A multi-granularity inter-satellite and intra-satellite phase-locking mechanism simulation system

Abstract

The invention discloses a multi-granularity intersatellite and intrasatellite phase-locking mechanism simulation system, comprising: a multi-granularity phase-locking mechanism simulation subsystem, which is used to respectively construct coarse-grained and fine-grained phase-locking mechanism simulation models, and realize phase-locking of a slave laser to a main laser; a multi-granularity intersatellite phase-locking mechanism simulation subsystem, which is used in two optical platforms of different spacecraft simulation platforms, after the optical platform where the slave laser is located receives the laser from another optical platform, phase-locking control of the laser is realized through a scientific interferometer, and an offset frequency is added; a multi-granularity intrasatellite phase-locking mechanism simulation subsystem, which is used in two optical platforms of the spacecraft simulation platform where the main laser is located, and main laser transmission is realized and an offset frequency is added; and it is also used in two optical platforms of a spacecraft model where a non-main laser is located, one laser is phase-locked to a received remote laser, and the other laser is phase-locked to a previous laser through a reference interferometer, and main laser transmission is realized and an offset frequency is added.

Description

Technical Field

[0001] The invention belongs to the field of computer technology, and in particular relates to a multi-granularity inter-satellite and intra-satellite phase-locking mechanism simulation system. Background Art

[0002] During the detection process of the space gravitational wave detector, three spacecraft and six optical platforms are involved. The laser power received by the local optical platform from millions of kilometers away is only in the picowatt level, and it is impossible to directly reflect it back to the original optical platform. In addition, since the Doppler shift causes the beat frequency to change, an offset frequency needs to be added to avoid the beat frequency exceeding the reasonable range. For the problem of weak light transmission and beat frequency control, the current common solution is to use a phase-locked loop to make the local optical platform a "phase transponder". On the one hand, the received weak light is phase-locked through the phase-locked mechanism PID feedback control loop, so that the local output laser is used as a copy of the incident light for subsequent interferometric measurement tasks. On the other hand, during the weak light phase-locking process, the offset frequency is added to the frequency of the local output laser through the phase-locked loop to ensure that the beat frequency is within the detection bandwidth of the phase meter and avoid interruption of scientific observations. Due to the limitations of ground experiments, the current ground experiments of the phase-locked mechanism can only provide verification of the phase-locked performance, and cannot construct ground experiments of satellite-to-satellite and intra-satellite phase-locked mechanisms, and cannot evaluate the impact on the final scientific interference signal. Therefore, it is necessary to construct simulation methods and systems for inter-satellite and intra-satellite phase-locking mechanisms. Summary of the invention

[0003] In view of the ground experiment limitations of the prior art and considering various noise coupling factors, the purpose of the present invention is to overcome the above-mentioned defects of the prior art and propose a multi-granularity inter-satellite and intra-satellite phase-locking mechanism simulation system in combination with computational efficiency.

[0004] In order to achieve the above-mentioned object, the present invention proposes a multi-granularity inter-satellite and intra-satellite phase-locking mechanism simulation system, including: a multi-granularity phase-locking mechanism simulation subsystem, a multi-granularity inter-satellite phase-locking mechanism simulation subsystem and a multi-granularity intra-satellite phase-locking mechanism simulation subsystem, wherein:

[0005] The multi-granularity phase-locking mechanism simulation subsystem is used to construct coarse-grained and fine-grained phase-locking mechanism simulation models respectively to achieve phase locking of the slave laser to the master laser;

[0006] The multi-granularity intersatellite phase-locking mechanism simulation subsystem is used in two optical platforms of different spacecraft simulation platforms. After the optical platform where the laser is located receives the laser from another optical platform, it takes into account various noises and realizes phase-locking control of the laser through a scientific interferometer, and simultaneously adds an offset frequency;

[0007] The multi-granularity on-board phase-locking mechanism simulation subsystem is used in two optical platforms of a spacecraft simulation platform where the main laser is located to achieve the main laser transmission and add an offset frequency thereto; it is also used in two optical platforms of a spacecraft model where the non-main laser is located, in which one laser of the two optical platforms is phase-locked to the received remote laser, and the other laser is phase-locked to the previous laser through a reference interferometer to achieve the main laser transmission and add an offset frequency.

[0008] Preferably, the system also includes: three spacecraft simulation platforms with the same structure are arranged in a counterclockwise direction, the angle between the two optical platforms arranged on each spacecraft simulation platform is 60 degrees, the six optical platforms form an equilateral triangle, two lasers and two mass blocks are placed inside the two optical platforms of each spacecraft, and each optical platform respectively transmits and receives lasers to two adjacent optical platforms.

