Laser gyroscope based on polarization beam splitting RAM noise suppression

Abstract

The invention discloses a laser gyroscope based on polarization beam splitting RAM noise suppression. The laser gyroscope comprises an electro-optical modulator which converts linear polarization laser into modulated light; the half-wave plate converts the modulated light into a composite light beam; the annular resonant cavity reflects the P polarization component and the S light sideband; the polarization splitting prism transmits the S light sideband to the first photoelectric detector and transmits the P polarization component to the second photoelectric detector; the first frequency mixer adopts a radio frequency signal to carry out frequency mixing on the first AC signal to obtain a PDH locking error signal; the first servo system adjusts the laser frequency of the laser according to the PDH locking error signal; the radio frequency signal source and the second frequency mixer demodulate the second AC signal to obtain an RAM noise error signal; and the second servo system adjusts the direct current bias voltage of the electro-optical modulator according to the RAM noise error signal. Therefore, double closed-loop control of frequency locking and RAM noise suppression can be realized through a polarization separation technology.

Description

Technical Field

[0001] This application relates to the field of passive laser gyroscope technology, and more specifically, to a laser gyroscope based on polarization-splitting RAM noise suppression. Background Technology

[0002] Large passive laser gyroscopes are widely used in Earth science research fields such as high-precision Earth orientation parameter measurement due to their high sensitivity and long-term stability.

[0003] Passive laser gyroscopes require locking an external laser beam to the resonant frequency of the ring cavity. PDH (Pound-Drever-Hall) locking technology, with its advantages of fast response time and large locking bandwidth, is particularly suitable for feedback locking of high-precision optical cavities. The basic structure of a passive laser gyroscope based on PDH locking technology is as follows: Figure 1 As shown, the laser output from the laser is first phase-modulated by an electro-optic modulator. The modulated laser, after spatial mode matching, is injected and coupled into the ring cavity. The laser reflected from the ring cavity is detected by a photodetector. The AC output signal of the detector is mixed and demodulated using the RF signal driving the electro-optic modulator to obtain a lock-in error signal. This error signal is filtered by a low-pass filter and then transmitted to a servo amplifier. The output signal of the servo amplifier acts on the laser's frequency feedback actuator, performing feedback control on the laser frequency, thereby precisely locking the laser frequency to the resonant frequency of the ring cavity.

[0004] However, residual amplitude modulation (RAM) noise in PDH locking technology has become one of the key issues limiting its long-term stability. Ideally, after the laser is modulated by the electro-optic modulator, it generates two sidebands with equal amplitude and opposite phase (ignoring higher-order terms of the Bessel expansion). However, due to the birefringence of the electro-optic modulation crystal and the parasitic etalon effect in the optical path, the two sidebands are not completely opposite in phase and not completely equal in amplitude, resulting in amplitude modulation components, i.e., RAM noise, mixed into the modulation signal. RAM noise is indistinguishable from the error signal during the frequency locking process, causing a shift in the laser's frequency locking point and ultimately leading to measurement errors in the Sagnac signal. Summary of the Invention

[0005] In view of this, this application provides a laser gyroscope based on polarization-splitting RAM noise suppression to solve the shortcomings of the prior art in the measurement error of Sagnac signal caused by RAM noise.

[0006] To achieve the above objectives, the following solution is proposed:

[0007] A laser gyroscope based on polarization beam splitting RAM noise suppression includes a laser, an electro-optic modulator, a radio frequency signal source, a half-wave plate, a ring resonant cavity, a polarization beam splitting prism, a first photodetector, a second photodetector, a first mixer, a second mixer, a first servo system, and a second servo system.

[0008] The laser outputs linearly polarized laser light.

[0009] The electro-optic modulator generates phase modulation under the drive of the radio frequency signal source, converting the linearly polarized laser into modulated light containing a carrier and two sidebands;

[0010] The half-wave plate adjusts the polarization state of the modulated light, converting the modulated light into a composite beam containing a P-polarization component and an S-polarization component. The P-polarization component includes a P-optical carrier and a P-optical sideband, and the S-polarization component includes an S-optical carrier and an S-optical sideband.

