Low-cost wavelength multiplexing demodulation equipment

Abstract

The utility model provides low-cost wavelength multiplexing demodulation equipment, which comprises a light emitting module, a light transmission module, a light sensing unit and a light demodulation module, broadband light emitted by the light emitting module faces the light transmission module, and the light transmission module splits the received broadband light to the light sensing unit and the light demodulation module; the optical sensing unit is a wavelength feedback type optical fiber sensor string formed by a plurality of wavelength feedback type optical fiber sensors, the optical demodulation module comprises a metal tube shell, and an optical fiber collimator, a beam splitter and a plurality of optical filters are sequentially arranged in the metal tube shell in the optical fiber propagation direction. And photoelectric conversion chips are arranged in the light splitting direction of the light splitting sheet and the light filtering direction of each light filter. According to the utility model, the channel multiplexing capability of edge filtering demodulation wavelength is improved, and the device has the advantages of low cost, strong multiplexing capability, easy equipment miniaturization and the like, and provides a feasible new idea for fiber grating multiplexing networking and engineering application.

Description

Technical Field

[0001] The utility model relates to the field of optical sensors, and specifically relates to a low-cost wavelength multiplexing demodulation device. Background Technique

[0002] As an optical sensor, the fiber grating has many advantages such as high sensitivity, small volume, anti-electromagnetic interference, high temperature resistance, and corrosion resistance, and has been widely used in fiber optic sensing fields such as engineering structure monitoring, geological exploration, military, and security.

[0003] In point measurement scenarios, fiber grating sensors are generally wavelength feedback optical sensors, that is, the physical quantities of the external environmental field are inversely measured through the change of wavelength. However, the actual direct detection method cannot directly read the wavelength information, and the wavelength information can only be demodulated through the change of light intensity. Common fiber grating demodulation methods include the tunable light source method, the tunable filter method, the edge filtering method, the diffraction grating + CCD method, the matching grating method, the interference measurement method, etc. The tunable light source method, the tunable filter method, and the interference measurement method have the advantages of high precision, suitability for multiplexing networking, and a relatively large demodulation range, but the cost is relatively high; the diffraction grating + CCD scheme is suitable for single-channel multi-channel multiplexing. When there are multiple channels, a matrix CCD needs to be used, and the cost is also high; the matching grating method has a small dynamic range and is not suitable for large-range measurement scenarios; the edge filtering method has a flexible implementation scheme and can be flexibly selected according to different filtering devices, such as the bulk filter method, the long-period fiber grating method, the AWG method, the WDM method, the ASE method, etc. Therefore, edge filtering is often used in low-cost and large-range application scenarios.

[0004] Although the edge filtering method has advantages in demodulating fiber gratings, its disadvantages are also obvious. When demodulating fiber gratings by the edge filtering method, it mainly utilizes the different transmittances of different wavelengths in the linear interval of the rising edge or falling edge of the filter, and calibrates the wavelength through the ratio of the optical power intensities, effectively eliminating the influence of the power jitter of the light source system on the wavelength. The system generally uses a broadband light source, such as the C band or the C + L band. However, the dynamic change range of an actual single-channel fiber grating sensor may be very small, perhaps only a few nm. When the number of channels gradually increases, the single-channel demodulation cost will increase. When multiplexing single-channel multi-channels, it is difficult to demodulate, thus restricting the multiplexing networking ability of the edge filtering scheme. Content of the Utility Model

[0005] In order to solve the problems of the prior art, the utility model provides a low-cost wavelength multiplexing demodulation device, which improves the channel multiplexing ability of edge filtering to demodulate wavelengths, has the advantages of low cost, strong multiplexing ability, and easy miniaturization of the device, and provides a feasible new idea for fiber grating multiplexing networking and engineering applications.

[0006] The utility model provides a low-cost wavelength multiplexing demodulation device, which includes an optical emission module, an optical transmission module, an optical sensing unit and an optical demodulation module. The broadband light emitted by the optical emission module is directed towards the optical transmission module, and the optical transmission module splits the received broadband light into the optical sensing unit and the optical demodulation module; the optical sensing unit is a wavelength feedback type fiber optic sensor string formed by a plurality of wavelength feedback type fiber optic sensors, and the optical demodulation module includes a metal housing. Inside the metal housing, an optical fiber collimator, a beam splitter and a plurality of optical filters are sequentially arranged along the optical fiber propagation direction. Photoelectric conversion chips are arranged in the splitting direction of the beam splitter and in the filtering direction of each optical filter.

