Ultra-stable laser tuning system and laser tuning method

Abstract

In the field of ultrastable laser technology, tuning an ultrastable laser maintains its performance indicators without increasing additional lock noise and out-of-loop drift. [Solution] One acoustic-optic modulator and one electro-optic modulator are introduced separately, and the laser device, frequency shift unit, PDH frequency stabilization control unit, and ultra-stable cavity are integrated. [Effects] By changing the frequency of the acousto-optic modulator, high-precision tuning of the ultra-stable laser can be achieved. By changing the frequency of the electro-optic modulator, wide-range tuning of the ultra-stable laser can be achieved, enabling wide-range, high-precision, and dead-zone-free frequency tuning.

Description

[Technical Field]

[0001] This application relates to the technical field of ultrastable lasers, and more particularly to an ultrastable laser tuning system and a laser tuning method. [Background technology]

[0002] In the fields of precision science and advanced technology applications, ultrastable laser devices play a crucial role. Known for their superior frequency stability and precision, these laser devices are essential technologies for various applications, including precise atomic control, precision measurement, long-distance quantum communication, and optical clock servo systems. These applications demand extremely high levels of tunable laser frequency range and precision, requiring wide-ranging frequency tuning at the hundreds of megahertz (MHz) and even gigahertz (GHz) levels, as well as high-precision tuning at the hertz (Hz), millihertz (mHz), and even microhertz (μHz) levels. The frequency stability of ultrastable laser devices primarily depends on the length of their resonant cavity, and to obtain optimal temperature characteristics, the resonant cavity design generally requires operation at the inflection point temperature. While such temperature control measures can improve frequency stability, the cavity length limits the tunable laser frequency range, typically at the MHz level. Therefore, ultrastable lasers require frequency tuning over a wide range and with high precision.

[0003] Conventional technology involves introducing another laser device and locking its frequency to the ultrastable laser using frequency offset locking technology in order to achieve wide-range and highly accurate tuning of ultrastable laser frequencies. However, this method requires the use of a narrow-linewidth laser device with an additional laser frequency locking control system, resulting in a complex system structure and high costs. Furthermore, locking the offset frequency of the additional laser device to the ultrastable laser introduces additional noise and out-of-loop drift, increasing the system's lock noise and out-of-loop drift, and degrading the performance metrics of the ultrastable laser. [Overview of the project] [Problems that the invention aims to solve]

[0004] To address the above-mentioned problems, this application provides an ultra-stable laser tuning system and a laser tuning method. [Means for solving the problem]

[0005] According to a first aspect, the present application provides an ultra-stable laser tuning system, the ultra-stable laser tuning system comprising a laser device, a frequency shift unit, a PDH frequency stabilization control unit, and an ultra-stable cavity. The laser device generates a narrow-linewidth laser and inputs the narrow-linewidth laser to the frequency shift unit, the frequency shift unit includes a first electro-optic modulator EOM1, a second electro-optic modulator EOM2, a first acousto-optic modulator AOM1, and a second acousto-optic modulator AOM2. The narrow-linewidth laser is modulated by the first acousto-optic modulator AOM1, then split into two lasers. The first laser is output as an optical signal, and the second laser is processed via the second acousto-optic modulator AOM2, the first electro-optic modulator EOM1, and the second electro-optic modulator EOM2. The frequency shift unit inputs the processed second laser into the ultrastable cavity, where the processed second laser resonates, and generates an error signal in the optical coupling control section based on the resonance result. The PDH frequency stabilization control unit detects the error signal and controls the laser device and the first acousto-optic modulator AOM1 to compensate for the frequency until the output frequency of the laser device is locked to the resonant frequency of the ultra-stable optical cavity.

[0006] Preferably, the frequency shift unit specifically generates an adjustable frequency sideband using the first electro-optic modulator EOM1, and by tuning the frequency of the adjustable frequency sideband, a wide range of frequency tuning is achieved. By adjusting the frequency of the second laser using the AOM2, high-precision tuning of the laser is achieved.

[0007] Preferably, the frequency shift unit further, The frequency of the laser device is scanned, and a target frequency point is selected from the transmitted signal displayed on the photoelectric detector based on the output frequency. The polarity of the frequency shift is determined based on the aforementioned target frequency point. A positive or negative frequency shift operation is performed based on the polarity of the frequency shift.

[0008] Preferably, the system further includes a control module that determines the polarity of the frequency shift and then decomposes it based on the frequency tuning amount. Specifically, the frequency shift unit achieves wide-range tuning by changing the modulation frequency of EOM1 based on the decomposed tuning amount, and achieves high-precision tuning by changing the modulation frequency of AOM2.

