A method for improving wavelength stability of a fiber-optic gyroscope and a fiber-optic gyroscope

Abstract

The application discloses a method for improving wavelength stability of a fiber-optic gyroscope and the fiber-optic gyroscope, and the method comprises the following steps: S1, light output by a light source travels back to an integrated optical modulator after reaching a fiber ring, and interference light is formed; S2, the interference light is divided into one high-power light and one low-power light through a second optical fiber coupler; S3, after receiving the low-power light, an optical wavelength detector is converted into an electrical signal and output to a wavelength signal amplifier for amplification; S4, the wavelength signal amplifier outputs the amplified signal to a light source driving circuit; and S5, the light source driving circuit adjusts the driving current of the input light source according to the signal input by the wavelength signal amplifier. The application adjusts the light power through an optical attenuator, acquires the optical wavelength information through an optical wavelength detector, and adjusts the wavelength of the fiber-optic gyroscope according to the optical wavelength information, so that the wavelength stability of the fiber-optic gyroscope is improved under the premise of maintaining the light power stability, and the scale factor stability of the fiber-optic gyroscope is further improved.

Description

Technical Field

[0001] This invention relates to the field of fiber optic gyroscope technology, and more particularly to a method for improving the wavelength stability of a fiber optic gyroscope and a fiber optic gyroscope itself. Background Technology

[0002] Compared to laser gyroscopes, fiber optic gyroscopes do not require high-precision machining of optical mirrors, strict sealing of optical cavities, or mechanical biasing technology. They can effectively overcome the latch-up phenomenon of laser gyroscopes and have the advantages of simple structure, low price, small size, and light weight. From a market perspective, fiber optic gyroscopes have a development trend of completely replacing laser gyroscopes.

[0003] Two key technical indicators for evaluating the performance of fiber optic gyroscopes are zero bias and scaling. Zero bias is affected by optical power stability. Traditional fiber optic gyroscopes using optically controlled light sources can achieve optical power stability by controlling the drive current of the light source through optical power feedback. However, changing the drive current of the light source will cause the operating wavelength of the fiber to drift, which in turn will cause the scaling factor of the fiber optic gyroscope to drift. In other words, the traditional optically controlled fiber optic gyroscope stabilizes zero bias but changes the scaling factor. In some applications requiring high scaling factor stability, the light source drive current control scheme through optical power feedback becomes unsuitable. How to improve the wavelength stability of the fiber optic gyroscope and thus improve the scaling factor stability while maintaining optical power stability has become an urgent problem to be solved. Summary of the Invention

[0004] This invention provides a method and a fiber optic gyroscope for improving wavelength stability, thereby improving the scaling factor stability of the fiber optic gyroscope while maintaining optical power stability.

[0005] To achieve the above objectives, in a first aspect, the present invention provides a method for improving the wavelength stability of a fiber optic gyroscope, comprising the following steps:

[0006] S1: The light output from the light source passes through the optical attenuator, the first fiber coupler and the integrated optical modulator in sequence before entering the fiber ring. The light then travels in opposite directions from the fiber ring back to the integrated optical modulator, forming interference light.

[0007] S2: The interference light is split into a high-power light and a low-power light through the second fiber optic coupler;

[0008] S3: The optical wavelength detector receives the low-power light and converts it into an electrical signal, which is then amplified by the wavelength signal amplifier.

[0009] S4: The wavelength signal amplifier outputs the amplified signal to the light source driving circuit;

[0010] S5: The light source driving circuit adjusts the driving current of the input light source according to the signal input by the wavelength signal amplifier.

[0011] Further, the step S1 is specifically:

[0012] S11: The light output by the light source is input into the first fiber coupler after being adjusted in light power by the optical attenuator;

[0013] S12: The light output by the optical attenuator is divided into two equal beams after passing through the first fiber coupler;

[0014] S13: The first beam of light output by the first fiber coupler is input into the fiber ring after passing through the integrated optical modulator.

[0015] Further, the second beam of light output by the first fiber coupler is input into the second optical power detector, the second optical power detector converts the input optical signal into an electrical signal and inputs the electrical signal into the power amplifier, and the power amplifier adjusts the attenuation rate of the optical attenuator according to the input signal.