[0011] The annular resonant cavity resonates with the S-light carrier, reflecting the P-polarization component and the S-light sideband to the polarization beam splitter.

[0012] The polarization beam splitter transmits the S-wave sideband to the first photodetector and the P-polarization component to the second photodetector.

[0013] The first photodetector generates a first AC signal based on the S-light sideband;

[0014] The first mixer uses the radio frequency signal output by the radio frequency signal source to mix the first AC signal to obtain the PDH lock-in error signal. The PDH lock-in error signal is input to the first servo system to reflect the deviation between the laser frequency of the laser and the resonant point of the ring resonant cavity.

[0015] The first servo system adjusts the laser frequency of the laser;

[0016] The second photodetector generates a second AC signal based on the P polarization component;

[0017] The radio frequency signal source and the second mixer demodulate the second AC signal to obtain a RAM noise error signal. The RAM noise error signal is input to the second servo system to reflect the phase shift and sideband amplitude inequality caused by RAM noise.

[0018] The second servo system adjusts the DC bias voltage of the electro-optic modulator.

[0019] Optionally, the annular resonant cavity is a closed resonant cavity composed of three or more highly reflective mirrors.

[0020] Optionally, the PDH lock-in error signal includes detuning information between the laser frequency of the laser and the resonant frequency of the ring resonant cavity, as well as RAM noise.

[0021] Optionally, the RAM noise error signal includes RAM noise.

[0022] Optionally, the frequency of the radio frequency signal source is the resonant frequency of the electro-optic modulator.

[0023] Optionally, it may also include a first phase shifter and a second phase shifter;

[0024] The first phase shifter controls the demodulation phase of the PDH lock-in error signal;

[0025] The second phase shifter controls the demodulation phase of the RAM noise error signal.

[0026] Optional, including:

[0027] The first phase shifter is located between the radio frequency signal source and the first mixer;

[0028] The second phase shifter is located between the radio frequency signal source and the second mixer.

[0029] A laser gyroscope based on polarization beam splitting RAM noise suppression includes a laser, an electro-optic modulator, a radio frequency signal source, a half-wave plate, a ring resonant cavity, a polarization beam splitting prism, a first photodetector, a second photodetector, a first mixer, a second mixer, a first servo system, and a second servo system.

[0030] The laser outputs linearly polarized laser light.

[0031] The electro-optic modulator generates phase modulation under the drive of the radio frequency signal source, converting the linearly polarized laser into modulated light containing a carrier and two sidebands;

[0032] The half-wave plate adjusts the polarization state of the modulated light, converting the modulated light into a composite beam containing a P-polarization component and an S-polarization component. The P-polarization component includes a P-optical carrier and a P-optical sideband, and the S-polarization component includes an S-optical carrier and an S-optical sideband.

[0033] The annular resonant cavity resonates with the P-light carrier, reflecting the S-polarization component and the P-light sideband to the polarization beam splitter.

[0034] The polarization beam splitter transmits the P-band to the first photodetector and the S-polarization component to the second photodetector.

[0035] The first photodetector generates a first AC signal based on the P-light sideband;

[0036] The first mixer uses the radio frequency signal output by the radio frequency signal source to mix the first AC signal to obtain the PDH lock-in error signal. The PDH lock-in error signal is input to the first servo system to reflect the deviation between the laser frequency of the laser and the resonant point of the ring resonant cavity.

[0037] The first servo system adjusts the laser frequency of the laser;

[0038] The second photodetector generates a second AC signal based on the S-polarization component;

[0039] The radio frequency signal source and the second mixer demodulate the second AC signal to obtain a RAM noise error signal. The RAM noise error signal is input to the second servo system to reflect the phase shift and sideband amplitude inequality caused by RAM noise.

[0040] The second servo system adjusts the DC bias voltage of the electro-optic modulator.

