Cross-band laser continuous frequency stabilization device and method applied to laser frequency stabilization

Abstract

The invention discloses a cross-band laser continuous frequency stabilization device applied to laser frequency stabilization, which comprises a reference laser, an atomic spectrum frequency stabilization module, an electro-optical modulator, a dichroic reflector, a broadband transmission optical cavity, a frequency locking servo module and a cavity length locking servo module, wherein the broadband transmission optical cavity is an optical cavity with a controllable cavity length, wherein an endoscope is provided with piezoelectric ceramics; the invention also discloses a method thereof. According to the invention, based on reference laser of atomic natural spectrum frequency stabilization, laser frequency modulation is carried out in combination with an electro-optical modulator, and cross-band continuous adjustable laser frequency stabilization of the laser can be realized through transmission of the broadband transmission optical cavity with the cavity length locked; the laser frequency stable wave band and frequency range can be greatly expanded, and the laser frequency stable controllability and flexibility are improved.

Description

Technical Field

[0001] This invention relates to the field of laser frequency stabilization technology, specifically to a cross-band laser continuous frequency stabilization device and a continuous frequency stabilization method. Background Technology

[0002] Based on the development of fundamental sciences such as optics, spectroscopy, and electronics, laser technology has been widely applied in various fields, including industry, agriculture, medicine, military, and science and technology, since its inception due to its immense theoretical and practical value. Due to external environmental disturbances and its own performance characteristics, the wavelength or frequency of laser light often drifts and fluctuates. Laser frequency stabilization technology, a product of advancements in laser physics, spectroscopy, and electronics, is used to stabilize the wavelength or frequency of laser light. Currently, laser frequency stabilization technology is widely used in fields such as cold atom interferometry, atomic clocks, optical frequency combs, and atomic spectroscopy. It plays a crucial role in significantly improving the frequency and wavelength selection range of laser frequency stabilization, and powerfully promoting research in atomic and molecular optical physics, precision measurement, metrology, geophysics, and spectroscopy.

[0003] In certain applications, random changes in the output wavelength or frequency of a laser are undesirable, particularly in atomic manipulation, precision measurement, optical frequency combs, or atomic clocks. These applications require not only extremely high monochromaticity but also precise frequency stability without drift, and may even necessitate further narrowing of the laser's spectral linewidth. However, certain specific applications (such as Rydberg atom preparation, manipulation, and measurement) lack effective frequency references to stabilize the laser frequency in these specific bands due to their unique characteristics. Furthermore, current frequency stabilization technologies have limitations, making it impossible to achieve stable and flexible frequency control in these specific bands to meet application requirements.

[0004] Therefore, developing a cross-band laser frequency stabilization continuous frequency stabilization device for laser frequency stabilization is of great significance for broadening the application scenarios of laser frequency stabilization technology and promoting the development of research fields such as atomic and molecular optical physics, precision measurement, metrology, geophysics, and spectroscopy. Summary of the Invention

[0005] One of the objectives of this invention is to provide a cross-band frequency stabilization laser continuous frequency stabilization device for laser frequency stabilization, so as to solve the problem of frequency stabilization and flexible controllability of lasers in special bands.

[0006] The technical solution adopted by this invention to solve its technical problem is: a cross-band laser continuous frequency stabilization device for laser frequency stabilization, comprising a reference laser, an atomic spectrum frequency stabilization module, a cavity length locking servo module, a frequency locking servo module, and an electro-optic modulation device, a dichroic mirror one, a wide-band transmission optical cavity, a dichroic mirror two, a photodetector one, and a photodetector two in the optical path. The wide-band transmission optical cavity is an optical cavity with an adjustable cavity length and a piezoelectric ceramic cavity mirror, wherein the piezoelectric ceramic is controlled by the cavity length locking servo module. The reference laser needs to be able to stabilize its frequency to the natural transition line of the atom through the atomic spectrum frequency stabilization module. After frequency modulation by the electro-optic modulation device, it is combined with the cross-band laser through the dichroic mirror one and injected into the wide-band transmission optical cavity. The reference laser and the cross-band laser output from the broadband transmission optical cavity reach the second dichroic mirror, which separates the two light signals. The first photodetector is used to detect the resonant transmission spectrum of the cross-band laser and the broadband transmission optical cavity, while the second photodetector is used to detect the resonant transmission spectrum of the reference laser and its modulation sidebands with the broadband transmission optical cavity. The cavity length locking servo module uses the resonant transmission spectrum signal of the reference laser modulation sidebands and the broadband transmission optical cavity detected by the second photodetector to feed back to the piezoelectric ceramic of the broadband transmission optical cavity for cavity length locking. The frequency locking servo module uses the resonant transmission spectrum signal of the cross-band laser and the broadband transmission optical cavity detected by the first photodetector to feed back to the current of the cross-band laser for frequency stabilization.