[0009] Preferably, the frequency shift unit specifically uses a high-frequency DDS frequency combiner to change the modulation frequency of the EOM1 to achieve wide-range frequency tuning of the ultrastable laser. By changing the modulation frequency of the AOM2 using a low-frequency DDS frequency synthesizer, high-precision frequency tuning of the ultra-stable laser is achieved.

[0010] Preferably, the system further includes a frequency display and control unit that displays the output frequency of the ultra-stable laser tuning system in real time, receives an external command, and accurately controls the modulation frequencies of the EOM1 and the AOM2 by adjusting the frequency register of the DDS, thereby achieving accurate tuning over a wide range of ultra-stable laser frequencies.

[0011] According to a second aspect, the present application provides an ultra-stable laser tuning method, which includes the steps of generating a narrow-linewidth laser and inputting the narrow-linewidth laser into a frequency shift unit including a first electro-optic modulator EOM1, a second electro-optic modulator EOM2, a first acousto-optic modulator AOM1, and a second acousto-optic modulator AOM2; after the narrow-linewidth laser is modulated by the first acousto-optic modulator AOM1, it is divided into two beams. The first beam is output as an optical signal, and the second beam is processed through the second acousto-optic modulator AOM2, the first electro-optic modulator EOM1, and the second electro-optic modulator EOM2; inputting the processed second beam into an ultra-stable cavity, where the processed second beam and the ultra-stable cavity resonate, and generating an error signal in an optical coupling control part based on the resonance result; detecting the error signal and controlling the laser device and the first acousto-optic modulator AOM1 to compensate the frequency until the output frequency of the laser device is locked to the resonance frequency of the ultra-stable optical cavity.

[0012] Preferably, before inputting the processed second beam into the ultra-stable cavity, the method includes the steps of scanning the frequency of the laser device and selecting a target frequency point from the transmission signal displayed on a photodetector based on the output frequency; determining the polarity of the frequency shift based on the target frequency point; The method further includes the step of performing a positive or negative frequency shift operation based on the polarity of the frequency shift.

[0013] Preferably, after determining the polarity of the frequency shift, the method is Steps to decompose based on the amount of frequency tuning, The method further includes the steps of changing the modulation frequency of EOM1 based on the decomposed tuning amount to achieve a wide tuning range, and changing the modulation frequency of AOM2 to achieve high-precision tuning.

[0014] Preferably, the steps of changing the modulation frequency of EOM1 based on the decomposed tuning amount to achieve a wide tuning range, and changing the modulation frequency of AOM2 to achieve high-precision tuning, are as follows: The steps include: changing the modulation frequency of the EOM1 using a high-frequency DDS frequency synthesizer to achieve wide-range frequency tuning of the ultrastable laser; The method includes the step of changing the modulation frequency of the AOM2 using a low-frequency DDS frequency synthesizer to achieve high-precision frequency tuning of the ultrastable laser. [Effects of the Invention]

[0015] This application provides an ultra-stable laser tuning system. The system includes a laser device, a frequency shift unit, a PDH frequency stabilization control unit, and an ultra-stable cavity. The laser device generates a narrow-linewidth laser and inputs the narrow-linewidth laser to the frequency shift unit, which includes a first electro-optic modulator EOM1, a second electro-optic modulator EOM2, a first acousto-optic modulator AOM1, and a second acousto-optic modulator AOM2. The narrow-linewidth laser is modulated by the first acousto-optic modulator AOM1 and then split into two, with the first laser being output as an optical signal and the second laser being output by the second acousto-optic modulator AOM2. The laser is processed via the first electro-optic modulator EOM1 and the second electro-optic modulator EOM2. The frequency shift unit inputs the processed second laser to the ultrastable cavity, where the processed second laser resonates and generates an error signal in the optical coupling control section based on the resonance result. The PDH frequency stabilization control unit detects the error signal and controls the laser device and the first acousto-optic modulator AOM1 to compensate for the frequency until the output frequency of the laser device is locked to the resonant frequency of the ultrastable optical cavity. According to the above system solution, an efficient and accurate laser frequency stabilization control system is realized, in which the laser device, frequency shift unit, PDH frequency stabilization control unit and ultrastable cavity are coupled, and accurate control of the ultrastable laser frequency is achieved through a well-designed modulation process. This system has the following beneficial effects: When tuning an ultrastable laser, by separately introducing one acousto-optic modulator and one electro-optic modulator, it ensures that the performance indicators of the ultrastable laser are maintained without increasing additional lock noise and out-of-loop drift. Furthermore, by changing the frequency of the acousto-optic modulator, high-precision tuning of the ultrastable laser can be achieved, and by changing the frequency of the electro-optic modulator, a wide range of tuning of the ultrastable laser can be achieved, resulting in wide-range, high-precision, and dead-band-free frequency tuning. [Brief explanation of the drawing]

