A dual-parameter optical fiber laser sensor based on sagnac ring cascaded liquid-filled MZI

Abstract

The utility model discloses a kind of double-parameter optical fiber laser sensors based on Sagnac ring cascaded liquid phase filling MZI, belong to optical fiber sensor technical field, by LD pumped laser source (1), wavelength division multiplexer (2), holmium-doped optical fiber (3), optical circulator (4), sensing probe A (5), first coupler (6), sensing probe B (7), second coupler (8), optical spectrum analyzer (9), first single-mode optical fiber (501) polished in side edge, large core diameter hollow optical fiber (502) fills PDMS (503), few-mode optical fiber (504), fiber bragg grating (505), second single-mode optical fiber (506), third single-mode optical fiber (701), first panda polarization maintaining fiber (702), second panda polarization maintaining fiber (703), fourth single-mode optical fiber (704);The utility model can effectively improve the sensitivity of device to temperature by hollow optical fiber filling PDMS;By panda polarization maintaining fiber rotation shaft fusion splicing makes that interference phase difference amplification, spectral line drift is more obvious, so improve the sensitivity of device to temperature;Different reflection peak signals of few-mode optical fiber grating and Sagnac interference spectrum signals can establish sensitivity matrix to realize double-parameter measurement to temperature and strain, with excellent reliability and stability.

Description

Technical Field

[0001] This utility model relates to a dual-parameter fiber laser sensor, and more particularly to a dual-parameter fiber laser sensor based on Sagnac ring cascade liquid-filled MZI, belonging to the field of fiber optic sensor technology. Background Technology

[0002] In recent years, fiber optic sensing technology has developed rapidly and has been widely used in aerospace, medicine, geological exploration, and power systems, playing a vital role in each field. Compared with traditional broadband light source fiber optic sensors, fiber laser sensors, with their advantages of good stability, narrow spectral width, and high signal-to-noise ratio, have become one of the most promising research directions in the field of fiber optic sensing. However, in the process of striving for high reliability and high sensitivity of fiber laser sensors, the existence of cross-sensitivity to temperature and strain seriously affects the accuracy and judgment of the sensing. Therefore, many current sensing structures can only measure a single parameter. Fiber laser sensors capable of measuring two parameters and possessing high sensitivity have become the hot topic for future research. Summary of the Invention

[0003] In order to overcome the shortcomings of the prior art, the present invention aims to provide a dual-parameter fiber laser sensor based on Sagnac ring cascade liquid-filled MZI. This laser has the characteristics of small size, simple structure, easy fabrication, high strain and temperature sensitivity, and the ability to achieve dual measurement of strain and temperature.

[0004] The technical solution adopted by this utility model to solve the technical problem is as follows:

[0005] A dual-parameter fiber laser sensor based on Sagnac ring-cascaded liquid-filled MZI, characterized by comprising an LD-pumped laser source (1), a wavelength division multiplexer (2), a holmium-doped fiber (3), an optical circulator (4), a sensing probe A (5), a first coupler (6), a sensing probe B (7), a second coupler (8), and a spectrometer (9); a side-polished first single-mode fiber (501), a large-core hollow fiber (502) filled with PDMS (503), a few-mode fiber (504), a fiber Bragg grating (505), a second single-mode fiber (506), a third single-mode fiber (701), and a fourth single-mode fiber (702). A panda-type polarization-maintaining fiber (702), a second panda-type polarization-maintaining fiber (703), and a fourth single-mode fiber (704); the LD pump laser source (1) is connected to two ports (202) of the wavelength division multiplexer (2), one port (201) of the wavelength division multiplexer (2) is connected to one end of the holmium-doped fiber (3), the other end of the holmium-doped fiber (3) is connected to one port (401) of the optical circulator (4), two ports (402) of the optical circulator (4) are connected to one end of the sensing probe A (5), the other end of the sensing probe A (5) is connected to one port (601) of the first coupler (6), and two ports (602) of the first coupler (6) are connected to one end of the sensing probe A (5). One end of the optical circulator (4) is connected to one end of the sensing probe B (7), and the other end of the sensing probe B (7) is connected to the three-port (603) of the first coupler (6). The three-port (403) of the optical circulator (4) is connected to one port (801) of the second coupler (8). The two-port (802) of the second coupler (8) is connected to the three-port (203) of the wavelength division multiplexer (2). The three-port (803) of the second coupler (8) is connected to the spectrometer (9). The sensing probe A (5) is formed by discharge fusion of the side-polished first single-mode fiber (501) and the large-core hollow fiber (502) filled with PDMS (503) at one end. A fiber Bragg grating (505) is written on the single-mode fiber (504) using a femtosecond laser. The other end of the large-core hollow fiber (502) filled with PDMS (503) is fused with the few-mode fiber (504) by discharge. The other end of the few-mode fiber (504) is fused with the second single-mode fiber (506) by discharge. The sensing probe B (7) is fused with the first panda-type polarization-maintaining fiber (702) by discharge from the third single-mode fiber (701). The other end of the first panda-type polarization-maintaining fiber (702) is fused with the second panda-type polarization-maintaining fiber (703) by discharge. The other end of the panda-type polarization-maintaining fiber (703) is fused with the fourth single-mode fiber (704) by discharge.