[0007] Further improvement, the wavelength feedback type fiber optic sensor is of fiber grating type or FP type, and the dynamic range of the wavelength feedback type fiber optic sensor is (i = 1~n). In the wavelength feedback type fiber optic sensor string, the dynamic ranges of the series-connected wavelength feedback type fiber optic sensors have no overlapping regions.

[0008] Further improvement, in the optical demodulation module, the central wavelength of each optical filter is , and the 3dB bandwidth is (i = 1~n), and there is no overlapping region in the 4-4-n bandwidth range of each filter.

[0009] Further improvement, the optical demodulation module also includes a temperature sensor and a TEC substrate.

[0010] Further improvement, the broadband light emitted by the optical emission module includes, but is not limited to, an ASE light source and an SLED in the C band or C+L band, and the effective spectral range is Δλ.

[0011] Further improvement, the optical transmission module is an optical waveguide chip integrated module, which adopts 1*N PLC and 1*2*N PLC optical waveguide integration or is a split-fused beam splitting and coupling device.

[0012] Further improvement, the optical demodulation module adopts on-chip integrated packaging, the reflectivity of the beam splitter is 10%~50%, and an anti-polarization film system is plated.

[0013] The beneficial effects of the utility model are as follows:

[0014] 1. The channel multiplexing ability of the wavelength demodulation system is improved. Each channel sensor can flexibly select non-overlapping dynamic ranges within the spectral range, which is suitable for flexible simultaneous measurement of multiple parameters. Theoretically, the wider the light source bandwidth and the narrower the dynamic range of each sensor unit, the more multiplexing channels there are.

[0015] 2. The system adopts modular integrated packaging, which is beneficial to the miniaturization design of the demodulation device while reducing the system demodulation cost. The system integration degree is very high, which is beneficial to the miniaturization design of the device;

[0016] 3. One channel can simultaneously multiplex and demodulate multiple wavelengths, reducing the costs of transmission channels and demodulation channels. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. 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.

[0018] Figure 1 is the system structure diagram;

[0019] Figure 2 is the structure diagram of the optical demodulation module.

[0020] Figure 3 is the reflectivity curve of the filter. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. 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.

[0022] The structure of the present invention is as Figure 1 shown, and it consists of an optical emission module 1, an optical transmission module 2, an optical sensing unit 3 and an optical demodulation module 4; the optical emission module 1 has the function of emitting broadband light, including but not limited to ASE light sources (C band / C+L band), SLEDs, etc., and the effective spectral range is Δλ; the optical transmission module 2 has the functions of multi-channel splitting and coupling, including but not limited to multi-channel optical waveguide chip integration modules, split and fused beam splitting and coupling devices; the optical sensing unit 3 is a wavelength feedback type fiber optic sensor string, including but not limited to fiber grating type, FP type, etc., and the dynamic range of a single sensor is (i = 1~n), and the dynamic ranges of the series-connected sensors have no overlapping regions;

[0023] The optical demodulation module 4 is as Figure 2As shown in the figure, it has the function of multi-channel demodulation of different wavelengths, mainly including a metal package 4-7, an optical fiber collimator 4-1, a beam splitter 4-2, n filters (including a first filter 4-4-1, a second filter to an nth filter 4-4-n), n photoelectric conversion chips (including a first photoelectric conversion chip 4-3-1, a second photoelectric conversion chip to an nth photoelectric conversion chip 4-3-n), a temperature sensor 4-5, a TEC substrate, etc. The beam splitter 4-2 has the functions of depolarization and beam splitting. The central wavelength of each filter 4-4-n is , and the 3dB bandwidth is (i = 1~n), and there is no overlapping area in the bandwidth range of each filter 4-4-n.

[0024] During operation, the optical emission module 1 emits broadband light with a spectral range of λ. After passing through the optical transmission module 2, it is divided into several paths N. Each path is composed of n wavelength feedback sensors 3 connected in series. After the wavelength feedback sensor 3 senses the physical quantities of the external environment field (such as strain, vibration, temperature, etc.), it is converted into a change in wavelength quantity. Then, after passing through the optical transmission module 2, it enters the optical demodulation module 4. The optical demodulation module 4 obtains a series of optical powers U1, U2...Un according to the photoelectric conversion chip 4-3-n, and the temperature sensor obtains the current temperature T. The system parameters have the following relationships:

[0025]

[0026] During actual wavelength demodulation, there are the following relationships:

[0027]

[0028] Among them, and are temperature-related constants, and the results can be obtained through environmental temperature calibration.