[0041] As can be seen from the above technical solution, the laser gyroscope based on polarization-splitting RAM noise suppression provided in this application may include a laser, an electro-optic modulator, a radio frequency signal source, a half-wave plate, a ring resonant cavity, a polarization beam splitter, a first photodetector, a second photodetector, a first mixer, a second mixer, a first servo system, and a second servo system; the laser outputs linearly polarized laser light; wherein, the electro-optic modulator generates phase modulation under the drive of the radio frequency signal source, converting the linearly polarized laser light into modulated light containing a carrier wave and two sidebands; the half-wave plate modulates the phase of the laser light... The polarization state of the light is adjusted to convert the modulated light into a composite beam containing a P-polarization component and an S-polarization component. The P-polarization component includes a P-carrier and a P-sideband, and the S-polarization component includes an S-carrier and an S-sideband. The ring resonant cavity resonates with the S-carrier and reflects the P-polarization component and the S-sideband to the polarization beam splitter. The polarization beam splitter transmits the S-sideband to the first photodetector and the P-polarization component to the second photodetector. The first photodetector generates a first AC signal based on the S-sideband. The first mixer uses the output signal from the radio frequency signal source. The first AC signal is mixed with a frequency signal to obtain a PDH locking error signal. The PDH locking error signal is input to the first servo system to reflect the deviation between the laser frequency of the laser and the resonant point of the ring resonator. In this case, the S-polarization component can be converted into a first AC signal, and a PDH locking error signal can be generated based on this. The PDH locking error signal can reflect whether the laser frequency deviates from the resonant point of the ring resonator. The first servo system adjusts the laser frequency of the laser. Therefore, the adjustment direction of the laser frequency can be determined based on the PDH locking error signal. The laser frequency is adjusted by the first servo system to make the laser frequency of the laser accurately locked to the resonant point of the ring resonator, thereby enhancing the matching degree between the laser frequency of the laser and the resonant frequency of the ring resonator. Subsequently, the second photodetector generates a second AC signal based on the P-polarization component. The RF signal source and the second mixer demodulate the second AC signal to obtain a RAM noise error signal. The RAM noise error signal is input to the second servo system to reflect the phase shift and sideband amplitude inequality caused by RAM noise. The second servo system adjusts the DC bias voltage of the electro-optic modulator. Based on this, since the magnitude of RAM noise is equal to the product of the target sine function value and other parameters, where the target sine function value is the sine function value of the sum of the phase difference caused by the natural birefringence effect and the phase difference caused by the DC voltage applied to the electro-optic modulator, the second servo system adjusts the DC bias voltage applied to the electro-optic modulator to make the target sine function value 0, thereby eliminating RAM noise.

[0042] In summary, this application, by adding a half-wave plate and adjusting the polarization state of the modulated light, converts the modulated light containing the carrier and two sidebands into mutually perpendicular P-polarization components and S-polarization components. This ensures that the S-polarization component and the P-polarization sideband share a completely identical optical path before entering the first and second photodetectors, guaranteeing that both light paths experience the same parasitic etalon structure. This improves the consistency of RAM noise between the two light paths, allowing the second servo system to adjust the DC bias voltage simultaneously, thereby reducing RAM noise in both paths, improving feedback control accuracy, effectively reducing PDH lock-up point offset, and enhancing the detection sensitivity of the laser gyroscope based on polarization-splitting RAM noise suppression in the low-frequency band. Therefore, this application can independently detect the P-polarization and S-polarization components of the modulated light using polarization separation technology. The P-polarization and S-polarization components extract PDH lock-up error signals and RAM noise error signals respectively upon entering the first and second photodetectors. Finally, a dual-servo system achieves dual closed-loop control for frequency locking and RAM noise suppression. Attached Figure Description

[0043] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0044] Figure 1 A schematic diagram of a passive laser gyroscope based on PDH locking technology is provided for an embodiment of this application;

[0045] Figure 2 This is a schematic diagram of a laser gyroscope based on polarization-splitting RAM noise suppression disclosed in an embodiment of this application;