[0006] The beneficial effects of this utility model are:

[0007] 1. Filling PDMS with hollow optical fiber can effectively improve the device's temperature sensitivity;

[0008] 2. By using panda-type polarization-maintaining fiber fusion splicing, the interference phase difference is amplified, and the spectral line drift becomes more obvious, thus improving the device's temperature sensitivity.

[0009] 3. A sensitivity matrix can be established using the different reflection peak signals of the few-mode fiber grating and the Sagnac interference spectrum signal to achieve dual-parameter measurement of temperature and strain, exhibiting excellent reliability and stability. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of the structure of a dual-parameter fiber laser sensor based on Sagnac ring cascade liquid-filled MZI. Figure 2 and Figure 3 They are respectively Figure 1 A schematic diagram of the structure of sensor probe A and sensor probe B. Figure 4 and Figure 5 These are schematic diagrams of the rotating shaft of sensor probe B.

[0011] 1 is an LD pump laser source; 2 is a wavelength division multiplexer; 3 is a holmium-doped fiber; 4 is an optical circulator; 5 is a sensing structure A; 6 is a first coupler; 7 is a sensing structure B; 8 is a second coupler; 9 is a spectrometer; the side-polished first single-mode fiber (501), the large-core hollow fiber (502) filled with PDMS (503), the few-mode fiber (504), the fiber Bragg grating (505), the second single-mode fiber (506), the third single-mode fiber (701), the first panda-type polarization-maintaining fiber (702), the second panda-type polarization-maintaining fiber (703), and the fourth single-mode fiber (704);

[0012] Specific implementation methods

[0013] The following is a detailed description of the structure and working principle of this utility model:

[0014] A dual-parameter fiber laser sensor based on Sagnac ring-cascaded liquid-filled MZI, characterized by comprising an LD-pumped laser source (1), a wavelength division multiplexer (2), a holmium-doped fiber (3), an optical circulator (4), a sensing probe A (5), a first coupler (6), a sensing probe B (7), a second coupler (8), and a spectrometer (9); a side-polished first single-mode fiber (501), a large-core hollow fiber (502) filled with PDMS (503), a few-mode fiber (504), a fiber Bragg grating (505), a second single-mode fiber (506), a third single-mode fiber (701), and a fourth single-mode fiber (702). A panda-type polarization-maintaining fiber (702), a second panda-type polarization-maintaining fiber (703), and a fourth single-mode fiber (704); the LD pump laser source (1) is connected to two ports (202) of the wavelength division multiplexer (2), one port (201) of the wavelength division multiplexer (2) is connected to one end of the holmium-doped fiber (3), the other end of the holmium-doped fiber (3) is connected to one port (401) of the optical circulator (4), two ports (402) of the optical circulator (4) are connected to one end of the sensing probe A (5), the other end of the sensing probe A (5) is connected to one port (601) of the first coupler (6), and two ports (602) of the first coupler (6) are connected to one end of the sensing probe A (5). One end of the optical circulator (4) is connected to one end of the sensing probe B (7), and the other end of the sensing probe B (7) is connected to the three-port (603) of the first coupler (6). The three-port (403) of the optical circulator (4) is connected to one port (801) of the second coupler (8). The two-port (802) of the second coupler (8) is connected to the three-port (203) of the wavelength division multiplexer (2). The three-port (803) of the second coupler (8) is connected to the spectrometer (9). The sensing probe A (5) is formed by discharge fusion of the side-polished first single-mode fiber (501) and the large-core hollow fiber (502) filled with PDMS (503) at one end. A fiber Bragg grating (505) is written on the single-mode fiber (504) using a femtosecond laser. The other end of the large-core hollow fiber (502) filled with PDMS (503) is fused with the few-mode fiber (504) by discharge. The other end of the few-mode fiber (504) is fused with the second single-mode fiber (506) by discharge. The sensing probe B (7) is fused with the first panda-type polarization-maintaining fiber (702) by discharge from the third single-mode fiber (701). The other end of the first panda-type polarization-maintaining fiber (702) is fused with the second panda-type polarization-maintaining fiber (703) by discharge. The other end of the panda-type polarization-maintaining fiber (703) is fused with the fourth single-mode fiber (704) by discharge.