[0016] To clearly illustrate the technical solutions of this embodiment or the prior art, the necessary drawings describing the embodiment or the prior art are briefly introduced below. The drawings described below represent only a few embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without performing any work commensurate with inventive step. [Figure 1] This is a schematic diagram of the structure of the ultra-stable laser tuning system provided by the embodiment of this application. [Figure 2] This is a schematic diagram of the transmitted signal provided by the embodiment of this application. [Figure 3] This is a schematic diagram of the structure of another ultrastable laser tuning system provided by the embodiments of this application. [Figure 4] This is a flowchart of the ultra-stable laser tuning method provided in the embodiment of this application. [Modes for carrying out the invention]

[0017] To make the purpose, technical solutions, and advantages of the embodiments of this application clearer, the drawings of the embodiments of this application are combined below to clearly and completely describe the technical solutions of the embodiments of this application. The embodiments described are not all embodiments, but only a selection of embodiments of this application. All other embodiments obtained based on the embodiments of this application, on the premise that a person skilled in the art does not perform work worthy of inventive step, all fall within the scope of protection of this application.

[0018] Figure 1 is a schematic diagram of the structure of an ultra-stable laser tuning system provided by an embodiment of this application. As shown in Figure 1, the ultra-stable laser tuning system provided by an embodiment of this application includes a laser device 10, a frequency shift unit 11, a PDH frequency stabilization control unit 12, and an ultra-stable cavity 13.

[0019] The laser device 10 is a narrow-linewidth laser device, which is a laser device capable of generating an extremely narrow-linewidth laser. Compared to conventional wide-linewidth laser devices, the narrow-linewidth laser device has a narrower linewidth of its vector, enabling higher temporal and frequency resolution. Specifically, the narrow-linewidth laser device provided in the embodiment of this application outputs a laser with frequency f, which is processed by the frequency shift unit 11 to obtain two lasers, the first laser acting as the final output beam of the ultrastable laser, and the second laser acting as the reference beam for ultrastable laser locking.

[0020] The frequency shift unit 11 includes a first electro-optic modulator EOM1, a second electro-optic modulator EOM2, a first acousto-optic modulator AOM1, and a second acousto-optic modulator AOM2, which process the second laser and input the processed second laser to the PDH frequency stabilization control unit. The narrow-linewidth laser device generates a narrow-linewidth laser and inputs it to the frequency shift unit 11. The first electro-optic modulator EOM1 in the frequency shift unit 11 processes the laser and outputs two lasers via an optical fiber beam splitter, the first of which acts as the final output light of the ultrastable laser, and the second of which acts as the reference light for ultrastable laser locking. The AOM1 may be a 1550 nm AOM1, i.e., its operating wavelength is 1550 nanometers (nm), and the optical fiber beam splitter is also 1550 nm.

[0021] After acquiring the first and second lasers, the second laser is first modulated by AOM2 in the frequency shift unit 11. The acousto-optic modulator achieves modulation of light by generating a periodically changing refractive index in the medium using ultrasound. Specific modulation parameters (e.g., modulation frequency, modulation depth, etc.) are determined according to the application needs. The second light is then modulated again by EOM1. The electro-optic modulator modulates the phase, intensity, or polarization state of light by changing the refractive index of the material. Specifically, the first electro-optic modulator EOM1 generates fixed frequency sidebands. Generally, this is achieved by applying a radio frequency (RF) signal to EOM1, and because of this signal, symmetrical sidebands appear in the laser frequency spectrum. The interval between these sidebands and the main laser frequency is equal to the frequency of the RF signal. Similar to AOM2, the specific modulation parameters of EOM1 are also set according to the application needs. The laser modulated by EOM1 enters EOM2 for radio frequency electro-optic phase modulation. Such modulation schemes allow for high-frequency (radio frequency range) phase modulation of optical signals and are commonly used in fields such as optical communications, sensing, and quantum information. Radio-frequency electro-optic phase modulation allows for precise control of the optical phase, which is crucial for experiments or applications requiring high-precision phase control. The second electro-optic modulator, EOM2, specifically generates tunable frequency sidebands used for frequency tuning. Similar to EOM1, EOM2 also generates sidebands by applying an RF signal, but here, since the RF signal frequency is tunable, it allows for fine control of the sideband frequency.