[0009] Preferably, the coarse-grained phase-locked mechanism simulation model includes a coarse-grained simulation module, and the processing process includes:

[0010] LASER 1 and LASER 2s represent the master laser and slave laser, respectively. The slave laser LASER 2s is phase-locked to LASER 1 and LASER 2s through the phase-locking mechanism. for:

[0011]

[0012]

[0013] in, represents the phase signal of LASER 1, which contains laser frequency noise and shot noise. t represents the time domain. Indicates the phase signal introduced by the phase-locking mechanism, L -1 {·} represents the inverse Laplace transform, represents the phase of the interference signal, and F1(s) represents the open-loop transfer function of the phase-locked mechanism, which satisfies the following formula:

[0014]

[0015] Wherein, G(s) represents the feedback control gain and s represents the frequency domain.

[0016] Preferably, the fine-grained phase-locked mechanism simulation model includes a fine-grained simulation model, and the processing process includes:

[0017] LASER 1 and LASER 2s represent the master laser and slave laser, respectively. The slave laser LASER 2s is phase-locked to LASER 1 and LASER 2s through the phase-locking mechanism. for:

[0018]

[0019]

[0020] in, represents the phase signal of LASER 1, which contains laser frequency noise and shot noise. t represents the time domain. The phase-locked phase signal introduced by the mechanism, L -1 {·} represents the inverse Laplace transform, represents the phase of the interference signal, and F2(s) represents the open-loop transfer function of the phase-locked mechanism, which satisfies the following formula:

[0021]

[0022] Among them, T(s) and P(s) represent the temperature controller and PZT controller respectively, G1(s), G2(s), G3(s) represent three gains respectively, and s represents the frequency domain.

[0023] Preferably, the multiple noises considered by the multi-granularity intersatellite phase-locking mechanism simulation subsystem include: laser frequency noise, optical platform noise, laser pointing jitter noise, readout noise, advance pointing optical path noise and breathing angle compensation optical path noise.

[0024] Preferably, the processing process of the multi-granularity intersatellite phase-locking mechanism simulation subsystem includes:

[0025] Laser A represents the laser emitted from the local optical platform, which is captured by the optical platform where Laser F is located after transmission. The received Laser A interferes with the local Laser F in the scientific interferometer and controls Laser F through the phase-locking mechanism, so that Laser F is phase-locked to Laser A.

[0026] After phase locking, the phase signal φ of Laser F F (t) is:

[0027]

[0028] φ AON (t) = φ LJN (t)+φ PAN (t)+φ BAN (t)+φ ON (t)

[0029] Among them, φ GW (t) represents the phase change caused by the gravitational wave signal, D represents the time delay operator, and They represent the phase change caused by the laser frequency noise of Laser A received by the optical platform where Laser F is located and the noise of the remote optical platform, respectively. RN (t),φ LFN (t),φ LJN (t),φ OBN (t),φ PAN (t),φ BAN (t) and φ ON (t) represents readout noise, laser frequency noise, laser pointing jitter noise, optical platform noise, advance pointing optical path noise, breathing angle compensation optical path noise and other noises respectively;

[0030] For the coarse-grained phase-locked mechanism simulation model:

[0031]

[0032] For fine-grained phase-locked mechanism simulation models:

[0033]

[0034] in, Indicates the phase signal introduced by the phase locking mechanism when Laser F is phase locked to Laser A. L -1 {·} denotes inverse Laplace transform, and s denotes frequency domain.

[0035] Preferably, the multi-granularity intra-satellite phase-locked mechanism simulation subsystem includes a first intra-satellite phase-locked mechanism simulation module, and the processing process includes:

[0036] Laser A represents the master laser emitted from the local optical platform, which is transmitted to the adjacent optical platform. Laser A interferes with the local slave laser Laser B in the reference interferometer and feedback controls Laser B through the phase-locking mechanism, so that Laser B is phase-locked to Laser A.

[0037] After phase locking, the phase signal φ of Laser B B (t) is:

[0038]

[0039] The reference interferometer phase signal φ after phase locking REF (t) is:

[0040]

[0041] For the coarse-grained phase-locked mechanism simulation model:

[0042]

[0043] For fine-grained phase-locked mechanism simulation models:

[0044]

[0045] Preferably, the multi-granularity intra-satellite phase-locked mechanism simulation subsystem includes a second intra-satellite phase-locked mechanism simulation module, and the processing process includes:

[0046] Laser A represents the master laser, Laser E and Laser F represent slave lasers. Laser A is emitted from the local optical platform and transmitted to the optical platform where Laser F is located. Laser A interferes with the local Laser F in the scientific interferometer and feedback controls Laser F through the phase-locking mechanism, so that Laser F is phase-locked to the incident light Laser A. At the same time, Laser F is transmitted to the adjacent optical platform and interferes with Laser E in the reference interferometer and feedback controls Laser E through the phase-locking mechanism, so that Laser E is phase-locked to Laser F.

