Light quantum gyro noise suppression system and method based on polarization control

Abstract

The invention provides a polarization control-based light quantum gyro noise suppression system and method. Comprising a first coherent light source, a second coherent light source, a photoelectric detector, a first polarization beam splitter, an atom ensemble, a modulator, a first half-wave plate, a first Faraday rotator, a second polarization beam splitter, a second half-wave plate, a second Faraday rotator, a third half-wave plate, a third Faraday rotator and an optical fiber ring. Through light path design cooperation of the Faraday rotator, the half-wave plate and the polarization beam splitter, complete suppression of backscattering noise and polarization crosstalk noise is realized.

Description

Technical Field

[0001] This invention belongs to the field of quantum precision measurement technology, specifically relating to a noise suppression system and method for optical quantum gyroscopes based on polarization control. Background Technology

[0002] The optical quantum gyroscope system combines the quantum correlation amplification principle with the Sagnac effect. It achieves quantized path beam splitting, signal amplification, and phase-sensitive detection through the atomic ensemble Raman scattering process. Its core advantage lies in using the quantum correlation between the light field and the atomic spin wave to amplify weak angular velocity signals. It has high sensitivity, anti-loss, and low noise performance, and is expected to significantly improve the ability to measure angular velocity and break through the shot noise limit.

[0003] The quantum enhancement effect of the optical quantum gyroscope system is directly related to the power of the Raman light. However, high-power Raman light can cause significant backscattering noise and polarization crosstalk noise, which seriously affect the quality of the final detected signal light. Therefore, certain optical path design or detection methods are needed to suppress the noise.

[0004] However, existing technologies only eliminate the influence of the newly generated signal light from backscattered light. The backscattering noise caused by the Raman light itself is consistent with the polarization state of the final signal light to be detected and cannot be filtered out. The high power characteristics of Raman light make its backscattering noise the most significant noise component in the optical quantum gyroscope system, severely affecting the detection of the final signal. Summary of the Invention

[0005] This invention proposes a noise suppression system and method for optical quantum gyroscopes based on polarization control. By combining the optical path design of Faraday rotators, half-wave plates, and polarization beam splitters, it achieves complete suppression of backscattering noise and polarization crosstalk noise.

[0006] The technical solution of the present invention: In a first aspect, this application provides a polarization-controlled optical quantum gyroscope noise suppression system, comprising: a first coherent light source 1, a second coherent light source 2, a photodetector 3, a first polarization beam splitter 4, an atomic ensemble 5, a modulator 6, a first half-wave plate 7, a first Faraday rotator 8, a second polarization beam splitter 9, a second half-wave plate 10, a second Faraday rotator 11, a third half-wave plate 12, a third Faraday rotator 13, and an optical fiber ring 14, wherein: The first coherent light source 1 generates pump light P, which enters the atomic ensemble 5. The second coherent light source 2 generates Raman light R, which is reflected by the first polarization beam splitter 4 and enters the atomic ensemble 5, generating Raman light R and signal light S. These light beams pass through the modulator 6, the first half-wave plate 7, and the first Faraday rotator 8, where they are split at the second polarization beam splitter 9. The Raman light R is reflected at the second polarization beam splitter 9 to the second half-wave plate 10 and the second Faraday rotator 11, and then enters the fiber loop 14. Finally, it exits from the fiber... The signal light S exits from the optical fiber ring 14, passes through the third Faraday rotator 13 and the third half-wave plate 12, is transmitted at the second polarization beam splitter 9, and returns along the same path. It is transmitted to the third half-wave plate 12 and the third Faraday rotator 13, enters the optical fiber ring 14, exits from the optical fiber ring 14, passes through the second Faraday rotator 11 and the second half-wave plate 10, is reflected at the second polarization beam splitter 9, returns, is transmitted at the first polarization beam splitter 4, and finally the signal light S is incident on the photodetector 3.

[0007] Specifically, the first coherent light source 1 is used to generate pump light P, which polarizes atomic spins. This light field is required to resonate with the atomic transition energy levels and operate in continuous mode. The second coherent light source 2 is used to generate incident Raman light R, which is coupled with atomic spin waves. This light field is required to be detuned to the atomic transition energy levels and operate in continuous mode.

[0008] Specifically, the first polarization beam splitter 4 is used to separate the horizontal and vertical polarization of the Raman light R, and the second polarization beam splitter 9 is used to separate the Raman light R from the signal light S. At the same time, it can guide the backscattering noise and polarization crosstalk noise with orthogonal polarization states out of the main optical path of the system.

[0009] Specifically, the first Faraday rotator 8, the second Faraday rotator 11, and the third Faraday rotator 13 are used to change the polarization direction of the Raman light R and the signal light S. They are used in conjunction with a half-wave plate: when the light passes in the forward direction, the half-wave plate changes the polarization state of the light by 45°, and the Faraday rotator changes the polarization state of the light by -45°, for a total change of 0°, ensuring that the polarization direction of the forward-transmitted light remains unchanged; when the light passes in the reverse direction, the half-wave plate changes the polarization state of the light by -45°, and the Faraday rotator changes the polarization state of the light by -45°, for a total change of -90°, making the polarization of the outgoing light and the incident light orthogonal.

[0010] Secondly, this application provides a method for suppressing noise in a polarization-controlled optical quantum gyroscope, including: Step 1: The first coherent light source 1 generates pump light P, which is incident on the atomic ensemble 5. The second coherent light source 2 generates Raman light R, which performs Raman scattering in the atomic ensemble 5, generating signal light S and atomic spin wave A. Step 2: After the signal light S and Raman light R leave the atomic ensemble 5, they are split by the second polarization beam splitter 9. The vertically polarized Raman light R and the horizontally polarized signal light S maintain their respective polarization states and are injected into the fiber loop 14. Step 3: The vertically polarized Raman light R and the horizontally polarized signal light S pass through the Faraday rotator and half-wave plate twice respectively, with their polarization states remaining unchanged, and return to the atomic ensemble 5 to undergo phase-sensitive interference. Step 4: Use a Faraday rotator, a half-wave plate, and a polarization beam splitter to suppress backscattering noise of the Raman light R and the signal light S, and then leave the optical quantum gyroscope system. Step 5: Use a Faraday rotator, a half-wave plate, and a polarization beam splitter to suppress polarization crosstalk noise between the Raman light R and the signal light S, and then leave the optical quantum gyroscope system.