[0007] The aforementioned cross-band laser continuous frequency stabilization device for laser frequency stabilization has a cavity mirror with a reflective coating covering both the reference laser and the cross-band frequency-stabilized laser wavelengths.

[0008] The aforementioned cross-band laser continuous frequency stabilization device for laser frequency stabilization requires that the modulation bandwidth of its electro-optic modulation device be able to reach more than 1 / 2 of the free spectral region of the wide-band transmission optical cavity.

[0009] The second objective of this invention is to provide a frequency stabilization method for the aforementioned cross-band frequency-stabilized laser continuous frequency stabilization device, comprising the following steps: S1, the reference laser frequency is stabilized on the atomic natural spectrum by the atomic spectrum stabilization module; S2, the cavity length of the broadband transmission optical cavity is locked to the sideband of the reference laser frequency modulated by the electro-optic modulator by the cavity length locking servo module through feedback of the piezoelectric ceramic; S3, the cross-band frequency-stabilized laser locks the laser frequency to the wide-band transmission optical cavity through the frequency-locking servo module; S4 achieves continuous and controllable frequency stabilization of cross-band frequency-stabilized laser by changing the modulation frequency of the electro-optic modulator.

[0010] The beneficial effects of this invention are: the continuous frequency stabilization technology of this invention is achieved by changing the modulation frequency of electro-optic modulation. While solving the frequency stability problem of cross-band frequency-stabilized lasers, it also realizes the continuous and controllable frequency stability of cross-band frequency-stabilized lasers, which can greatly broaden the application scenarios of laser frequency stabilization technology and promote the research and development of fields such as atomic and molecular optical physics, precision measurement, metrology, geophysics, and spectroscopy. Attached Figure Description

[0011] Figure 1 This is a schematic diagram illustrating the principle of the present invention.

[0012] The labels in the attached figures are as follows: 01—Reference laser, 02—Cross-band frequency-stabilized laser, 31—Electro-optic modulation device, 41—Dichroic mirror one, 42—Dichroic mirror two, 5—Wide-band transmission optical cavity, 6—Piezoelectric ceramic, 71—Photodetector one, 72—Photodetector two, 8—Cavity mirror, 9—Frequency-locked servo module, 10—Cavity length-locked servo module, 11—Atomic spectral frequency-stabilized module. Detailed Implementation

[0013] The present invention will now be described in further detail with reference to specific embodiments, so that those skilled in the art can more clearly understand the present invention.

[0014] The following embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. All other embodiments obtained by those skilled in the art based on the specific embodiments of the invention without inventive effort are within the protection scope of the invention.

