Ultra-high-speed fiber Bragg grating bevel intensity type demodulation device and method

Abstract

The invention discloses an ultra-high-speed fiber grating bevel intensity type demodulation device, comprising a broadband light source, an optical fiber splitter, a detector, an acquisition card and a computer. The broadband light source is connected to the optical fiber splitter, and the optical fiber splitter is also connected to a high-power erbium-doped optical fiber amplifier 1, a high-power erbium-doped optical fiber amplifier 2, a high-power erbium-doped optical fiber amplifier 3 and a high-power erbium-doped optical fiber amplifier 4 respectively. The high-power erbium-doped optical fiber amplifier 1, the high-power erbium-doped optical fiber amplifier 2, the high-power erbium-doped optical fiber amplifier 3 and the high-power erbium-doped optical fiber amplifier 4 are respectively connected to a coupler 1, a coupler 2, a coupler 3 and a coupler 4 in sequence. The ultra-high-speed fiber grating bevel intensity type demodulation device provided by the invention has an ultra-high-speed response frequency of 4 MHz / s, and can perform real-time solution and storage on the collected data. The ultra-high-speed fiber grating bevel intensity type demodulation device has 16 channels for simultaneous solution.

Description

Technical Field

[0001] The invention relates to the field of optical fiber technology, in particular to an ultra-high-speed optical fiber grating bevel intensity type demodulation device and method. Background Art

[0002] The fiber Bragg grating is commonly used in fiber grating, that is, FBG. Its principle is to use ultraviolet laser to irradiate the fiber core to form a grating. According to the fiber coupling model theory, when the continuous broadband light emitted by the wide-spectrum light source is injected through the transmission fiber, the light that meets the Bragg condition at the grating will be reflected, and the rest of the broadband light will continue to be transmitted. In essence, a narrowband (transmission or reflection) filter or reflector is formed in the fiber core. If there is a fiber Bragg grating next, it will be reflected at the next grating with a different central wavelength. When the central wavelength of the reflected light wave is fixed, the change in temperature or strain is linearly related to the wavelength offset. Therefore, as long as the external physical parameters (such as the temperature and strain mentioned above) are applied to the fiber Bragg grating, it can be used to modulate the fiber Bragg wavelength, thereby obtaining relevant information of the physical parameters, thus achieving the purpose of sensing.

[0003] Fiber Bragg grating sensor is a fiber optic sensor with low cost, wavelength division multiplexing capability, and the ability to work in harsh environments. It has been widely used in biotechnology, petrochemical, civil engineering and other fields. Different fiber Bragg grating signal demodulation technologies have their own advantages and disadvantages, so choosing the right demodulation technology is a key step in engineering applications. Based on the basic theory and demodulation method of fiber Bragg grating, a sensing scheme is designed to indirectly transfer the ultra-fast vibration force to the fiber Bragg grating, and then obtain relevant parameters. At present, the patents related to intensity demodulation are the Chinese patent "An intensity demodulation type fiber optic gas sensing device and its sensing method" filed on December 10, 2014 with application number 201410756602.X. And the Chinese patent "Intensity demodulation type wind speed fiber optic sensor" filed on October 14, 2015 with application number 201520791439.0. Fiber Bragg grating sensor is used to measure ultra-fast vibration frequency, and there is currently no demodulation device that can respond to ultra-fast frequency. Summary of the invention

[0004] The object of the present invention is to provide an ultra-high-speed fiber Bragg grating slant-edge intensity type demodulation device and method to solve the problems raised in the above-mentioned background technology.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] An ultra-high-speed fiber Bragg grating bevel intensity type demodulation device comprises a broadband light source, a fiber splitter, a detector, an acquisition card and a computer. The broadband light source is connected to the fiber splitter, and the fiber splitter is also connected to a high-power erbium-doped fiber amplifier 1, a high-power erbium-doped fiber amplifier 2, a high-power erbium-doped fiber amplifier 3 and a high-power erbium-doped fiber amplifier 4 respectively. The high-power erbium-doped fiber amplifier 1, the high-power erbium-doped fiber amplifier 2, the high-power erbium-doped fiber amplifier 3 and the high-power erbium-doped fiber amplifier 4 are respectively connected to a coupler 1, a coupler 2, a coupler 3 and a coupler 4 in sequence. Four sideband filters are connected to the coupler 1, the coupler 2, the coupler 3 and the coupler 4, and each sideband filter is connected to a circulator through a fiber Bragg grating. The circulator is also connected to the detector, and the detector is also connected to the computer through the acquisition card.

[0007] As a further solution of the present invention: there are 16 sideband filters, 16 fiber gratings, 16 circulators, the detector is a 16-channel detector, and the acquisition card is a 16-channel acquisition card.

[0008] As a further solution of the present invention: the coupler 1, the coupler 2, the coupler 3 and the coupler 4 are all 1*4 couplers.

[0009] As a further solution of the present invention: the optical fiber splitter is a 1*4 optical fiber splitter.

[0010] As a further solution of the present invention: the coupler 1, the coupler 2, the coupler 3 and the coupler 4 can all be replaced by 1*4 optical fiber splitters.

