Low-cost optical fiber sensing equipment suitable for multi-channel and multi-parameter monitoring

Abstract

The utility model provides a low-cost optical fiber sensing device suitable for multi-channel and multi-parameter monitoring, which comprises a light emitting module, a light transmission coupling module, a light channel selection module, a sensing unit and a filtering demodulation module, the optical transmission coupling module splits the received light to the optical channel selection module and the filtering demodulation module; the optical channel selection module is provided with a plurality of selectively communicated optical paths, each optical path is connected with a sensing unit, and the sensing units are wavelength feedback type optical fiber sensors; the filtering demodulation module comprises an optical fiber collimator, a beam splitter and a filter which are sequentially arranged in the light path direction, and photodiodes are arranged in the light splitting direction of the beam splitter and the light filtering direction of the filter. According to the utility model, the system cost can be reduced, the number of optical switch channels can be flexibly selected, and multi-channel, multi-parameter and low-cost demodulation in a low-rate and slow-variable scene can be realized.

Description

Technical Field

[0001] The utility model relates to the technical field of fiber optic sensing detection, and specifically to a low-cost fiber optic sensing device applicable to multi-channel and multi-parameter monitoring. Background Technique

[0002] Existing fiber optic sensing detection technologies mainly have two directions. One is single-point measurement, and the other is distributed or quasi-distributed measurement. In the single-point measurement scenario, the number of measurement channels is often limited, generally ranging from several to dozens of channels, but the types of measured physical quantities are diverse, such as strain, temperature, vibration, etc.; in the distributed or quasi-distributed measurement scenario, there are often many measurement points, generally ranging from hundreds to tens of thousands, but the measured physical quantity is relatively single. In terms of cost, the single-point measurement system generally has a lower cost than the distributed or quasi-distributed system, but the cost of the single-point measurement system is generally strongly correlated with the number of detection channels. Users often require as many detection points as possible on the basis of multi-parameter measurement to ensure measurement accuracy.

[0003] Common single-point fiber Bragg grating sensing demodulation mainly includes scanning light source schemes, tunable filter schemes, edge filtering schemes, linear CCD schemes, etc. Among them, the edge filter scheme has the lowest relative cost. The advantage of the edge filter scheme lies in the scenario with fewer channels. After the number of channels gradually increases, the advantage is not obvious, and even the cost will be higher than that of other schemes. Content of the Utility Model

[0004] In order to solve the problems of the existing technology, the utility model provides a low-cost fiber optic sensing device applicable to multi-channel and multi-parameter monitoring. It adopts a multi-channel optical switch structure, so that a wavelength demodulation module can be shared, reducing the increase in system cost caused by the increase in the number of channels. Moreover, the number of channels of the optical switch can be flexibly selected. At the same time, the optical path structure is optimized, systematically reducing the increase in optical devices caused by the increase in detection channels in the traditional method, realizing multi-channel and multi-parameter low-cost demodulation in low-rate and slow-variable scenarios.

[0005] The utility model provides a low-cost fiber optic sensing device applicable to multi-channel and multi-parameter monitoring, including an optical emission module, an optical transmission coupling module, an optical channel selection module, a sensing unit, and a filtering and demodulation module. The light emitted by the optical emission module is directed towards the optical transmission coupling module, and the optical transmission coupling module splits the received light into the optical channel selection module and the filtering and demodulation module; the optical channel selection module has several selectively connected optical paths, each optical path is connected to a sensing unit, and the sensing unit is a wavelength feedback type fiber optic sensor; the filtering and demodulation module includes a fiber optic collimator, a beam splitter, and a filter arranged in sequence along the optical path direction. Photoelectric diodes are arranged in the splitting direction of the beam splitter and the filtering direction of the filter.

[0006] Further improvement: The wavelength feedback type fiber optic sensor is of FBG type, diffraction grating type or F-P type.

[0007] Further improvement: The optical transmission coupling module adopts an N×M tapered coupler, an N-port circulator or an N×M PLC splitter.

[0008] Further improvement: The optical channel selection module selectively turns on or off a specified optical path as needed, and the number of channels is 2 to 128, including but not limited to mechanical optical switches, magneto-optical switches, and silicon-based electro-optical switches.

[0009] Further improvement: The optical channel selection module provides a switching speed of not less than 10 Hz.

[0010] Further improvement: The optical emission module is a C-band broadband light source, including but not limited to an ASE light source and an SLED light source.