[0046] Figure 3 This is a schematic diagram of another laser gyroscope based on polarization-splitting RAM noise suppression disclosed in an embodiment of this application;

[0047] in, Figures 2 to 3 The correspondence between the component designations and the reference numerals in the accompanying drawings is shown below:

[0048] Laser 1, electro-optic modulator 2, half-wave plate 3, ring resonator 4, polarizing beam splitter 5, first photodetector 6, second photodetector 7, first mixer 8, second mixer 9, first servo system 10, second servo system 11, radio frequency signal source 12, first phase shifter 13 and second phase shifter 14. Detailed Implementation

[0049] 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, and 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.

[0050] The laser gyroscope based on polarization-splitting RAM noise suppression of this application will now be described in detail with reference to the accompanying drawings. It should be noted that the orientation of the structures shown in the drawings is for ease of understanding and does not limit the orientation of the embodiments disclosed in actual implementation. Furthermore, the shape and size of the entirety or a portion of the structures shown in the drawings are not limited to their actual shape and size.

[0051] Next, we will combine Figure 2 This application provides a detailed description of the laser gyroscope based on polarization-splitting RAM noise suppression.

[0052] See Figure 2 It can be seen that the laser gyroscope based on polarization beam splitting RAM noise suppression in this application may include a laser 1, an electro-optic modulator 2, an RF signal source 12, a half-wave plate 3, a ring resonant cavity 4, a polarization beam splitting prism 5, a first photodetector 6, a second photodetector 7, a first mixer 8, a second mixer, a first servo system, and a second servo system.

[0053] Laser 1 can output linearly polarized light to electro-optic modulator 2.

[0054] The electro-optic modulator 2 generates phase modulation under the drive of the radio frequency signal source 12, converting the linearly polarized laser into modulated light containing a carrier and two sidebands.

[0055] The modulated light is transmitted to half-wave plate 3.

[0056] The half-wave plate 3 adjusts the polarization state of the modulated light, converting the modulated light into a composite beam containing P-polarization and S-polarization components.

[0057] The P-polarization component may include the P-optical carrier and the P-optical sideband, and the S-polarization component may include the S-optical carrier and the S-optical sideband.

[0058] The annular resonant cavity 4 resonates with the S-light carrier, reflecting the P-polarization component and the S-light sideband to the polarization beam splitter 5.

[0059] Specifically, by adjusting the reflection coefficients of the P-polarized and S-polarized components in the ring resonant cavity 4, the ring resonant cavity 4 can be made to resonate with the S-optical carrier but not with the P-polarized component.

[0060] The polarization beam splitter 5 transmits the S-wave sideband to the first photodetector 6 and the P-polarization component to the second photodetector 7.

[0061] The first photodetector 6 generates a first AC signal based on the S-light sideband.

[0062] The first mixer 8 uses the radio frequency signal output by the radio frequency signal source 12 to mix the first AC signal to obtain the PDH lock error signal. The PDH lock error signal is input to the first servo system 10 to reflect the deviation between the laser frequency of the laser 1 and the resonant point of the ring resonant cavity 4.

[0063] The PDH lock-in error signal may include the deviation between the laser frequency of laser 1 and the resonant point of the ring resonant cavity 4, as well as RAM noise.

[0064] The first servo system 10 adjusts the laser frequency of the laser 1.

[0065] The second photodetector 7 generates a second AC signal based on the P polarization component.

[0066] The radio frequency signal source 12 and the second mixer demodulate the second AC signal to obtain a RAM noise error signal. The RAM noise error signal is input to the second servo system 11 to reflect the phase shift and sideband amplitude inequality caused by RAM noise.

[0067] RAM noise error signals can include RAM noise.

[0068] The second servo system 11 adjusts the DC bias voltage of the electro-optic modulator 2.