[0011] As a further solution of the present invention: a fiber Bragg grating sensor is provided between the sideband filter and the fiber Bragg grating.

[0012] The invention discloses an ultra-high-speed fiber Bragg grating (FBG) bevel intensity type demodulation method, comprising the following steps: step 1, a broadband light source is divided into four equal parts through a 1*4 optical fiber splitter; step 2, the broadband light is amplified through a high-power erbium-doped fiber amplifier (EDFA); step 3, the amplified broadband light is divided into four parts through a 1*4 coupler; step 4, broadband light of equal intensity at different wavelengths is converted into light of different intensity corresponding to different wavelengths through a sideband filter; step 5, the intensity of the maximum wavelength of the sideband is determined through the fiber Bragg grating; step 6, the light of different intensity is output through the circulator 1 port and the circulator 2 port; step 7, the light reflected back by the fiber Bragg grating sensor is input through the circulator 2 port; step 8, the light is output through the circulator 3 port and photoelectrically converted through a detector; step 9, the electrical signal after photoelectric conversion is collected by an acquisition card; step 10, the data after collection is high-speed resolved by the FPGA of the acquisition card; step 11, the data collected by the acquisition card is transmitted to a computer through a network cable for data processing.

[0013] Compared with the prior art, the present invention has the following beneficial effects: 1. The ultra-high-speed fiber Bragg grating intensity demodulation device has an ultra-high-speed response frequency of 4 MHz / s and can respond to ultra-fast vibrations.

[0014] 2. Ultra-high-speed fiber Bragg grating intensity demodulation device collects and stores the raw data of ultra-fast vibrations to facilitate subsequent data analysis.

[0015] 3. Ultra-high-speed fiber Bragg grating intensity demodulation device, using the FPGA of the acquisition card, can ultra-fast decode the original data.

[0016] 4. Ultra-high-speed fiber Bragg grating intensity demodulation device, with 16 measurement channels, can monitor multiple ultra-fast vibration point data simultaneously. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a schematic structural diagram of an embodiment of the present invention;

[0018] In the figure: broadband light source-1, optical fiber splitter-2, high power erbium-doped fiber amplifier 1-3, high power erbium-doped fiber amplifier 2-4, high power erbium-doped fiber amplifier 3-5, high power erbium-doped fiber amplifier 4-6, coupler 1-7, coupler 2-8, coupler 3-9, coupler 4-10, sideband filter-11, fiber grating-12, circulator-13, detector-14, acquisition card-15, computer-16. DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] Example 1: Please refer to Figure 1 In the embodiment of the present invention, an ultra-high-speed fiber Bragg grating bevel intensity type demodulation device includes a broadband light source 1, an optical fiber splitter 2, a high-power erbium-doped fiber amplifier 1 3, a high-power erbium-doped fiber amplifier 2 4, a high-power erbium-doped fiber amplifier 3 5, a high-power erbium-doped fiber amplifier 4 6, a coupler 1 7, a coupler 2 8, a coupler 3 9, a coupler 4 10, and 16 sideband filters 11 (such as Figure 1 11-1, 11-2, 11-3, 11-4, ..., 11-13, 11-14, 11-15, 11-16), 16 fiber Bragg gratings 12 (such as Figure 112-1, 12-2, 12-3, 12-4, ..., 12-13, 12-14, 12-15, 12-16), 16 circulators 13 (such as Figure 1 13-1, 13-2, 13-3, 13-4, ..., 13-13, 13-14, 13-15, 13-16), 16-channel detector 14, 16-channel acquisition card 15, computer 16. Coupler 1 7, coupler 2 8, coupler 3 9, coupler 4 104 are all 1*4 couplers. Fiber splitter 2 is a 1*4 fiber splitter.

[0021] The output end of the broadband light source 1 is connected to the input end of the optical fiber splitter 2, which is used to divide the output optical power of the broadband light source 1 into four equal parts. The output end of the optical fiber splitter 2 is connected to the input end of the high-power erbium-doped fiber amplifier 1 3, which is used for optical power amplification. The output end of the optical fiber splitter 2 is connected to the input end of the high-power erbium-doped fiber amplifier 2 4, which is used for optical power amplification. The output end of the optical fiber splitter 2 is connected to the input end of the high-power erbium-doped fiber amplifier 3 5, which is used for optical power amplification. The output end of the optical fiber splitter 2 is connected to the input end of the high-power erbium-doped fiber amplifier 4 6, which is used for optical power amplification. The output end of the high-power erbium-doped fiber amplifier 1 3 is connected to the input end of the coupler 1 7, which is used to divide the amplified broadband light into four equal parts. The output end of the high-power erbium-doped fiber amplifier 2 4 is connected to the input end of the coupler 2 8, which is used to divide the amplified broadband light into four equal parts. The output end of the high-power erbium-doped fiber amplifier 3 5 is connected to the input end of the coupler 9, which is used to divide the amplified broadband light into four equal parts. The output end of the high-power erbium-doped fiber amplifier four 6 is connected to the input end of the coupler four 10, which is used to divide the amplified broad-spectrum light into four equal parts.