[0015] Working principle of a dual-parameter fiber laser sensor based on Sagnac ring cascade liquid-filled MZI:

[0016] A dual-parameter fiber laser sensor based on Sagnac ring cascade liquid-filled MZI is based on Figure 1After all the components are connected, the 980nm pump light output from the LD pump laser source (1) is coupled into the linear optical path through the two ports of the wavelength division multiplexer (2), passes through the holmium-doped fiber (3), enters through the one port (401) of the optical circulator (4), and enters the sensing probe A (5) through the two ports (402) of the optical circulator (4). In the sensing probe A (5), the light enters the large-core hollow fiber (502) filled with PDMS (503) through the side-polished first single-mode fiber (501). Due to the large-core waveguide effect, the light will be separated into two independent beams in the large-core hollow fiber (502), which will propagate along the cladding and the liquid core respectively. The two beams will couple at the few-mode fiber (504). When the light is transmitted to the fiber Bragg grating (505), due to the reflection of part of the fiber Bragg grating (505) and the fact that the few-mode fiber allows more than one mode to propagate in the fiber core, multiple different characteristic peaks will appear. Another portion of the light enters the second single-mode fiber (506) and is transmitted to one port (601) of the first coupler (6). After passing through the first coupler (6), it is split into two beams and transmitted to the sensing probe B (7) through the two ports (602) and three ports (603) of the first coupler (6). The light input from the two ports of the first coupler (6) passes through the third single-mode fiber (701). The light passes through the first panda-type polarization-maintaining fiber (702) through the third single-mode fiber (701). Due to the birefringence effect of the polarization-maintaining fiber, the light is split into two beams of polarized light that are orthogonal to each other and have different optical paths. When the light is transmitted to the fusion splice of the rotating shaft, the two orthogonal polarized lights will form 4 components on the second panda-type polarization-maintaining fiber (703). During the transmission along the second panda-type polarization-maintaining fiber (703), a phase difference will also be generated. After that, the light is recoupled into the fourth single-mode fiber (704). The light input from the three ports of the first coupler (6) passes through the fourth single-mode fiber (704) and the second panda-type polarization-maintaining fiber (703). Due to the birefringence effect of the polarization-maintaining fiber, the light is split into two mutually orthogonal polarized beams with different optical paths. When the light is transmitted to the fusion splice of the rotating shaft, the two mutually orthogonal polarized beams will form four components on the first panda-type polarization-maintaining fiber (702). During the transmission along the first panda-type polarization-maintaining fiber (702), a phase difference will also be generated. After that, the light is recoupled into the third single-mode fiber (701) and output from both ends of the sensing probe B (7). The light converges at the two-port (602) and three-port (603) of the first coupler (6) to form interference light. The interference light enters the sensing probe A (5) again through the one-port (601) of the first coupler (6). Then the interference light is transmitted to the second coupler (8) through the three-port (403) of the optical circulator (4). After passing through the second coupler (8), the light is split into two beams. One beam is transmitted to the wavelength division multiplexer (2) through the two-port (802) of the second coupler (8); the other beam is transmitted to the spectrometer (9) through the three-port (803) of the second coupler (8). Example