[0016] Further, the high-power light is input into the first optical power detector, the first optical power detector converts the optical signal into an electrical signal and inputs the electrical signal into the AD converter, the AD converter converts the analog electrical signal into a digital electrical signal and inputs the digital electrical signal into the digital signal processor, the digital signal processor outputs one-way fiber gyro information according to the input electrical signal, and the other way outputs the digital electrical signal to the DA converter, the DA converter converts the input digital electrical signal into an analog electrical signal and outputs the analog electrical signal to the integrated optical modulator as a feedback modulation signal.

[0017] In a second aspect, the present application also provides an optical fiber gyroscope, which is applied to the method for improving the wavelength stability of the optical fiber gyroscope according to any one of claims 1-4.

[0018] Further, the fiber-optic gyroscope comprises an optical path composed of a light source, a light attenuator, a first fiber-optic coupler, an integrated optical modulator and a fiber-optic ring connected in sequence, and an electric circuit composed of a first light power detector, an AD converter, a digital signal processor and a DA converter connected in sequence, further comprising a second fiber-optic coupler, and an optical wavelength detector, a wavelength signal amplifier and a light source driving circuit connected in sequence, the first fiber-optic coupler comprises four symmetrically arranged ports, wherein the first port and the second port are located on the same side, the third port and the fourth port are located on the same side, the first port and the fourth port are connected with the light attenuator and the integrated optical modulator respectively, the input end of the second fiber-optic coupler is connected with the second port of the first fiber-optic coupler, the first output end of the second fiber-optic coupler is connected with the input end of the optical wavelength detector, the second output end of the second fiber-optic coupler is connected with the input end of the first light power detector, the output end of the light source driving circuit is connected with the light source, and the output end of the DA converter is connected with the feedback end of the integrated optical modulator.

[0019] Further, the fiber-optic gyroscope comprises an optical path composed of a light source, a light attenuator, a first fiber-optic coupler, an integrated optical modulator and a fiber-optic ring connected in sequence, and an electric circuit composed of a first light power detector, an AD converter, a digital signal processor and a DA converter connected in sequence, further comprising a second fiber-optic coupler, and an optical wavelength detector, a wavelength signal amplifier and a light source driving circuit connected in sequence, the first fiber-optic coupler comprises four symmetrically arranged ports, wherein the first port and the second port are located on the same side, the third port and the fourth port are located on the same side, the first port and the fourth port are connected with the light attenuator and the integrated optical modulator respectively, the input end of the second fiber-optic coupler is connected with the second port of the first fiber-optic coupler, the first output end of the second fiber-optic coupler is connected with the input end of the optical wavelength detector, the second output end of the second fiber-optic coupler is connected with the input end of the first light power detector, the output end of the light source driving circuit is connected with the light source, and the output end of the DA converter is connected with the feedback end of the integrated optical modulator.

[0020] Further, the second fiber-optic coupler is a large-ratio fiber-optic coupler, which divides the input light into two light outputs with different powers.

[0021] The method and the fiber-optic gyroscope have the following advantages: the wavelength information of the fiber-optic gyroscope is sampled from the interference light returned from the fiber-optic ring, which can improve the effectiveness of the wavelength signal extraction; the wavelength information is fed back to the fiber-optic gyroscope through the wavelength signal amplifier to change the driving current of the light source driving circuit, thereby stabilizing the wavelength of the fiber-optic gyroscope; the light power is adjusted by the light attenuator, the wavelength information is obtained by the optical wavelength detector, and the wavelength of the fiber-optic gyroscope is adjusted according to the wavelength information, thereby improving the wavelength stability of the fiber-optic gyroscope and the scale factor stability of the fiber-optic gyroscope under the premise of maintaining the light power stability.

[0022] In addition to the objects, features and advantages described above, the present application has other objects, features and advantages. The present application will be further described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0023] The accompanying drawings, which form a part of this application, are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the application and, together with the description, serve to explain the application. In the drawings:

[0024] Figure 1 is a flow chart of a method for improving wavelength stability of a fiber-optic gyroscope according to an embodiment of the application;

[0025] Figure 2 is a structural schematic diagram of a fiber-optic gyroscope according to another embodiment of the application.

[0026] In the drawings, the following reference signs apply:

[0027] 1, light source; 2, optical attenuator; 3, first optical fiber coupler; 4, second optical fiber coupler; 5, optical wavelength detector; 6, wavelength signal amplifier; 7, light source driving circuit; 8, integrated optical modulator; 9, fiber-optic ring; 10, second optical power detector; 11, power amplifier; 12, first optical power detector; 13, AD converter; 14, digital signal processor; 15, DA converter. DETAILED DESCRIPTION

[0028] Embodiments of the application will be described in detail below with reference to the drawings, but the application can be implemented in a variety of different ways as defined and covered by the claims.

