth of the filtered vacuum ultraviolet light and determining whether the vacuum ultraviolet light meets a preset output linewidth condition based on a second identification result.

[0043] Understandably, the spectral filter employs a specially designed narrowband filter with a bandwidth of 10 nm to filter out vacuum ultraviolet light from the mixed light, while effectively suppressing interference from fundamental frequency light (375 nm and 710 nm) and other stray light. In this embodiment, a photomultiplier tube detector monitors the photomultiplier tube output power in real time and compares it with preset output power conditions to determine whether the vacuum ultraviolet laser meets the preset output power conditions required for nuclear optical clock applications. The linewidth detection module performs precise spectral analysis on the 148.4 nm vacuum ultraviolet laser after filtering by the spectral filter, comparing the second identification result with preset output linewidth conditions (e.g., free-running state <1 MHz, locked state <100 Hz) to ensure that the output laser always meets the preset output linewidth conditions.

[0044] Therefore, the embodiments of this application employ cadmium vapor, utilizing its high transition matrix elements (such as 5).1 P1→6 1 The dipole moment of S0 is 4.199 au1, which significantly enhances the third-order nonlinear magnetic susceptibility (χ³). By adjusting the laser beam confocal parameters and cadmium vapor density, and combining rare gases (such as krypton and xenon) to compensate for wave vector mismatch, the maximum phase-matching function G(bNΔk) is achieved. A 6-phase laser beam is selected as the maximum phase-matching function G(bNΔk). 1 S0 or 5 1 D2, as a two-photon resonant state, significantly improves conversion efficiency when combined with the incident laser wavelength (e.g., 375 nm × 2 + 710 nm).

[0045] To facilitate those skilled in the art to further understand the apparatus for generating continuous-wave vacuum ultraviolet laser based on cadmium vapor four-wave mixing in the embodiments of this application, the following is in conjunction with... Figures 4 to 6 The embodiments shown will be described in detail.

[0046] Specifically, such as Figure 4 As shown, Figure 4 This diagram illustrates the output power performance of a device for generating continuous-wave vacuum ultraviolet laser based on cadmium vapor four-wave mixing, according to one embodiment of this application, in the 147.0 nm to 153.7 nm range. It shows the output power performance of the laser in the 147.0 nm to 153.7 nm range, with input powers of 0.17 W @ 375 nm and 1.8 W @ 679.6 ~ 850 nm, further verifying the stability and effectiveness of the laser output in this wavelength band. The laser wavelength generated in this embodiment is 148.4 nm and can be effectively filtered by a specially designed narrowband filter (10 nm bandwidth). When the input power is 1.4 W @ 375 nm and 1.8 W @ 710 nm, the output power is >100 nW; at higher input powers (3 W @ 375 nm and 6 W @ 710 nm), the expected output power can reach 10 μW. Real-time monitoring of the photomultiplier tube count rate confirms that the generated 148.4 nm laser is a continuous wave.

[0047] Furthermore, such as Figure 5 As shown, Figure 5 This is an interference diagram of a 148.4 nm laser from an embodiment of this application, illustrating the interference fringes of a 148.4 nm laser generated after passing through two different cadmium vapor chambers (exposure time 10 s). It demonstrates that the laser linewidth broadening introduced by the four-wave mixing process is <0.1 Hz. Locking the fundamental frequencies of 375 nm and 710 nm into the ultrastable cavity produces a 148.4 nm linewidth <100 Hz.

[0048] Furthermore, such as Figure 6 As shown, Figure 6 This embodiment of the present application provides a schematic diagram showing the quadratic relationship between the VUV light power and the power of 375 nm light and the linear relationship with the power of 710 nm light in a device for generating continuous wave vacuum ultraviolet laser based on cadmium vapor four-wave mixing. It illustrates that the power of VUV light can increase quadratically and linearly with the power of 375 nm and 710 nm light, respectively, within a certain range.

[0049] Furthermore, such as Figure 7 As shown, Figure 7 This is a line diagram of the VUV two-photon resonance of a device for generating continuous-wave vacuum ultraviolet laser based on four-wave mixing of cadmium vapor according to an embodiment of this application. It illustrates that by selecting the 61S0 state of cadmium atoms as the two-photon resonance state and combining it with one of the wavelengths of the input laser being 375 nm, the VUV light conversion efficiency can be significantly improved.