[0022] By using EOM1 or AOM2 in conjunction with the frequency shift unit, precise control and adjustment of the laser frequency are achieved, generating sidebands for PDH frequency locking.

[0023] The second laser processed by the frequency shift unit enters the ultrastable cavity 13 via the spatial optical path of the optical coupling control unit. In the ultrastable cavity, the processed second laser resonates and generates an error signal in the optical coupling control unit based on the resonance result. The PDH frequency stabilization control unit detects the error signal and controls the laser device and the first acousto-optic modulator AOM1 to compensate for the frequency until the output frequency of the laser device is locked to the resonant frequency of the ultrastable optical cavity.

[0024] After the second laser processed by the frequency shift unit enters the PDH frequency stabilization control unit, it is necessary to perform frequency stabilization processing using PDH frequency stabilization technology. First, frequency errors are detected for the processed second laser and the ultrastable cavity to obtain detuning information, and then the PDH frequency stabilization control unit tunes the laser frequency generated from the laser device based on the detuning information until the output frequency of the laser device is locked to the resonant frequency of the ultrastable optical cavity.

[0025] The following describes the process of performing frequency stabilization in the PDH frequency stabilization control unit by combining specific examples.

[0026] First, scan the second laser processed by the adjustment unit, and use a photodetector to inspect the signal of the transmitted light during the scanning process. Three frequency points can be observed from the photodetector. As shown in FIG. 2, FIG. 2 is a schematic diagram of the transmitted signal provided by the embodiment of the present application. Due to the modulation effect of EOM1 or AOM2, symmetric sidebands are generated on both sides of the original laser frequency. The difference between the frequencies of these sidebands and the original laser frequency is equal to the modulation frequency of the modulator. The first frequency point is the addition result of the original laser frequency and one of the sideband frequencies generated by modulation with EOM1 or AOM2. If this frequency point is selected, since the modulation frequency of EOM1 or AOM2 is added to the original frequency, the output laser frequency is slightly higher than the resonance frequency of the ultra-stable cavity (i.e., a positive frequency shift). The second frequency point is the original unmodulated laser frequency. However, in PDH frequency stabilization control, generally, this frequency point is not directly selected because it does not contain the information generated by modulation and is disadvantageous for frequency stability and locking. The third frequency point is the addition result of the original laser frequency and the other sideband frequency generated by modulation with EOM or AOM. Contrary to the first frequency point, if this frequency point is selected due to the subtraction effect of the modulation frequency, the output laser frequency is slightly lower than the resonance frequency of the stable cavity (i.e., a negative frequency shift).

[0027] When the first frequency point (positive frequency shift) is selected, the output frequency (f out ) is obtained by subtracting the modulation frequency (f fp ) of AOM2 from the resonance frequency (f s1 ) of the ultra-stable cavity and then adding the modulation frequency (f s2 ) of EOM1. That is, f out =f fp -f s1 +f s2 .

[0028] When the third frequency point (negative frequency shift) is selected, the output frequency (f out ) is the resonance frequency (f fp) from the modulation frequency (f s1 Subtract the modulation frequency (f) of EOM1. s2 This subtracts ). That is, f out =f fp -f s1 -f s2 That is the case.

[0029] After selecting a frequency point, the laser signal modulated by EOM2 is introduced into the ultrastable cavity via a spatial optical path. As a high-precision optical resonator, the ultrastable cavity amplifies and feeds back the input laser signal, generating reflected light signals. These reflected light signals contain crucial information about the frequency detuning between the laser and the ultrastable cavity. A photoelectric detector captures these reflected light signals and converts them into electrical signals. Phase demodulation techniques are then used to extract the frequency detuning information between the laser and the ultrastable cavity from these electrical signals. After processing, this information forms an error signal, which accurately reflects the deviation between the current laser frequency and the ultrastable cavity resonant frequency. Further processing of the error signal is necessary to correct this deviation.

