An optical structure for achieving non-reciprocal modulation

Abstract

This invention discloses an optical structure for achieving non-reciprocal modulation, comprising a first circulator, a photoelectric modulator, and a second circulator. Port ③ of the first circulator is connected to port ④ of the photoelectric modulator, port ① of the first circulator is connected to port ⑧ of the second circulator, and port ⑤ of the photoelectric modulator is connected to port ⑥ of the second circulator. Port ② of the first circulator and port ⑦ of the second circulator serve as optical signal inputs or outputs. Light input from port ② of the first circulator passes through ports ②, ③, ④, ⑤, ⑥, and ⑦ in sequence, achieving light transmission from left to right. Light input from port ② of the second circulator passes through ports ⑦, ⑧, ①, and ② in sequence, achieving light transmission from right to left. Since the light traveling in opposite directions follows different optical paths, only light from left to right passes through the photoelectric modulator, thus non-reciprocal modulation can be applied only to light in that direction. By utilizing the photoelectric modulator, non-reciprocal free modulation of the optical signal is achieved, including three dimensions: phase, DC bias, and amplitude.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of fiber lasers, and particularly relates to an optical structure for realizing non-reciprocal modulation. BACKGROUND

[0002] A fiber optic gyroscope (FOG) is a precision inertial measurement device based on the principle of optical interference and using a fiber ring sensor to detect angular velocity, and is widely used in aerospace, navigation, unmanned driving, oil exploration, precision positioning and other fields, and is one of the key components in an inertial navigation system.

[0003] The detection principle of an interferometric fiber optic gyroscope is based on the Sagnac effect: a laser beam is divided into two beams by a coupler, and propagates in the same fiber loop in opposite directions. If the gyroscope does not rotate, the propagation times of the two beams are the same, and no phase difference occurs when interference occurs; if the gyroscope rotates, the light propagating clockwise and the light propagating counterclockwise will have different propagation times in the fiber loop, resulting in a change in phase difference. By measuring the size of the phase difference, the angular velocity of the gyroscope can be calculated. If the fiber loop length is L and the loop diameter is D, the expression of the Sagnac phase shift in the fiber structure can be written as: ; wherein, represents the wavelength of light in vacuum, and c represents the speed of light in vacuum.

[0004] In the engineering test of a fiber optic gyroscope, a three-axis turntable is a necessary calibration device. For example, when evaluating the scale factor nonlinearity index of a fiber optic gyroscope, different rotation speeds of the turntable are set, the output results of the fiber optic gyroscope under different rotation speed inputs are collected, and an input-output straight line is fitted through multiple output results, so as to evaluate the linearity of the output results of the fiber optic gyroscope within the normal working range. The essence of this method is to introduce different angular velocities to realize different Sagnac phase shifts inside the gyroscope according to the above formula (1).

[0005] In addition, using a fiber optic gyroscope to measure angular acceleration is also a high-precision measurement method. In the test and calibration process of angular acceleration, an angular vibration table is used to measure nonlinearity, range, bandwidth and other indicators. However, the highest precision of the angular vibration table is only 100ppm (part per million), and the angular vibration table is unstable in operation. For high-precision angular accelerometers, the calibration equipment does not meet the calibration requirements, and a high-precision calibration method is urgently needed.

[0006] In the prior art, the common way to change the Sagnac phase shift is to use a turntable or a vibration table to generate different angular velocities or angular accelerations, but this way has the following disadvantages: 1. The purchase cost of a high-precision turntable or angular vibration table is high, which increases the calibration threshold; 2. Some errors only exist in the circuit, and when the device is calibrated, the tooling error of the instrument will be included in the calibration error, affecting the calibration accuracy; 3. The working mode of the turntable is generally constant speed running, which cannot support self-programming speed and acceleration rate variable speed running.

[0007] Therefore, in order to solve the above technical problems, the present application provides an improved optical structure for realizing non-reciprocal modulation. SUMMARY

[0008] In view of the defects in the prior art, the purpose of the present application is to provide an optical structure for realizing non-reciprocal modulation, which realizes optical non-reciprocal free modulation by using an optoelectronic modulator, including three dimensions of phase, direct current bias and amplitude, thereby realizing higher precision of gyro parameter calibration effect, and solving the technical problem that the measurement accuracy in the angular acceleration test calibration process of the existing fiber optic gyroscope is limited by high-precision turntables, vibration tables and other devices.