[0029] Embodiment 1, a method for improving wavelength stability of a fiber-optic gyroscope.

[0030] As shown in the drawings, Figure 1 the method for improving wavelength stability of a fiber-optic gyroscope according to the embodiment includes the following steps:

[0031] S1: light output by the light source 1 is input into the fiber-optic ring 9 after sequentially passing through the optical attenuator 2, the first optical fiber coupler 3 and the integrated optical modulator 8, and travels towards the integrated optical modulator 8 from the fiber-optic ring 9 to form interference light;

[0032] S2: the interference light is divided into a high-power light and a low-power light by the second optical fiber coupler 4;

[0033] S3: the optical wavelength detector 5 receives the low-power light and converts it into an electrical signal which is output to the wavelength signal amplifier 6 for amplification;

[0034] S4: the wavelength signal amplifier 6 outputs the amplified signal to the light source driving circuit 7;

[0035] S5: the light source driving circuit 7 adjusts the driving current of the input light source 1 according to the signal input by the wavelength signal amplifier 6.

[0036] In the step S1, the light output by the light source 1 is input into the fiber-optic ring 9 after sequentially passing through the optical attenuator 2, the first optical fiber coupler 3 and the integrated optical modulator 8, and travels towards the integrated optical modulator 8 from the fiber-optic ring 9 to form interference light.

[0037] S11: the light outputted by the light source 1 is inputted into the first fiber coupler 3 after being adjusted by the optical attenuator 2;

[0038] S12: the light outputted by the optical attenuator 2 is divided into two equal beams after passing through the first fiber coupler 3;

[0039] S13: the first beam of light outputted by the first fiber coupler 3 is inputted into the fiber ring 9 after passing through the integrated optical modulator 8.

[0040] In the method for improving the wavelength stability of the fiber-optic gyroscope in the embodiment, the second beam of light outputted by the first fiber coupler 3 is inputted into the second optical power detector 10, the second optical power detector 10 converts the inputted light signal into an electric signal and inputs the electric signal into the power amplifier 11, the power amplifier 11 adjusts the attenuation rate of the optical attenuator 2 according to the inputted signal, the feedback adjustment of the optical attenuator 2 is used to control the light power stability of the working light path into the fiber ring 9, so that the light power of the light path into the fiber ring 9 is not changed when the driving current of the light source 1 is adjusted.

[0041] In the method for improving the wavelength stability of the fiber-optic gyroscope in the embodiment, the high-power light is inputted into the first optical power detector 12, the first optical power detector 12 converts the light signal into an electric signal and inputs the electric signal into the AD converter 13, the AD converter 13 converts the analog electric signal into a digital electric signal and inputs the digital electric signal into the digital signal processor 14, the digital signal processor 14 outputs one-way fiber-optic gyroscope information according to the inputted electric signal, and outputs the other-way digital electric signal to the DA converter 15, the DA converter 15 converts the inputted digital electric signal into an analog electric signal and outputs the analog electric signal to the integrated optical modulator 8 as a feedback modulating signal.

[0042] The working principle of the embodiment is as follows: the light of the light source 1 enters the first optical fiber coupler 3 through the optical attenuator 2 and is divided into two equal parts, one of which directly enters the second optical power detector 10 and is converted into an electric signal as a feedback signal of optical power, the optical power feedback signal is connected to the feedback control end of the optical attenuator 2 through the power amplifier 11, when the optical power is too large, the attenuation rate of the optical attenuator 2 is increased, when the optical power is too small, the attenuation rate of the optical attenuator 2 is decreased, so as to realize the stability of the optical power, the other part of the light enters the integrated optical modulator 8 and is divided into two beams, which enter two ends of the optical fiber ring 9, travel in opposite directions through the optical fiber ring 9, return to the integrated optical modulator 8, and form interference light, the interference light returns to the first optical fiber coupler 3 as a rotation speed signal, and then is divided into two parts of different powers through the second optical fiber coupler 4, the high-power light enters the first optical power detector 12, the signal of the first optical power detector 12 is converted by the AD converter and the digital processor, and then the rotation speed value is output by the digital signal processor 14, at the same time, the electric signal output by the digital signal processor 14 is converted by the DA converter as a modulation signal and is fed back to the integrated optical modulator 8, and the low-power light output by the second optical fiber coupler 4 enters the optical wavelength detector 5 and is amplified by the wavelength signal amplifier 6, which is used for adjusting the driving current of the light source 1 and changing the optical wavelength, so as to realize the stability of the optical wavelength.