[0015] Reference Figure 1As shown, this invention first provides a cross-band frequency stabilization laser continuous frequency stabilization device for laser frequency stabilization, including a reference laser 01, an atomic spectrum frequency stabilization module 11, a cavity length locking servo module 10, a frequency locking servo module 9, and an electro-optic modulation device 31, a dichroic mirror 41, a wide-band transmission optical cavity 5, a dichroic mirror 42, a photodetector 71, and a photodetector 72 on the optical path. The atomic spectrum frequency stabilization module 11 is a laser frequency stabilization module based on atomic spectral lines, which can lock the frequency of the reference laser 01 to the atomic spectral lines. The dichroic mirrors 41 and 42 are used for beam combining and splitting of light. Photodetector 1 71 and photodetector 2 72 are used to detect the transmission spectrum of the wideband transfer optical cavity 5. The modulation bandwidth of the electro-optic modulator 31 needs to be able to reach more than 1 / 2 of the free spectral region of the wideband transfer optical cavity 5. The wideband transfer optical cavity 5 is an optical cavity with an adjustable cavity length, which is a cavity mirror 8 with a piezoelectric ceramic 6. The wideband transfer optical cavity 5 is used for frequency stabilization between two lasers of different wavelengths. The cavity mirror 8 is equipped with a reflective coating to cover the two wavelengths of the reference laser 01 and the cross-band frequency-stabilized laser 02. The frequency locking servo module 9 is connected to the cross-band laser 02. The piezoelectric ceramic 6 is controlled by the cavity length locking servo module 10.

[0016] The reference laser 01 needs to be able to stabilize the laser frequency to the natural transition line of the atom through the atomic spectrum stabilization module 11. After frequency modulation by the electro-optic modulation device 31, it is injected into the broadband transmission optical cavity 5 together with the cross-band laser 02 through the dichroic reflector 41. The dichroic reflector 42 is used to separate the two light signals of the reference laser 01 and the cross-band laser 02.

[0017] The photodetector 71 is used to detect the resonant transmission spectrum of the cross-band laser 02 and the wide-band transmission optical cavity 5; the photodetector 72 is used to detect the resonant transmission spectrum of the reference laser 01 and its modulation sidebands and the wide-band transmission optical cavity 5.

[0018] The cavity length locking servo module 10 uses the resonance transmission spectrum signal of the reference laser 01 modulation sideband detected by photodetector 2 72 and the broadband transmission optical cavity 5 to feed back to the piezoelectric ceramic 6 of the broadband transmission optical cavity 5 for cavity length locking.

[0019] The frequency locking servo module 9 stabilizes the frequency of the cross-band laser 02 by feeding back the current of the cross-band laser 02 through the resonant transmission spectrum signal of the cross-band laser 02 detected by the photodetector 71 and the broadband transmission optical cavity 5.

[0020] This invention relates to a cross-band frequency-stabilized laser continuous frequency stabilization technology. A reference laser 01, based on the atomic natural spectrum, is frequency-modulated by an electro-optic modulator 31, which then locks the cavity length of a wide-band transmission optical cavity 5. The cross-band frequency-stabilized laser 02 uses the wide-band transmission optical cavity 5 as a reference for laser frequency stabilization. Furthermore, by continuously changing the modulation frequency of the electro-optic modulator 31, the frequency of the cross-band frequency-stabilized laser 02 is continuously adjustable, achieving laser frequency stability. This technology can be widely applied in research fields such as atomic and molecular optical physics, precision measurement, metrology, geophysics, and spectroscopy.

[0021] The present invention also provides an implementation method for the above-mentioned cross-band frequency-stabilized laser continuous frequency stabilization technology. Example 1 specifically includes the following steps.

[0022] S1, the reference laser 01 frequency is stabilized on the atomic natural spectrum by the atomic spectrum stabilization module 11.

[0023] S2, the cavity length of the wideband transmission optical cavity 5 is locked to the sideband of the reference laser 01, which is frequency modulated by the electro-optic modulator, through the cavity length locking servo module 10. That is, the cavity length of the wideband transmission optical cavity 5 is locked by the frequency modulation sideband of the reference laser 01.

[0024] S3, the cross-band frequency-stabilized laser 02 locks the laser frequency on the wide-band transmission optical cavity 5 through the frequency locking servo module 9.

[0025] S4, by changing the modulation frequency of the electro-optic modulator 3, achieves continuous and controllable frequency stabilization of cross-band frequency-stabilized laser O2.