[0009] Specifically, the technical problem to be solved by the present application is to provide an optical structure for realizing non-reciprocal modulation in view of the above-mentioned deficiencies in the prior art, comprising a first circulator, an optoelectronic modulator and a second circulator; wherein the port ③ of the first circulator is connected with the port ④ of the optoelectronic modulator, the port ① of the first circulator is connected with the port ⑧ of the second circulator, the port ⑤ of the optoelectronic modulator is connected with the port ⑥ of the second circulator, and the port ② of the first circulator and the port ⑦ of the second circulator are used as optical signal input or output; the light input from the port ② of the first circulator passes through the ports ②, ③, ④, ⑤, ⑥ and ⑦ in sequence, realizing the transmission of light from left to right; the light input from the port ② of the second circulator passes through the ports ⑦, ⑧, ① and ② in sequence, realizing the transmission of light from right to left, since the optical paths of the light transmitted in opposite directions are different, only the light from left to right will pass through the optoelectronic modulator, so that non-reciprocal modulation can be applied to the light in this direction.

[0010] Preferably, the first circulator, the optoelectronic modulator and the second circulator are single mode devices or polarization maintaining devices.

[0011] Preferably, the optical fiber used in the optical structure is a single mode fiber or a polarization maintaining fiber.

[0012] Preferably, the optoelectronic modulator is a piezoelectric ceramic or crystal modulator, or other devices capable of modulating optical signals, and the modulation includes three dimensions of phase, direct current bias and amplitude; the applied modulation signal is any continuous or discrete signal.

[0013] Preferably, the port transmission relationship of the first circulator is port 1 in, port 2 out, port 2 in, port 3 out, the port transmission relationship of the second circulator (3) is port 6 in, port 7 out, port 7 in, port 8 out, and the port transmission relationship of the electro-optical modulator (2) is port 4 in, port 5 out, or port 5 in, port 4 out.

[0014] Preferably, the working waveband of the first circulator includes 850 nm±10 nm, 1310 nm±20 nm, and C+L waveband: 1530 nm-1625 nm.

[0015] Preferably, the working waveband of the electro-optical modulator includes 850 nm±10 nm, 1310 nm±20 nm, and C+L waveband: 1530 nm-1625 nm.

[0016] Preferably, the working waveband of the second circulator includes 850 nm±10 nm, 1310 nm±20 nm, and C+L waveband: 1530 nm-1625 nm.

[0017] Preferably, an adjustable attenuator is added between port 1 of the first circulator and port 7 of the second circulator, the loss is adjusted through the adjustable attenuator, the loss of the light transmitted from right to left is increased, and the insertion loss of the two light beams transmitted in opposite directions is balanced.

[0018] Compared with the prior art, the present application has the following positive effects: (1) the present application guarantees the stability and miniaturization of the optical structure through all-fiber design, can be made into a plug-in type and connected with the required equipment, and does not need processes such as shaft adjustment and optical path adjustment; (2) the optical structure in the present application is free from the limitation of devices such as a turntable and a vibration table, and the modulation accuracy generated by the electro-optical modulator is much higher than the stability of the turntable, so that the nonlinear response of the electro-optical system in the fiber-optic gyroscope can be more accurately calibrated, and the tooling error can be avoided; (3) the electro-optical modulator in the present application has high freedom degree of acceptable modulation signals, can design corresponding modulation signals according to the experimental scene requirements, and replaces the external excitation introduced by the actual equipment to simulate the test of various scenes such as angular velocity, angular acceleration and angular jerk. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 The figure is a schematic diagram of the optical structure for realizing the non-reciprocal modulation in the present application.

[0020] Figure 2 The figure is a verification effect diagram for actual test use of the present application.

