Compression-enhanced phase noise suppression system

Abstract

The invention relates to the technical field of optics, and provides a compression-enhanced phase noise suppression system, which comprises an original laser generation module, a compressed light preparation module, a phase noise conversion module and a feedback control module, the original laser generation module is used for generating original laser and providing an original incident light source for the compressed light preparation module and the phase noise conversion module; the compressed light preparation module is used for generating a compressed light field, the phase noise conversion module is used for generating a reflected light field and converting phase noise of the reflected light field into intensity noise in a semi-detuning state, and the compressed light field and the reflected light field are coupled in a zero phase; and the feedback control module is used for feeding back the measured noise of the inner ring to the original laser generation module, realizing negative feedback of the phase noise and directly feeding back the noise to the outer ring. Light field phase noise is converted into amplitude noise through the half-detuning state of the narrow-linewidth over-coupling cavity, and laser phase noise is effectively suppressed in combination with compressed light injection.

Description

Technical Field

[0001] This invention relates to the field of optical technology, and more particularly to a compression-enhanced phase noise suppression system. Background Technology

[0002] With the rapid advancement of science and technology, laser technology is constantly iterating and upgrading, and coherent laser technology has emerged in many cutting-edge fields with its unique advantages. Ideally, a laser should be a stable monochromatic wave with excellent coherence, maintaining a high degree of consistency in frequency, phase, and other characteristics during propagation. However, in practical applications, the thorny problem of phase noise persists, eroding the coherence of the laser like a persistent ailment.

[0003] Essentially, phase noise originates from various physical processes within the laser, such as spontaneous emission of the gain medium and minute disturbances in the external environment. These factors cause random fluctuations in the laser's phase, thereby disrupting its coherence. When the same laser beam travels across a certain spatial distance or over a long time interval during propagation, the cumulative effect of phase noise makes it difficult to maintain coherence. For two laser beams, achieving coherence becomes even more challenging because their respective phase noises interfere with each other, making it difficult to achieve stable phase matching.

[0004] This coherence degradation problem severely limits many critical applications that rely on laser coherence. In the field of gravitational wave detection, the signal of gravitational waves is extremely weak, usually manifesting as a tiny perturbation to the length of the laser interferometer arms. Larger phase noise couples into the arms of the laser interferometer like background noise, masking the gravitational wave signal and limiting the detection sensitivity to a low level, hindering scientists from capturing and analyzing the faint gravitational wave signals from deep space.

[0005] In the field of optical atomic clocks, they are among the most accurate timekeeping tools available today, with their high precision relying on the high stability of the laser frequency. However, the presence of phase noise can cause random drift in the laser frequency, making the frequency standard unstable and thus reducing the accuracy of the optical atomic clock. This affects its application in scenarios with extremely high time accuracy requirements, such as global positioning systems and fundamental physics research.

[0006] LiDAR, an advanced technology for target detection and distance measurement, relies on emitting and receiving laser signals to acquire target information. Phase noise can cause instability in the phase of the emitted laser and interference with the phase of the received signal, leading to measurement errors and affecting the accuracy and reliability of its applications in fields such as autonomous driving, terrain mapping, and atmospheric monitoring.

[0007] In coherent optical communication, information is carried on physical quantities such as the phase and amplitude of the laser beam. Phase noise distorts the phase of the optical signal, making it difficult for the receiver to accurately recover the original information, increasing the bit error rate, limiting communication capacity and transmission distance, and hindering the development of high-speed, high-capacity optical communication networks.

[0008] Fiber optic sensing technology uses changes in the properties of light transmitted through optical fibers to sense external physical quantities, such as temperature, pressure, and strain. Phase noise interferes with the phase changes of light in the fiber, contaminating the sensing signal, reducing sensing accuracy and sensitivity, and affecting its performance in applications such as structural health monitoring, oil exploration, and smart grids.

[0009] Given the crucial role of these fields in scientific research, national defense, and the national economy, increasingly stringent requirements have been placed on the suppression of phase noise in laser sources. Traditional laser sources are no longer sufficient to meet the ever-growing demands for high precision, necessitating the development of new, high-performance laser sources to reduce the impact of phase noise. Therefore, in-depth research and further suppression of phase noise are of paramount practical significance for promoting technological progress and application expansion in related fields, and represent one of the key research topics in the current field of laser technology. Summary of the Invention

[0010] To address the aforementioned problems, the present invention aims to provide a compression-enhanced phase noise suppression system. This system converts optical field phase noise into amplitude noise through a narrow-linewidth overcoupled cavity in a semi-detuned state. Combined with compressed light injection, it effectively suppresses laser phase noise, breaks through the classical noise reduction limit, improves laser coherence, and meets the needs of fields with high laser coherence requirements, such as gravitational wave detection.

