Laser frequency stabilization device based on etalon frequency measurement technology

Abstract

The utility model relates to the technical field of laser application, in particular to a laser frequency stabilization device based on an etalon frequency measurement technology, which comprises a laser emission unit, a frequency detection unit, a frequency stabilization laser output end and a master control adjusting unit, the frequency detection unit comprises an optical splitter, an optical attenuator, a first photoelectric detector, an etalon and a second photoelectric detector. An etalon in the frequency detection unit is used as a frequency reference, an optical attenuator is arranged to reduce temperature rise and improve precision, a first photoelectric detector and a second photoelectric detector are used to provide a frequency measurement error signal and a reference signal, and the master control adjustment unit is used to carry out analysis and calculation according to the error measurement signal and the reference signal. And the laser emitting unit adjusts the laser frequency according to the adjusting signal, so that the frequency stabilization adjustment of the laser is realized.

Description

Technical Field

[0001] This utility model relates to the field of laser application technology, and more specifically, to a laser frequency stabilization device based on etalon frequency measurement technology. Background Technology

[0002] Narrow-linewidth ultrastable lasers are laser devices that achieve spectral linewidth compression through precise frequency stabilization technology. Their core parameters include kHz-level spectral linewidth, GHz / K-level temperature tuning coefficient, and ultra-low relative noise intensity. In 2023, the Institute of Physics, Chinese Academy of Sciences, achieved 243 nm laser output by using Pound-Drever-Hall (PDH) frequency stabilization technology and ultrastable Fabry-Perot cavity locking, compressing the spectral linewidth to the sub-Hz level. This technology was applied to the detection of 1S–2S two-photon transitions in hydrogen atoms. This type of laser has significant research value in atomic physics, quantum optics, communications, atomic clocks and time / frequency standards, manufacturing, and processing.

[0003] In practical applications, lasers can experience frequency drift due to changes in temperature, mechanical vibration, and electrical fluctuations in their operating environment, which in turn affects the accuracy of laser output. For some high-precision measurement and practical engineering applications, laser equipment with higher precision is required to meet production needs. Utility Model Content

[0004] To overcome the shortcomings of the prior art where lasers have low accuracy due to frequency drift, this utility model provides a laser frequency stabilization device based on etalon frequency measurement technology, which reduces frequency drift and improves laser output accuracy.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by this utility model is: a laser frequency stabilization device based on etalon frequency measurement technology, comprising: a laser emitting unit, a frequency detection unit, a frequency-stabilized laser output terminal connected to the output terminal of the laser emitting unit, and a main control adjustment unit connected to the output terminal of the frequency detection unit and the input terminal of the laser emitting unit respectively; the frequency detection unit includes a beam splitter connected to the output terminal of the laser emitting unit, an optical attenuator and a first photodetector connected to the output terminal of the beam splitter respectively, an etalon connected to the output terminal of the optical attenuator, and a second photodetector connected to the output terminal of the etalon; the output terminal of the main control adjustment unit is connected to the laser emitting unit, and the output terminals of the first photodetector and the second photodetector are both connected to the main control adjustment unit.

[0006] The laser emitting unit emits two laser beams with the same frequency. One beam is input to the frequency-stabilized laser output terminal for output, while the other is input to the frequency detection unit for frequency detection. The main control and adjustment unit then analyzes the detection results and dynamically outputs an adjustment signal. The laser emitting unit simultaneously adjusts both laser beams based on the adjustment signal, thereby achieving frequency stabilization. Specifically, in the frequency detection unit, the etalon is adapted to the laser center frequency. The etalon is an interference device containing two parallel reflective surfaces. When the beam enters the etalon, multi-beam interference occurs. The nature of the interference signal is mainly determined by the distance between the two reflective surfaces of the resonant cavity and the medium. A suitable etalon is customized based on the laser center frequency and the adjustable frequency range. Furthermore, the etalon employs a Fabry-Perot interferometer. An optical attenuator attenuates the laser beam, reducing the laser power input to the etalon and preventing excessive temperature rise caused by multiple reflections of high-power laser within the etalon. This reduces the etalon's temperature rise, decreases errors, and improves accuracy. The first and second photodetectors are used to detect the two optical signals before and after entering the etalon and convert the optical signals into electrical signals. The detected frequency measurement error signal and the reference signal are then fed into the main control and adjustment unit. The main control and adjustment unit is a computer equipped with a high-speed acquisition card. The reference optical signal and the etalon interference signal are acquired and processed by the main control and adjustment unit.