[0026] In Example 1, the wavelength of the reference laser 01 is 671 nm, and the frequency of the reference laser 01 is stabilized on the natural spectrum of lithium atoms by the atomic spectrum stabilization module 11; the cavity mirror 8 has a reflective coating covering 300-800 nm, and the free spectral region is 600 MHz; the wavelength of the cross-band frequency-stabilized laser 02 is 350 nm; and the modulation bandwidth of the electro-optic modulation device 31 is 1 GHz.

[0027] Example 2: In this example, the wavelength of the reference laser 01 is 780nm, and the frequency of the reference laser 01 is stabilized on the natural spectrum of rubidium atoms by the atomic spectrum stabilization module 11; the cavity mirror 8 has a reflective coating covering 600-1100nm, and the free spectral region is 300MHz; the wavelength of the cross-band frequency-stabilized laser 02 is 1064nm; and the modulation bandwidth of the electro-optic modulation device 3 is 1GHz.

[0028] Comparative Example 1: The difference between this comparative example and Example 1 is that the wavelength of the cross-band frequency-stabilized laser O2 is 1050nm.

[0029] Comparative Example 2: The difference between this comparative example and Example 1 is that the modulation bandwidth of the electro-optic modulator 31 is 200MHz.

[0030] Comparative Example 3: The difference between this comparative example and Example 2 is that the reflective coating of the cavity mirror 8 of the wideband transmission optical cavity 5 covers 300-800nm.

[0031] Comparative Example 4: The difference between this comparative example and Example 2 is that the free spectral region of the wideband transmission optical cavity 5 is 10 GHz.

[0032] Comparative Example 5: The difference between this comparative example and Example 1 is that the atomic natural spectrum is the natural spectrum of iodine atoms.

[0033] Performance evaluation: The performance of the cross-band frequency-stabilized laser O2 in Examples 1-2 and Comparative Examples 1-5 was tested, and the test results are shown below.

[0034] Example 1 can effectively achieve long-term frequency stability of the 350nm cross-band frequency-stabilized laser O2, and can achieve continuously adjustable frequency stabilization of the 1064nm cross-band frequency-stabilized laser O2 by changing the modulation frequency of the electro-optic modulator 31.

[0035] Example 2 can effectively achieve long-term frequency stability of the 1064nm cross-band frequency-stabilized laser 02, and can achieve continuously adjustable frequency stability of the 350nm cross-band frequency-stabilized laser 02 by changing the modulation frequency of the electro-optic modulator 31.

[0036] Comparative Example 1 cannot achieve frequency stabilization of 1050nm cross-band frequency-stabilized laser 02 on wide-band transmission optical cavity 5.

[0037] Comparative Example 2 can achieve long-term frequency stability of the 350nm cross-band frequency-stabilized laser 02, and the frequency stabilization of the 350nm cross-band frequency-stabilized laser 02 can be adjusted by changing the modulation frequency of the electro-optic modulation device 31. However, the frequency stabilization adjustment cannot be continuous and there are discontinuities.

[0038] Comparative Example 3 cannot achieve frequency stabilization of the 1064nm cross-band frequency-stabilized laser 02 on the wide-band transmission optical cavity 5.

[0039] Comparative Example 4 can achieve long-term frequency stability of the 1064nm cross-band frequency-stabilized laser 02, and the frequency stabilization of the 1064nm cross-band frequency-stabilized laser 02 can be adjusted by changing the modulation frequency of the electro-optic modulation device 31. However, the frequency stabilization adjustment cannot be continuous and there are discontinuous intervals.

[0040] Comparative Example 5 cannot achieve frequency stabilization of the 671nm reference laser 01 based on the atomic natural spectrum.

[0041] By comparing the embodiments and Comparative Examples 1 and 3, it can be seen that only when the wavelength of the cross-band frequency-stabilized laser 02 is within the working wavelength range of the wide-band transmission optical cavity 5 can the cross-band frequency-stabilized laser 02 be guaranteed to be frequency-stabilized with the wide-band transmission optical cavity 5 as a reference, thereby realizing the continuous adjustment of the frequency stabilization frequency of the cross-band frequency-stabilized laser 02.