[0021] The marks in the figure are: 1-first circulator, 2-electro-optical modulator, 3-second circulator. DETAILED DESCRIPTION

[0022] The following will be described in combination withFigures 1-2 The specific embodiments further illustrate the present application.

[0023] Figure 1 A schematic diagram of an optical structure for implementing non-reciprocal modulation in the embodiments of the present application is shown, comprising a first circulator 1, an electro-optical modulator 2 and a second circulator 3; wherein the port ③ of the first circulator 1 is connected to the port ④ of the electro-optical modulator 2, the port ① of the first circulator 1 is connected to the port ⑧ of the second circulator 3, the port ⑤ of the electro-optical modulator 2 is connected to the port ⑥ of the second circulator 3, and the port ② of the first circulator 1 and the port ⑦ of the second circulator 3 serve as the input or output of the optical signal; the light input from the port ② of the first circulator 1 passes through the ports ②, ③, ④, ⑤, ⑥ and ⑦ in sequence, realizing the transmission of the light from left to right; the light input from the port ② of the second circulator 3 passes through the ports ⑦, ⑧, ① and ② in sequence, realizing the transmission of the light from right to left; since the optical paths of the light transmitted in opposite directions are different, only the light from left to right will pass through the electro-optical modulator, so that non-reciprocal modulation can be applied to the light in this direction; the first circulator 1, the electro-optical modulator 2 and the second circulator 3 are single-mode devices or polarization maintaining devices, and the optical fiber used in the optical structure is a single-mode optical fiber or a polarization maintaining optical fiber.

[0024] The electro-optical modulator 2 is specifically a piezoelectric ceramic or crystal modulator, or other similar devices capable of implementing modulation of the optical signal, and the modulation includes three dimensions of phase, direct current bias and amplitude; the applied modulation signal is an arbitrary continuous or discrete signal; the port transmission relationship of the first circulator 1 is that the port ① enters the port ② and exits, the port ② enters the port ③ and exits, the port transmission relationship of the second circulator 3 is that the port ⑥ enters the port ⑦ and exits, the port ⑦ enters the port ⑧ and exits, and the port transmission relationship of the electro-optical modulator 2 is that the port ④ enters the port ⑤ and exits, and the port ⑤ enters the port ④ and exits or does not exit; the working wavelength range of the first circulator 1, the electro-optical modulator 2 and the second circulator 3 includes 850 nm±10 nm, 1310 nm±20 nm and C+L band: 1530 nm-1625 nm; in the above-mentioned optical structure for implementing non-reciprocal modulation, an adjustable attenuator is added between the port ① of the first circulator 1 and the port ⑧ of the second circulator 3 to adjust the loss and increase the loss of the light transmitted from right to left, thereby balancing the loss of the two beams of light transmitted in opposite directions.

[0025] As shown in Figure 2 , a custom non-reciprocal modulation effect diagram implemented using the optical structure for implementing non-reciprocal modulation of the present application is shown, and non-reciprocal modulation test verification is realized.

[0026] The present application ensures the stability and miniaturization of the optical structure through all-fiber design, can be made into a plug-in type and connected with the required equipment, and does not need processes such as adjustment of the shaft and adjustment of the optical path.

[0027] The optical structure in the application realizes optical non-reciprocal free modulation, including three dimensions of phase, direct current bias and amplitude, so that higher precision gyro parameter calibration effect is realized, the technical problem that the measurement precision in the existing optical fiber gyro angular acceleration test calibration process is limited by high-precision turntable, vibration table and other equipment is solved, so as to get rid of the limitation of turntable, vibration table and other equipment, and the modulation precision generated by the photoelectric modulator is much better than the stability of the turntable, which can more accurately calibrate the nonlinear response of the photoelectric system in the optical fiber gyro, and avoid tooling error.

[0028] The photoelectric modulator in the application can accept high degree of freedom of modulation signal, can design corresponding modulation signal according to experimental scene requirements, replace external excitation introduced by actual equipment, simulate angular velocity, angular acceleration, angular jerk and other scene tests.