[0011] Specifically, step 1 includes: Step 11: The first coherent light source 1 generates pump light P, which is incident on the atomic ensemble 5, polarizing the atomic spin and preparing the initial state of the atom; Step 12: The second coherent light source 2 generates Raman light R, which passes through the first polarization beam splitter 4. The vertically polarized Raman light R enters the atomic ensemble 5 and undergoes Raman scattering. Step 13: Under the combined action of pump light P and Raman light R, atomic ensemble 5 realizes the Raman scattering process, generating signal light S and atomic spin wave A.

[0012] Specifically, step 2 includes: Step 21: The atomic spin wave A remains in atomic ensemble 5, while the signal light S is emitted along with the Raman light R, leaving atomic ensemble 5. Step 22: After passing through the first half-wave plate 7 and the first Faraday rotator 8 in the forward direction, the polarization states of the two beams remain unchanged. After passing through the second polarization beam splitter 9, the signal light S and the Raman light R are spatially separated. Step 23: The Raman light R passes through the second half-wave plate 10 and the second Faraday rotator 11 in the forward direction, and its polarization state remains vertically polarized; the signal light S passes through the third half-wave plate 12 and the third Faraday rotator 13 in the forward direction, and its polarization state remains horizontally polarized. Step 24: The signal light S and the Raman light R are injected into the clockwise and counterclockwise paths of the fiber ring 14, respectively, and the two beams are transmitted in opposite directions in the fiber ring 14.

[0013] Specifically, step 3 includes: Step 31: The signal light S and Raman light R exit the fiber loop 14. The vertically polarized Raman light R passes in the opposite direction through the second Faraday rotator 11 and the second half-wave plate 10 and becomes horizontally polarized. Step 32: The horizontally polarized signal light S passes in the reverse direction through the third Faraday rotator 13 and the third half-wave plate 12, and becomes vertically polarized; Step 33: The two beams of light are combined by the second polarization beam splitter 9, and after passing in the opposite direction through the first Faraday rotator 8 and the first half-wave plate 7, the polarization states of the signal light S and the Raman light R are exchanged. The Raman light becomes vertically polarized and the signal light becomes horizontally polarized. Step 34: The two beams of light pass through modulator 6 and return to atomic ensemble 5, where they are combined with atomic spin wave A in space and stimulated Raman scattering occurs. The signal light S and atomic spin wave A generate quantum correlation enhancement and amplification, and phase-sensitive interference occurs. The signal light S is detected by the first photodetector 3.

[0014] Specifically, step 4 includes: Step 41: The backscattering noise of the Raman light R is in a vertical polarization state. It is emitted in the opposite direction from the fiber ring 14, passes through the second Faraday rotator 11 and the second half-wave plate 10 along the transmission path, and becomes horizontally polarized. After passing through the second polarization beam splitter 9, it leaves the optical quantum gyroscope system directly and will not return to the original optical path and will not be received by the detection end. Step 42: Similarly, the backscattering noise of the signal light S is horizontally polarized. It is emitted in the opposite direction from the fiber ring 14, passes through the third Faraday rotator 13 and the third half-wave plate 12 along the transmission path, and becomes vertically polarized. After passing through the second polarization beam splitter 9, it leaves the optical quantum gyroscope system directly and will not return to the original optical path, and will not be received by the detection end.

[0015] Specifically, step 5 includes: Step 51: The polarization crosstalk noise of the Raman light R is in a horizontal polarization state. It is emitted in the forward direction from the fiber ring 14, passes through the third Faraday rotator 13 and the third half-wave plate 12 along the transmission path, and becomes vertically polarized. After passing through the second polarization beam splitter 9, it leaves the optical quantum gyroscope system directly and will not return to the original optical path and will not be received by the detection end. Step 52: Similarly, the polarization crosstalk noise of the signal light S is in a horizontal polarization state. It is emitted in the forward direction from the fiber ring 14, passes through the second Faraday rotator 11 and the second half-wave plate 10 along the transmission path, and becomes vertically polarized. After passing through the second polarization beam splitter 9, it leaves the optical quantum gyroscope system directly and will not return to the original optical path and will not be received by the detection end.

[0016] The beneficial effects of this invention are: This invention is based on an optical quantum gyroscope system. Through the coordinated optical path design of a half-wave plate, a Faraday rotator, and a polarization beam splitter, it achieves complete suppression of backscattering noise and polarization crosstalk noise, providing a high-fidelity signal extraction solution for optical quantum gyroscopes.

[0017] 1. Backscattering noise suppression: After passing through the polarization state control element, the backscattering noise of Raman light changes its polarization state. When passing through the polarization beam splitter, the backscattering noise will be separated from the main optical path of the system and will not enter the detection end. 2. Polarization crosstalk noise suppression: Since the polarization state of polarization crosstalk noise differs from that of normal signal light, after passing through the polarization state adjustment and polarization beam splitter in the optical path, it will be separated from the main optical path of the system by the polarization beam splitter and will not enter the detection end.

[0018] 3. Improved System Signal-to-Noise Ratio: By completely suppressing backscattering noise and polarization crosstalk noise, the proportion of effective signal in the detected signal light is significantly increased. The signal-to-noise ratio of the quantum correlation signal is significantly improved, enhancing the angular velocity measurement accuracy of the optical quantum gyroscope and enabling the detection of more subtle angular velocity changes. This provides more reliable technical support for high-precision navigation, precision measurement, and other fields. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention 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 some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is an overall architecture diagram of the optical quantum gyroscope noise suppression system based on polarization control in the embodiments of the invention.

[0021] Figure 2 This is a flowchart of the optical quantum gyroscope noise suppression method based on polarization control in the embodiments of the invention.

[0022] Figure 3 The working medium in the embodiments of the invention 87 Rb atom energy levels and corresponding optical frequency diagrams.

[0023] Figure 4 The working medium in the embodiments of the invention 133 Cs atomic energy levels and corresponding optical frequency diagrams.

