A SERF gyro closed-loop detection device and method based on optical fiber EOAM modulation

Abstract

The present invention provides a closed-loop detection device and method for a SERF gyro based on optical fiber EOAM modulation. Firstly, optical fiber EOAM is used to modulate the detection light to reduce the influence of 1 / f noise on the stability of the gyro, improve the detection sensitivity of the system, and facilitate the miniaturization and integration of the system; secondly, a closed-loop control system is introduced into the optical path to achieve signal modulation and detection light stability. The present invention can reduce the influence of physical factors such as temperature on the drift of the optical fiber EOAM working point, ensure the stability of the modulated light intensity, and effectively improve the comprehensive performance of the SERF gyro.

Description

Technical Field

[0001] The present invention relates to the field of quantum precision measurement, and in particular to a SERF gyro closed-loop detection device and method based on optical fiber EOAM modulation. Background Art

[0002] The spin-exchange relaxation-free (SERF) gyroscope is a quantum effect-based gyroscope that theoretically has ultra-high sensitivity and ultra-high precision, thus attracting widespread attention from researchers at home and abroad. Currently, the research work on SERF gyroscopes is mainly focused on improving their sensitivity and precision. SERF gyroscope detection technology, as one of the key technologies, is a hot spot and difficulty in current technical research.

[0003] The commonly used SERF gyro detection scheme is the polarization-balanced differential detection scheme, which is easy to implement but difficult to suppress the influence of 1 / f noise. Therefore, a series of detection schemes that can reduce 1 / f noise have been proposed, such as Faraday modulation detection scheme, photoelastic modulation detection scheme, acousto-optic modulation detection scheme, and electro-optic modulation detection scheme. However, most of these schemes use spatial light modulators, which are difficult to miniaturize and integrate. At the same time, the polarization error caused by the device itself will restrict the improvement of system accuracy.

[0004] In order to solve the above problems, this paper proposes a SERF gyro closed-loop detection scheme based on fiber EOAM modulation, which can effectively improve the integration of the SERF gyro detection system, suppress the influence of 1 / f noise, and ultimately improve the comprehensive performance of the SERF gyro. Summary of the invention

[0005] The present invention provides a SERF gyro closed-loop detection device and method based on optical fiber EOAM modulation, which reduces the influence of 1 / f noise on gyro stability, improves system detection sensitivity, and is conducive to system miniaturization and integration; secondly, a closed-loop control system is introduced into the optical path, which can simultaneously realize signal modulation and detection light stability. The present invention can reduce the influence of physical factors such as temperature on EOAM working point drift, and ensure the stability of modulated light intensity, effectively improving the comprehensive performance of SERF gyro.

[0006] The technical solution of the present invention is:

[0007] A SERF gyro closed-loop detection device based on optical fiber EOAM modulation, comprising: a pigtailed laser 1 for generating detection laser, an optical fiber EOAM 2 for amplitude modulating the detection laser, an optical fiber EOAM DC end control system 3 for controlling the working point of the optical fiber EOAM 2, an optical fiber collimator 4 for converting the optical fiber light output by the optical fiber EOAM 2 into spatial light, a polarizer 5 for adjusting the spatial light into linearly polarized light, a first half-wave plate 6 for changing the polarization direction of the linearly polarized light, and a linearly polarized light output by the first half-wave plate 6 into A first polarization beam splitter prism 7 and a second polarization beam splitter prism 13 for two beams of light, a first photodetector 8, a second photodetector 14 and a third photodetector 15 for converting optical signals in the optical path into electrical signals, an optical fiber EOAM modulation closed-loop control system 9 for generating stable high-frequency modulation signals, a pumping laser and an optical path 10 for generating pumping lasers, an air chamber and a magnetic shielding compensation system 11 for filling atoms and performing magnetic field shielding and compensation, a first phase-locked amplifier 16 and a second phase-locked amplifier 17 for demodulating signals, and a PID control module 18 for performing PID calculations.