[0029] It is worth noting that the above description is only exemplary for understanding the inventive concept according to the present disclosure, although each operation is described in a specific order, but it should be understood that the operation is required to be performed in the specific order shown or in a sequential order, or all the illustrated operations should be performed to obtain the desired results. In certain circumstances, multitasking and parallel processing can be advantageous. Similarly, although several specific implementation details are included in the above discussion, these should not be interpreted as limiting the scope of the present disclosure. Certain features described in the context of separate embodiments can also be combined for implementation in a single implementation. Conversely, various features described in the context of a single implementation can also be implemented separately or in any suitable subcombination.

[0030] Although the present subject matter has been described in terms of specific structural features and / or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as illustrative forms of implementing the claims.

[0031] The above has described the embodiments of the present disclosure, the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes are obvious to those skilled in the art without departing from the scope and spirit of the described embodiments. The choice of terms used herein is intended to best explain the principles of the embodiments, practical application or technical improvement in the market, or to make other.

[0032] In summary, only the preferred technical solutions of the present application are embodied, some changes made by the skilled person to some parts thereof also embody the principles of the present application, and should be within the technical scope of the present application.

Claims

1. An optical structure implementing a non-reciprocal modulation, characterized in that, The optical structure comprises a first circulator (1), an optoelectronic modulator (2) and a second circulator (3); wherein the port ③ of the first circulator (1) is connected with the port ④ of the optoelectronic modulator (2), the port ① of the first circulator (1) is connected with the port ⑧ of the second circulator (3), the port ⑤ of the optoelectronic modulator (2) is connected with the port ⑥ of the second circulator (3), and the port ② of the first circulator (1) and the port ⑦ of the second circulator (3) are used as optical signal input or output; the light input from the port ② of the first circulator (1) passes through the ports ②, ③, ④, ⑤, ⑥ and ⑦ in sequence to realize left-to-right optical transmission; the light input from the port ⑦ of the second circulator (3) passes through the ports ⑦, ⑧, ① and ② in sequence to realize right-to-left optical transmission; the optoelectronic modulator (2) is a piezoelectric ceramic or crystal modulator or other device capable of realizing optical signal modulation; the modulation includes three dimensions of phase, direct current bias and amplitude, and the applied modulation signal is an arbitrary continuous or discrete signal; the optical structure for realizing non-reciprocal modulation is used for gyro parameter calibration in the process of angular acceleration test and calibration of an optical fiber gyroscope.

2. An optical structure for implementing non-reciprocal modulation as claimed in claim 1, characterized in that, The first circulator (1), the optoelectronic modulator (2) and the second circulator (3) are single-mode devices or polarization maintaining devices.

3. An optical structure for implementing non-reciprocal modulation as defined in claim 1, wherein, The optical fiber used in the optical structure is a single-mode optical fiber or a polarization maintaining optical fiber.

4. An optical structure for implementing non-reciprocal modulation as defined in claim 1, wherein, The port transmission relationship of the first circulator (1) is that the port ① enters the port ② and exits, the port ② enters the port ③ and exits, the port transmission relationship of the second circulator (3) is that the port ⑥ enters the port ⑦ and exits, the port ⑦ enters the port ⑧ and exits, and the port transmission relationship of the optoelectronic modulator (2) is that the port ④ enters the port ⑤ and exits, the port ⑤ enters the port ④ and exits or does not exit.

5. An optical structure for implementing non-reciprocal modulation as defined in claim 1, wherein, The working waveband of the first circulator (1) is 850 nm±10 nm, or 1310 nm±20 nm, or C+L waveband: 1530 nm-1625 nm.

6. An optical structure for implementing non-reciprocal modulation as defined in claim 1, wherein, The working waveband of the optoelectronic modulator (2) is 850 nm±10 nm, or 1310 nm±20 nm, or C+L waveband: 1530 nm-1625 nm.

7. An optical structure for implementing non-reciprocal modulation as defined in claim 1, wherein, The working waveband of the second circulator (3) is 850 nm±10 nm, or 1310 nm±20 nm, or C+L waveband: 1530 nm-1625 nm.

8. An optical structure for implementing non-reciprocal modulation as defined in claim 1, wherein, An adjustable attenuator is added between the port ① of the first circulator (1) and the port ⑧ of the second circulator (3).

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