[0047] Compared with the prior art, the advantages of the present invention are:

[0048] 1. The present invention establishes coarse-grained and fine-grained phase-locked mechanism simulation methods and constructs a multi-granularity phase-locked mechanism simulation module, on which inter-satellite and intra-satellite phase-locked mechanisms can be constructed to realize intra-satellite and inter-satellite phase-locked mechanism simulation systems;

[0049] 2. The present invention adopts coarse-grained and fine-grained phase-locked mechanism simulation models respectively, constructs a multi-granularity simulation method of the inter-satellite phase-locked mechanism, and realizes the simulation of the inter-satellite phase-locked mechanism;

[0050] 3. The present invention adopts coarse-grained and fine-grained phase-locked mechanism simulation models respectively, constructs a multi-granularity simulation method of the intra-satellite phase-locked mechanism, and realizes the simulation of the intra-satellite phase-locked mechanism. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 This is a diagram showing the coarse-grained phase-locking mechanism;

[0052] Figure 2 This is a diagram showing the fine-grained phase-locking mechanism;

[0053] Figure 3 This is a diagram showing the intersatellite phase-locking mechanism;

[0054] Figure 4 It is a SIMULINK simulation model of the intersatellite phase-locking mechanism;

[0055] Figure 5 This is a diagram showing the intra-satellite phase-locking mechanism on the optical platform where the main laser is located;

[0056] Figure 6This is a diagram showing the intra-satellite phase-locking mechanism of the optical platform where the non-master laser is located;

[0057] Figure 7 It is the SIMULINK simulation model of the intra-satellite phase-locking mechanism;

[0058] Figure 8 It is the reference interferometer signal output calculation module;

[0059] Fig. 9 REF1 and REF1s signal output. DETAILED DESCRIPTION

[0060] The space gravitational wave detection mission includes three spacecraft, and the three spacecraft are placed in an equilateral triangle with an interferometer arm length of 3 million kilometers. Each spacecraft contains two optical platforms, which are used to establish laser links with the other two spacecraft, complete ultra-long-distance laser ranging, and realize the detection of gravitational wave signals. Each optical platform contains three interferometers, namely the scientific interferometer, the test mass interferometer and the reference interferometer. The space gravitational wave detector contains the following two phase-locking mechanisms, namely the inter-satellite phase-locking mechanism completed by the scientific interferometer and the intra-satellite phase-locking mechanism completed by the reference interferometer. Among them, the intra-satellite phase-locking mechanism is further subdivided into two types: the phase-locking mechanism of the optical platform where the main laser is located and the phase-locking mechanism of the optical platform where the non-main laser is located.

[0061] In order to realize multi-granularity simulation of inter-satellite and intra-satellite phase-locking mechanism, the present invention proposes a multi-granularity inter-satellite and intra-satellite phase-locking mechanism simulation system, including: a multi-granularity phase-locking mechanism simulation method, a multi-granularity inter-satellite phase-locking mechanism simulation method and system, and a multi-granularity intra-satellite phase-locking mechanism simulation method and system.

[0062] 1. Multi-granularity phase-locked mechanism simulation method

[0063] Assume that LASER 1 and LASER 2s represent the master laser and the slave laser, respectively. The slave laser LASER 2s is phase-locked to LASER 1 through feedback control of the phase-locking mechanism. After phase locking, the laser emitted by LASER 2s can be regarded as a copy of LASER 1. The expressions of LASER1 and LASER 2s are as follows:

[0064]

[0065] Among them, f1 and f 2s Represent the frequencies of the two laser beams, and Represents the phase of two laser beams, which includes noises such as laser frequency noise and shot noise.

[0066] After the two laser beams interfere, the interference power P is expressed as follows:

[0067]

[0068] Among them, f 1-2s represents the interference signal beat frequency, represents the phase of the interference signal, which includes not only the phase change caused by gravitational waves, but also the phase change caused by various noises. For the coarse-grained simulation model, assuming that G(s) represents the feedback control gain, the open-loop transfer function of the phase-locked mechanism is as follows:

[0069]

[0070] The phase signal output by Laser 2s after phase locking is constructed as follows:

[0071]

[0072] in,

[0073]

[0074] For the fine-grained simulation model, assume that T(s) and P(s) represent the temperature controller and PZT controller respectively, and G1(s), G2(s), and G3(s) represent three gains respectively. The open-loop transfer function using this structure is as follows:

[0075]

[0076] The phase signal output by Laser 2s after phase locking is constructed as follows:

[0077]

[0078] in,

[0079]

[0080] L -1 {·} denotes inverse Laplace transform.

[0081] 2. Multi-granularity intersatellite phase-locking mechanism simulation method

[0082] The intersatellite phase-locking mechanism is applied to two optical platforms of different spacecraft. After the optical platform where the laser is located receives the laser from another optical platform, the incident light is weakly phase-locked.

[0083] The noises involved in the intersatellite phase-locking mechanism include laser frequency noise, optical platform noise, laser pointing jitter noise, readout noise, advance pointing optical path noise, and breathing angle compensation optical path noise.