[0024] The components in the diagram are represented by numbers: 1 First coherent light source, 2 Second coherent light source, 3 Photodetector, 4 First polarization beam splitter, 5 Atomic ensemble, 6 Modulator, 7 First half-wave plate, 8 First Faraday rotator, 9 Second polarization beam splitter, 10 Second half-wave plate, 11 Second Faraday rotator, 12 Third half-wave plate, 13 Third Faraday rotator, 14 Fiber optic ring. Detailed Implementation

[0025] The invention will be further described in detail below with reference to the specific embodiments and accompanying drawings. Except for the contents specifically mentioned below, the processes, conditions, and experimental methods for implementing the invention are all common knowledge and general knowledge in the art, and the invention does not have any particular limitations.

[0026] Example 1 like Figure 1 As shown, this invention provides a polarization-controlled optical quantum gyroscope noise suppression system, comprising: a first coherent light source 1, a second coherent light source 2, a photodetector 3, a first polarization beam splitter 4, an atomic ensemble 5, a modulator 6, a first half-wave plate 7, a first Faraday rotator 8, a second polarization beam splitter 9, a second half-wave plate 10, a second Faraday rotator 11, a third half-wave plate 12, a third Faraday rotator 13, and an optical fiber ring 14, wherein: The first coherent light source 1 generates pump light P, which enters the atomic ensemble 5. The second coherent light source 2 generates Raman light R, which is reflected by the first polarization beam splitter 4 and enters the atomic ensemble 5, generating Raman light R and signal light S. These light passes through the modulator 6, the first half-wave plate 7, and the first Faraday rotator 8. The Raman light R and the signal light S are split at the second polarization beam splitter 9. The Raman light R is reflected at the second polarization beam splitter 9 to the second half-wave plate 10 and the second Faraday rotator 11, enters the fiber ring 14, exits from the fiber ring 14, passes through the third Faraday rotator 13 and the third half-wave plate 12, and is transmitted back along the same path after being transmitted at the second polarization beam splitter 9. The signal light S is transmitted to the third half-wave plate 12 and the third Faraday rotator 13, enters the fiber ring 14, exits from the fiber ring 14, passes through the second Faraday rotator 11 and the second half-wave plate 10, is reflected at the second polarization beam splitter 9 and returns, is transmitted at the first polarization beam splitter 4, and finally the signal light S is incident on the photodetector 3.

[0027] Specifically, the first coherent light source 1 is used to generate pump light P, which polarizes atomic spins. This light field is required to resonate with the atomic transition energy levels and operate in continuous mode. The second coherent light source 2 is used to generate incident Raman light R, which is coupled to atomic spin waves. This light field is required to be detuned to the atomic transition energy levels and operate in continuous mode.

[0028] Specifically, the first polarization beam splitter 4 is used to separate the horizontal polarization and vertical polarization of the Raman light R, and the second polarization beam splitter 9 is used to separate the Raman light R from the signal light S. At the same time, it can guide the backscattering noise and polarization crosstalk noise with orthogonal polarization states out of the main optical path of the system and work with the Faraday rotator and half-wave plate to achieve noise suppression.

[0029] Specifically, the photodetector 3 is used to convert optical signals into electrical signals through the photoelectric effect, and to measure the interference signal light S.

[0030] Specifically, the atomic ensemble 5 is used to generate quantum-correlated signal light S and atomic spin wave A through Raman scattering process under the action of pump light P and Raman light R.

[0031] Specifically, modulator 6 is used to apply phase modulation to signal light S and Raman light R. Under the drive of external voltage, it changes the refractive index difference between the fast axis and the slow axis, thereby generating a phase difference, which is used for phase shifting of the interference signal of the system.

[0032] Specifically, the first half-wave plate 7, the second half-wave plate 10, and the third half-wave plate 12 are used to change the polarization direction of the Raman light R and the signal light S.

[0033] Specifically, the first Faraday rotator 8, the second Faraday rotator 11, and the third Faraday rotator 13 are used to change the polarization direction of the Raman light R and the signal light S, and are used in conjunction with a half-wave plate: when the light passes in the forward direction, the half-wave plate changes the polarization state of the light by 45°, and the Faraday rotator changes the polarization state of the light by -45°, for a total change of 0°, ensuring that the polarization direction of the forward-transmitted light remains unchanged. When the light passes in the reverse direction, the half-wave plate changes the polarization state of the light by -45°, and the Faraday rotator changes the polarization state of the light by -45°, for a total change of -90°, making the polarization of the outgoing light orthogonal to that of the incident light.

[0034] Specifically, the fiber optic ring 14 is made of polarization-maintaining fiber to enhance the Sagnac effect. When the gyroscope is subjected to angular velocity, the two optical signal beams and the Raman beam propagating in the clockwise and counterclockwise directions in the fiber optic ring 14 will obtain phase modulation introduced by the angular velocity.

[0035] In summary, this invention provides a polarization-controlled optical quantum gyroscope noise suppression system. By designing the optical path of the optical quantum gyroscope system using a Faraday rotator, a half-wave plate, and a polarization beam splitter, backscattering noise and polarization crosstalk noise are completely exported from the system during transmission, achieving complete suppression of backscattering noise and polarization crosstalk noise, and providing a high-fidelity signal extraction scheme for optical quantum gyroscopes.

[0036] Example 2 like Figure 2 As shown, this invention provides a method for suppressing noise in a polarization-controlled optical quantum gyroscope, comprising: Step 1: The first coherent light source 1 generates pump light P, which is incident on the atomic ensemble 5. The second coherent light source 2 generates Raman light R, which realizes the Raman scattering process in the atomic ensemble 5, generating signal light S and atomic spin wave A.

[0037] Specifically, step 1 includes: Step 11: The first coherent light source 1 generates pump light P, which is incident on the atomic ensemble 5, polarizing the atomic spin and preparing the initial state of the atom.

[0038] Step 12: The second coherent light source 2 generates Raman light R. The Raman light R passes through the first polarization beam splitter 4, and the vertically polarized Raman light R enters the atomic ensemble 5 to undergo the Raman scattering process.

[0039] Step 13: Under the combined action of pump light P and Raman light R, atomic ensemble 5 realizes the Raman scattering process, generating signal light S and atomic spin wave A.