[0043] Compared with the conventional fiber-optic gyroscope test, the characteristics of the embodiment are shown in Table 1.

[0044]

[0045] Table 1

[0046] It can be seen that the method for improving the wavelength stability of the fiber-optic gyroscope can keep the working wavelength of the fiber-optic gyroscope stable under the conditions of temperature change and time change, and further improve the scale factor stability of the fiber-optic gyroscope, under the control of the optical attenuator 2, the working optical power of the fiber-optic gyroscope is kept stable, so that the zero bias stability of the fiber-optic gyroscope is kept stable.

[0047] Embodiment 2, a fiber-optic gyroscope.

[0048] The fiber-optic gyroscope of the embodiment is applied to the method for improving the wavelength stability of the fiber-optic gyroscope of embodiment 1.

[0049] As Figure 2As shown, the fiber-optic gyroscope of the embodiment includes an optical path composed of a light source 1, an optical attenuator 2, a first fiber-optic coupler 3, an integrated optical modulator 8 and a fiber-optic ring 9 connected in sequence, and an electric circuit composed of a first optical power detector 12, an AD converter 13, a digital signal processor 14 and a DA converter 15 connected in sequence, further includes a second fiber-optic coupler 4, and an optical wavelength detector 5, a wavelength signal amplifier 6 and a light source driving circuit 7 connected in sequence, the first fiber-optic coupler 3 includes four symmetrically arranged ports, wherein the first port and the second port are located on the same side, the third port and the fourth port are located on the same side, the first port and the fourth port are connected with the optical attenuator 2 and the integrated optical modulator 8 respectively, the input end of the second fiber-optic coupler 4 is connected with the second port of the first fiber-optic coupler 3, the first output end of the second fiber-optic coupler 4 is connected with the input end of the optical wavelength detector 5, the second output end of the second fiber-optic coupler 4 is connected with the input end of the first optical power detector 12, the output end of the light source driving circuit 7 is connected with the light source 1, and the output end of the DA converter 15 is connected with the feedback end of the integrated optical modulator 8.

[0050] Specifically, the light signal is selected from the interference light of the first fiber-optic coupler 3 as the wavelength information sampling point of the fiber-optic gyroscope optical path, which can improve the effectiveness of the wavelength signal extraction, the wavelength information is fed back to the wavelength signal amplifier 6 to change the wavelength of the fiber-optic gyroscope, thereby controlling the light source driving circuit 7 to change the driving current of the light source 1, and then stabilizing the wavelength of the fiber-optic gyroscope, and the stability of the optical power is maintained through the feedback adjustment of the optical attenuator 2.

[0051] In order to realize the feedback of the optical power, the fiber-optic gyroscope of the embodiment further includes a second optical power detector 10 and a power amplifier 11, the input end of the second optical power detector 10 is connected with the third port of the first fiber-optic coupler 3, the output end of the second optical power detector 10 is connected with the input end of the power amplifier 11, and the output end of the power amplifier 11 is connected with the feedback end of the optical attenuator 2.

[0052] The fiber-optic gyroscope of the embodiment, the second fiber-optic coupler 4 is a large splitting ratio coupler, which divides the input light into two light outputs with different powers, wherein the low-power light is connected to the optical wavelength detector 5, and the high-power end is connected to the first optical power detector 12, thereby reducing the loss of interference light signals in the fiber-optic gyroscope.

[0053] The working principle of the fiber-optic gyroscope of the embodiment is the same as that of the embodiment 1, which will not be described here. The working wavelength of the fiber-optic gyroscope of the embodiment can remain stable under temperature changes and time changes, thereby improving the scale factor stability of the fiber-optic gyroscope, and under the control of the optical attenuator 2, the working optical power of the fiber-optic gyroscope remains stable, which can keep the zero bias stability of the fiber-optic gyroscope stable.

[0054] The above merely provides the preferred embodiments of the present application, and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the principles and technical scope of the present application shall fall into the scope of the present application.