[0084] The intersatellite phase-locking mechanism is implemented through a scientific interferometer. Assume that the two laser beams are Laser A and Laser B. After Laser A is emitted from the local optical platform, it is captured by the optical platform where Laser F is located after a transmission of 3 million kilometers. Afterwards, the received Laser A interferes with the local Laser F in the scientific interferometer and controls Laser F through the phase-locking mechanism, so that Laser F is phase-locked to Laser A.

[0085] Without considering the phase-locking mechanism, the phase signal output of the scientific interferometer on the optical platform where Laser F is located is

[0086]

[0087] in,

[0088]

[0089] Among them, φ SCI (t) represents the output signal of the scientific interferometer; φ GW (t) represents the phase change caused by the gravitational wave signal, φ RN (t),φ LFN (t),φ LJN (t),φ OBN (t),φ PAN (t),φ BAN (t) and φ ON (t) represents readout noise, laser frequency noise, laser pointing jitter noise, optical platform noise, advance pointing optical path noise, breathing angle compensation optical path noise and other noises respectively; D represents the delay operator, and It represents the phase change caused by the laser frequency noise of Laser A received by the optical platform where Laser F is located and the noise of the remote optical platform. To simplify the formula, and They represent the far-end laser frequency noise received by the optical platform where Laser F is located. and optical bench noise The local laser frequency noise and the optical table noise φ OBN (t) The difference in phase change caused by AON (t) represents the set of phase changes caused by several additive noises involved in the intersatellite phase-locking mechanism.

[0090] After phase locking, the phase of Laser F becomes

[0091]

[0092] For the coarse-grained phase-locked mechanism,

[0093]

[0094] For fine-grained phase locking mechanism

[0095]

[0096] 3. Multi-granularity intra-satellite phase-locking mechanism simulation method

[0097] The intra-satellite phase-locking mechanism is implemented by using a reference interferometer.

[0098] There are two types of intra-satellite phase-locking mechanisms, namely, the intra-satellite phase-locking mechanism of the optical platform where the main laser is located and the intra-satellite phase-locking mechanism of the optical platform where the non-main laser is located. The former is applied to the two optical platforms of the spacecraft where the main laser is located to realize the transmission of the main laser and add the offset frequency therein. The second is applied to the two optical platforms of the spacecraft where the non-main laser is located, one of the two lasers in the two optical platforms is phase-locked to the received remote laser, and the other laser is phase-locked to the previous laser through a reference interferometer to realize the transmission of the main laser and add the offset frequency.

[0099] Phase-locking mechanism within the optical platform where the master laser is located: Assume that Laser A is the master laser and Laser B is the slave laser. After Laser A is emitted from the local optical platform, it is transmitted to the adjacent optical platform. After that, Laser A interferes with the local Laser B in the reference interferometer and controls Laser B through the phase-locking mechanism, so that Laser B is phase-locked to Laser A.

[0100] Without considering the phase-locked loop, the reference interferometer phase signal output of the optical platform where Laser B is located is:

[0101]

[0102] in,

[0103]

[0104] Among them, φ REF (t) represents the output signal of the scientific interferometer; φ RN (t),φ LFN (t) and φ ON (t) represent readout noise, laser frequency noise and other noise respectively; to simplify the formula, and They represent the laser frequency noise of the adjacent optical platform received by the optical platform where Laser B is located. and optical bench noise The local laser frequency noise and the optical table noise φ OBN (t) is the difference in phase change caused by

[0105] After phase locking, the phase of Laser B becomes

[0106]

[0107] Therefore, theoretically, the reference interferometer phase signal output after phase locking is:

[0108]

[0109] Among them, for the coarse-grained phase-locked mechanism simulation model:

[0110]

[0111] Among them, for the fine-grained phase-locked mechanism simulation model:

[0112]

[0113] The intra-satellite phase-locking mechanism of the optical platform where the non-master laser is located: Assume that Laser A is the master laser, and Laser E and Laser F are slave lasers. After Laser A is emitted from the local optical platform, it is transmitted to the optical platform where Laser F is located after 3 million kilometers. Laser A interferes with the local Laser F in the scientific interferometer and feedback controls Laser F through the phase-locking mechanism, so that Laser F is phase-locked to the incident light Laser A. At the same time, Laser F is transmitted to the adjacent optical platform and interferes with Laser E in the reference interferometer and feedback controls Laser E through the phase-locking mechanism, so that Laser E is phase-locked to Laser F.

[0114] The intra-satellite phase-locking mechanism of the optical platform where the non-master laser is located is essentially a combination of the inter-satellite phase-locking mechanism and the intra-satellite phase-locking mechanism of the optical platform where the master laser is located, and can be obtained by combining the two.