[0008] The present invention also proposes a SERF gyro closed-loop detection method based on optical fiber EOAM modulation, comprising the following implementation steps:

[0009] 1) The pumping laser and its optical path 10 emit pumping light, which then enters the gas chamber and magnetic shielding compensation system 11 and polarizes the atoms;

[0010] 2) The detection laser emitted by the pigtailed laser 1 enters the optical fiber EOAM2 controlled by the optical fiber EOAM DC end control system 3 and the optical fiber EOAM modulation closed-loop control system 9. After amplitude modulation is performed in the optical fiber EOAM2, the generated modulated light passes through the optical fiber collimator 4, the polarizer 5, and the first half-wave plate 6 in sequence. The modulated light passes through the first polarization beam splitter prism 7 and is divided into two paths of light. One path enters the air chamber and the magnetic shielding compensation system 11 and interacts with the atoms in the magnetic shielding compensation system 11. The other path enters the first photodetector 8 and is converted into an electrical signal and enters the optical fiber EOAM modulation closed-loop control system 9 to perform detection light closed-loop control.

[0011] 3) After the modulated light entering the air chamber and the magnetic shielding compensation system 11 interacts with the atoms, it passes through the second half-wave plate 12 and the second polarization splitter prism 13 in sequence, and then is divided into two beams of detection light. The two beams of detection light enter the second photodetector 14 and the third photodetector 15 respectively and are converted into two electrical signals. The two electrical signals are connected to the input end of the first phase-locked amplifier 16 after differential operation; the optical fiber EOAM modulation closed-loop control system 9 outputs the modulation signal as the reference signal of the first phase-locked amplifier 16, and the output end of the first phase-locked amplifier 16 outputs the SERF gyro detection signal.

[0012] Further, in step 2), the light intensity signal detected by the first photodetector 8 is

[0013]

[0014] Where I1 is the output intensity of pigtailed laser 1, V π is the half-wave voltage of the optical fiber EOAM, V mod is the voltage amplitude of the modulation signal applied to the AC end of the optical fiber EOAM, ω is the modulation frequency of the modulation signal applied to the AC end of the optical fiber EOAM, V DC is the voltage value applied to the DC end of the optical fiber EOAM.

[0015] Further, in the step 2), the optical fiber EOAM modulation closed-loop control system 9 is implemented by a second phase-locked amplifier 17 and a PID control module 18, wherein the second phase-locked amplifier 17 extracts a frequency-doubled signal of the light intensity signal of the first photodetector 8 and uses the frequency-doubled signal as the input of the PID control module 18, and the output of the PID control module 18 is used as the modulation amplitude of the modulation signal applied to the AC end of the optical fiber EOAM, wherein the frequency-doubled signal extracted by the second phase-locked amplifier 17 is

[0016]

[0017] Where J1 is the first-order Bessel coefficient.

[0018] Furthermore, in the step 2), the EOAM DC terminal control system 3 is implemented by applying a fixed DC voltage to the DC terminal through a signal generator.

[0019] Further, in step 3), the input of the first lock-in amplifier 16 is

[0020]

[0021] The gyro signal output by the first lock-in amplifier 16 is

[0022]

[0023] Wherein, θ is the phase deflection angle of the linearly polarized light after passing through the gas cell.

[0024] The advantages of the present invention compared with the prior art are:

[0025] 1. The present invention uses optical fiber EOAM to modulate the detection optical power, which has a higher degree of integration compared to the traditional spatial light modulator modulation scheme, is conducive to reducing the volume of the detection optical path while suppressing the influence of 1 / f noise.

[0026] 2. The present invention introduces a closed-loop control system into the SERF gyro detection scheme based on optical fiber EOAM modulation. By adjusting the amplitude of the EOAM modulation signal, the frequency stability of the input signal is ensured, which is beneficial to reduce the influence of physical factors such as temperature on the drift of the EOAM working point, and synchronously realizes the stability of signal modulation and detection light. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is the structural diagram of the SERF gyro closed-loop detection device based on fiber EOAM modulation.