[0069] As can be seen from the above technical solution, the laser gyroscope based on polarization-splitting RAM noise suppression provided in this application may include a laser 1, an electro-optic modulator 2, a radio frequency signal source 12, a half-wave plate 3, a ring resonant cavity 4, a polarization beam splitter prism 5, a first photodetector 6, a second photodetector 7, a first mixer 8, a second mixer 9, a first servo system, and a second servo system; the laser 1 outputs linearly polarized laser; wherein, the electro-optic modulator 2 generates phase modulation under the drive of the radio frequency signal source 12, converting the linearly polarized laser into modulated light containing a carrier wave and two sidebands; the half-wave plate 3... The polarization state of the modulated light is adjusted to convert it into a composite beam containing a P-polarization component and an S-polarization component. The P-polarization component includes a P-carrier and a P-sideband, and the S-polarization component includes an S-carrier and an S-sideband. The ring resonant cavity 4 resonates with the S-carrier and reflects the P-polarization component and the S-sideband to the polarization beam splitter 5. The polarization beam splitter 5 transmits the S-sideband to the first photodetector 6 and the P-polarization component to the second photodetector 7. The first photodetector 6 generates a first AC signal based on the S-sideband. The first mixer 8 uses the signal output from the radio frequency signal source 12. The first AC signal is mixed with the frequency signal to obtain the PDH lock-in error signal. The PDH lock-in error signal is input to the first servo system 10 to reflect the deviation between the laser frequency of the laser 1 and the resonant point of the ring resonant cavity 4. In this case, the S-polarization component can be converted into the first AC signal, and the PDH lock-in error signal can be generated based on this. The PDH lock-in error signal can reflect whether the laser frequency deviates from the resonant point of the ring resonant cavity 4. The first servo system 10 adjusts the laser frequency of the laser 1. Therefore, the adjustment direction of the laser frequency of the laser 1 can be determined based on the PDH lock-in error signal, and the first servo system 10 can be used to adjust the laser frequency of the laser 1. The servo system 10 adjusts the laser frequency to precisely lock the laser frequency of the laser 1 to the resonant point of the ring resonant cavity 4, thereby enhancing the matching degree between the laser frequency of the laser 1 and the resonant frequency of the ring resonant cavity 4. Subsequently, the second photodetector 7 of this application generates a second AC signal based on the P-polarization component. The radio frequency signal source 12 and the second mixer demodulate the second AC signal to obtain a RAM noise error signal. The RAM noise error signal is input to the second servo system 11 to reflect the phase shift and sideband amplitude inequality caused by RAM noise. The second servo system 11 adjusts the DC bias voltage of the electro-optic modulator 2.Based on this, since the magnitude of RAM noise is equal to the product of the target sine function value and other parameters, where the target sine function value is the sine function value of the sum of the phase difference caused by the natural birefringence effect and the phase difference caused by the DC voltage applied to the electro-optic modulator 2, the second servo system 11 adjusts the DC bias voltage applied to the electro-optic modulator 2 to make the target sine function value 0, thereby eliminating RAM noise.

[0070] In summary, this application, by adding a half-wave plate 3, adjusts the polarization state of the modulated light, converting the modulated light containing the carrier and two sidebands into mutually perpendicular P-polarization components and S-polarization components. This ensures that the S-polarization component and the P-polarization sideband share a completely identical optical path before entering the first photodetector 6 and the second photodetector 7, guaranteeing that both light paths experience the same parasitic etalon structure. This improves the consistency of RAM noise between the two light paths, allowing the second servo system 11 to adjust the DC bias voltage simultaneously, thereby reducing RAM noise in both light paths, improving feedback control accuracy, effectively reducing PDH lock point offset, and enhancing the detection sensitivity of the laser gyroscope based on polarization-splitting RAM noise suppression in the low-frequency band. Therefore, this application can use polarization separation technology to independently detect the P-polarization and S-polarization components of the modulated light, allowing the P-polarization and S-polarization components to extract PDH lock error signals and RAM noise error signals respectively upon entering the first photodetector 6 and the second photodetector 7. Then, a dual-servo system is used to achieve dual closed-loop control for frequency locking and RAM noise suppression.