[0030] First, a low-pass filter removes high-frequency noise from the error signal, retaining the low-frequency portion to obtain more accurate deviation information. The filtered error signal is then sent to a proportional-integral circuit (PI circuit). The PI circuit generates a control signal based on the magnitude and duration of the error signal, and both the magnitude and direction of this control signal are precisely calculated to effectively compensate for the deviation in the laser frequency. Finally, this control signal is fed back to the piezoelectric ceramics or acousto-optic modulator of the laser device. The piezoelectric ceramics fine-tune the output frequency of the laser device through minute displacements, while the acousto-optic modulator achieves greater adjustment by changing the frequency of the optical signal. Through the combined action of both, the output frequency of the laser device gradually approaches the resonant frequency of the ultrastable cavity, ultimately achieving stable locking of the laser frequency.

[0031] Through the feedback and control process described above, the output frequency of the narrow-linewidth laser device is gradually adjusted to match the resonant frequency of the ultrastable optical cavity. When the laser frequency is stably locked to the resonant frequency of the optical cavity, the output of the ultrastable laser is achieved.

[0032] As mentioned above, the output frequency of a narrow-linewidth laser device must be tuned in order to gradually adjust it to match the resonant frequency of the ultrastable optical cavity, and the ultrastable laser tuning system introduced in the embodiments of this application further includes a control module for achieving precise control of the laser frequency.

[0033] Specifically, in a PDH frequency stabilization control system, frequency adjustment is generally performed by decomposing the frequency shift polarity and the required tuning amount. In a PDH frequency stabilization control system, first, the polarity of the frequency detuning (i.e., the direction of the frequency deviation) between the laser and the ultrastable cavity is determined using phase demodulation techniques. This is generally achieved by comparing the phase difference between the reflected light signal and the reference signal.

[0034] Once the polarity of the frequency shift is determined, the tuning task needs to be broken down based on the required tuning amount. Generally, wide-range frequency tuning is achieved with an EOM because it can rapidly change the phase or frequency of the optical signal, making it suitable for rapid, wide-range tuning. High-precision tuning is achieved with an AOM because it can precisely control the optical signal frequency, making it suitable for fine tuning. In this application, the portion larger than the resolution of the high-frequency DDS frequency combiner is the modulation frequency f of EOM1. s2 By changing this, a wide range of tuning is achieved, and the part smaller than the resolution of the high-frequency DDS frequency combiner is the modulation frequency f of AOM2. s1By changing these parameters, high-precision tuning is achieved. As shown in Figure 3, Figure 3 is a schematic diagram of the structure of another ultra-stable laser tuning system provided by an embodiment of this application. This ultra-stable laser tuning system further includes a high-frequency DDS (Direct Digital Frequency Synthesizer) frequency synthesizer and a low-frequency DDS frequency synthesizer, and by changing the modulation frequencies of the EOM and AOM respectively, a wide range of high-precision tuning is achieved.

[0035] Wide-ranging tuning with EOM1: The modulation frequency of EOM1 is changed using a high-frequency DDS frequency synthesizer, and the modulated frequency is f s2 As shown, the DDS frequency synthesizer can quickly generate accurate and stable frequency signals, which is crucial for achieving wide-range tuning of the EOM1. By adjusting the frequency output of the DDS, the modulation frequency of the EOM1 can be controlled, enabling wide-range adjustment of the laser frequency.

[0036] High-precision tuning with AOM2: The modulation frequency of AOM2 is changed using a low-frequency DDS frequency synthesizer. Because AOM is more sensitive to changes in the optical signal frequency, precise control of the AOM2 modulation frequency can be achieved by using a low-frequency DDS. In this way, AOM2 can be finely tuned with respect to the laser frequency to achieve high-precision frequency stabilization control, and the modulated frequency is f s1 This is shown.

[0037] In the tuning process described above, the tuning capabilities of EOM and AOM are combined to achieve efficient control of the laser frequency. EOM is used for broad-range coarse tuning, and AOM is used for high-precision fine tuning; the two complement each other to improve the overall tuning efficiency of the system. Accurate tuning is ensured by precisely controlling the modulation frequencies of EOM and AOM using a DDS frequency combiner. High-frequency DDS is used for broad-range tuning with EOM, and low-frequency DDS is used for high-precision tuning with AOM, ensuring the frequency stabilization accuracy of the entire system. Such tuning measures allow for flexible adjustment of the tuning range and accuracy according to needs. By changing the frequency output of the DDS, the modulation frequencies of EOM and AOM can be easily adjusted, enabling flexible control of the laser frequency.

[0038] As described above, by combining the tuning capabilities of EOM and AOM and precisely controlling their modulation frequencies using a DDS frequency combiner, efficient, accurate, and flexible control of the laser frequency can be achieved, which is extremely important for PDH frequency stabilization control systems.