[0028] Among them, there are a pigtailed fiber laser 1, an optical fiber EOAM 2, an optical fiber EOAM DC end control system 3, an optical fiber collimator 4, a polarizer 5, a first half-wave plate 6, a second half-wave plate 12, a first polarization beam splitter prism 7, a second polarization beam splitter prism 13, a first photodetector 8, a second photodetector 14, a third photodetector 15, an optical fiber EOAM modulation closed-loop control system 9, a pumping laser and an optical path 10, an air chamber and a magnetic shielding compensation system 11, a first phase-locked amplifier 16, a second phase-locked amplifier 17, and a PID control module 18. DETAILED DESCRIPTION

[0029] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0030] like Figure 1 The structure diagram of the SERF gyro closed-loop detection device based on optical fiber EOAM modulation provided by the present invention is shown as follows. Figure 1 As shown, the SERF gyro closed-loop detection device based on optical fiber EOAM modulation includes: a pigtailed fiber laser 1 for generating a detection laser, an optical fiber electro-optical amplitude modulator 2, i.e., an optical fiber EOAM 2, for amplitude modulating the detection laser, an optical fiber EOAM DC end control system 3 for controlling the optical fiber EOAM working point, an optical fiber collimator 4 for converting the optical fiber light output by the optical fiber EOAM into spatial light, a polarizer 5 for adjusting the spatial light into linearly polarized light, a first half-wave plate 6 for changing the polarization direction of the linearly polarized light, and a first polarization plate 6 for dividing the linearly polarized light output by the first half-wave plate 6 into two A first polarization beam splitter prism 7 and a second polarization beam splitter prism 13 for beaming light, a first photodetector 8, a second photodetector 14 and a third photodetector 15 for converting optical signals in the optical path into electrical signals, an optical fiber EOAM modulation closed-loop control system 9 for generating stable high-frequency modulation signals, a pumping laser and an optical path 10 for generating pumping lasers, an air chamber and a magnetic shielding compensation system 11 for filling atoms and performing magnetic field shielding and compensation, a first phase-locked amplifier 16 (phase-locked amplifier is referred to as LIA) and a second phase-locked amplifier 17 for demodulating signals, and a PID control module 18 for performing PID calculations.

[0031] The following is a detailed introduction to the steps of the SERF gyro closed-loop detection method based on optical fiber EOAM modulation:

[0032] 1) The pumping laser and its optical path 10 emit pumping light, which then enters the gas chamber and magnetic shielding compensation system 11 and polarizes the atoms;

[0033] 2) The detection laser emitted by the pigtailed laser 1 enters the optical fiber EOAM2 controlled by the optical fiber EOAM DC end control system 3 and the optical fiber EOAM modulation closed-loop control system 9. After amplitude modulation is performed in the optical fiber EOAM2, the generated modulated light passes through the optical fiber collimator 4, the polarizer 5, and the first half-wave plate 6 in sequence. The modulated light passes through the first polarization beam splitter prism 7 and is divided into two paths of light. One path enters the air chamber and the magnetic shielding compensation system 11 and interacts with the atoms in the magnetic shielding compensation system 11. The other path enters the first photodetector 8 and is converted into an electrical signal and enters the optical fiber EOAM modulation closed-loop control system 9 to perform detection light closed-loop control.

[0034] 3) After the modulated light entering the air chamber and the magnetic shielding compensation system 11 interacts with the atoms, it passes through the second half-wave plate 12 and the second polarization splitter prism 13 in sequence, and then is divided into two beams of detection light. The two beams of detection light enter the second photodetector 14 and the third photodetector 15 respectively and are converted into two electrical signals. The two electrical signals are connected to the input end of the first phase-locked amplifier 16 after differential operation; the optical fiber EOAM modulation closed-loop control system 9 outputs the modulation signal as the reference signal of the first phase-locked amplifier 16, and the output end of the first phase-locked amplifier 16 outputs the SERF gyro detection signal.