[0011] The above-mentioned objective of this invention is achieved through the following technical solutions:

[0012] A compression-enhanced phase noise suppression system includes: a raw laser generation module, a compressed light preparation module, a phase noise conversion module, and a feedback control module;

[0013] The original laser generation module is used to generate the original laser, providing the original incident light source for the compressed light preparation module and the phase noise conversion module;

[0014] The compressed light preparation module is used to generate a compressed light field, the phase noise conversion module is used to generate a reflected light field, and converts the phase noise of the reflected light field into intensity noise in a half-detuned state, and the compressed light field and the reflected light field are coupled with zero phase;

[0015] The feedback control module is used to feed back the measured noise of the inner loop to the original laser generation module to achieve negative feedback of phase noise, and to directly feed back noise to the outer loop.

[0016] Furthermore, the original laser generation module includes a laser, a phase modulator, an optical filter cavity, and an optical beam splitter;

[0017] The laser output from the laser first passes through the phase modulator, which acts as a feedback device. After the high-frequency noise is filtered out by the optical filter cavity, the output laser is split into two beams by the optical beam splitter.

[0018] The first laser beam emitted by the optical beam splitter serves as the incident light field of the compressed light preparation module to generate the compressed light field, and the second laser beam emitted by the optical beam splitter serves as the incident light field of the phase noise conversion module to generate the reflected light field.

[0019] Furthermore, the compressed light preparation module includes a first dichroic mirror, a frequency doubling cavity, a frequency doubling high-reflection mirror, a second dichroic mirror, and an optical parametric cavity;

[0020] The first laser beam emitted by the optical beam splitter enters the frequency doubling cavity through the first dichroic mirror to generate frequency-doubled light. The generated frequency-doubled light then passes through the frequency-doubled high-reflection mirror and the second dichroic mirror before entering the optical parametric cavity to generate the compressed light field.

[0021] Furthermore, the phase noise conversion module includes an overcoupled cavity, a first detector, a first servo feedback control system, and a beam splitter;

[0022] The second laser beam emitted by the optical beam splitter serves as the incident field of the feedback loop. Since the phase noise of the optical field cannot be directly detected, the second laser beam is first converted into noise through the overcoupled cavity. The overcoupled cavity is then locked in a semi-detuned state through the first detector and the first servo feedback control system, thereby converting the phase noise of the reflected optical field into intensity noise.

[0023] The reflected light field and the compressed light field are coupled at 0 phase on the beam splitter.

[0024] Furthermore, the feedback control module includes a second detector and a second servo feedback control system; the second detector, as an inner loop detector, is connected to the beam splitter, and feeds back the measured noise to the phase modulator through the second servo feedback control system. Negative feedback is performed in the process to suppress the noise.

[0025] Furthermore, the feedback control module also includes a third detector;

[0026] The third detector, acting as an outer loop detector, is used to detect and observe the final noise suppression level.

[0027] Furthermore, in the phase noise conversion module, the phase noise of the reflected light field is converted into intensity noise in a half-detuned state, and the specific formula is as follows:

[0028] Utilizing the dispersion characteristics of the narrow-linewidth overcoupled cavity in its semi-detuned state, with a detuning amount Δ = 0.5, the phase noise of the optical field is converted into amplitude noise. The orthogonal amplitude component δp(v) and orthogonal phase component δq(v) of the overcoupled cavity reflected field are expressed as:

[0029]

[0030] Where δα(v) and δα*(-v) represent amplitude fluctuations and their conjugates with frequencies of v and -v, respectively. Indicates phase as coherent light field components, Indicates phase lag The coherent optical field components, where i is the imaginary unit, have orthogonal amplitude components that are in phase with the average field complex amplitude, while orthogonal phase components are orthogonal to the average field complex amplitude. By manipulating the relative phase between the carrier and the sidebands, phase fluctuations can be converted into amplitude fluctuations. When the resonant cavity is in a half-detuned state Δ = 0.5, the phase function value related to the detuning amount Δ is...