Claims

1. A method for improving the wavelength stability of a fiber optic gyroscope, characterized in that, The method comprises the following steps: S1: the light output by the light source (1) is input into the optical fiber ring (9) after passing through the optical attenuator (2), the first optical fiber coupler (3) and the integrated optical modulator (8) in sequence, and the light is returned to the integrated optical modulator (8) by the optical fiber ring (9) moving towards each other to form interference light; S2: the interference light is divided into high-power light and low-power light by the second optical fiber coupler (4); S3: the optical wavelength detector (5) converts the low-power light into an electrical signal and outputs the electrical signal to the wavelength signal amplifier (6) for amplification; S4: the wavelength signal amplifier (6) outputs the amplified signal to the light source driving circuit (7); S5: the light source driving circuit (7) adjusts the driving current of the input light source (1) according to the signal input by the wavelength signal amplifier (6).

2. The method for improving the wavelength stability of a fiber optic gyroscope according to claim 1, wherein, The step S1 specifically comprises: S11: the light output by the light source (1) is input into the first optical fiber coupler (3) after the light power is adjusted by the optical attenuator (2); S12: the light output by the optical attenuator (2) is divided into two equal beams after passing through the first optical fiber coupler (3); S13: the first beam of light output by the first optical fiber coupler (3) is input into the optical fiber ring (9) after passing through the integrated optical modulator (8).

3. The method for improving the wavelength stability of a fiber optic gyroscope according to claim 2, wherein, The second beam of light output by the first optical fiber coupler (3) is input into the second optical power detector (10), the second optical power detector (10) converts the input optical signal into an electrical signal and inputs the electrical signal into the power amplifier (11), and the power amplifier (11) adjusts the attenuation rate of the optical attenuator (2) according to the input signal.

4. The method for improving the wavelength stability of a fiber optic gyroscope according to claim 1, wherein, The high-power light is input into the first optical power detector (12), the first optical power detector (12) converts the optical signal into an electrical signal and inputs the electrical signal into the AD converter (13), the AD converter (13) converts the analog electrical signal into a digital electrical signal and inputs the digital electrical signal into the digital signal processor (14), the digital signal processor (14) outputs one-way fiber-optic gyroscope information according to the input electrical signal, and outputs the other-way digital electrical signal to the DA converter (15), the DA converter (15) converts the input digital electrical signal into an analog electrical signal and outputs the analog electrical signal to the integrated optical modulator (8) as a feedback modulation signal.

5. An optical fiber gyroscope, characterized by The fiber-optic gyroscope is applied to the method for improving the wavelength stability of the fiber-optic gyroscope according to any one of claims 1-4.

6. The fiber optic gyroscope of claim 5, wherein, The optical path comprises a light source (1), a light attenuator (2), a first optical fiber coupler (3), an integrated optical modulator (8) and an optical fiber ring (9) connected in sequence, and the circuit comprises a first optical power detector (12), an AD converter (13), a digital signal processor (14) and a DA converter (15) connected in sequence, further comprising a second optical fiber coupler (4), and a light wavelength detector (5), a wavelength signal amplifier (6) and a light source driving circuit (7) connected in sequence, the first optical fiber coupler (3) comprises four symmetrically arranged ports, wherein the first port and the second port are located on the same side, the third port and the fourth port are located on the same side, the first port and the fourth port are respectively connected to the light attenuator (2) and the integrated optical modulator (8), the input end of the second optical fiber coupler (4) is connected to the second port of the first optical fiber coupler (3), the first output end of the second optical fiber coupler (4) is connected to the input end of the light wavelength detector (5), the second output end of the second optical fiber coupler (4) is connected to the input end of the first optical power detector (12), the output end of the light source driving circuit (7) is connected to the light source (1), and the output end of the DA converter (15) is connected to the feedback end of the integrated optical modulator (8).

7. The fiber optic gyroscope of claim 6, wherein, Further comprising a second optical power detector (10) and a power amplifier (11), the input end of the second optical power detector (10) is connected to the third port of the first optical fiber coupler (3), the output end of the second optical power detector (10) is connected to the input end of the power amplifier (11), and the output end of the power amplifier (11) is connected to the feedback end of the light attenuator (2).

8. The fiber optic gyroscope of claim 6, wherein, The second optical fiber coupler (4) is a large-ratio optical splitter, which divides the input light into two light outputs with different powers.

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