[0039] The following example illustrates the frequency tuning process of an ultrastable laser. In this example, the AOM2 is driven using a low-frequency DDS with a system clock of 200 MHz, and its frequency control bits reach 48 bits, providing a frequency control accuracy of approximately 0.7 μHz. To achieve a positive frequency shift of 1.2 GHz, first, the target frequency shift amount f shift Based on equation f s2 =f shift +f s1 Then, the frequency control register of the high-frequency DDS is set. In this example, the frequency control register of the high-frequency DDS is set to 1533916891, and the output frequency of EOM1 is set to f s2 This is brought up to 1249999999.650754Hz. Then, equation f s1 =f s2 -f shiftThe required output frequency for the low-frequency DDS is calculated and set to 49999999.650754Hz. In this way, the collaborative action of EOM1 and AOM2 achieves frequency tuning with better accuracy than 1μHz.

[0040] To achieve a negative frequency shift of 1.2 GHz, you can calculate and set it using the same formula as above. For a negative frequency shift, formula f s2 =f shift -f s1 Then, set the frequency control register of the high-frequency DDS and set the output frequency f of EOM1. s2 Obtain the expression f. s1 =f shift -f s2 Then calculate the required output frequency of the low-frequency DDS. In this example, the frequency control register of the high-frequency DDS is set to 1411203540, and the output frequency of EOM1 is f s2 The frequency is set to 1149999999.906868Hz. The output frequency of the low-frequency DDS is set to 50000000.093132Hz. This method achieves frequency tuning with better accuracy than 1μHz.

[0041] In the above embodiment, we introduced the adjustment of the modulation frequency by combining an EOM (electro-optic modulator) and an AOM (acousto-optic modulator), and the achievement of wide-range and highly accurate tuning of ultra-stable laser frequencies using a high-frequency DDS and a low-frequency DDS frequency combiner. However, a complete laser frequency stabilization system requires not only the precise cooperation of these hardware components, but also a unit that can monitor and flexibly control these components in real time.

[0042] Therefore, a frequency display and control unit is introduced, which plays a crucial role in the system. The main functions of this unit are, firstly, to display the output frequency of the ultra-stable laser tuning system in real time, providing the operator with intuitive frequency status information, and secondly, to receive external commands and adjust the frequency control registers of the DDS to accurately control the modulation frequencies of EOM1 and AOM2, thereby achieving precise control of the ultra-stable laser frequency.

[0043] Specifically, the frequency display and control unit reads the values ​​of the DDS frequency control registers to calculate the modulation frequencies of EOM1 and AOM2 in real time, and based on this, calculates the output frequency of the ultrastable laser. This frequency value is then displayed on the user interface for the operator's reference. The operator also inputs frequency adjustment commands via the user interface, which are received by the frequency display and control unit, converted to the corresponding DDS frequency control register values, and written to the DDS to enable precise adjustment of the modulation frequencies of EOM1 and AOM2.

[0044] In this manner, the frequency display and control unit not only improves the degree of automation of the laser frequency stabilization system but also significantly enhances the system's flexibility and controllability. To meet the needs of different experiments and applications, the operator can adjust the laser frequency at any time according to their requirements. Furthermore, the real-time frequency information provides the operator with an important reference point, allowing them to better understand the system's operating status.

[0045] The above embodiment introduces an ultra-stable laser tuning system, and this application further provides a corresponding ultra-stable laser tuning method for that ultra-stable laser tuning system. Below, specific embodiments are combined to introduce the ultra-stable laser tuning method provided by the embodiments of this application, and as shown in Figure 4, Figure 4 is a flowchart of the ultra-stable laser tuning method provided by the embodiments of this application: S401: Generate a narrow-linewidth laser and input the narrow-linewidth laser into a frequency shift unit which includes a first electro-optic modulator EOM1, a second electro-optic modulator EOM2, a first acousto-optic modulator AOM1, and a second acousto-optic modulator AOM2; S402: After being modulated by the first acousto-optic modulator AOM1, the narrow-linewidth laser is split into two; the first laser is output as an optical signal, and the second laser is processed via the second acousto-optic modulator AOM2, the first electro-optic modulator EOM1, and the second electro-optic modulator EOM2; S403: The processed second laser is input to the ultrastable cavity, and the processed second laser and the ultrastable cavity resonate within the ultrastable cavity, generating an error signal in the optical coupling control section based on the resonance result; S404: The error signal is detected, and the laser device and the first acousto-optic modulator AOM1 are controlled to compensate for the frequency until the modulation frequency output from the laser device is locked to the resonant frequency of the ultrastable optical cavity.