[0031] Therefore we will Substituting the orthogonal phase component, the orthogonal phase component becomes:

[0032]

[0033] A complete noise ellipse rotation of two orthogonal components was achieved, that is, the phase noise of the light field was converted into intensity noise.

[0034] Set relative analysis frequency Where ν′=ν / δν c ν is the analysis frequency, δν c To achieve the linewidth of the overcoupled cavity, the effects of the carrier and sideband are completely separated, and the complete conversion between the phase and amplitude components of the noise is realized.

[0035] Furthermore, the feedback control module also includes calculating the noise variance of the cavity reflection field, specifically:

[0036]

[0037] Where a is the impedance matching factor, i is the imaginary unit, and the analysis frequency ν and cavity linewidth δν are... c Vin The variance of the input optical field noise is denoted as .

[0038] Furthermore, the feedback control module also includes calculating the noise variance of the outer loop and the noise variance of the inner loop of the feedback loop, specifically:

[0039] Noise variance of the outer loop of the feedback loop:

[0040]

[0041] Where η is the photodetector efficiency, ε is the beam splitter transmittance, h(w) is the loop gain parameter, and V R V represents the noise variance of the cavity reflection field. s (w) represents the noise variance of the compressed light;

[0042] Noise variance of the inner loop of the feedback loop:

[0043]

[0044] Where η is the photodetector efficiency, ε is the beam splitter transmittance, h(w) is the loop gain parameter, and V R V represents the noise variance of the cavity reflection field. s (w) represents the noise variance of the compressed light.

[0045] Compared with existing technologies, this invention achieves highly efficient suppression of laser phase noise through an innovative combination of "noise conversion + compression injection + feedback control," with specific beneficial effects including at least the following:

[0046] (1) Breaking through the classical noise reduction limit and improving suppression efficiency: Utilizing the quantum noise reduction characteristics (low quantum noise characteristics) of compressed light to replace the traditional vacuum noise source, breaking through the noise reduction limit of classical feedback control, especially in the suppression of outer loop noise.

[0047] (2) Achieving efficient conversion and precise suppression of phase noise: By utilizing the dispersion characteristics of the narrow-linewidth overcoupled cavity in a semi-detuned state (detuning amount = 0.5), the phase noise, which is difficult to measure directly, is linearly converted into easily detectable amplitude noise, thus solving the problem of difficult phase noise characterization. Combined with dual-loop feedback control (inner loop and outer loop), the core function of the inner loop structure is to construct a closed-loop feedback link—the reflected light field and the compressed light field are coupled through a beam splitter, the noise signal is collected in real time by a second detector, and the control command is transmitted to the phase modulator through a second servo feedback control system, forming a dynamic negative feedback adjustment loop, thereby achieving precise suppression of input field noise and real-time noise during coupling. The outer ring design focuses on monitoring the overall system performance and supporting applications: the third detector, as the core component of the outer ring, is responsible for quantitatively detecting the final noise suppression level, providing data support for evaluating the comprehensive effectiveness of compressed light injection and feedback control; in addition, the signal output of the outer ring link can be directly connected to downstream application scenarios such as gravitational wave detection and optical atomic clocks, ensuring that the suppressed high coherence laser can meet actual needs, forming a complete technical closed loop from noise suppression to application implementation.

[0048] (3) Significantly improves laser coherence to meet the requirements of high-precision applications: It effectively improves the coherence characteristics of lasers, which can meet the requirements of fields with extremely high coherence requirements such as gravitational wave detection, optical atomic clocks, and lidar. For example, in gravitational wave detection, it reduces the limitation of phase noise on the sensitivity of interferometers and improves the ability to detect weak signals; in optical atomic clocks, it stabilizes the laser frequency standard and improves timing accuracy. Attached Figure Description

[0049] Figure 1 This is a block diagram of the compression-enhanced phase noise suppression method of the present invention;

[0050] Figure 2 This is a diagram of the compression-enhanced phase noise suppression device of the present invention;

[0051] Figure 3 This is a schematic diagram of the phase noise variance of the outer ring when there is no compression injection according to the present invention;

[0052] Figure 4 This is a schematic diagram of the phase noise variance of the inner loop when there is no compression injection according to the present invention.