[0050] It should be noted that the key indicators such as the output laser wavelength (148.4±0.1 nm), power (≥10 µW), and linewidth (<100 Hz) of the embodiments of this application can be directly measured by a standard spectrometer (such as a high-resolution VUV monochromator), photomultiplier tube, and heterodyne interferometry. The embodiments of this application use a combination of parameters such as cadmium atomic vapor, specific temperature, and phase matching conditions, which can be obtained through equipment disassembly, vapor chamber composition analysis, and beam profile analyzer.

[0051] Therefore, this invention, based on cadmium vapor four-wave mixing technology, achieves high-power, narrow-linewidth laser output in the 148.4 nm band by optimizing cadmium vapor medium selection, two-photon resonance enhancement, and phase matching techniques; the output power can reach 10 µW (3-4 orders of magnitude higher than existing frequency combs), and the linewidth is <100 Hz (7 orders of magnitude lower than pulsed lasers), which can precisely drive nuclear clock transitions (such as Th-229). 3+ This invention enables high-resolution spectroscopy research; by utilizing the high-transition matrix elements of cadmium vapor and combining phase-matched modulation, it overcomes the bottlenecks of excessively wide linewidth and insufficient frequency comb power in traditional pulsed lasers; supporting multiple fields such as nuclear clocks, molecular spectroscopy, and quantum information. The light source of this invention can efficiently drive nuclear clock transitions (such as Th-229). 3+ It supports high-precision spectroscopy research and quantum information processing, fills the gap in high-power narrow-linewidth continuous-wave VUV light sources, and provides key technological breakthroughs for the fields of nuclear physics and nonlinear optics.

[0052] According to the apparatus for generating continuous-wave vacuum ultraviolet laser based on cadmium vapor four-wave mixing proposed in the embodiments of this application, the light source system of this embodiment is used to emit multiple beams of incident light satisfying a preset wavelength range; the optical focusing system is used to focus the multiple beams of incident light satisfying the preset wavelength range onto the target region within the cadmium atomic vapor chamber to obtain vacuum ultraviolet light; and the beam splitting system is used to separate the vacuum ultraviolet light from the multiple beams of incident light satisfying the preset wavelength range. This solves the problem of inefficient generation of continuous-wave vacuum ultraviolet laser and provides an ideal laser source for nuclear optical clocks that can directly drive nuclear transitions.

[0053] Next, with reference to the accompanying drawings, a method for generating continuous wave vacuum ultraviolet laser according to an embodiment of this application is described.

[0054] like Figure 8 As shown, the method for generating continuous-wave vacuum ultraviolet laser, employing any of the aforementioned apparatuses based on cadmium vapor four-wave mixing to generate continuous-wave vacuum ultraviolet laser, includes the following steps: In step S801, multiple beams of incident light satisfying a preset wavelength range are emitted using a light source system. In step S802, an optical focusing system is used to focus multiple beams of incident light that meet the preset wavelength range onto the target area in the cadmium atom vapor chamber to obtain vacuum ultraviolet light.

[0055] In step S803, a beam splitting system is used to separate vacuum ultraviolet light from multiple incident beams that meet a preset wavelength range. Optionally, in some embodiments, after separating the vacuum ultraviolet light from multiple incident lights that meet the preset wavelength range using a beam splitting system, the method further includes: using a vacuum ultraviolet light detection system to detect the vacuum ultraviolet light, and determining whether the vacuum ultraviolet light meets the preset output power condition and the preset output linewidth condition based on the detection result.

[0056] It should be noted that the foregoing explanation of the device embodiment for generating continuous-wave vacuum ultraviolet laser based on cadmium vapor four-wave mixing also applies to the method for generating continuous-wave vacuum ultraviolet laser in this embodiment, and will not be repeated here.

[0057] According to the method for generating continuous-wave vacuum ultraviolet laser proposed in this application, the method utilizes a light source system to emit multiple beams of incident light satisfying a preset wavelength range; an optical focusing system focuses these multiple beams of incident light satisfying the preset wavelength range onto a target region within a cadmium atomic vapor chamber to obtain vacuum ultraviolet light; and a beam splitting system separates the vacuum ultraviolet light from the multiple beams of incident light satisfying the preset wavelength range. This solves the problem of inefficient generation of continuous-wave vacuum ultraviolet laser, providing an ideal laser source for nuclear optical clocks that can directly drive nuclear transitions.