[0007] Using a standard etalon in the frequency detection unit as a frequency reference, an optical attenuator is set to reduce temperature rise and improve accuracy. The first and second photodetectors provide frequency measurement error signals and reference signals. The main control adjustment unit then analyzes and calculates based on the error signals and reference signals and issues real-time adjustment signals. The laser emission unit adjusts the laser frequency according to the adjustment signals to achieve stable laser frequency adjustment.

[0008] Preferably, the frequency detection unit further includes an optical amplifier disposed between the etalon and the second photodetector.

[0009] Optical amplifiers are used to amplify optical signals. Ethers are used to compare changes in the intensity of interference light. Therefore, after amplifying the laser output from the etalon, the difference becomes larger, the sensitivity is improved, and the frequency stabilization effect is better.

[0010] Preferably, the frequency detection unit further includes a thermoelectric temperature controller connected to the etalon.

[0011] A thermoelectric temperature controller is used to regulate the temperature of the etalon. Placing the etalon within the controller isolates it from external temperature influences, maintaining the stability of its resonant peak as a frequency reference. The operating temperature is monitored in real-time by a computer. Furthermore, the thermoelectric temperature controller consists of a metal thermostatic bath, a semiconductor cooling element, a temperature sensor, and a temperature feedback control circuit.

[0012] Preferably, the thermoelectric temperature controller is signal-connected to the main control and regulation unit.

[0013] Preferably, the laser emitting unit includes a signal generator and a laser connected to the output of the signal generator. The signal generator and the laser are also connected to the output of the main control adjustment unit, and the output of the laser is connected to the frequency-stabilized laser output and the beam splitter, respectively.

[0014] The laser is used to emit laser light, and the signal generator is used to achieve coarse adjustment of the laser light.

[0015] Preferably, the laser emitting unit further includes an acousto-optic modulator connected to the laser output terminal and an acousto-optic modulation driver connected to the acousto-optic modulator. The acousto-optic modulation driver is connected to the main control adjustment unit, and the output terminal of the acousto-optic modulator is connected to the frequency-stabilized laser output terminal and the beam splitter, respectively.

[0016] Acousto-optic modulators are used to achieve fine-tuning of lasers and improve tuning accuracy.

[0017] Preferably, the laser emitting unit further includes an optical isolator disposed between the laser and the acousto-optic modulator.

[0018] Optical isolators are used to prevent small amounts of reflected light from the etalon from entering the laser and damaging its lifespan and operational stability.

[0019] Preferably, the laser emitting unit further includes an optical coupler connected to the output of the acousto-optic modulator, and the output of the optical coupler is connected to the frequency-stabilized laser output and the beam splitter, respectively.

[0020] Both the optical coupler and the aforementioned beam splitter are used to ensure that the laser is output normally to the frequency detection section and to output the laser after frequency stabilization.

[0021] Preferably, the signal generator is a triangular wave signal generator.

[0022] Preferably, the beam splitter splits light in a 40%:60% ratio, with the 40% end connected to the optical attenuator and the 60% end connected to the first photodetector.

[0023] The beam splitter divides the laser into two paths, with the smaller path being input into the optical attenuator, which is then input into the etalon to further reduce the temperature rise of the etalon. This smaller path accounts for 40% of the laser's output, achieving the effect of reducing temperature rise while ensuring the required reflection power of the etalon.