[0053] Figure Labels

[0054] 1: Laser; 2: Phase modulator; 3: Optical filter cavity; 4: Optical beam splitter; 5: First dichroic mirror; 6: Frequency doubling cavity; 7: Frequency doubling high-reflection mirror; 8: Second dichroic mirror; 9: Optical parametric cavity; 10: Overcoupled cavity; 11: First detector; 12: First servo feedback control system; 13: Beam splitter; 14: Second detector; 15: Second servo feedback control system; 16: Third detector. Detailed Implementation

[0055] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0056] Those skilled in the art will understand that, unless specifically stated otherwise, the singular forms “a,” “an,” “the,” and “the” used herein may also include the plural forms. It should be further understood that the term “comprising” as used in this specification means the presence of the stated features, integers, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0057] First Embodiment

[0058] like Figure 1 As shown, this embodiment provides a compression-enhanced phase noise suppression system, including: a raw laser generation module, a compressed light preparation module, a phase noise conversion module, and a feedback control module;

[0059] The original laser generation module is used to generate the original laser, providing the original incident light source for the compressed light preparation module and the phase noise conversion module;

[0060] The compressed light preparation module is used to generate a compressed light field, the phase noise conversion module is used to generate a reflected light field, and converts the phase noise of the reflected light field into intensity noise in a half-detuned state, and the compressed light field and the reflected light field are coupled with zero phase;

[0061] The feedback control module is used to feed back the measured noise of the inner loop to the original laser generation module to achieve negative feedback of phase noise, and to directly feed back noise to the outer loop.

[0062] The technical solutions of each module of the compression-enhanced phase noise suppression system of the present invention are described in detail below:

[0063] (1) Original laser generation module

[0064] The original laser generation module includes a laser 1, a phase modulator 2, an optical filter cavity 3, and an optical beam splitter 4;

[0065] The laser output from the laser 1 first passes through the phase modulator 2, which acts as a feedback device. After the high-frequency noise is filtered by the optical filter cavity 3, the output laser is split into two beams by the optical beam splitter 4. The first laser beam emitted by the optical beam splitter 4 serves as the incident light field of the compressed light preparation module to generate the compressed light field, and the second laser beam emitted by the optical beam splitter 4 serves as the incident light field of the phase noise conversion module to generate the reflected light field.

[0066] (2) Compressed light preparation module

[0067] The compressed light preparation module includes a first dichroic mirror 5, a frequency doubling cavity 6, a frequency doubling high-reflection mirror 7, a second dichroic mirror 8, and an optical parametric cavity 9;

[0068] The first laser beam emitted by the optical beam splitter 4 enters the frequency doubling cavity 6 through the first dichroic mirror 5 to generate frequency-doubled light. The generated frequency-doubled light then passes through the frequency-doubled high-reflection mirror 7 and the second dichroic mirror 8 before entering the optical parametric cavity 9 to generate the compressed light field.

[0069] Among them, the first dichroic mirror 5 is highly reflective of the fundamental frequency light and highly transparent of the second-order frequency light, while the second dichroic mirror 8 is highly reflective of the second-order frequency light and highly transparent of the fundamental frequency light.

[0070] (3) Phase noise conversion module

[0071] The phase noise conversion module includes an overcoupled cavity 10, a first detector 11, a first servo feedback control system 12, and a beam splitter 13;

[0072] The second laser beam emitted by the optical beam splitter 4 serves as the incident field of the feedback loop. Since the phase noise of the optical field cannot be directly detected, the second laser beam is first converted into noise through the overcoupled cavity 10. The overcoupled cavity 10 is then locked in a semi-detuned state through the first detector 11 and the first servo feedback control system 12, thereby converting the phase noise of the reflected light field into intensity noise. The reflected light field and the compressed light field are coupled at 0 phase on the beam splitter 13.

[0073] (4) Feedback control module

[0074] The feedback control module includes a second detector 14 and a second servo feedback control system 15. The second detector 14 is connected to the beam splitter 13 as an inner loop detector. The measured noise is fed back to the phase modulator 2 through the second servo feedback control system 15. Negative feedback is performed in the process to suppress the noise.

[0075] The feedback control module also includes a third detector 16; the third detector 16 serves as an outer loop detector for detecting and observing the final noise suppression level.