[0115] The technical solution of the present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0116] Example

[0117] The embodiment of the present invention proposes a multi-granularity inter-satellite and intra-satellite phase-locking mechanism simulation system, including: a multi-granularity phase-locking mechanism simulation subsystem, a multi-granularity inter-satellite phase-locking mechanism simulation subsystem and a multi-granularity intra-satellite phase-locking mechanism simulation subsystem, wherein:

[0118] The multi-granularity phase-locking mechanism simulation subsystem is used to construct coarse-grained and fine-grained phase-locking mechanism simulation models respectively to achieve phase-locking of the slave laser to the master laser;

[0119] The multi-granularity intersatellite phase-locking mechanism simulation subsystem is used in two optical platforms of different spacecraft simulation platforms. After the optical platform where the laser is located receives the laser from another optical platform, it takes into account various noises and realizes the phase-locking control of the laser through a scientific interferometer, and at the same time adds the offset frequency;

[0120] The multi-granularity on-board phase-locking mechanism simulation subsystem is used in the two optical platforms of the spacecraft simulation platform where the main laser is located to realize the transmission of the main laser and add an offset frequency to it; it is also used in the two optical platforms of the spacecraft model where the non-main laser is located. One of the lasers in the two optical platforms is phase-locked to the received remote laser, and the other laser is phase-locked to the previous laser through a reference interferometer to realize the transmission of the main laser and add an offset frequency.

[0121] The phase-locking mechanism can achieve phase locking of one laser to another. Assume that LASER 1 and LASER 2s represent the master laser and the slave laser respectively. The slave laser LASER 2s is phase-locked to LASER 1 through feedback control of the phase-locking mechanism. After phase locking, the laser emitted by LASER2s can be regarded as a copy of LASER 1. The coarse-grained and fine-grained phase-locking mechanisms are shown in the figure below. Figure 1 shown.

[0122] The intersatellite phase-locking mechanism is applied to two optical platforms of different spacecraft. After the optical platform where the laser is located receives the laser from another optical platform, the laser is phase-locked and controlled through a scientific interferometer, while adding an offset frequency.

[0123] Compared with the intra-satellite phase-locking mechanism, the inter-satellite phase-locking mechanism involves more noise, including laser frequency noise, optical platform noise, laser pointing jitter noise, readout noise, advance pointing optical path noise, and breathing angle compensation optical path noise.

[0124] like Figure 2 Shown is a diagram showing a fine-grained phase-locking mechanism.

[0125] The laser link model for the intersatellite phase-locking mechanism is shown in FIG. Figure 3In the figure, SCI, TM and REF represent scientific interferometer, test quality interferometer and reference interferometer respectively; Phasemeter represents phase meter; PID represents the feedback control system of the phase-locking mechanism, and the dotted line connecting the PID module represents the signal transmission of the feedback control system. In the figure, the laser emitted by Laser A and the laser emitted by Laser F are represented by two dotted lines, respectively, where Laser A is the master laser and Laser F is the slave laser. After Laser A is emitted from the local optical platform, it is captured by the optical platform where Laser F is located after 3 million kilometers of transmission. Afterwards, the received Laser A interferes with the local Laser F in the scientific interferometer and controls Laser F through PID feedback, so that Laser F is phase-locked to Laser A.

[0126] Without considering the phase-locked loop, the phase signal output of the scientific interferometer on the optical platform where Laser F is located is:

[0127]

[0128] in,

[0129]

[0130] Among them, φ SCI (t) represents the output signal of the scientific interferometer; φ GW (t) represents the phase change caused by the gravitational wave signal, φ RN (t),φ LFN (t),φ LJN (t),φ OBN (t),φ PAN (t),φ BAN (t) and φ ON (t) represents readout noise, laser frequency noise, laser pointing jitter noise, optical platform noise, advance pointing optical path noise, breathing angle compensation optical path noise and other noises respectively; D represents the delay operator, and It represents the phase change caused by the laser frequency noise of Laser A received by the optical platform where Laser F is located and the noise of the remote optical platform. To simplify the formula, and They represent the far-end laser frequency noise received by the optical platform where Laser F is located. and optical bench noise The local laser frequency noise and the optical table noise φ OBN (t) The difference in phase change caused by AON(t) represents the set of phase changes caused by several additive noises involved in the intersatellite phase-locking mechanism.

[0131] After phase locking, the phase of Laser F becomes

[0132]

[0133] For the coarse-grained phase-locked mechanism,

[0134]

[0135] For fine-grained phase locking mechanism

[0136]

[0137] According to the above analysis, the inter-satellite phase-locking mechanism is simulated using SIMULINK, and its simulation model is as follows: Figure 4 shown.

[0138] Figure 4 LFN, OBN, RN and AON represent the laser frequency noise, optical platform noise, readout noise and other noise sum signals in each optical platform, respectively. The serial number of each noise represents the number of the optical platform where it is located. L1s and L3 represent gravitational wave signals. For simplicity, they are set to 0 in the simulation experiment of interstellar phase-locking mechanism; DelayModule represents the timing delay module, which is used to add the time-varying delay caused by interstellar motion. Delay12 and delay21 represent interstellar delays, which are both set to 10s in the simulation experiment. The DPLL module represents the phase-locked loop used in the simulation process. Its input signals include the laser frequency noise signal of the master and slave lasers, the noise sum signal, the gravitational wave signal, the offset frequency signal and the laser frequency signal. Its output has two signals, namely the scientific interferometer signal of this optical platform and the laser phase signal after phase locking. The phase-locked laser phase signal is transmitted to the remote optical platform through a telescope for further calculation to obtain the reference interferometer signal of the adjacent optical platform.