[0040] In this process, the signal light S forms a quantum correlation with the atomic spin wave A.

[0041] In this case, the signal light S is perpendicular to the polarization state of the Raman light R, and the signal light generated by the Raman light with the vertical polarization state is the horizontal polarization state.

[0042] Step 2: After leaving the atomic ensemble 5, the signal light S and the Raman light R are split by the second polarization beam splitter 9. The vertically polarized Raman light R and the horizontally polarized signal light S are injected into the fiber ring 14 while maintaining their respective polarization states.

[0043] Specifically, step 2 includes: Step 21: The atomic spin wave A remains in atomic ensemble 5, and the signal light S is emitted along with the Raman light R, leaving atomic ensemble 5.

[0044] Step 22: After passing through the first half-wave plate 7 and the first Faraday rotator 8 in the forward direction, the polarization states of the two beams remain unchanged. After passing through the second polarization beam splitter 9, the signal light S and the Raman light R are spatially separated.

[0045] Step 23: The Raman light R passes through the second half-wave plate 10 and the second Faraday rotator 11 in the forward direction, and its polarization state remains vertically polarized; the signal light S passes through the third half-wave plate 12 and the third Faraday rotator 13 in the forward direction, and its polarization state remains horizontally polarized.

[0046] Step 24: The signal light S and the Raman light R are injected into the clockwise and counterclockwise paths of the fiber ring 14, respectively, and the two beams are transmitted in opposite directions in the fiber ring 14.

[0047] When an optical fiber is placed on a rotating platform and rotated, the phase information resulting from the rotation will be coupled into the optical field.

[0048] Step 3: The vertically polarized Raman light R and the horizontally polarized signal light S pass through the Faraday rotator and the half-wave plate twice respectively, with the polarization state unchanged, and return to the atomic ensemble 5 to undergo phase-sensitive interference.

[0049] Specifically, step 3 includes: Step 31: The signal light S and Raman light R are emitted from the fiber ring 14. The vertically polarized Raman light R is reversed and passes through the second Faraday rotator 11 and the second half-wave plate 10, becoming horizontally polarized.

[0050] Step 32: The horizontally polarized signal light S passes in the reverse direction through the third Faraday rotator 13 and the third half-wave plate 12, and becomes vertically polarized.

[0051] Step 33: The two beams of light are combined by the second polarization beam splitter 9, and after passing in the opposite direction through the first Faraday rotator 8 and the first half-wave plate 7, the polarization states of the signal light S and the Raman light R are exchanged. The Raman light becomes vertically polarized and the signal light becomes horizontally polarized.

[0052] Step 34: The two beams of light pass through modulator 6 and return to atomic ensemble 5, where they are combined with atomic spin wave A in space and stimulated Raman scattering occurs. The signal light S and atomic spin wave A generate quantum correlation enhancement and amplification, and phase-sensitive interference occurs. The signal light S is detected by the first photodetector 3.

[0053] By analyzing the interference signal, the relationship between the platform's rotational angular velocity and the signal strength can be extracted, thereby enabling the measurement of the angular velocity.

[0054] Step 4: Use a Faraday rotator, a half-wave plate, and a polarization beam splitter to suppress the backscattering noise of the Raman light R and the signal light S, and leave the optical quantum gyroscope system.

[0055] Specifically, step 4 includes: Step 41: The backscattering noise of the Raman light R is in a vertical polarization state. It is emitted in the opposite direction from the fiber ring 14, passes through the second Faraday rotator 11 and the second half-wave plate 10 along the transmission path, and becomes horizontally polarized. After passing through the second polarization beam splitter 9, it leaves the optical quantum gyroscope system directly and will not return to the original optical path, so it will not be received by the detection end.

[0056] Step 42: Similarly, the backscattering noise of the signal light S is horizontally polarized. It is emitted in the opposite direction from the fiber ring 14, passes through the third Faraday rotator 13 and the third half-wave plate 12 along the transmission path, and becomes vertically polarized. After passing through the second polarization beam splitter 9, it leaves the optical quantum gyroscope system directly and will not return to the original optical path, and will not be received by the detection end.

[0057] Step 5: Use a Faraday rotator, a half-wave plate, and a polarization beam splitter to suppress polarization crosstalk noise between the Raman light R and the signal light S, and then leave the optical quantum gyroscope system.

[0058] Specifically, step 5 includes: Step 51: The polarization crosstalk noise of the Raman light R is in a horizontal polarization state. It is emitted in the forward direction from the fiber ring 14, passes through the third Faraday rotator 13 and the third half-wave plate 12 along the transmission path, and becomes vertically polarized. After passing through the second polarization beam splitter 9, it leaves the optical quantum gyroscope system directly and will not return to the original optical path, so it will not be received by the detection end.

[0059] Step 52: Similarly, the polarization crosstalk noise of the signal light S is in a horizontal polarization state. It is emitted in the forward direction from the fiber ring 14, passes through the second Faraday rotator 11 and the second half-wave plate 10 along the transmission path, and becomes vertically polarized. After passing through the second polarization beam splitter 9, it leaves the optical quantum gyroscope system directly and will not return to the original optical path and will not be received by the detection end.

[0060] In this invention, the interaction medium unit of the atomic ensemble 5 can be an atom, ion, molecule, or quantum dot in its ground state.

[0061] The innovative aspects of this invention: 1. Backscattering noise suppression: Backscattering noise has the same polarization state as the main beam but is transmitted in the opposite direction. After polarization state modulation through a non-reciprocal optical path, its polarization state changes. When passing through a polarization beam splitter, the backscattering noise will be separated from the main optical path of the system and will not enter the detection end. 2. Polarization crosstalk noise suppression: Polarization crosstalk noise has the same transmission direction as the main beam but a different polarization state. Because its polarization state differs from that of the normal signal light, it is separated from the main optical path by the polarization beam splitter when it passes through the Faraday rotator and half-wave plate in the optical path and will not enter the detection end.