[0076] The following explains the specific calculation formulas for phase noise conversion, noise variance, outer loop noise variance, and inner loop noise variance of this invention:

[0077] (1) Phase noise conversion

[0078] Phase noise in lasers, which refers to the random fluctuations or delays in the phase of the light field over time, is difficult to characterize in applications. However, light field intensity is easily measured using photodetectors, so phase information can be measured by converting phase information into amplitude information through interferometry experiments.

[0079] This invention utilizes the dispersion characteristics of the narrow-linewidth overcoupled cavity 10 in its half-detuned state, with a detuning amount Δ = 0.5, to convert the phase noise of the optical field into amplitude noise. The orthogonal amplitude component δp(v) and orthogonal phase component δq(v) of the reflected field of the overcoupled cavity 10 are expressed as follows:

[0080]

[0081] Where δα(v) and δα*(-v) represent amplitude fluctuations and their conjugates with frequencies of v and -v, respectively. Indicates phase as coherent light field components, Indicates phase lag The coherent optical field components, where i is the imaginary unit, have orthogonal amplitude components that are in phase with the average field complex amplitude, while orthogonal phase components are orthogonal to the average field complex amplitude. By manipulating the relative phase between the carrier and the sidebands, phase fluctuations can be converted into amplitude fluctuations. When the resonant cavity is in a half-detuned state Δ = 0.5, the phase function value related to the detuning amount Δ is...

[0082] Therefore we will Substituting the orthogonal phase component, the orthogonal phase component becomes:

[0083]

[0084] A complete transformation of the two orthogonal components (noise ellipse rotation) was achieved, that is, the phase noise of the light field was converted into intensity noise. The relative analysis frequency was set. Where ν′=ν / δν c ν is the analysis frequency, δν c To achieve the linewidth of the overcoupled cavity 10, the effects of the carrier and sideband are completely separated, and the complete conversion between the phase component and amplitude component of the noise is realized.

[0085] (2) Noise variance of cavity reflection field

[0086] The phase noise is converted into easily measurable amplitude noise by using the semi-detuned state of the overcoupled cavity. The amplitude noise signal is then collected by the feedback control loop, and combined with the quantum noise reduction characteristics of compressed light, the original phase noise is indirectly suppressed.

[0087] Classical feedback control suppresses phase noise by adjusting gain, but it is limited by the classical noise reduction limit and cannot be further improved. Injecting a compressed state light field into the vacuum port of the beam splitter replaces the traditional vacuum noise source. By utilizing the low quantum noise characteristics of compressed light, the noise suppression limit of traditional solutions is broken. While maintaining signal integrity, the noise suppression efficiency is improved by combining "noise conversion + compression injection".

[0088]

[0089] Where a is the impedance matching factor, i is the imaginary unit, and the analysis frequency ν and cavity linewidth δν are... c V in The variance of the input optical field noise is denoted as .

[0090] (3) Noise variance of the outer loop of the feedback loop:

[0091]

[0092] Where η is the photodetector efficiency, ε is the beam splitter transmittance, h(w) is the loop gain parameter, and V R V represents the noise variance of the cavity reflection field. s (w) represents the noise variance of the compressed light;

[0093] (4) Noise variance of the inner loop of the feedback loop:

[0094]

[0095] Where η is the photodetector efficiency, ε is the beam splitter transmittance, h(w) is the loop gain parameter, and V R V represents the noise variance of the cavity reflection field. s (w) represents the noise variance of the compressed light.

[0096] The overall workflow of this embodiment is as follows:

[0097] The laser output from laser 1 first passes through phase modulator 2 as a feedback device. After high-frequency noise is filtered by optical filter cavity 3, it is split into two beams by optical beam splitter 4. One beam is used to generate a compressed light field, which enters frequency doubling cavity 6 to generate frequency-doubled light. The generated frequency-doubled light passes through frequency-doubled high-reflection mirror 7 and dichroic mirror 8 and enters optical parametric cavity 9 to generate compressed light. The other beam serves as the incident field of the feedback loop. Since the phase noise of the light field cannot be directly detected, it is first converted by overcoupler cavity 10. Overcoupler cavity 10 is locked in a semi-detuned state by first detector 11 and first servo feedback control system 12, which converts the phase noise of its reflected light field into intensity noise. The reflected field and the compressed light are coupled at 0 phase on beam splitter 13. Second detector 14, as an inner loop detector, feeds back the measured noise to phase modulator 2 through second servo feedback control system 15. Negative feedback is performed in this process, thus achieving noise suppression. Finally, the noise suppression level is detected and observed by third detector 16.