[0071] In some embodiments of this application, the ring resonant cavity 4 is a closed resonant cavity composed of three or more highly reflective mirrors.

[0072] Specifically, see Figure 3 It can be seen that the ring resonant cavity 4 of this application can be formed by combining four highly reflective mirrors.

[0073] The reflection coefficients of the high-reflectivity mirrors in the ring resonant cavity 4 can be the same or different.

[0074] The center points of any two high-reflectivity mirrors lie on the same straight line.

[0075] The centers of the four high-reflectivity mirrors are located at the four vertices of the square.

[0076] The four high-reflectivity mirrors are tilted relative to the horizontal line.

[0077] The center points of the laser 1, the electro-optic modulator 2, the half-wave plate 3, and the two high-reflection mirrors therein are located on the same straight line; the center points of the first photodetector 6, the second photodetector 7, the first mixer 8, and the radio frequency signal source 12 are located on the same straight line; the center points of the second mixer and the second servo system are located on the same straight line, such as... Figure 2 and Figure 3 As shown.

[0078] As can be seen from the above technical solution, this embodiment provides a way of arranging and combining the various components of a laser gyroscope based on polarization-splitting RAM noise suppression. Through the above method, different light can be better input to the corresponding components, thereby improving the accuracy of parameter measurement.

[0079] In some embodiments of this application, the frequency of the radio frequency signal source 12 may be the resonant frequency of the electro-optic modulator 2.

[0080] As can be seen from the above technical solution, in this embodiment, by setting the frequency of the radio frequency signal source 12 to the resonant frequency of the electro-optic modulator 2, a standing wave resonance is formed inside the electro-optic modulator 2, which enhances the sideband signal strength. In the resonant state, the demand for radio frequency driving power can be reduced, and the heating of the electro-optic modulation crystal and nonlinear distortion can be reduced.

[0081] Considering the phase delay between the photodetector and the radio frequency signal source 12, in some embodiments of this application, the laser gyroscope based on polarization-splitting RAM noise suppression may further include a first phase shifter 13 and a second phase shifter 14 to adjust the signal phase.

[0082] See Figure 2 It can be observed that the first phase shifter 13 is located between the radio frequency signal source 12 and the first mixer 8;

[0083] The first phase shifter 13 controls the demodulation phase of the PDH lock-in error signal, making the PDH lock-in error signal in phase with the first AC signal;

[0084] The second phase shifter 14 is located between the radio frequency signal source 12 and the second mixer.

[0085] The second phase shifter 14 controls the demodulation phase of the RAM noise error signal, making the RAM noise error signal in phase with the second AC signal.

[0086] As can be seen from the above technical solution, compared with the previous embodiment, this embodiment adds a first phase shifter 13 and a second phase shifter 14 to perform phase demodulation on the PDH lock error signal and the RAM noise error signal, so that each error signal is in phase with the AC signal output by the photodetector, obtain the maximum error signal amplitude, and further improve the feedback accuracy and feedback reliability of this application.

[0087] Considering that the reflection coefficients of each high-reflection mirror in the ring resonant cavity 4 can be adjusted, the resonant point of the ring resonant cavity 4 can be adjusted, thereby making the ring resonant cavity 4 resonate with the P-light carrier. Similarly, the laser gyroscope based on polarization splitting RAM noise suppression in this case can also generate PDH locking error signal and RAM noise error signal, thereby achieving RAM noise suppression.

[0088] Next, this application will provide a detailed description of the laser gyroscope based on polarization-splitting RAM noise suppression.

[0089] The laser gyroscope based on polarization-splitting RAM noise suppression described below can be used as a reference with the laser gyroscope based on polarization-splitting RAM noise suppression provided above.

[0090] The schematic diagram of this laser gyroscope based on polarization-splitting RAM noise suppression is also as follows. Figure 2 As shown.

[0091] The laser gyroscope based on polarization beam splitting RAM noise suppression may include a laser 1, an electro-optic modulator 2, an RF signal source 12, a half-wave plate 3, a ring resonant cavity 4, a polarization beam splitting prism 5, a first photodetector 6, a second photodetector 7, a first mixer 8, a second mixer 8, a first servo system, and a second servo system.