[0017] Figure 1 This is a schematic diagram of the structure of a dual-parameter fiber laser sensor based on Sagnac ring cascade liquid-filled MZI according to the present invention. The first single-mode fiber (501) with side polishing is formed by thinning the side cladding through fiber polishing technology. The large-core hollow fiber (502) has a core diameter of 75μm, a cladding of 125μm, and a length of 300μm. The few-mode fiber (504) is a fourth-order few-mode fiber with a length of 20mm. The fiber Bragg grating (505) is written by a femtosecond laser, has a length of 17mm, and a reflectivity of 80%-90%. The first panda-type polarization-maintaining fiber (702) and the second panda-type polarization-maintaining fiber (703) have a length of 10cm. The LD pump laser source (1) has a laser wavelength of 980nm. The wavelength division multiplexer (2) is 980 / 1550nm. The first coupler (5) has a coupling ratio of 50:50, and the second coupler (8) has a coupling ratio of 90:10. The LD pump laser source (1) is connected to two ports (202) of the wavelength division multiplexer (2). One port (201) of the wavelength division multiplexer (2) is connected to one end of the holmium-doped fiber (3). The other end of the holmium-doped fiber (3) is connected to one port (401) of the optical circulator (4). Two ports (402) of the optical circulator (4) are connected to one end of the sensing probe A (5). The other end of the sensing probe A (5) is connected to one port (601) of the first coupler (6). The first coupler (6) has its two-port (602) connected to one end of the sensing probe B (7), and the other end of the sensing probe B (7) connected to the three-port (603) of the first coupler (6). The three-port (403) of the optical circulator (4) is connected to one-port (801) of the second coupler (8), and the two-port (802) of the second coupler (8) is connected to the three-port (203) of the wavelength division multiplexer (2). The three-port (803) is connected to the spectrometer (9); among them, the sensing probe A (5) is a first single-mode fiber (501) with side polishing and a large-core hollow fiber (502) filled with PDMS (503) with one end being fused together by discharge. A fiber Bragg grating (505) is written on the few-mode fiber (504) with a femtosecond laser. The other end of the large-core hollow fiber (502) filled with PDMS (503) is fused together with the few-mode fiber (504) by discharge. The other end of the few-mode fiber (504) is fused together with the second single-mode fiber (506) by discharge. The sensing probe B (7) is a third single-mode fiber (701) with a first panda-type polarization-maintaining fiber (702) by discharge. The other end of the first panda-type polarization-maintaining fiber (702) is fused together with the second panda-type polarization-maintaining fiber (703) with a 45° rotation axis by discharge. The other end of the panda-type polarization-maintaining fiber (703) is fused together with the fourth single-mode fiber (704) by discharge.