[0011] Further improvement: The filtering and demodulation module integrates functions of beam splitting, filtering, photoelectric conversion, and temperature monitoring on a chip, integrating a beam splitting chip structure, an optical filtering structure, a photodiode component, and a temperature sensor on a chip.

[0012] In the filtering and demodulation module, the fiber collimator has an operating wavelength range of 1508 to 1598 nm and a spot diameter <0.2 mm.

[0013] In the filtering and demodulation module, the beam splitting chip is coated with a depolarization elimination film, the beam splitting ratio is 50%, the polarization correlation of transmission is ≤0.1%, the polarization correlation of reflection is ≤0.1%, and the transmission surface is coated with an antireflection film with a transmittance >99%.

[0014] In the filtering and demodulation module, the filter chip is a band-pass filter film system, with a center wavelength of 1510 to 1590 nm, a full width at half maximum ≥20 nm, and the transmission surface is coated with an antireflection film with a transmittance >99%.

[0015] The beneficial effects of the present utility model are as follows:

[0016] 1. By using a multi-channel optical switch, the wavelength demodulation module can be shared, so that one wavelength demodulation module is shared, reducing the increase in system cost caused by the increase in the number of channels.

[0017] 2. The number of channels of the optical switch can be flexibly selected, and at the same time, the optical path structure is optimized, systematically reducing the increase in optical devices caused by the increase in detection channels in the traditional method, realizing multi-channel and multi-parameter low-cost demodulation in low-rate and slow-variable scenarios.

[0018] 3. Integrating the wavelength demodulation module on-chip is beneficial to the miniaturized design of the demodulation device, reduces the number of discrete devices, optimizes the spatial volume of the demodulation device. At the same time, temperature monitoring, beam splitting, filtering, and optoelectronic conversion are in the same space, which is conducive to reducing the number of temperature monitoring points and avoiding inaccurate calibration of device characteristics caused by uneven temperature. Brief Description of the Drawings

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0020] Figure 1 It is a system structure diagram;

[0021] Figure 2 It is a schematic diagram of the filter demodulation module. Detailed Embodiments

[0022] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0023] The structure of the present invention is as Figure 1 shown, including an optical emission module 1, an optical transmission coupling module 2, an optical channel selection module 3, a sensing unit 4, and a filter demodulation module 5; among them, the optical emission module 1 has the function of emitting broadband light and includes a C / L band broadband light source (including but not limited to ASE light source, SLED light source, etc.) inside; the optical transmission coupling module 2 provides the function of directing the optical path and includes but not limited to N×M couplers, N-port circulators; the optical channel selection module 3 functions as an optical path selection, can select or close the specified optical path as needed, and the number of selectable channels is generally 2 to 128, including but not limited to mechanical optical switches, magneto-optical switches, silicon-based electro-optical switches, etc.; the sensing unit 4 is composed of N wavelength feedback type fiber optic sensors (including but not limited to FBG type, diffraction grating type, F-P type), and multiple types can be combined to realize multi-parameter measurement; the main function of the filter demodulation module 5 is band-pass filtering and optoelectronic conversion, and includes a beam splitting structure, an optical filtering structure, and a photodiode component.

[0024] The filter demodulation module 5 is as Figure 2As shown in the figure, it is composed of an optical fiber collimator 5-1, a beam splitter 5-2, a filter 5-3, a first PD (photodiode) 5-4, a second PD (photodiode) 5-5, and a temperature sensor 5-6. The working wavelength band of the optical fiber collimator is 1508~1598nm, and the spot diameter <0.2mm; the beam splitter is coated with a depolarization film, the beam splitting ratio is 50%, the polarization dependence of transmission ≤0.1%, the polarization dependence of reflection ≤0.1%, and the transmission surface is coated with an anti-reflection film with a transmittance >99%; the filter is a band-pass filter film system, the central wavelength is 1510~1590nm, the full width at half maximum ≥20nm, the transmission surface is coated with an anti-reflection film with a transmittance >99%, and the material is preferably WMS-15 material, which is used to reduce the central wavelength drift caused by thermal expansion.

[0025] The demodulated wavelength is jointly determined by the PD values of two channels and the temperature value. In the formula, A and B are uniquely determined by the temperature T, and U1 and U2 are the powers of the first PD and the second PD.