[0062] 3. Optical Path Collaborative Noise Reduction Design: This design organically combines polarization state control elements such as Faraday rotators, half-wave plates, and polarization beam splitters to form a complete noise filtering optical path centered on "polarization control - noise separation - directional extraction." It can accurately distinguish light of different polarization states, and with orthogonal polarization state conversion, it directionally guides backscattered noise and polarization crosstalk noise out of the system during transmission, achieving simultaneous and complete suppression of both main types of noise. This solves the problem of difficulty in simultaneously suppressing both types of noise in existing technologies.

[0063] 4. Fidelity Transmission of Quantum Correlation Signals: While suppressing noise, the optical path design ensures that the quantum correlation characteristics between the signal light and the atomic spin waves remain unaffected. The coordinated operation of components such as the coherent light source, atomic ensemble, modulator, and polarization control optical path ensures the effective generation, amplification, and transmission of quantum correlation signals during Raman scattering.

[0064] This invention proposes a noise suppression system and method for optical quantum gyroscopes. By designing the optical path of the optical quantum gyroscope system using a Faraday rotator, a half-wave plate, and a polarization beam splitter, backscattering noise and polarization crosstalk noise are completely extracted from the optical system during transmission, achieving complete suppression of backscattering noise and polarization crosstalk noise, and providing a high-fidelity signal extraction scheme for optical quantum gyroscopes.

[0065] Example 3 This embodiment uses ensemble 5 as the basis for preparing pure atoms in the ground state.87 The method will be illustrated using the Rb atom ensemble as an example. The method includes the following steps: Step 1: The first coherent light source 1 generates pump light P with a wavelength of 780 nm, corresponding to the D2 line of the Rb atom, incident on the atomic ensemble 5, polarizing the atomic spin, and preparing the initial state of the atom.

[0066] In a quantum optical gyroscope, the initial atomic states should be prepared first, and all the initial states of the atomic ensemble should be distributed in ensemble 5. 2 S 1 / 2 F = 1, ground state energy level, or 5 2 S 1 / 2 At the ground state energy level F=2, we will take F=1 as an example for explanation.

[0067] in, Figure 3 What is displayed is 87 Rb atom energy levels and corresponding optical frequency diagrams. Among them, 5 2 S 1 / 2 5 2 P 1 / 2 5 2 P 3 / 2 for 87 The fine structure of Rb atoms, F=1 and F=2 are fine structures. 2 S 1 / 2 The hyperfine splitting has an energy level difference of 6.83 GHz, and the dashed lines represent virtual energy levels.

[0068] Step 2: The second coherent light source 2 generates Raman light R, which realizes the Raman scattering process in the atomic ensemble 5, generating signal light S and atomic spin wave A.

[0069] Specifically, step 2 includes: Step 21: The second coherent light source 2 generates Raman light R with a wavelength of 795 nm, corresponding to the D1 line of the Rb atom. The Raman light passes through the first polarization beam splitter 4, and the vertically polarized Raman light R enters the atomic ensemble 5 to undergo the Raman scattering process.

[0070] Step 22: Under the combined action of the pump light P and Raman light R in step 1, the atomic ensemble 5 realizes the Raman scattering process, generates the signal light S, and at the same time generates the atomic spin wave A.

[0071] The signal light S forms a quantum correlation with the atomic spin wave A. The signal light S and the Raman light R have a fixed frequency difference of 6.83 GHz.

[0072] In this case, the signal light S is perpendicular to the polarization state of the Raman light R, and the signal light generated by the Raman light with the vertical polarization state is the horizontal polarization state.

[0073] Step 3: After the signal light S and the Raman light R leave the atomic ensemble 5, they are split by the second polarization beam splitter 9.

[0074] Specifically, step 3 includes: Step 31: The atomic spin wave A remains in atomic ensemble 5, and the signal light S is emitted along with the Raman light R, leaving atomic ensemble 5.

[0075] Step 32: After passing through modulator 6, the signal light S and the Raman light R are modulated by modulator 6.

[0076] Step 33: After passing through the first half-wave plate 7 and the first Faraday rotator 8 in the forward direction, the polarization states of the two beams remain unchanged. After passing through the second polarization beam splitter 9, the signal light S and the Raman light R are spatially separated.

[0077] Step 4: The vertically polarized Raman light R and the horizontally polarized signal light S are injected into the fiber ring 14 while maintaining their respective polarization states.

[0078] Specifically, step 4 includes: Step 41: The Raman light R passes through the second half-wave plate 10 and the second Faraday rotator 11 in the forward direction, and its polarization state remains vertically polarized.

[0079] Step 42: The signal light S passes through the third half-wave plate 12 and the third Faraday rotator 13 in the forward direction, and its polarization state remains horizontal.

[0080] Step 43: The signal light S and the Raman light R are injected into the clockwise and counterclockwise paths of the fiber ring 14, respectively, and the two beams are transmitted in opposite directions in the fiber ring 14.

[0081] When the fiber ring 14 is placed on a rotating platform and rotated, the phase information brought about by the rotation will be coupled into the optical field.

[0082] Step 5: The vertically polarized Raman light R and the horizontally polarized signal light S pass through the Faraday rotator and the half-wave plate twice, respectively, and their polarization states remain unchanged.

[0083] Specifically, step 5 includes: Step 51: The signal light S and Raman light R are emitted from the fiber ring 14. The vertically polarized Raman light R is reversed and passes through the second Faraday rotator 11 and the second half-wave plate 10, becoming horizontally polarized.

[0084] Step 52: The horizontally polarized signal light S passes in the reverse direction through the third Faraday rotator 13 and the third half-wave plate 12, and becomes vertically polarized.

[0085] Step 53: The two beams of light are combined by the second polarization beam splitter 9, and after passing in the opposite direction through the first Faraday rotator 8 and the first half-wave plate 7, the polarization states of the signal light S and the Raman light R are exchanged. The Raman light becomes vertically polarized and the signal light becomes horizontally polarized.

[0086] Step 6: The two beams of light pass through modulator 6 and return to the atomic ensemble 5, where they are combined with the atomic spin wave A in space and stimulated Raman scattering occurs. The signal light S and the atomic spin wave A generate quantum correlation enhancement and amplification, and phase-sensitive interference occurs. The signal light S is detected by the first photodetector 3.

[0087] By analyzing the interference signal, the relationship between the platform's rotational angular velocity and the signal strength can be extracted, thereby enabling the measurement of the angular velocity.