[0024] Compared with the prior art, the beneficial effects of this utility model are:

[0025] Using a standard etalon in the frequency detection unit as a frequency reference, an optical attenuator is set to reduce temperature rise and improve accuracy. The first and second photodetectors provide frequency measurement error signals and reference signals. The main control adjustment unit then analyzes and calculates based on the error signals and reference signals and issues real-time adjustment signals. The laser emission unit adjusts the laser frequency according to the adjustment signals to achieve stable laser frequency adjustment. Attached Figure Description

[0026] Figure 1 This is a block diagram of the first embodiment of the laser frequency stabilization device based on etalon frequency measurement technology of this utility model;

[0027] Figure 2 This is a block diagram of the second embodiment of the laser frequency stabilization device based on etalon frequency measurement technology of this utility model;

[0028] Figure 3 This is a block diagram of the third embodiment of the laser frequency stabilization device based on etalon frequency measurement technology of this utility model.

[0029] In the diagram: 1. Laser emitting unit; 2. Frequency detection unit; 3. Frequency-stabilized laser output terminal; 4. Main control and adjustment unit; 5. Beam splitter; 6. Optical attenuator; 7. First photodetector; 8. Erebaum; 9. Second photodetector; 10. Optical amplifier; 11. Thermoelectric temperature controller; 12. Signal generator; 13. Laser; 14. Acousto-optic modulator; 15. Acousto-optic modulation driver; 16. Optical isolator; 17. Optical coupler. Detailed Implementation

[0030] The accompanying drawings are for illustrative purposes only and should not be construed as limiting this patent. To better illustrate this embodiment, some components in the drawings may be omitted, enlarged, or reduced, and do not represent the actual dimensions of the product. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings. The positional relationships described in the drawings are for illustrative purposes only and should not be construed as limiting this patent.

[0031] In the accompanying drawings of this utility model, the same or similar reference numerals correspond to the same or similar components. In the description of this utility model, it should be understood that if terms such as "upper," "lower," "left," "right," "long," and "short" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting this patent. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0032] The technical solution of this utility model will be further described in detail below through specific embodiments and with reference to the accompanying drawings:

[0033] Example 1

[0034] like Figure 1 The image shows a first embodiment of a laser frequency stabilization device based on etalon frequency measurement technology, comprising: a laser emitting unit 1, a frequency detection unit 2, a frequency-stabilized laser output terminal 3 connected to the output terminal of the laser emitting unit 1, and a main control adjustment unit 4 connected to the output terminal of the frequency detection unit 2 and the input terminal of the laser emitting unit 1 respectively; the frequency detection unit 2 includes a beam splitter 5 connected to the output terminal of the laser emitting unit 1, an optical attenuator 6 and a first photodetector 7 connected to the output terminal of the beam splitter 5 respectively, an etalon 8 connected to the output terminal of the optical attenuator 6, and a second photodetector 9 connected to the output terminal of the etalon 8; the output terminal of the main control adjustment unit 4 is connected to the laser emitting unit 1, and the output terminals of the first photodetector 7 and the second photodetector 9 are both connected to the main control adjustment unit 4.

[0035] Laser emitting unit 1 emits two laser beams with the same frequency. One beam is input to the frequency-stabilized laser output terminal 3 for output, while the other is input to the frequency detection unit 2 for frequency detection. The main control and adjustment unit 4 then analyzes the detection results and dynamically outputs an adjustment signal. Laser emitting unit 1 adjusts both laser beams simultaneously based on the adjustment signal, thereby achieving frequency stabilization. Specifically, in the frequency detection unit 2, the etalon 8 is adapted to the laser center frequency. The etalon 8 is an interference device containing two parallel reflective surfaces. When the beam enters the etalon 8, multi-beam interference occurs. The nature of the interference signal is mainly determined by the distance between the two reflective surfaces of the resonant cavity and the medium. A suitable etalon 8 is customized based on the laser center frequency and the adjustable frequency range. Furthermore, the etalon 8 employs a Fabry-Perot interferometer. The optical attenuator 6 attenuates the laser, reducing the laser power input to the etalon 8, avoiding excessive temperature rise caused by multiple reflections of high-power laser within the etalon 8, thus reducing the temperature rise of the etalon 8, minimizing errors, and improving accuracy. The first photodetector 7 and the second photodetector 9 are used to detect the two optical signals before and after entering the etalon 8, convert the optical signals into electrical signals, and input the detected frequency measurement error signal and the reference signal into the main control and adjustment unit 4. The main control and adjustment unit 4 is a computer equipped with a high-speed acquisition card. The interference signal between the reference optical signal and the etalon 8 is acquired and processed by the main control and adjustment unit 4.