[0139] The simulation was performed using 3Hz simulation data with a simulation duration of 11000s. The data of the first 1000s was deleted, and only the simulation data of 10000s after the subsequent interference link was stabilized was included. The scientific interferometer outputs of the master optical platform and the slave optical platform were used to verify the correctness of the intersatellite phase-locking mechanism simulation. After the slave optical platform receives the laser from the master optical platform, it phase-locks and transmits the master optical platform. The scientific interferometer readouts of the master optical platform and the slave optical platform are expressed as SCI 1 and SCI 1s, respectively. It can be seen from the figure that the output of the scientific interferometer of the slave optical platform is almost 0. The reason is that the phases of the two laser beams become consistent after phase locking.

[0140] There are two types of intra-satellite phase-locking mechanisms: one is the intra-satellite phase-locking mechanism of the optical platform where the master laser is located, and the other is the intra-satellite phase-locking mechanism of the optical platform where the non-master laser is located. In the intra-satellite phase-locking mechanism, since the two laser beams involved in the phase-locking are located on the same spacecraft, there is no ultra-long-distance laser transmission involved, so the types of noise involved are relatively small.

[0141] The intra-satellite phase-locking mechanism is realized through a reference interferometer. The noises involved in the intra-satellite phase-locking mechanism include laser frequency noise, optical platform noise, readout noise and other noises, among which laser frequency noise is the dominant one.

[0142] (1) Phase-locking mechanism within the optical platform where the main laser is located

[0143] The intra-satellite phase-locking mechanism of the optical platform where the main laser is located is realized by a reference interferometer. The laser link model for this intra-satellite phase-locking mechanism is as follows: Figure 5 shown.

[0144] Figure 5 In the figure, the laser beams involved in the phase-locking process are represented by colors, and the remaining laser beams and interferometers are represented by gray solid lines. The figure shows two laser beams, one emitted by Laser A and the other emitted by Laser B, where Laser A is the master laser and Laser B is the slave laser. After Laser A is emitted from the local optical platform, it is transmitted to the adjacent optical platform through the optical fiber. After that, Laser A interferes with the local Laser B in the reference interferometer and controls Laser B through the phase-locking mechanism, so that Laser B is phase-locked to Laser A.

[0145] (2) Phase-locking mechanism within the optical platform where the non-master laser is located

[0146] The intra-satellite phase-locking mechanism of the optical platform where the non-master laser is located is also realized by the reference interferometer. The difference is that the lasers in the two optical platforms in the spacecraft need to be phase-locked to the incident light of one of the optical platforms. The laser link model is as follows: Figure 6 In the figure, the laser beams involved in the phase-locking process are represented in color, and the remaining laser beams and interferometers are represented in gray. Figure 6Three laser beams are shown, namely the laser emitted by Laser A, the laser emitted by Laser E and the laser emitted by Laser F, where Laser A is the master laser and Laser E and Laser F are slave lasers. After being emitted from the local optical platform, Laser A is transmitted to the optical platform where Laser F is located after traveling 3 million kilometers. Laser A interferes with the local Laser F in the scientific interferometer and feedback controls Laser F through the phase-locking mechanism, so that Laser F is phase-locked to the incident light Laser A. At the same time, Laser F is transmitted to the adjacent optical platform through the optical fiber and interferes with Laser E in the reference interferometer and feedback controls Laser E through the phase-locking mechanism, so that Laser E is phase-locked to Laser F.

[0147] Phase-locking mechanism within the optical platform where the master laser is located: Assume that Laser A is the master laser and Laser B is the slave laser. After Laser A is emitted from the local optical platform, it is transmitted to the adjacent optical platform. After that, Laser A interferes with the local Laser B in the reference interferometer and controls Laser B through the phase-locking mechanism, so that Laser B is phase-locked to Laser A.

[0148] Without considering the phase-locked loop, the reference interferometer phase signal output of the optical platform where Laser B is located is:

[0149]

[0150] in,

[0151]

[0152] Among them, φ REF (t) represents the output signal of the scientific interferometer; φ RN (t),φ LFN (t) and φ ON (t) represent readout noise, laser frequency noise and other noise respectively; to simplify the formula, and They represent the laser frequency noise of the adjacent optical platform received by the optical platform where Laser B is located. and optical bench noise The local laser frequency noise and the optical table noise φ OBN (t) is the difference in phase change caused by

[0153] After phase locking, the phase of Laser B becomes

[0154]

[0155] Therefore, theoretically, the reference interferometer phase signal output after phase locking is:

[0156]

[0157] Among them, for the coarse-grained phase-locked mechanism simulation model:

[0158]

[0159] Among them, for the fine-grained phase-locked mechanism simulation model:

[0160]

[0161] The intra-satellite phase-locking mechanism of the optical platform where the non-master laser is located: Assume that Laser A is the master laser, and Laser E and Laser F are slave lasers. After Laser A is emitted from the local optical platform, it is transmitted to the optical platform where Laser F is located after 3 million kilometers. Laser A interferes with the local Laser F in the scientific interferometer and feedback controls Laser F through the phase-locking mechanism, so that Laser F is phase-locked to the incident light Laser A. At the same time, Laser F is transmitted to the adjacent optical platform and interferes with Laser E in the reference interferometer and feedback controls Laser E through the phase-locking mechanism, so that Laser E is phase-locked to Laser F.