[0042] By comparing the embodiments and Comparative Examples 2 and 4, it can be seen that only when the modulation bandwidth of the electro-optic modulation device 31 can reach more than 1 / 2 of the free spectral region of the wide-band transmission optical cavity 5 can the frequency stabilization of the cross-band frequency-stabilized laser 02 be continuously adjustable without any breaks.

[0043] By comparing the examples and Comparative Example 5, it can be seen that the selected atomic natural spectrum must match the wavelength of the reference laser 01 in order to achieve frequency stabilization of the reference laser 01 based on the atomic natural spectrum, and thus realize the continuously adjustable frequency stabilization technology of the cross-band frequency stabilized laser 02.

[0044] It should be noted that the above embodiments are only for further elaboration and explanation of the technical solution of the present invention, and are not intended to further limit the technical solution of the present invention. The method of the present invention is only a preferred embodiment and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A cross-band continuous laser frequency stabilization device for laser frequency stabilization, characterized in that: The system includes a reference laser (01), an atomic spectrum stabilization module (11), a cavity length locking servo module (10), a frequency locking servo module (9), and an electro-optic modulation device (31), a dichroic mirror (41), a wideband transmission optical cavity (5), a dichroic mirror (42), a photodetector (71), and a photodetector (72) on the optical path. The wideband transmission optical cavity (5) is an optical cavity with a cavity mirror (8) and a piezoelectric ceramic (6) whose cavity length can be adjusted. The piezoelectric ceramic (6) is controlled by the cavity length locking servo module (10). The reference laser (01) stabilizes its laser frequency to the natural transition line of the atom through the atomic spectrum stabilization module (11). After frequency modulation by the electro-optic modulation device (31), it is combined with the cross-band laser (02) through the dichroic mirror (41) and injected into the wideband transmission optical cavity (5). The reference laser (01) and the cross-band laser (02) output from the segment transmission optical cavity (5) are separated by the dichroic reflector (42). The photodetector (71) detects the resonant transmission spectrum of the cross-band laser (02) and the wide-band transmission optical cavity (5). The photodetector (72) detects the resonant transmission spectrum of the reference laser (01) and its modulation sideband with the wide-band transmission optical cavity (5). The cavity length locking servo module (10) uses the resonant transmission spectrum signal of the reference laser (01) modulation sideband with the wide-band transmission optical cavity (5) detected by the photodetector (72) to feed back the cavity length to the piezoelectric ceramic (6) of the wide-band transmission optical cavity (5). The frequency locking servo module (9) uses the resonant transmission spectrum signal of the cross-band laser (02) and the wide-band transmission optical cavity (5) detected by the photodetector (71) to feed back the frequency of the cross-band laser (02).

2. The cross-band laser continuous frequency stabilization device for laser frequency stabilization according to claim 1, characterized in that, The cavity mirror (8) is provided with a reflective coating covering two bands: the reference laser (01) and the cross-band frequency-stabilized laser (02).

3. A cross-band laser continuous frequency stabilization device for laser frequency stabilization according to claim 1 or 2, characterized in that, The modulation bandwidth of the electro-optic modulation device (31) is more than 1 / 2 of the free spectral region of the wide-band transmission optical cavity (5).

4. A cross-band continuous laser frequency stabilization method for laser frequency stabilization, employing the frequency stabilization device described in claim 1, characterized in that, Includes the following steps: S1, the reference laser (01) frequency is stabilized on the atomic natural spectrum by the atomic spectrum stabilization module (11); S2, the cavity length of the wideband transmission optical cavity (5) is fed back to the piezoelectric ceramic (6) through the cavity length locking servo module (10) and locked on the sideband of the reference laser (01) frequency modulated by the electro-optic modulator (31); S3, the cross-band frequency-stabilized laser (02) locks the laser frequency on the wide-band transmission optical cavity (5) through the frequency locking servo module (9); S4, by changing the modulation frequency of the electro-optic modulator (31), the frequency stabilization of cross-band frequency-stabilized laser (02) is continuously controllable.

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