[0098] Second Embodiment

[0099] like Figure 2 As shown, this embodiment provides an example of a specific experimental setup for a compression-enhanced phase noise suppression system. The optical filter cavity 3 is a mode cleaner 3, the optical beam splitter 4 is a beam splitter prism 4, and the beam splitter 13 is a 99:1 beam splitter (99% reflectivity, 1% transmittance). The specific workflow of this embodiment is as follows:

[0100] The laser output from laser 1 first passes through phase modulator 2 as a feedback device. After high-frequency noise is filtered by mode cleaner 3, it is split into two beams by beam splitter prism 4. One beam is used to generate a compressed light field, which enters frequency doubling cavity 6 to generate frequency-doubled light. The generated frequency-doubled light passes through frequency-doubled high-reflection mirror 7 and dichroic mirror 8 to enter optical parametric cavity 9 to generate compressed light. The other beam serves as the incident field of the feedback loop. Since the phase noise of the light field cannot be directly detected, it is first converted by overcoupler cavity 10. Overcoupler cavity 10 is locked in a semi-detuned state by first detector 11 and first servo feedback control system 12, which converts the phase noise of its reflected light field into intensity noise. The reflected field and compressed light are coupled at 0 phase on 99:1 beam splitter 13. Second detector 14, as an inner loop detector, feeds back the measured noise to phase modulator 2 through second servo feedback control system 15. Negative feedback is performed in this process, thus achieving noise suppression. Finally, the noise suppression level is detected and observed by third detector 16.

[0101] Third Embodiment

[0102] like Figure 3 and 4As shown in the figure, this embodiment provides a theoretical verification of the changes in phase noise with gain and compression.

[0103] like Figure 3 As shown, the solid black line represents the outer loop noise variance without compressed light injection, the dashed black line represents the outer loop noise variance after compressed light injection, and the dotted black line represents the difference in outer loop noise variance before and after compressed light injection. By comparing the solid black line and the dashed black line, it can be clearly seen that the injection of compressed light further suppresses the outer loop noise variance, and the suppression effect of compressed light tends to stabilize when the gain reaches about 30dB.

[0104] like Figure 4 As shown, the solid black line represents the inner-loop noise variance without compressed light injection, the dashed black line represents the inner-loop noise variance after compressed light injection, and the dotted black line represents the difference in inner-loop noise variance before and after compressed light injection. Compared to the outer-loop optical field, the phase noise variance curves of the inner-loop optical field are closer after compressed light injection, with little change, indicating that the injection of the compressed optical field has little impact on the inner-loop optical field's ability to break through the noise reduction limit of the classical feedback control system. This is because the main noise source of the inner-loop optical field comes from the noise of the input field, while the influence of the beam splitter is relatively small.

[0105] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

[0106] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0107] It should be noted that the above embodiments can be freely combined as needed. The above description is only a preferred embodiment of the present invention. It should be pointed out that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A compression-enhanced phase noise suppression system, characterized in that, include: The system includes a primary laser generation module, a compressed light preparation module, a phase noise conversion module, and a feedback control module. The original laser generation module is used to generate the original laser, providing the original incident light source for the compressed light preparation module and the phase noise conversion module; The compressed light preparation module is used to generate a compressed light field, the phase noise conversion module is used to generate a reflected light field, and converts the phase noise of the reflected light field into intensity noise in a half-detuned state, and the compressed light field and the reflected light field are coupled with zero phase; The feedback control module is used to feed back the measured noise of the inner loop to the original laser generation module to achieve negative feedback of phase noise, and to directly feed back noise to the outer loop.

2. The compression-enhanced phase noise suppression system according to claim 1, characterized in that, The original laser generation module includes a laser, a phase modulator, an optical filter cavity, and an optical beam splitter; The laser output from the laser first passes through the phase modulator, which acts as a feedback device. After the high-frequency noise is filtered out by the optical filter cavity, the output laser is split into two beams by the optical beam splitter. The first laser beam emitted by the optical beam splitter serves as the incident light field of the compressed light preparation module to generate the compressed light field, and the second laser beam emitted by the optical beam splitter serves as the incident light field of the phase noise conversion module to generate the reflected light field.