[0088] Step 7: Use a Faraday rotator, a half-wave plate, and a polarization beam splitter to suppress the backscattering noise of the Raman light R and the signal light S, and leave the optical quantum gyroscope system.

[0089] Specifically, step 7 includes: Step 71: The backscattering noise of the Raman light R is in a vertical polarization state. It is emitted in the opposite direction from the fiber ring 14, passes through the second Faraday rotator 11 and the second half-wave plate 10 along the transmission path, and becomes horizontally polarized. After passing through the second polarization beam splitter 9, it leaves the optical quantum gyroscope system directly and will not return to the original optical path, so it will not be received by the detection end.

[0090] Step 72: Similarly, the backscattering noise of the signal light S is horizontally polarized. It is emitted in the opposite direction from the fiber ring 14, passes through the third Faraday rotator 13 and the third half-wave plate 12 along the transmission path, and becomes vertically polarized. After passing through the second polarization beam splitter 9, it leaves the optical quantum gyroscope system directly and will not return to the original optical path, and will not be received by the detection end.

[0091] Step 8: Use a Faraday rotator, a half-wave plate, and a polarization beam splitter to suppress polarization crosstalk noise between the Raman light R and the signal light S, and leave the optical quantum gyroscope system.

[0092] Specifically, step 8 includes: Step 81: The polarization crosstalk noise of the Raman light R is in a horizontal polarization state. It is emitted in the forward direction from the fiber ring 14, passes through the third Faraday rotator 13 and the third half-wave plate 12 along the transmission path, and becomes vertically polarized. After passing through the second polarization beam splitter 9, it leaves the optical quantum gyroscope system directly and will not return to the original optical path, so it will not be received by the detection end.

[0093] Step 82: Similarly, the polarization crosstalk noise of the signal light S is horizontally polarized. It is emitted in the forward direction from the fiber ring 14, passes through the second Faraday rotator 11 and the second half-wave plate 10 along the transmission path, and becomes vertically polarized. After passing through the second polarization beam splitter 9, it leaves the optical quantum gyroscope system directly and will not return to the original optical path and will not be received by the detection end.

[0094] Example 4 This embodiment uses ensemble 5 as the basis for preparing pure atoms in the ground state. 133This method will be illustrated using the Cs atom ensemble as an example. The steps include: Step 1: The first coherent light source 1 generates pump light P with a wavelength of 894 nm, corresponding to the D2 line of the Cs atom, incident on the atomic ensemble 5, polarizing the atomic spin, and preparing the initial state of the atom.

[0095] In a quantum optical gyroscope, the initial atomic states should be prepared first, and all the initial states of the atomic ensemble 5 should be distributed in atomic ensemble 6. 2 S 1 / 2 F = 3, ground state energy level, or 6 2 S 1 / 2 At the ground state energy level of F=4, we will take F=3 as an example for explanation.

[0096] in, Figure 4 What is displayed is 133 Cs atomic energy levels and corresponding optical frequency diagrams. Among them, 6 2 S 1 / 2 6 2 P 1 / 2 6 2 P 3 / 2 for 133 The fine structure of Cs atoms, F=3 and F=4 are fine structures. 2 S 1 / 2 The hyperfine splitting has an energy level difference of 9.19 GHz, and the dashed lines represent virtual energy levels.

[0097] Step 2: The second coherent light source 2 generates Raman light R, which realizes the Raman scattering process in the atomic ensemble 5, generating signal light S and atomic spin wave A.

[0098] Specifically, step 2 includes: Step 21: The second coherent light source 2 generates Raman light R with a wavelength of 852 nm, corresponding to the D1 line of Cs atom. The Raman light passes through the first polarization beam splitter 4, and the vertically polarized Raman light R enters the atomic ensemble 5 to undergo the Raman scattering process.

[0099] Step 22: Under the combined action of the pump light P and Raman light R in step 1, the atomic ensemble 5 realizes the Raman scattering process, generates the signal light S, and at the same time generates the atomic spin wave A.

[0100] The signal light S forms a quantum correlation with the atomic spin wave A. The signal light S and the Raman light R have a fixed frequency difference of 9.19 GHz.

[0101] In this case, the signal light S is perpendicular to the polarization state of the Raman light R, and the signal light generated by the Raman light with the vertical polarization state is the horizontal polarization state.

[0102] Step 3: After the signal light S and the Raman light R leave the atomic ensemble 5, they are split by the second polarization beam splitter 9.

[0103] Specifically, step 3 includes: Step 31: The atomic spin wave A remains in atomic ensemble 5, and the signal light S is emitted along with the Raman light R, leaving atomic ensemble 5.

[0104] Step 32: After passing through modulator 6, the signal light S and the Raman light R are modulated by modulator 6.

[0105] Step 33: After passing through the first half-wave plate 7 and the first Faraday rotator 8 in the forward direction, the polarization states of the two beams remain unchanged. After passing through the second polarization beam splitter 9, the signal light S and the Raman light R are spatially separated.

[0106] Step 4: The vertically polarized Raman light R and the horizontally polarized signal light S are injected into the fiber ring 14 while maintaining their respective polarization states.

[0107] Specifically, step 4 includes: Step 41: The Raman light R passes through the second half-wave plate 10 and the second Faraday rotator 11 in the forward direction, and its polarization state remains vertically polarized.

[0108] Step 42: The signal light S passes through the third half-wave plate 12 and the third Faraday rotator 13 in the forward direction, and its polarization state remains horizontal.

[0109] Step 43: The signal light S and the Raman light R are injected into the clockwise and counterclockwise paths of the fiber ring 14, respectively, and the two beams are transmitted in opposite directions in the fiber ring 14.

[0110] When the fiber ring 14 is placed on a rotating platform and rotated, the phase information brought about by the rotation will be coupled into the optical field.

[0111] Step 5: The vertically polarized Raman light R and the horizontally polarized signal light S pass through the Faraday rotator and the half-wave plate twice, respectively, and their polarization states remain unchanged.

[0112] Specifically, step 5 includes: Step 51: The signal light S and Raman light R are emitted from the fiber ring 14. The vertically polarized Raman light R is reversed and passes through the second Faraday rotator 11 and the second half-wave plate 10, becoming horizontally polarized.