[0035] The specific principles are as follows:

[0036] The detection optical power output by the pigtailed laser 1 is I1. After passing through the optical fiber EOAM2, the detection optical power becomes:

[0037]

[0038] Where I1 is the output intensity of pigtailed laser 1, V π is the half-wave voltage of the optical fiber EOAM, V mod is the voltage amplitude of the modulation signal applied to the AC end of the optical fiber EOAM, ω is the modulation frequency of the modulation signal applied to the AC end of the optical fiber EOAM, V DC is the voltage value applied to the DC end of the optical fiber EOAM.

[0039] The detection laser through EOAM is transmitted along the x direction, and the polarization direction is along the z axis. The corresponding electric field vector can be expressed by the Jones matrix as follows:

[0040]

[0041] where |E1| 2 =I EOAM .

[0042] The Jones matrices after passing through the fiber collimator 4, the polarizer 5, and the first half-wave plate 6 are:

[0043]

[0044]

[0045]

[0046] The Jones matrices of transmission and reflection of the first polarization beam splitter prism 7 are:

[0047]

[0048]

[0049] Therefore, after passing through the first polarization beam splitter prism 7, the detection light is reflected to the first photodetector 8, and the electric field vector detected by the first photodetector 8 is:

[0050] E8=E 72 ·E6·E5·E4·E EOAM

[0051] Therefore, the light intensity signal detected by the first photodetector 8 is:

[0052]

[0053] The above light intensity signal is input to the optical fiber EOAM modulation closed-loop control system 9, and the second lock-in amplifier 17 extracts the frequency-doubled signal of the light intensity signal of the first photodetector 8 as follows:

[0054]

[0055] Where J1 is the first-order Bessel coefficient.

[0056] The EOAM DC terminal control system 3 is implemented by applying a fixed DC voltage to the DC terminal through a signal generator. However, as the working environment changes, V DC Will change with temperature.

[0057] When the frequency-doubled signal V DC and I1 changes, by adjusting V modThis ensures that I3 is a constant value. Therefore, the collected double frequency signal is used as the input of the PID control module 18, and its set value is given according to the experimental conditions. The output of the PID control module 18 is used as the modulation amplitude of the modulation signal applied to the optical fiber EOAM AC end to realize the optical fiber EOAM2 modulation closed loop.

[0058] After passing through the first polarization beam splitter prism 7, the other detection light is transmitted to the air chamber, and the Jones matrix of the air chamber is:

[0059]

[0060] Wherein, θ is the phase deflection angle of the detection light after passing through the air chamber, which is positively correlated with the angular velocity measured by the gyroscope. The electric field vectors detected by the second photodetector 14 and the third photodetector 15 are respectively:

[0061] E 14 =E 71 ·E6·E 气室 ·E 71 ·E6·E5·E4·E EOAM

[0062] E 15 =E 72 ·E6·E 气室 ·E 71 ·E6·E5·E4·E EOAM

[0063] Therefore, the input of the first lock-in amplifier 16 can be calculated as:

[0064]

[0065] The gyro signal output by the first lock-in amplifier 16 is:

[0066]

[0067] The contents not described in detail in the specification of the present invention belong to the prior art known to the professional and technical personnel in this field.