[0036] The beneficial effects of this embodiment are as follows: the standard etalon 8 in the frequency detection unit 2 is used as a frequency reference, the optical attenuator 6 is set to reduce the temperature rise and improve the accuracy, and the first photodetector 7 and the second photodetector 9 provide the frequency measurement error signal and the reference signal. Then, the main control adjustment unit 4 analyzes and calculates the error signal and the reference signal and sends out a real-time adjustment signal. The laser emission unit 1 adjusts the laser frequency according to the adjustment signal to achieve laser frequency stabilization adjustment.

[0037] Example 2

[0038] This embodiment further defines the features of Embodiment 1, and its difference from Embodiment 1 lies in:

[0039] like Figure 2 As shown, the frequency detection unit 2 also includes an optical amplifier 10 disposed between the etalon 8 and the second photodetector 9. The frequency detection unit 2 also includes a thermoelectric temperature controller 11 connected to the etalon 8. The thermoelectric temperature controller 11 is signal-connected to the main control adjustment unit 4.

[0040] Optical amplifier 10 amplifies the optical signal. The etalon 8 reflects changes in the intensity of the contrasting interference light. Therefore, after amplifying the laser output from the etalon 8, the difference becomes larger, its sensitivity is improved, and the frequency stabilization effect is better. A thermoelectric temperature controller 11 regulates the temperature of the etalon 8. Placing the etalon 8 within the thermoelectric temperature controller 11 isolates it from the influence of external temperature, maintaining the stability of the resonant peak of the etalon 8, which serves as a frequency reference. Its operating temperature is monitored in real-time by a computer. Furthermore, the thermoelectric temperature controller 11 consists of a metal thermostatic bath, a semiconductor cooling chip, a temperature sensor, and a temperature feedback control circuit.

[0041] The remaining features and working principles of this embodiment are the same as those of Embodiment 1.

[0042] Example 3

[0043] Based on Example 1 or Example 2, Example 1 or Example 2 are further defined, with the following differences:

[0044] like Figure 3 As shown, the laser emitting unit 1 includes a signal generator 12 and a laser 13 connected to the output of the signal generator 12. The signal generator 12 and laser 13 are also connected to the output of the main control and adjustment unit 4. The output of the laser 13 is connected to the frequency-stabilized laser output terminal 3 and the beam splitter 5, respectively. The laser emitting unit 1 also includes an acousto-optic modulator 14 connected to the output of the laser 13, and an acousto-optic modulation driver 15 connected to the acousto-optic modulator 14. The acousto-optic modulation driver 15 is connected to the main control and adjustment unit 4. The output of the acousto-optic modulator 14 is connected to the frequency-stabilized laser output terminal 3 and the beam splitter 5, respectively. The laser emitting unit 1 also includes an optical isolator 16 disposed between the laser 13 and the acousto-optic modulator 14. The laser emitting unit 1 also includes an optical coupler 17 connected to the output of the acousto-optic modulator 14. The output of the optical coupler 17 is connected to the frequency-stabilized laser output terminal 3 and the beam splitter 5, respectively. The signal generator 12 is a triangular wave signal generator. The beam splitter 5 splits the light in a 40%:60% ratio, with the 40% ratio end connected to the optical attenuator 6 and the 60% ratio end connected to the first photodetector 7.