[0113] Step 52: The horizontally polarized signal light S passes in the reverse direction through the third Faraday rotator 13 and the third half-wave plate 12, and becomes vertically polarized.

[0114] Step 53: The two beams of light are combined by the second polarization beam splitter 9, and after passing in the opposite direction through the first Faraday rotator 8 and the first half-wave plate 7, the polarization states of the signal light S and the Raman light R are exchanged. The Raman light becomes vertically polarized and the signal light becomes horizontally polarized.

[0115] Step 6: The two beams of light pass through modulator 6 and return to the atomic ensemble 5, where they are combined with the atomic spin wave A in space and stimulated Raman scattering occurs. The signal light S and the atomic spin wave A generate quantum correlation enhancement and amplification, and phase-sensitive interference occurs. The signal light S is detected by the first photodetector 3.

[0116] By analyzing the interference signal, the relationship between the platform's rotational angular velocity and the signal strength can be extracted, thereby enabling the measurement of the angular velocity.

[0117] Step 7: Use a Faraday rotator, a half-wave plate, and a polarization beam splitter to suppress the backscattering noise of the Raman light R and the signal light S, and leave the optical quantum gyroscope system.

[0118] Specifically, step 7 includes: Step 71: The backscattering noise of the Raman light R is in a vertical polarization state. It is emitted in the opposite direction from the fiber ring 14, passes through the second Faraday rotator 11 and the second half-wave plate 10 along the transmission path, and becomes horizontally polarized. After passing through the second polarization beam splitter 9, it leaves the optical quantum gyroscope system directly and will not return to the original optical path, so it will not be received by the detection end.

[0119] Step 72: Similarly, the backscattering noise of the signal light S is horizontally polarized. It is emitted in the opposite direction from the fiber ring 14, passes through the third Faraday rotator 13 and the third half-wave plate 12 along the transmission path, and becomes vertically polarized. After passing through the second polarization beam splitter 9, it leaves the optical quantum gyroscope system directly and will not return to the original optical path, and will not be received by the detection end.

[0120] Step 8: Use a Faraday rotator, a half-wave plate, and a polarization beam splitter to suppress polarization crosstalk noise between the Raman light R and the signal light S, and leave the optical quantum gyroscope system.

[0121] Specifically, step 8 includes: Step 81: The polarization crosstalk noise of the Raman light R is in a horizontal polarization state. It is emitted in the forward direction from the fiber ring 14, passes through the third Faraday rotator 13 and the third half-wave plate 12 along the transmission path, and becomes vertically polarized. After passing through the second polarization beam splitter 9, it leaves the optical quantum gyroscope system directly and will not return to the original optical path, so it will not be received by the detection end.

[0122] Step 82: Similarly, the polarization crosstalk noise of the signal light S is horizontally polarized. It is emitted in the forward direction from the fiber ring 14, passes through the second Faraday rotator 11 and the second half-wave plate 10 along the transmission path, and becomes vertically polarized. After passing through the second polarization beam splitter 9, it leaves the optical quantum gyroscope system directly and will not return to the original optical path and will not be received by the detection end.

[0123] The specific embodiments of the present invention have been described in detail above, but they are merely examples, and the present invention is not limited to the specific embodiments described above. For those skilled in the art, any equivalent modifications and substitutions to the present invention are also within the scope of the present invention. Therefore, all equivalent transformations and modifications made without departing from the spirit and scope of the present invention should be covered within the scope of the present invention.

Claims

1. A polarization-controlled optical quantum gyroscope noise suppression system, characterized in that, include: The system comprises: a first coherent light source (1), a second coherent light source (2), a photodetector (3), a first polarization beam splitter (4), an atomic ensemble (5), a modulator (6), a first half-wave plate (7), a first Faraday rotator (8), a second polarization beam splitter (9), a second half-wave plate (10), a second Faraday rotator (11), a third half-wave plate (12), a third Faraday rotator (13), and an optical fiber ring (14), wherein: The first coherent light source (1) generates pump light P, which enters the atomic ensemble (5). The second coherent light source (2) generates Raman light R, which is reflected by the first polarization beam splitter (4) and enters the atomic ensemble (5), generating Raman light R and signal light S. These light passes through the modulator (6), the first half-wave plate (7), and the first Faraday rotator (8). The Raman light R and signal light S are split at the second polarization beam splitter (9). The Raman light R is reflected at the second polarization beam splitter (9) to the second half-wave plate (10) and the second Faraday rotator (11), and enters the fiber loop (14). It then exits from the fiber... The signal light S exits from the ring (14), passes through the third Faraday rotator (13) and the third half-wave plate (12), and is transmitted at the second polarization beam splitter (9). It then returns along the same path and is transmitted to the third half-wave plate (12) and the third Faraday rotator (13), enters the fiber ring (14), exits from the fiber ring (14), passes through the second Faraday rotator (11) and the second half-wave plate (10), is reflected at the second polarization beam splitter (9), and returns. It is transmitted at the first polarization beam splitter (4), and finally the signal light S is incident on the photodetector (3).

2. The optical quantum gyroscope noise suppression system according to claim 1, characterized in that, Specifically, the first coherent light source (1) is used to generate pump light P, which polarizes atomic spins. The light field is required to resonate with the atomic transition energy level and operate in continuous mode. The second coherent light source (2) is used to generate incident Raman light R, which is coupled with atomic spin waves. The light field is required to be detuned with the atomic transition energy level and operate in continuous mode.

3. The optical quantum gyroscope noise suppression system according to claim 1, characterized in that, Specifically, the first polarization beam splitter (4) is used to separate the horizontal polarization and vertical polarization of the Raman light R, and the second polarization beam splitter (9) is used to separate the Raman light R from the signal light S. At the same time, it can guide the backscattering noise and polarization crosstalk noise with orthogonal polarization states out of the main optical path of the system.