[0046] In one embodiment of the present application, before inputting the processed second laser into the ultrastable cavity, the method, The steps include scanning the frequency of the laser device and selecting a target frequency point from the transmitted signal displayed on the photoelectric detector based on the output frequency, A step of determining the polarity of the frequency shift based on the target frequency point, The method further includes the step of performing a positive or negative frequency shift operation based on the polarity of the frequency shift.

[0047] In one embodiment of the present application, after determining the polarity of the frequency shift, the method Steps to decompose based on the amount of frequency tuning, The method further includes the steps of changing the modulation frequency of EOM1 based on the decomposed tuning amount to achieve a wide tuning range, and changing the modulation frequency of AOM2 to achieve high-precision tuning.

[0048] In one embodiment of the present application, the steps of changing the modulation frequency of EOM1 based on the decomposed tuning amount to achieve a wide tuning range and changing the modulation frequency of AOM2 to achieve high-precision tuning are as follows: The steps include: changing the modulation frequency of the EOM1 using a high-frequency DDS frequency synthesizer to achieve wide-range frequency tuning of the ultrastable laser; The method includes the step of changing the modulation frequency of the AOM2 using a low-frequency DDS frequency synthesizer to achieve high-precision frequency tuning of the ultrastable laser.

[0049] The specific implementation process of the ultra-stable laser tuning method is based on the ultra-stable laser tuning system in the above embodiment, and no further explanation of the specific implementation process will be provided.

[0050] The ultra-stable laser frequency tuning method and system provided by the present invention have the effect of achieving ultra-stable laser tuning over a wide range and with high precision, and offer the following advantages over conventional solutions that add a laser frequency lock control system: 1. By utilizing high-frequency and low-frequency DDS drive, a combination of an acousto-optic modulator and an electro-optic modulator is achieved to realize wide-range, high-precision, and dead-band-free frequency tuning of an ultra-stable laser. 2. Ensure that the performance indicators of the ultrastable laser are not degraded by avoiding the introduction of additional lock noise and out-of-loop drift.

[0051] Herein, in this specification, relational terms such as the first and second are merely for distinguishing one entity or operation from another, and do not necessarily require or imply that there is an actual relationship or order between these entities or operations. The terms “include,” “incorporate,” or any other variation are intended to include non-exclusive inclusion, so that a process, method, article, or apparatus containing a set of elements includes not only those elements but also other elements not explicitly listed, or even elements inherent to such process, method, article, or apparatus. Unless otherwise specified, the element limited by the phrase “includes XX” does not preclude the process, method, article, or apparatus containing that element from having other identical elements.

[0052] Furthermore, each embodiment in this specification is described in a progressive manner, and similar or identical parts between embodiments may be referenced to one another, with each embodiment primarily describing the differences from the other embodiments. In particular, the embodiments of equipment and apparatus are basically similar to the embodiments of methods, and their description is simple; in that regard, it is sufficient to refer to part of the description of the method embodiments. The embodiments of equipment and installation described above are illustrative only, and units described as individual components may or may not be physically separated, and components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Based on actual needs, some or all of these modules can be selected to achieve the objectives of the solutions of this embodiment. Those skilled in the art will be able to understand and implement these without performing work commensurate with inventive step.

[0053] The foregoing is merely one specific embodiment of the present application, and the scope of protection of this application is not limited thereto. Any modification or substitution that a person skilled in the art could easily conceive within the scope of the art disclosed in this application should fall within the scope of protection of this application. Accordingly, the scope of protection of this application is based on the scope of protection of the claims.

Claims

1. It is an ultra-stable laser tuning system, The ultra-stable laser tuning system includes a laser device, a frequency shift unit, a PDH frequency stabilization control unit, and an ultra-stable cavity. The laser device generates a narrow-linewidth laser and inputs the narrow-linewidth laser to the frequency shift unit, the frequency shift unit includes a first electro-optic modulator EOM1, a second electro-optic modulator EOM2, a first acousto-optic modulator AOM1, and a second acousto-optic modulator AOM2. The narrow-linewidth laser is modulated by the first acousto-optic modulator AOM1, then split into two lasers. The first laser is output as an optical signal, and the second laser is processed via the second acousto-optic modulator AOM2, the first electro-optic modulator EOM1, and the second electro-optic modulator EOM2. The frequency shift unit inputs the processed second laser into the ultrastable cavity, where the processed second laser resonates, and generates an error signal in the optical coupling control section based on the resonance result. An ultra-stable laser tuning system characterized in that the PDH frequency stabilization control unit detects the error signal and controls the laser device and the first acousto-optic modulator AOM1 to compensate for the frequency until the output frequency of the laser device is locked to the resonant frequency of the ultra-stable optical cavity.