3. The compression-enhanced phase noise suppression system according to claim 2, characterized in that, The compressed light preparation module includes a first dichroic mirror, a frequency doubling cavity, a frequency doubling high-reflection mirror, a second dichroic mirror, and an optical parametric cavity; The first laser beam emitted by the optical beam splitter enters the frequency doubling cavity through the first dichroic mirror to generate frequency-doubled light. The generated frequency-doubled light then passes through the frequency-doubled high-reflection mirror and the second dichroic mirror before entering the optical parametric cavity to generate the compressed light field.

4. The compression-enhanced phase noise suppression system according to claim 2, characterized in that, The phase noise conversion module includes an overcoupled cavity, a first detector, a first servo feedback control system, and a beam splitter; The second laser beam emitted by the optical beam splitter serves as the incident field of the feedback loop. Since the phase noise of the optical field cannot be directly detected, the second laser beam is first converted into noise through the overcoupled cavity. The overcoupled cavity is then locked in a semi-detuned state through the first detector and the first servo feedback control system, thereby converting the phase noise of the reflected optical field into intensity noise. The reflected light field and the compressed light field are coupled at 0 phase on the beam splitter.

5. The compression-enhanced phase noise suppression system according to claim 1, characterized in that, The feedback control module includes a second detector and a second servo feedback control system. The second detector, acting as an inner-loop detector, is connected to the beam splitter. The measured noise is fed back to the phase modulator through the second servo feedback control system. Negative feedback is performed during the process to suppress the noise.

6. The compression-enhanced phase noise suppression system according to claim 1, characterized in that, The feedback control module also includes a third detector; The third detector, acting as an outer loop detector, is used to detect and observe the final noise suppression level.

7. The compression-enhanced phase noise suppression system according to claim 1, characterized in that, In the phase noise conversion module, the phase noise of the reflected light field is converted into intensity noise in a half-detuned state, and the specific formula is as follows: Utilizing the dispersion characteristics of the narrow-linewidth overcoupled cavity in its semi-detuned state, with a detuning amount Δ = 0.5, the phase noise of the optical field is converted into amplitude noise. The orthogonal amplitude component δp(v) and orthogonal phase component δq(v) of the overcoupled cavity reflected field are expressed as: Where δα(v) and δα*(-v) represent amplitude fluctuations and their conjugates with frequencies of v and -v, respectively. Indicates phase as coherent light field components, Indicates phase lag The coherent optical field components, where i is the imaginary unit, have orthogonal amplitude components that are in phase with the average field complex amplitude, while orthogonal phase components are orthogonal to the average field complex amplitude. By manipulating the relative phase between the carrier and the sidebands, phase fluctuations can be converted into amplitude fluctuations. When the resonant cavity is in a half-detuned state Δ = 0.5, the phase function value related to the detuning amount Δ is... Therefore we will Substituting the orthogonal phase component, the orthogonal phase component becomes: A complete noise ellipse rotation of two orthogonal components was achieved, that is, the phase noise of the light field was converted into intensity noise.

8. The compression-enhanced phase noise suppression system according to claim 7, characterized in that, Also includes: Set relative analysis frequency Where ν′=ν / δν c ν is the analysis frequency, δν c To achieve the linewidth of the overcoupled cavity, the effects of the carrier and sideband are completely separated, and the complete conversion between the phase and amplitude components of the noise is realized.

9. The compression-enhanced phase noise suppression system according to claim 1, characterized in that, The feedback control module also includes calculating the noise variance of the cavity reflection field, specifically: Where a is the impedance matching factor, i is the imaginary unit, and the analysis frequency ν and cavity linewidth δν are... c V in The variance of the input optical field noise is denoted as .

10. The compression-enhanced phase noise suppression system according to claim 9, characterized in that, The feedback control module further includes calculating the noise variance of the outer loop and the noise variance of the inner loop of the feedback loop, specifically: Noise variance of the outer loop of the feedback loop: Where η is the photodetector efficiency, ε is the beam splitter transmittance, h(w) is the loop gain parameter, and V R V represents the noise variance of the cavity reflection field. s (w) represents the noise variance of the compressed light; Noise variance of the inner loop of the feedback loop: Where η is the photodetector efficiency, ε is the beam splitter transmittance, h(w) is the loop gain parameter, and V R V represents the noise variance of the cavity reflection field. s (w) represents the noise variance of the compressed light.

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