[0092] The laser 1 outputs linearly polarized laser;

[0093] The electro-optic modulator 2 generates phase modulation under the drive of the radio frequency signal source 12, converting the linearly polarized laser into modulated light containing a carrier and two sidebands;

[0094] The half-wave plate 3 adjusts the polarization state of the modulated light and converts the modulated light into a composite beam containing a P-polarization component and an S-polarization component. The P-polarization component includes a P-optical carrier and a P-optical sideband, and the S-polarization component includes an S-optical carrier and an S-optical sideband.

[0095] The ring resonant cavity 4 resonates with the P-light carrier, reflecting the S-polarization component and the P-light sideband to the polarization beam splitter 5;

[0096] The polarization beam splitter 5 transmits the P-band to the first photodetector 6 and the S-polarization component to the second photodetector 7.

[0097] Specifically, in order to transmit the P-light sideband to the first photodetector 6 and the S-polarization component to the second photodetector 7, the polarization beam splitter 5 here has complementary reflection or transmission characteristics to the polarization beam splitter 5 mentioned above.

[0098] The first photodetector 6 generates a first AC signal based on the P-light sideband;

[0099] The first mixer 8 uses the radio frequency signal output by the radio frequency signal source 12 to mix the first AC signal to obtain the PDH lock error signal. The PDH lock error signal is input to the first servo system 10 to reflect the deviation between the laser frequency of the laser 1 and the resonant point of the ring resonant cavity 4.

[0100] The first servo system 10 adjusts the laser frequency of the laser 1;

[0101] The second photodetector 7 generates a second AC signal based on the S polarization component;

[0102] The radio frequency signal source 12 and the second mixer demodulate the second AC signal to obtain a RAM noise error signal. The RAM noise error signal is input to the second servo system 11 to reflect the phase shift and sideband amplitude inequality caused by RAM noise.

[0103] The second servo system 11 adjusts the DC bias voltage of the electro-optic modulator 2.

[0104] As can be seen from the above technical solution, this embodiment can also suppress RAM noise and improve parameter measurement accuracy by constructing RAM noise error signals and PDH lock error signals.

[0105] Similarly, the laser gyroscope based on polarization-splitting RAM noise suppression can also include a first phase shifter 13 and a second phase shifter 14, such as... Figure 3 As shown, it is used to perform phase demodulation on RAM noise error signal and PDH lock-in error signal.

[0106] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0107] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0108] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. The various embodiments of this application can be combined with each other. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A laser gyro based on polarization spectroscopy RAM noise suppression, characterized in that, The laser, the electro-optical modulator, the radio frequency signal source, the half-wave plate, the ring resonator, the polarization beam splitter, the first photoelectric detector, the second photoelectric detector, the first frequency mixer, the second frequency mixer, the first servo system, the second servo system; The laser outputs linearly polarized laser light; The electro-optical modulator generates phase modulation under the driving of the radio frequency signal source, and converts the linearly polarized laser light into modulated light containing a carrier and two sidebands; The half-wave plate adjusts the polarization state of the modulated light, and converts the modulated light into a composite light beam containing a P-polarized component and an S-polarized component, the P-polarized component including a P-light carrier and a P-light sideband, and the S-polarized component including an S-light carrier and an S-light sideband; The ring resonator resonates with the S-light carrier, and reflects the P-polarized component and the S-light sideband to the polarization beam splitter; The polarization beam splitter transmits the S-light sideband to the first photoelectric detector, and transmits the P-polarized component to the second photoelectric detector; The first photoelectric detector generates a first AC signal based on the S-light sideband; The first frequency mixer mixes the first AC signal with a radio frequency signal output by the radio frequency signal source to obtain a PDH locking error signal, and the PDH locking error signal is input to the first servo system to reflect the deviation between the laser frequency of the laser and the resonance point of the ring resonator; The first servo system adjusts the laser frequency of the laser; The second photoelectric detector generates a second AC signal based on the P-polarized component; The radio frequency signal source and the second frequency mixer demodulate the second AC signal to obtain a RAM noise error signal, and the RAM noise error signal is input to the second servo system to reflect the phase shift and the unequal sideband amplitude caused by the RAM noise; The second servo system adjusts the direct current bias voltage of the electro-optical modulator.