4. The optical quantum gyroscope noise suppression system according to claim 1, characterized in that, Specifically, the first Faraday rotator (8), the second Faraday rotator (11), and the third Faraday rotator (13) are used to change the polarization direction of the Raman light R and the signal light S. They are used in conjunction with a half-wave plate: when the light passes in the forward direction, the half-wave plate changes the polarization state of the light by 45°, and the Faraday rotator changes the polarization state of the light by -45°, for a total change of 0°, ensuring that the polarization direction of the forward-transmitted light remains unchanged; when the light passes in the reverse direction, the half-wave plate changes the polarization state of the light by -45°, and the Faraday rotator changes the polarization state of the light by -45°, for a total change of -90°, making the polarization of the outgoing light and the incident light orthogonal.

5. A method for suppressing noise in a polarization-controlled optical quantum gyroscope, characterized in that, include: Step 1: The first coherent light source (1) generates pump light P, which is incident on the atomic ensemble (5). The second coherent light source (2) generates Raman light R, which performs Raman scattering in the atomic ensemble (5), generating signal light S and atomic spin wave A. Step 2: After the signal light S and Raman light R leave the atomic ensemble (5), they are split by the second polarization beam splitter (9). The vertically polarized Raman light R and the horizontally polarized signal light S are injected into the fiber ring (14) while maintaining their respective polarization states. Step 3: The vertically polarized Raman light R and the horizontally polarized signal light S pass through the Faraday rotator and half-wave plate twice respectively, with the polarization states remaining unchanged, and return to the atomic ensemble (5) to undergo phase-sensitive interference. Step 4: Use a Faraday rotator, a half-wave plate, and a polarization beam splitter to suppress backscattering noise of the Raman light R and the signal light S, and then leave the optical quantum gyroscope system. Step 5: Use a Faraday rotator, a half-wave plate, and a polarization beam splitter to suppress polarization crosstalk noise between the Raman light R and the signal light S, and then leave the optical quantum gyroscope system.

6. The method for suppressing noise in a quantum gyroscope according to claim 5, characterized in that, Step 1 includes: Step 11: The first coherent light source (1) generates pump light P, which is incident on the atomic ensemble (5), polarizing the atomic spin and preparing the initial state of the atom; Step 12: The second coherent light source (2) generates Raman light R. The Raman light R passes through the first polarization beam splitter (4). The vertically polarized Raman light R enters the atomic ensemble (5) and undergoes the Raman scattering process. Step 13: The atomic ensemble (5) realizes the Raman scattering process under the combined action of pump light P and Raman light R, generating signal light S and atomic spin wave A.

7. The method for suppressing noise in a quantum gyroscope according to claim 5, characterized in that, Step 2 includes: Step 21: The atomic spin wave A remains in the atomic ensemble (5), and the signal light S is emitted along with the Raman light R, leaving the atomic ensemble (5). Step 22: After passing through the first half-wave plate (7) and the first Faraday rotator (8) in the forward direction, the polarization states of the two beams remain unchanged. After passing through the second polarization beam splitter (9), the signal light S and the Raman light R are spatially separated. Step 23: The Raman light R passes through the second half-wave plate (10) and the second Faraday rotator (11) in the forward direction, and its polarization state remains vertically polarized; the signal light S passes through the third half-wave plate (12) and the third Faraday rotator (13) in the forward direction, and its polarization state remains horizontally polarized. Step 24: The signal light S and the Raman light R are injected into the clockwise and counterclockwise paths of the fiber ring (14) respectively, and the two beams are transmitted in opposite directions in the fiber ring (14).

8. The method for suppressing noise in a quantum gyroscope according to claim 5, characterized in that, Step 3 includes: Step 31: The signal light S and the Raman light R are emitted from the fiber loop (14). The vertically polarized Raman light R is reversed and passes through the second Faraday rotator (11) and the second half-wave plate (10) to become horizontally polarized. Step 32: The horizontally polarized signal light S passes in the reverse direction through the third Faraday rotator (13) and the third half-wave plate (12), and becomes vertically polarized; Step 33: The two beams of light are combined by the second polarization beam splitter (9), and after passing in the opposite direction through the first Faraday rotator (8) and the first half-wave plate (7), the polarization states of the signal light S and the Raman light R are exchanged. The Raman light becomes vertically polarized and the signal light becomes horizontally polarized. Step 34: The two beams of light pass through the modulator (6) and return to the atomic ensemble (5), where they are combined with the atomic spin wave A in space and stimulated Raman scattering occurs. The signal light S and the atomic spin wave A generate quantum correlation enhancement and amplification, and phase-sensitive interference occurs. The signal light S is detected by the first photodetector (3).

9. The method for suppressing noise in a quantum gyroscope according to claim 5, characterized in that, Step 4 includes: Step 41: The backscattering noise of the Raman light R is in a vertical polarization state. It is emitted in the opposite direction from the fiber ring (14), passes through the second Faraday rotator (11) and the second half-wave plate (10) along the transmission path, and becomes horizontally polarized. After passing through the second polarization beam splitter (9), it leaves the optical quantum gyroscope system directly and will not return to the original optical path and will not be received by the detection end. Step 42: Similarly, the backscattering noise of the signal light S is horizontally polarized. It is emitted in the opposite direction from the fiber ring (14), passes through the third Faraday rotator (13) and the third half-wave plate (12) along the transmission path, and becomes vertically polarized. After passing through the second polarization beam splitter (9), it leaves the optical quantum gyroscope system directly and will not return to the original optical path and will not be received by the detection end.

10. The method for suppressing noise in a quantum gyroscope according to claim 5, characterized in that, Step 5 includes: Step 51: The polarization crosstalk noise of the Raman light R is in a horizontal polarization state. It is emitted in the forward direction from the fiber ring (14), passes through the third Faraday rotator (13) and the third half-wave plate (12) along the transmission path, and becomes vertically polarized. After passing through the second polarization beam splitter (9), it leaves the optical quantum gyroscope system directly and will not return to the original optical path and will not be received by the detection end. Step 52: Similarly, the polarization crosstalk noise of the signal light S is horizontally polarized. It is emitted in the forward direction from the fiber ring (14), passes through the second Faraday rotator (11) and the second half-wave plate (10) along the transmission path, and becomes vertically polarized. After passing through the second polarization beam splitter (9), it leaves the optical quantum gyroscope system directly and will not return to the original optical path and will not be received by the detection end.

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