[0045] Laser 13 is used to emit laser light, and signal generator 12 is used to achieve coarse adjustment of the laser. Laser 13 is selected as a single-mode laser or an external cavity laser. The frequency fluctuation of this type of laser 13 is relatively small, which can effectively avoid frequency lock-up. Acousto-optic modulator 14 is used to achieve fine adjustment of the laser and improve the adjustment accuracy. Optical isolator 16 is used to prevent a small amount of reflected light from etalon 8 from entering laser 13 and damaging its working life and working stability. Optical coupler 17 and the aforementioned beam splitter 5 are used to ensure that the laser is output normally to the frequency detection section and outputs the frequency-stabilized laser. After passing through acousto-optic modulator 14, the laser is split by a 3dB 1×2 beam splitter 5. The laser is split into two paths. The smaller proportion is input into optical attenuator 6, and then input into etalon 8 to further reduce the temperature rise of etalon 8. The proportion is set to 40%, which achieves the effect of reducing temperature rise while ensuring the reflection power requirements of etalon 8.

[0046] Specifically, under the influence of the triangular wave signal, laser 13 periodically changes the frequency of its output laser. Simultaneously, the operating current of signal generator 12 alters the laser's center frequency, shifting it to near one of the resonance peaks of the etalon 8, i.e., one of the Fabry-Perot interferometers, thus generating an error signal containing laser frequency drift information. The operating current of signal generator 12 achieves coarse adjustment of the laser 13's output frequency, while acousto-optic modulator 14, driven by a driver, achieves fine adjustment of the laser frequency within a small range.

[0047] The triangular wave signal generator 12 is connected to the laser 13, and the acousto-optic modulation driver 15 is connected to the acousto-optic modulator 14. The frequency measurement error signal detected by the first photodetector 7 and the second photodetector 9, along with the reference signal, are connected to the high-speed acquisition card. The laser beam modulated by the triangular wave signal generator 12 passes through the optical isolator 16 and then enters the acousto-optic modulator 14. After being split twice, one of the laser beams enters the Fabry-Perot interferometer for interference, while the other beam directly enters the first photodetector 7 and is converted into an electrical signal, which serves as the reference signal. Together, they enter the high-speed acquisition card in the computer of the main control and adjustment unit 4.

[0048] The laser entering the Fabry-Perot interferometer undergoes multiple reflections within the resonant cavity before interfering. Only lasers of specific wavelengths that meet the resonance conditions can transmit through the interferometer after multi-beam interference, forming sharp interference peaks. Placing the Fabry-Perot interferometer within a thermoelectric temperature controller 11 prevents the resonant cavity length from changing with temperature, thus avoiding lateral shifts in the laser wavelength value of the interference peaks (which serve as error signals) due to temperature variations. The interference signal from the Fabry-Perot interferometer is then converted into an electrical signal by the second photodetector 9 and used as a reference signal along with the drive signal from the laser 13 before being fed into a high-speed data acquisition card.

[0049] Laser 13 is subjected to internal modulation frequency scanning using a triangular wave voltage signal. Under the modulation of the triangular wave, the laser frequency output by laser 13 periodically increases and decreases. When the laser's frequency sweep range passes on both sides of the selected Fabry-Perot interferometer interference peak frequency, two peaks appear in the interference signal. Due to the amplitude modulation effect accompanying the internal modulation of laser 13, it is necessary to divide the interference signal of the etalon 8 by the reference light signal to eliminate this effect.

[0050] In trigger-based acquisition mode, the phase of the reference signal remains constant. The phase of the interference signal from the Fabry-Perot interferometer is shifted, and while the two peaks are of equal height, their valleys are not. When the laser's center frequency is not aligned with the selected interference peak frequency, the heights of the valleys in the interference signal will be inconsistent, and the phase of the interference signal will shift left and right as the laser's center frequency drifts.

[0051] By calculating the height ratio between the interference valleys and combining the simulation results, a rough estimate of the laser frequency drift can be obtained. In this step, it can be determined whether the magnitude of the frequency drift is within the adjustable range of the acousto-optic modulator 14. If the drift of the laser center frequency is greater than the adjustable range of the acousto-optic modulator 14, the operating voltage and operating current of the laser 13 are changed to coarsely adjust the center frequency of the laser 13.