[0162] The intra-satellite phase-locking mechanism of the optical platform where the non-master laser is located is essentially a combination of the inter-satellite phase-locking mechanism and the intra-satellite phase-locking mechanism of the optical platform where the master laser is located, and can be obtained by combining the two.

[0163] According to the above analysis, SIMULINK is used for simulation. The simulation model of the first type of intra-satellite phase-locking mechanism is as follows: Figure 7 As shown. Two optical platforms are constructed here, namely optical platform A and optical platform B. Laser B in optical platform B is phase-locked to laser A in optical platform A.

[0164] LFN, OBN, RN and ON represent laser frequency noise, optical platform noise, readout noise and other noises respectively. The serial number of each noise represents the number of the optical platform where it is located. The DPLL module represents the phase-locked loop used in the simulation process. Its input signals include the laser frequency noise signal of the master and slave lasers, the noise sum signal, the gravitational wave signal, the offset frequency signal and the laser frequency signal. Its output is the laser phase signal after phase locking. REF1 represents the reference interferometer signal output of optical platform A, and REF1s represents the reference interferometer signal output of optical platform B. REF module is as follows Figure 8As shown, it is used to calculate the reference interferometer signal between two optical tables.

[0165] Similarly, the simulation is performed using 3Hz simulation data for 11000s. The first 1000s of data are deleted, and only the last 10000s of simulation data are retained for display. It should be noted that the frequency item is not configured at present, that is, its input is set to 0. The output of REF1 and REF1s signals is as follows: Fig. 9 Theoretically, the outputs of REF1 and REF1s should be 0 (or a constant), but due to the large magnitude of the introduced laser frequency noise and the imperfect phase locking, the interference result after phase locking is not 0 (or a constant).

[0166] Summary:

[0167] Aiming at the problem of simulating inter-satellite and intra-satellite phase-locking mechanisms with high detection accuracy, long period, complex on-orbit environment, and long period of on-orbit motion characteristics that are difficult to achieve in ground experiments, a multi-granularity inter-satellite and intra-satellite phase-locking mechanism simulation method and system are proposed. Considering various noise coupling factors, a simulation method for inter-satellite and intra-satellite phase-locking mechanisms for space gravitational wave detection is constructed, and combined with computational efficiency, a multi-granularity inter-satellite and intra-satellite phase-locking mechanism simulation system is constructed.

[0168] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention is described in detail with reference to the embodiments, it should be understood by those skilled in the art that any modification or equivalent replacement of the technical solutions of the present invention does not depart from the spirit and scope of the technical solutions of the present invention and should be included in the scope of the claims of the present invention.

Claims

1. A multi-granularity inter-satellite and intra-satellite phase-locking mechanism simulation system, characterized in that: include: Multi-granularity phase-locked mechanism simulation subsystem, multi-granularity inter-satellite phase-locked mechanism simulation subsystem and multi-granularity intra-satellite phase-locked mechanism simulation subsystem, among which, The multi-granularity phase-locking mechanism simulation subsystem is used to construct coarse-grained and fine-grained phase-locking mechanism simulation models respectively to achieve phase locking of the slave laser to the master laser; The multi-granularity intersatellite phase-locking mechanism simulation subsystem is used in two optical platforms of different spacecraft simulation platforms. After the optical platform where the laser is located receives the laser from another optical platform, it takes into account various noises and realizes phase-locking control of the laser through a scientific interferometer, and simultaneously adds an offset frequency; The multi-granularity on-board phase-locking mechanism simulation subsystem is used in two optical platforms of the spacecraft simulation platform where the main laser is located, so as to realize the transmission of the main laser and add the offset frequency therein; it is also used in two optical platforms of the spacecraft model where the non-main laser is located, one laser of the two optical platforms is phase-locked to the received remote laser, and the other laser is phase-locked to the previous laser through a reference interferometer, so as to realize the transmission of the main laser and add the offset frequency; The system further comprises: three spacecraft simulation platforms with the same structure are arranged in a counterclockwise direction, the angle between the two optical platforms arranged on each spacecraft simulation platform is 60 degrees, the six optical platforms form an equilateral triangle, two lasers and two mass blocks are placed inside the two optical platforms of each spacecraft, and each optical platform transmits and receives lasers to two adjacent optical platforms respectively; The coarse-grained phase-locked mechanism simulation model includes a coarse-grained simulation module, and the processing process includes: LASER 1 and LASER 2s represent the master laser and slave laser, respectively. The slave laser LASER2s is phase-locked to LASER 1 and LASER 2s through the phase-locking mechanism. for: in, represents the phase signal of LASER 1, which contains laser frequency noise and shot noise. t represents the time domain. Indicates the phase signal introduced by the phase-locking mechanism, L -1 {·} represents the inverse Laplace transform, represents the phase of the interference signal, and F1(s) represents the open-loop transfer function of the phase-locked mechanism, which satisfies the following formula: Where G(s) represents the feedback control gain, and s represents the frequency domain; The fine-grained phase-locked mechanism simulation model includes a fine-grained simulation model, and the processing process includes: LASER 1 and LASER 2s represent the master laser and slave laser, respectively. The slave laser LASER2s is phase-locked to LASER 1 and LASER 2s through the phase-locking mechanism. for: in, represents the phase signal of LASER 1, which contains laser frequency noise and shot noise. t represents the time domain. Indicates the phase signal introduced by the phase-locking mechanism, L -1 {·} represents the inverse Laplace transform, represents the phase of the interference signal, and F2(s) represents the open-loop transfer function of the phase-locked mechanism, which satisfies the following formula: Among them, T(s) and P(s) represent the temperature controller and PZT controller respectively, G1(s), G2(s), G3(s) represent three gains respectively, and s represents the frequency domain.