2. Specifically, the frequency shift unit generates an adjustable frequency sideband using the first electro-optic modulator EOM1, and the adjustable frequency sideband is used for frequency tuning, thereby achieving wide-range frequency tuning. The ultra-stable laser tuning system according to claim 1, characterized in that high-precision tuning of the laser is achieved by adjusting the frequency of the second laser using the AOM2.

3. The frequency shift unit further, The frequency of the laser device is scanned, and a target frequency point is selected from the transmitted signal displayed on the photoelectric detector based on the output frequency. The polarity of the frequency shift is determined based on the aforementioned target frequency point. The ultra-stable laser tuning system according to claim 1, characterized in that a positive or negative frequency shift operation is performed based on the polarity of the frequency shift.

4. The system further includes a control module that determines the polarity of the frequency shift and then decomposes it based on the frequency tuning amount. The ultra-stable laser tuning system according to claim 3, characterized in that the frequency shift unit specifically changes the modulation frequency of the EOM1 based on the decomposed tuning amount to achieve a wide tuning range, and changes the modulation frequency of the AOM2 to achieve high-precision tuning.

5. Specifically, the frequency shift unit uses a high-frequency DDS frequency combiner to change the modulation frequency of the EOM1, thereby achieving wide-range frequency tuning of the ultra-stable laser. The ultra-stable laser tuning system according to claim 4, characterized in that the modulation frequency of the AOM2 is changed using a low-frequency DDS frequency synthesizer to achieve high-precision frequency tuning of the ultra-stable laser.

6. The ultra-stable laser tuning system according to any one of claims 1 to 5, further comprising a frequency display and control unit that displays the output frequency of the ultra-stable laser tuning system in real time, receives an external command, and adjusts the frequency register of the DDS to accurately control the modulation frequencies of the EOM1 and AOM2, thereby achieving accurate tuning over a wide range of ultra-stable laser frequencies.

7. An ultra-stable laser tuning method, wherein the method is The steps include generating a narrow-linewidth laser and inputting the narrow-linewidth laser into a frequency shift unit which includes a first electro-optic modulator EOM1, a second electro-optic modulator EOM2, a first acousto-optic modulator AOM1, and a second acousto-optic modulator AOM2, The narrow-linewidth laser is modulated by the first acousto-optic modulator AOM1, then split into two lasers. The first laser is output as an optical signal, and the second laser is processed via the second acousto-optic modulator AOM2, the first electro-optic modulator EOM1, and the second electro-optic modulator EOM2. The process involves inputting a processed second laser into an ultrastable cavity, resonating between the processed second laser and the ultrastable cavity within the cavity, and generating an error signal in the optical coupling control section based on the resonance result. A method characterized by including the step of detecting the error signal and controlling the laser device and the first acousto-optic modulator AOM1 to compensate for the frequency until the output frequency of the laser device is locked to the resonant frequency of the ultrastable optical cavity.

8. Before inputting the processed second laser into the ultrastable cavity, the method, The steps include scanning the frequency of the laser device and selecting a target frequency point from the transmitted signal displayed on the photoelectric detector based on the output frequency, A step of determining the polarity of the frequency shift based on the target frequency point, The method according to 7, further comprising the step of performing a positive or negative frequency shift operation based on the polarity of the frequency shift.

9. After determining the polarity of the frequency shift, the method is as follows: Steps to decompose based on the amount of frequency tuning, The method according to 8, further comprising the steps of changing the modulation frequency of the EOM1 based on the decomposed tuning amount to achieve a wide tuning range, and changing the modulation frequency of the AOM2 to achieve high-precision tuning.

10. The steps described above, which involve changing the modulation frequency of EOM1 based on the decomposed tuning amount to achieve a wide range of tuning and changing the modulation frequency of AOM2 to achieve high-precision tuning, The steps include: changing the modulation frequency of the EOM1 using a high-frequency DDS frequency synthesizer to achieve wide-range frequency tuning of the ultrastable laser; The method according to 9, characterized by comprising the step of changing the modulation frequency of the AOM2 using a low-frequency DDS frequency synthesizer to achieve high-precision frequency tuning of the ultrastable laser.

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