[0018] The 980nm pump light output from the LD pump laser source (1) is coupled into the linear optical path through the two ports of the wavelength division multiplexer (2), passes through the holmium-doped fiber (3), enters through the one port (401) of the optical circulator (4), and enters the sensing probe A (5) through the two ports (402) of the optical circulator (4). In the sensing probe A (5), the light enters the large-core hollow fiber (502) filled with PDMS (503) through the side-polished first single-mode fiber (501). Due to the large-core waveguide effect, the light is split into two independent beams in the large-core hollow fiber (502), which propagate along the cladding and the liquid core, respectively. The two beams are coupled at the few-mode fiber (504). When the light is transmitted to the fiber Bragg grating (505), due to the reflection of part of the fiber Bragg grating (505) and the fact that the few-mode fiber allows more than one mode to propagate in the fiber core, multiple different characteristic peaks will appear. Another portion of the light enters the second single-mode fiber (506) and is transmitted to one port (601) of the first coupler (6). After passing through the first coupler (6), it is split into two beams and transmitted to the sensing probe B (7) through the two ports (602) and three ports (603) of the first coupler (6). The light input from the two ports of the first coupler (6) passes through the third single-mode fiber (701). The light passes through the first panda-type polarization-maintaining fiber (702) through the third single-mode fiber (701). Due to the birefringence effect of the polarization-maintaining fiber, the light is split into two beams of polarized light that are orthogonal to each other and have different optical paths. When the light is transmitted to the fusion splice of the rotating shaft, the two orthogonal polarized lights will form 4 components on the second panda-type polarization-maintaining fiber (703). During the transmission along the second panda-type polarization-maintaining fiber (703), a phase difference will also be generated. After that, the light is recoupled into the fourth single-mode fiber (704). The light input from the three ports of the first coupler (6) passes through the fourth single-mode fiber (704) and the second panda-type polarization-maintaining fiber (703). Due to the birefringence effect of the polarization-maintaining fiber, the light is split into two mutually orthogonal polarized beams with different optical paths. When the light is transmitted to the fusion splice of the rotating shaft, the two mutually orthogonal polarized beams will form four components on the first panda-type polarization-maintaining fiber (702). During the transmission along the first panda-type polarization-maintaining fiber (702), a phase difference will also be generated. After that, the light is recoupled into the third single-mode fiber (701) and output from both ends of the sensing probe B (7). The light converges at the two-port (602) and three-port (603) of the first coupler (6) to form interference light. The interference light enters the sensing probe A (5) again through the one-port (601) of the first coupler (6). Then the interference light is transmitted to the second coupler (8) through the three-port (403) of the optical circulator (4). After passing through the second coupler (8), the light is split into two beams. One beam is transmitted to the wavelength division multiplexer (2) through the two-port (802) of the second coupler (8); the other beam is transmitted to the spectrometer (9) through the three-port (803) of the second coupler (8).

[0019] The above embodiments are only one of the preferred embodiments among all the solutions of this utility model. Other simple modifications to a dual-parameter fiber laser sensor based on Sagnac ring cascade liquid-filled MZI are all within the scope of protection of this utility model.

Claims

1. A dual-parameter fiber laser sensor based on a Sagnac ring cascaded liquid-filled MZI, characterized in that... Includes an LD pump laser source (1), a wavelength division multiplexer (2), a holmium-doped fiber (3), an optical circulator (4), a sensor probe A (5), a first coupler (6), a sensor probe B (7), a second coupler (8), and a spectrometer (9); a side-polished first single-mode fiber (501), a large-core hollow fiber (502) filled with PDMS (503), a few-mode fiber (504), a fiber Bragg grating (505), a second single-mode fiber (506), a third single-mode fiber (701), a first panda-type polarization-maintaining fiber (702), and a second panda-type polarization-maintaining fiber (703). ), and the fourth single-mode fiber (704); the LD pump laser source (1) is connected to the two ports (202) of the wavelength division multiplexer (2), one port (201) of the wavelength division multiplexer (2) is connected to one end of the holmium-doped fiber (3), the other end of the holmium-doped fiber (3) is connected to one port (401) of the optical circulator (4), the two ports (402) of the optical circulator (4) are connected to one end of the sensing probe A (5), the other end of the sensing probe A (5) is connected to one port (601) of the first coupler (6), the two ports (602) of the first coupler (6) are connected to one end of the sensing probe B (7), the sensing The other end of probe B (7) is connected to the three-port (603) of the first coupler (6), the three-port (403) of the optical circulator (4) is connected to the one-port (801) of the second coupler (8), the two-port (802) of the second coupler (8) is connected to the three-port (203) of the wavelength division multiplexer (2), and the three-port (803) of the second coupler (8) is connected to the spectrometer (9); among them, the sensing probe A (5) is formed by discharge fusion of the side-polished first single-mode fiber (501) and the large-core hollow fiber (502) filled with PDMS (503) at one end, and on the few-mode fiber (504) A fiber Bragg grating (505) is written using a femtosecond laser. The other end of a large-core hollow fiber (502) filled with PDMS (503) is fused with a few-mode fiber (504) by discharge. The other end of the few-mode fiber (504) is fused with a second single-mode fiber (506) by discharge. The sensing probe B (7) is fused with a first panda-type polarization-maintaining fiber (702) by discharge from a third single-mode fiber (701). The other end of the first panda-type polarization-maintaining fiber (702) is fused with a second panda-type polarization-maintaining fiber (703) by discharge. The other end of the panda-type polarization-maintaining fiber (703) is fused with a fourth single-mode fiber (704) by discharge.

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