Claims

1. A SERF gyro closed-loop detection device based on optical fiber EOAM modulation, characterized in that: include: A pigtailed laser (1) for generating a detection laser, an optical fiber EOAM (2) for amplitude modulating the detection laser, an optical fiber EOAM DC end control system (3) for controlling the working point of the optical fiber EOAM (2), an optical fiber collimator (4) for converting the optical fiber light output by the optical fiber EOAM (2) into spatial light, a polarizer (5) for adjusting the spatial light into linearly polarized light, a first half-wave plate (6) for changing the polarization direction of the linearly polarized light, a first polarization beam splitter (7) for splitting the linearly polarized light output by the first half-wave plate (6) into two beams of light, and a second polarization beam splitter prism (13), a first photodetector (8), a second photodetector (14) and a third photodetector (15) for converting an optical signal in an optical path into an electrical signal, an optical fiber EOAM modulation closed-loop control system (9) for generating a stable high-frequency modulation signal, a pumping laser and an optical path (10) for generating a pumping laser, an air chamber and a magnetic shielding compensation system (11) for filling atoms and performing magnetic field shielding and compensation, a first lock-in amplifier (16) and a second lock-in amplifier (17) for demodulating a signal, and a PID control module (18) for performing PID calculation; The pumping laser and its optical path (10) emit pumping light, which then enters the gas chamber and magnetic shielding compensation system (11) and polarizes the atoms; The detection laser light emitted by the pigtailed laser (1) enters the optical fiber EOAM (2) controlled by the optical fiber EOAM DC end control system (3) and the optical fiber EOAM modulation closed-loop control system (9), and after amplitude modulation is performed in the optical fiber EOAM (2), the generated modulated light passes through the optical fiber collimator (4), the polarizer (5), and the first half-wave plate (6) in sequence. The modulated light passes through the first polarization beam splitter (7) and is divided into two paths of light, one of which enters the air chamber and interacts with the magnetic shielding compensation system (11) and interacts with the atoms in the magnetic shielding compensation system (11), and the other enters the first photoelectric detector (8) and is converted into an electrical signal and enters the optical fiber EOAM modulation closed-loop control system (9) to perform detection light closed-loop control. After the modulated light enters the air chamber and the magnetic shielding compensation system (11), it interacts with the atoms and then passes through the second half-wave plate (12) and the second polarization beam splitter (13) in sequence, and then is divided into two beams of detection light. The two beams of detection light enter the second photodetector (14) and the third photodetector (15) respectively and are converted into two electrical signals. The two electrical signals are connected to the input end of the first lock-in amplifier (16) after differential operation. The optical fiber EOAM modulation closed-loop control system (9) outputs the modulation signal as a reference signal of the first lock-in amplifier (16), and the output end of the first lock-in amplifier (16) outputs the SERF gyro detection signal.

2. The SERF gyro closed-loop detection device based on optical fiber EOAM modulation according to claim 1 is characterized in that: The light intensity signal detected by the first photodetector (8) is: Where I1 is the output intensity of the pigtailed laser (1), is the half-wave voltage of the optical fiber EOAM, V mod is the voltage amplitude of the modulation signal applied to the AC end of the optical fiber EOAM, is the modulation frequency of the modulation signal applied to the AC end of the optical fiber EOAM, V DC is the voltage value applied to the DC end of the optical fiber EOAM.

3. The SERF gyro closed-loop detection device based on optical fiber EOAM modulation according to claim 2 is characterized in that: The optical fiber EOAM modulation closed-loop control system (9) is implemented by a second lock-in amplifier (17) and a PID control module (18), wherein the second lock-in amplifier (17) extracts a frequency-doubled signal of the light intensity signal of the first photodetector (8) and uses the frequency-doubled signal as an input of the PID control module (18), and the output of the PID control module (18) serves as the modulation amplitude of the modulation signal applied to the AC end of the optical fiber EOAM, wherein the frequency-doubled signal extracted by the second lock-in amplifier (17) is: Where J1 is the first-order Bessel coefficient.

4. The SERF gyro closed-loop detection device based on optical fiber EOAM modulation according to claim 1, characterized in that: The EOAM DC terminal control system (3) is implemented by applying a fixed DC voltage to the DC terminal through a signal generator.

5. The SERF gyro closed-loop detection device based on optical fiber EOAM modulation according to claim 3 is characterized in that: The input of the first lock-in amplifier (16) is: The gyro signal output by the first phase-locked amplifier (16) is: Wherein, θ is the phase deflection angle of the linearly polarized light after passing through the gas cell.

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