[0026]

[0027] During operation, the optical emission module 1 emits broadband light in the C / L band to the optical transmission coupling module 2, and then enters the optical channel selection module 3 through the optical transmission coupling module 2. The optical channel selection module 3 sequentially selects and closes each channel at a certain frequency. Each channel is connected to a sensing unit 4 for measuring various parameters. The sensing unit returns the real-time status of various parameters (such as strain, temperature, and vibration) in the form of wavelength. After passing through the optical channel selection module 3 and the optical transmission coupling module 2, it enters the filter demodulation module 5. The optical channel selection module performs time-domain switching of each channel at a certain frequency. Finally, the filter demodulation is used to filter and demodulate the wavelength of each channel, and the magnitude of the measured physical quantity is determined through the calibration relationship between the wavelength and the physical quantity.

[0028] Each embodiment in this specification is described in a progressive manner. The same or similar parts between each embodiment can be referred to each other, and the key points of each embodiment are the differences from other embodiments. In particular, for the device embodiment, the above description is only the preferred embodiment of the present invention. Since it is basically similar to the method embodiment, the description is relatively simple. For the relevant parts, refer to the partial description of the method embodiment. The above is only the specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of changes or substitutions for those of ordinary skill in the art. Without departing from the principle of the present invention, they should all be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A low-cost fiber optic sensing device applicable to multi-channel and multi-parameter monitoring, characterized in that: It includes an optical emission module, an optical transmission coupling module, an optical channel selection module, a sensing unit, and a filtering and demodulation module. The light emitted by the optical emission module is directed towards the optical transmission coupling module, and the optical transmission coupling module splits the received light into the optical channel selection module and the filtering and demodulation module; the optical channel selection module has several selectively connected optical paths, each optical path is connected to a sensing unit, and the sensing unit is a wavelength feedback type fiber optic sensor; the filtering and demodulation module includes a fiber collimator, a beam splitter, and a filter arranged in sequence along the optical path direction. Photoelectric diodes are arranged in both the beam splitting direction of the beam splitter and the filtering direction of the filter.

2. The low-cost fiber optic sensing device applicable to multi-channel and multi-parameter monitoring according to claim 1, wherein: The wavelength feedback type fiber optic sensor is of FBG type, diffraction grating type or F-P type.

3. The low-cost optical fiber sensing device applicable to multi-channel and multi-parameter monitoring according to claim 1, characterized in that: The optical transmission coupling module adopts an N×M tapered coupler, an N-port circulator or an N×M PLC splitter.

4. The low-cost fiber optic sensing device applicable to multi-channel and multi-parameter monitoring according to claim 1, characterized in that: The optical channel selection module selectively turns on or off a specified optical path as needed, and the number of channels is 2 to 128, including but not limited to mechanical optical switches, magneto-optical switches, and silicon-based electro-optic switches.

5. The low-cost fiber optic sensing device applicable to multi-channel and multi-parameter monitoring according to claim 1 or 4, characterized in that: The optical channel selection module provides a switching speed of not less than 10 Hz.

6. The low-cost fiber optic sensing device applicable to multi-channel and multi-parameter monitoring according to claim 1, characterized in that: The optical emission module is a C-band broadband light source, including but not limited to an ASE light source and an SLED light source.

7. The low-cost fiber optic sensing device applicable to multi-channel and multi-parameter monitoring according to claim 1, characterized in that: The filtering and demodulation module integrates functions such as beam splitting, filtering, photoelectric conversion, and temperature monitoring. A beam splitting structure, an optical filtering structure, a photodiode component, and a temperature sensor are integrated on a chip.

8. The low-cost fiber optic sensing device applicable to multi-channel and multi-parameter monitoring according to claim 1 or 7, characterized in that: In the filtering and demodulation module, the operating wavelength band of the fiber collimator is 1508~1598 nm, and the spot diameter <0.2 mm.

9. The low-cost fiber optic sensing device applicable to multi-channel and multi-parameter monitoring according to claim 1 or 7, characterized in that: In the filtering and demodulation module, the beam splitter is coated with a depolarization film, the beam splitting ratio is 50%, the polarization dependence of transmission ≤0.1%, the polarization dependence of reflection ≤0.1%, and an antireflection film with a transmittance of >99% is coated on the transmission surface.

10. The low-cost optical fiber sensing device applicable to multi-channel and multi-parameter monitoring according to claim 1 or 7, characterized in that: In the filtering and demodulation module, the filter is a band-pass filter film system, the central wavelength is 1510~1590 nm, the full width at half maximum ≥20 nm, and an antireflection film with a transmittance of >99% is coated on the transmission surface.

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