[0029] Specifically implemented:

[0030] The optical emission module is a C-band broadband light source, including but not limited to an ASE light source (C / C+L band), an SLED light source;

[0031] The optical transmission module is an integrated optical device of an optical waveguide chip, using 1*N PLC and 1*2*N PLC optical waveguide integration, which can provide N-way beam splitting and coupling functions;

[0032] The sensing unit module is composed of N wavelength feedback fiber optic sensors, including but not limited to using FBG type, F-P cavity type, etc.

[0033] The optical demodulation module is composed of a metal package, an optical fiber collimator, a beam splitter, a filter, a photoelectric conversion chip, a temperature sensor, and a TEC substrate. The central wavelength of each filter 4-4-n is , and the 3dB bandwidth is (i = 1 to n), the bandwidth ranges of each filter have no overlapping regions. As Figure 3 shown, when in use, the rising edge or falling edge of the curve can be selected for filtering processing. Specifically, 4 filters are used, and 4 channels with a dynamic range ≥ 5 nm can be demodulated simultaneously.

[0034] Each embodiment in this specification is described in a progressive manner. For the same and similar parts between the embodiments, reference can be made to each other. The key point of each embodiment is to illustrate 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, reference can be made to the partial description of the method embodiment. The above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. For any person skilled in the art within the technical scope disclosed by the present invention, for those of ordinary skill in the art in this technical field, any changes or substitutions that can be easily thought of without departing from the principle of the present invention should 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 wavelength multiplexing demodulation device, characterized in that: It includes an optical emission module, an optical transmission module, an optical sensing unit and an optical demodulation module. The broadband light emitted by the optical emission module is directed towards the optical transmission module, and the optical transmission module splits the received broadband light into the optical sensing unit and the optical demodulation module; the optical sensing unit is a wavelength feedback type fiber optic sensor string formed by a plurality of wavelength feedback type fiber optic sensors, and the optical demodulation module includes a metal package. Inside the metal package, an optical fiber collimator, a beam splitter and a plurality of optical filters are sequentially arranged along the optical fiber propagation direction. Photoelectric conversion chips are arranged in the splitting direction of the beam splitter and in the filtering direction of each optical filter.

2. The low-cost wavelength division multiplexing demodulation device according to claim 1, wherein: The wavelength feedback type fiber optic sensor is of fiber grating type or F-P cavity type.

3. The low-cost wavelength multiplexing demodulation device according to claim 1, characterized in that: The dynamic range of the wavelength feedback type fiber optic sensor is , where i = 1 to n.

4. The low-cost wavelength multiplexing demodulation device according to claim 1 or 3, characterized in that: In the wavelength feedback type fiber optic sensor string, the dynamic ranges of the serially connected wavelength feedback type fiber optic sensors have no overlapping regions.

5. The low-cost wavelength multiplexing demodulation device according to claim 1, characterized in that: In the optical demodulation module, the central wavelength of each optical filter is , and the 3dB bandwidth is , where i = 1 to n.

6. The low-cost wavelength multiplexing demodulation device according to claim 1 or 5, characterized in that: In the optical demodulation module, the bandwidth ranges of each filter have no overlapping regions.

7. The low-cost wavelength multiplexing demodulation device according to claim 1, wherein: The optical demodulation module further includes a temperature sensor and a TEC substrate.

8. The low-cost wavelength multiplexing demodulation device according to claim 1, characterized in that: The broadband light emitted by the optical emission module includes, but is not limited to, an ASE light source and an SLED in the C band or the C+L band, and the effective spectral range is Δλ.

9. The low-cost wavelength multiplexing demodulation device according to claim 1, wherein: The optical transmission module is an optical waveguide chip integrated module, and is integrated by 1*N PLC and 1*2*N PLC optical waveguides or is a split and fused beam splitting and coupling device.

10. The low-cost wavelength multiplexing demodulation device according to claim 1, characterized in that: The optical demodulation module adopts on-chip integrated packaging, the reflectivity of the beam splitter is 10% - 50%, and an anti-polarization film system is plated.

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