[0058] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0059] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "N" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0060] Any process or method described in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or more N executable instructions for implementing custom logic functions or processes, and the scope of the preferred embodiments of this application includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the functions involved, as should be understood by those skilled in the art to which embodiments of this application pertain.

[0061] It should be understood that the various parts of this application can be implemented using hardware, software, firmware, or a combination thereof. In the above embodiments, the N steps or methods can be implemented using software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

Claims

1. A device for generating continuous-wave vacuum ultraviolet laser based on cadmium vapor four-wave mixing, characterized in that, include: The system includes a light source system, an optical focusing system, a cadmium atomic vapor chamber, and a spectrophotometer system. The light source system is used to emit multiple beams of incident light that meet a preset wavelength range; The optical focusing system is used to focus the multiple beams of incident light that meet the preset wavelength range onto the target area in the cadmium atom vapor chamber to obtain vacuum ultraviolet light; The beam splitting system is used to separate the vacuum ultraviolet light from the multiple incident beams that meet the preset wavelength range.

2. The apparatus according to claim 1, characterized in that, Also includes: The vacuum ultraviolet light detection system is used to detect the vacuum ultraviolet light and determine whether the vacuum ultraviolet light meets the preset output power condition and the preset output linewidth condition based on the detection results.

3. The apparatus according to claim 1, characterized in that, The cadmium atomic vapor chamber contains cadmium atomic vapor.

4. The apparatus according to claim 3, characterized in that, The cadmium atom vapor chamber includes: A temperature control unit is used to adjust the temperature of the cadmium atomic vapor based on the number density requirements of the cadmium atomic vapor.

5. The apparatus according to claim 1, characterized in that, The light source system includes: A first laser source device, used to emit the first incident laser; The second laser source device is used to emit the second incident laser.

6. The apparatus according to claim 1, characterized in that, The optical focusing system includes: a first waveplate, a first laser beam expander, a second waveplate, a second laser beam expander, a long-pass dichroic mirror, and a focusing assembly, wherein... The first waveplate is used to adjust the polarization of the incident first laser beam. The first laser beam expander is used to expand the first incident laser beam after it has been adjusted by the first waveplate to obtain the first expanded laser beam. The second waveplate is used to adjust the polarization of the incident second laser beam; The second laser beam expander is used to expand the second incident laser beam after it has been adjusted by the second waveplate to obtain a second expanded laser beam; The long-pass dichroic mirror is used to combine the first expanded laser beam and the second expanded laser beam to obtain a combined laser beam. The focusing component is used to focus the combined laser beam onto the target area within the cadmium atom vapor chamber to obtain vacuum ultraviolet light.

7. The apparatus according to claim 6, characterized in that, The deviation of the confocal parameters of the first incident laser and the second incident laser is within a first preset range; The deviation between the focal positions of the first incident laser and the second incident laser is within a second preset range.

8. The apparatus according to claim 2, characterized in that, The vacuum ultraviolet light detection system includes: A spectral filter is used to filter the vacuum ultraviolet light to obtain filtered vacuum ultraviolet light; The power detection module is used to identify the output power of the filtered vacuum ultraviolet light and determine whether the vacuum ultraviolet light meets the preset output power condition based on the first identification result. The linewidth detection module is used to identify the linewidth of the filtered vacuum ultraviolet light and determine whether the vacuum ultraviolet light meets the preset output linewidth condition based on the second identification result.

9. A method for generating continuous-wave vacuum ultraviolet laser, characterized in that, The apparatus for generating continuous-wave vacuum ultraviolet laser based on cadmium vapor four-wave mixing as described in any one of claims 1-8, wherein the method comprises the following steps: The light source system emits multiple beams of incident light that meet a preset wavelength range; The optical focusing system is used to focus the multiple beams of incident light that meet the preset wavelength range onto the target area in the cadmium atom vapor chamber to obtain vacuum ultraviolet light; The vacuum ultraviolet light is separated from the multiple incident light beams that meet the preset wavelength range using the aforementioned beam splitting system.

10. The method according to claim 9, characterized in that, After separating the vacuum ultraviolet light from the multiple incident beams satisfying a preset wavelength range using the aforementioned beam splitting system, the method further includes: The vacuum ultraviolet light is detected using a vacuum ultraviolet light detection system, and the detection results are used to determine whether the vacuum ultraviolet light meets the preset output power conditions and preset output linewidth conditions.

Images