2. The polarization spectroscopy RAM noise suppressed laser gyroscope of claim 1, wherein, The ring resonator is a closed resonator composed of three or more high-reflectivity mirrors.

3. The polarization-based optical RAM noise rejection ring laser gyroscope of claim 1, wherein, The PDH locking error signal includes the detuning information between the laser frequency of the laser and the resonance frequency of the ring resonator and the RAM noise.

4. The polarization spectroscopy RAM noise suppressed laser gyroscope of claim 1, wherein, The RAM noise error signal includes the RAM noise.

5. The polarization spectroscopy RAM noise suppressed laser gyroscope of claim 1, wherein, The frequency of the radio frequency signal source is the resonance frequency of the electro-optical modulator.

6. The polarization spectroscopy RAM noise suppressed laser gyroscope of claim 1, wherein, Further comprising a first phase shifter and a second phase shifter; The first phase shifter controls the demodulation phase of the PDH locking error signal; The second phase shifter controls the demodulation phase of the RAM noise error signal.

7. The polarization spectroscopy RAM noise suppressed ring laser gyroscope of claim 6, wherein, Comprising: The first phase shifter is located between the radio frequency signal source and the first frequency mixer; The second phase shifter is located between the radio frequency signal source and the second frequency mixer.

8. A laser gyro based on polarization spectroscopy RAM noise suppression, characterized in that The laser, the electro-optical modulator, the radio frequency signal source, the half-wave plate, the ring resonator, the polarization beam splitter, the first photoelectric detector, the second photoelectric detector, the first frequency mixer, the second frequency mixer, the first servo system, the second servo system; The laser outputs linearly polarized laser light; The electro-optical modulator generates phase modulation under the driving of the radio frequency signal source, and converts the linearly polarized laser light into modulated light containing a carrier and two sidebands; The half-wave plate adjusts the polarization state of the modulated light and converts the modulated light into a composite light beam containing a P-polarization component and an S-polarization component, the P-polarization component including a P-light carrier and a P-light sideband, and the S-polarization component including an S-light carrier and an S-light sideband; The ring resonator resonates with the P-light carrier and reflects the S-polarization component and the P-light sideband to the polarization beam splitter prism; The polarization beam splitter prism transmits the P-light sideband to the first photodetector and transmits the S-polarization component to the second photodetector; The first photodetector generates a first AC signal based on the P-light sideband; The first mixer mixes the first AC signal with a radio frequency signal output by the radio frequency signal source to obtain a PDH locking error signal, and the PDH locking error signal is input to the first servo system to reflect the deviation between the laser frequency of the laser and the resonance point of the ring resonator; The first servo system adjusts the laser frequency of the laser; The second photodetector generates a second AC signal based on the S-polarization component; The radio frequency signal source and the second mixer demodulate the second AC signal to obtain a RAM noise error signal, and the RAM noise error signal is input to the second servo system to reflect the phase shift and the difference in sideband amplitude caused by the RAM noise; The second servo system adjusts the direct current bias voltage of the electro-optical modulator.

9. The polarization spectroscopy RAM noise suppressed laser gyroscope of claim 8, wherein, Further comprising a first phase shifter and a second phase shifter; The first phase shifter controls the demodulation phase of the PDH locking error signal; The second phase shifter controls the demodulation phase of the RAM noise error signal.

10. The polarization spectroscopy RAM noise suppressed laser gyroscope of claim 8, wherein, Comprise: The first phase shifter is located between the radio frequency signal source and the first mixer; The second phase shifter is located between the radio frequency signal source and the second mixer.

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