2. The multi-granularity inter-satellite and intra-satellite phase-locking mechanism simulation system according to claim 1 is characterized in that: The multiple noises considered by the multi-granularity intersatellite phase-locking mechanism simulation subsystem include: laser frequency noise, optical platform noise, laser pointing jitter noise, readout noise, advance pointing optical path noise and breathing angle compensation optical path noise.

3. The multi-granularity inter-satellite and intra-satellite phase-locking mechanism simulation system according to claim 2 is characterized in that: The processing process of the multi-granularity intersatellite phase-locking mechanism simulation subsystem includes: Laser A represents the laser emitted from the local optical platform, which is captured by the optical platform where Laser F is located after transmission. The received Laser A interferes with the local Laser F in the scientific interferometer and controls Laser F through the phase-locking mechanism, so that Laser F is phase-locked to Laser A. After phase locking, the phase signal φ of Laser F F (t) is: f AON (t)=φ LJN (t)+φ PAN (t)+φ BAN (t)+φ ON (t) Among them, φ GW (t) represents the phase change caused by the gravitational wave signal, D represents the time delay operator, and They represent the phase change caused by the laser frequency noise of Laser A received by the optical platform where Laser F is located and the noise of the remote optical platform, respectively. RN (t),φ LFN (t),φ LJN (t),φ OBN (t),φ PAN (t),φ BAN (t) and φ ON (t) represents readout noise, laser frequency noise, laser pointing jitter noise, optical platform noise, advance pointing optical path noise, breathing angle compensation optical path noise and other noises respectively; For the coarse-grained phase-locked mechanism simulation model: For fine-grained phase-locked mechanism simulation models: in, Indicates the phase signal introduced by the phase locking mechanism when Laser F is phase locked to Laser A. L -1 {·} denotes inverse Laplace transform, and s denotes frequency domain.

4. The multi-granularity inter-satellite and intra-satellite phase-locking mechanism simulation system according to claim 3 is characterized in that: The multi-granularity intra-satellite phase-locking mechanism simulation subsystem includes a first intra-satellite phase-locking mechanism simulation module, and the processing process includes: Laser A represents the master laser emitted from the local optical platform, which is transmitted to the adjacent optical platform. Laser A interferes with the local slave laser Laser B in the reference interferometer and feedback controls Laser B through the phase-locking mechanism, so that Laser B is phase-locked to Laser A. After phase locking, the phase signal φ of Laser B B (t) is: The reference interferometer phase signal φ after phase locking REF (t) is: For the coarse-grained phase-locked mechanism simulation model: For fine-grained phase-locked mechanism simulation models:

5. The multi-granularity inter-satellite and intra-satellite phase-locking mechanism simulation system according to claim 4 is characterized in that: The multi-granularity intra-satellite phase-locked mechanism simulation subsystem includes a second intra-satellite phase-locked mechanism simulation module, and the processing process includes: Laser A represents the master laser, Laser E and Laser F represent slave lasers, Laser A is emitted from the local optical platform and transmitted to the optical platform where Laser F is located; Laser A interferes with the local Laser F in the scientific interferometer and feedback controls Laser F through the phase-locking mechanism, so that Laser F is phase-locked to the incident light Laser A; at the same time, Laser F is transmitted to the adjacent optical platform and interferes with Laser E in the reference interferometer and feedback controls Laser E through the phase-locking mechanism, so that Laser E is phase-locked to Laser F.

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