[0052] The remaining working principles and processes of this embodiment are the same as those of Embodiment 1 or Embodiment 2.

[0053] In the specific implementation of the above embodiments, the technical features can be combined in any non-contradictory way. For the sake of brevity, not all possible combinations of the above technical features are described. However, as long as the combination of these technical features is not contradictory, it should be considered to be within the scope of this specification.

[0054] Obviously, the above embodiments of this utility model are merely examples for clearly illustrating this utility model, and are not intended to limit the implementation of this utility model. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this utility model should be included within the protection scope of the claims of this utility model.

Claims

1. A laser frequency stabilization device based on etalon frequency measurement technology, characterized in that, include: The laser emitting unit (1), frequency detection unit (2), frequency-stabilized laser output terminal (3) connected to the output terminal of the laser emitting unit (1), and main control adjustment unit (4) connected to the output terminal of the frequency detection unit (2) and the input terminal of the laser emitting unit (1) respectively; the frequency detection unit (2) includes a beam splitter (5) connected to the output terminal of the laser emitting unit (1), an optical attenuator (6) and a first photodetector (7) connected to the output terminal of the beam splitter (5) respectively, an etalon (8) connected to the output terminal of the optical attenuator (6), and a second photodetector (9) connected to the output terminal of the etalon (8); the output terminal of the main control adjustment unit (4) is connected to the laser emitting unit (1), and the output terminals of the first photodetector (7) and the second photodetector (9) are both connected to the main control adjustment unit (4).

2. The laser frequency stabilization device based on etalon frequency measurement technology according to claim 1, characterized in that: The frequency detection unit (2) further includes an optical amplifier (10) disposed between the etalon (8) and the second photodetector (9).

3. The laser frequency stabilization device based on etalon frequency measurement technology according to claim 1, characterized in that: The frequency detection unit (2) also includes a thermoelectric temperature controller (11) connected to the etalon (8).

4. The laser frequency stabilization device based on etalon frequency measurement technology according to claim 3, characterized in that: The thermoelectric temperature controller (11) is connected to the main control and regulation unit (4) via signal.

5. The laser frequency stabilization device based on etalon frequency measurement technology according to claim 1, characterized in that: The laser emitting unit (1) includes a signal generator (12) and a laser (13) connected to the output of the signal generator (12). The signal generator (12) and the laser (13) are also connected to the output of the main control adjustment unit (4). The output of the laser (13) is connected to the frequency stabilized laser output terminal (3) and the beam splitter (5).

6. The laser frequency stabilization device based on etalon frequency measurement technology according to claim 5, characterized in that: The laser emitting unit (1) further includes an acousto-optic modulator (14) connected to the output end of the laser (13) and an acousto-optic modulation driver (15) connected to the acousto-optic modulator (14). The acousto-optic modulation driver (15) is connected to the main control adjustment unit (4). The output end of the acousto-optic modulator (14) is connected to the frequency-stabilized laser output end (3) and the beam splitter (5), respectively.

7. The laser frequency stabilization device based on etalon frequency measurement technology according to claim 6, characterized in that: The laser emitting unit (1) further includes an optical isolator (16) disposed between the laser (13) and the acousto-optic modulator (14).

8. The laser frequency stabilization device based on etalon frequency measurement technology according to claim 6, characterized in that: The laser emitting unit (1) further includes an optical coupler (17) connected to the output end of the acousto-optic modulator (14), and the output end of the optical coupler (17) is connected to the frequency-stabilized laser output end (3) and the beam splitter (5) respectively.

9. The laser frequency stabilization device based on etalon frequency measurement technology according to claim 5, characterized in that: The signal generator (12) is a triangular wave signal generator.

10. The laser frequency stabilization device based on etalon frequency measurement technology according to claim 1, characterized in that: The beam splitter (5) splits light in a ratio of 40% to 60%, with the 40% end connected to the optical attenuator (6) and the 60% end connected to the first photodetector (7).

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