[0022] The output port of the coupler 7 (such as Figure 1 The one connected to the right of coupler 1 7 is divided into four paths) and is respectively connected to the input ports of the sideband filters 11-1, 11-2, 11-3 and 11-4. Let the broadband light pass through the sideband filters. Within the bandwidth of the sideband filters, different wavelengths correspond to lights of different intensities. The output ports of coupler 2 8 are respectively connected to the input ports of the sideband filters that are independently connected. Let the broadband light pass through the sideband filters. Within the bandwidth of the sideband filters, different wavelengths correspond to lights of different intensities. The output ports of coupler 3 9 are respectively connected to the input ports of the sideband filters that are independently connected. Let the broadband light pass through the sideband filters. Within the bandwidth of the sideband filters, different wavelengths correspond to lights of different intensities. The output port of coupler 4 10 (similarly, as Figure 1 The middle coupler 10 is connected to the right and is divided into four paths, which are respectively connected to the input ports of the sideband filters independently. The wide spectrum light passes through the sideband filter. Within the bandwidth of the sideband filter, different wavelengths correspond to different intensity lights.

[0023] 16 sideband filters 11 (such as Figure 1 The output ports of 11-1, 11-2, 11-3, 11-4, ..., 11-13, 11-14, 11-15, 11-16) are respectively connected to 16 fiber Bragg gratings 12 (such as Figure 1 12-1, 12-2, 12-3, 12-4, ..., 12-13, 12-14, 12-15, 12-16) are connected to the input ports of the optical fiber gratings 12 (such as 12-1, 12-2, 12-3, 12-4, ..., 12-13, 12-14, 12-15, 12-16) in order to filter out the light with the highest wavelength, so that the highest wavelength of the hypotenuse can be determined in the measurement. Figure 1 The output ports of 12-1, 12-2, 12-3, 12-4, ..., 12-13, 12-14, 12-15, 12-16) are respectively connected to 16 circulators 13 (such as Figure 1 13-1, 13-2, 13-3, 13-4, ..., 13-13, 13-14, 13-15, 13-16). The 2nd port of the 16 circulators is used as the device output optical port, which is used to connect the fiber Bragg grating sensor outside the device. The light reflected back by the fiber Bragg grating sensor enters through the 2nd port of the 16 circulators, and then outputs from the 3rd port of the circulator. The 16 circulators 13 (such as Figure 1 The three-port outputs of 13-1, 13-2, 13-3, 13-4, ..., 13-13, 13-14, 13-15, and 13-16 are respectively connected to the input ports of the 16-channel detector 14 for photoelectric conversion. The input ports of the 16-channel detector 14 are respectively connected to the 16-channel acquisition card 15 for data collection and data analysis. The 16-channel acquisition card 15 is connected to the computer 16 via a network cable for data transmission.

[0024] Embodiment 2: Based on Embodiment 1, a coupler (e.g., Figure 1 The coupler 1 7, coupler 2 8, coupler 3 9, coupler 4 10) in the optical fiber splitter can be replaced by an optical fiber splitter (for example, Figure 1 The fiber splitter in the fiber optic splitter 2). The broadband light source and high-power erbium-doped fiber amplifier EDFA can be replaced with a high-power broadband light source. A low-band wavelength fiber grating sensor is connected behind the sideband filter to determine the lowest wavelength position of the sideband filter.

[0025] The invention discloses an ultra-high-speed fiber Bragg grating (FBG) bevel intensity type demodulation method, comprising the following steps: step 1, a broadband light source is divided into four equal parts through a 1*4 optical fiber splitter; step 2, the broadband light is amplified through a high-power erbium-doped fiber amplifier (EDFA); step 3, the amplified broadband light is divided into four parts through a 1*4 coupler; step 4, broadband light of equal intensity at different wavelengths is converted into light of different intensity corresponding to different wavelengths through a sideband filter; step 5, the intensity of the maximum wavelength of the sideband is determined through the fiber Bragg grating; step 6, the light of different intensity is output through the circulator 1 port and the circulator 2 port; step 7, the light reflected back by the fiber Bragg grating sensor is input through the circulator 2 port; step 8, the light is output through the circulator 3 port and photoelectrically converted through a detector; step 9, the electrical signal after photoelectric conversion is collected by an acquisition card; step 10, the data after collection is high-speed resolved by the FPGA of the acquisition card; step 11, the data collected by the acquisition card is transmitted to a computer through a network cable for data processing.

[0026] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0027] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. An ultra-high-speed fiber Bragg grating bevel intensity type demodulation device, comprising a broadband light source (1), a fiber splitter (2), a detector (14), an acquisition card (15) and a computer (16), characterized in that: The broadband light source (1) is connected to an optical fiber splitter (2), and the optical fiber splitter (2) is further connected to a high-power erbium-doped optical fiber amplifier 1 (3), a high-power erbium-doped optical fiber amplifier 2 (4), a high-power erbium-doped optical fiber amplifier 3 (5), and a high-power erbium-doped optical fiber amplifier 4 (6), respectively. The high-power erbium-doped optical fiber amplifier 1 (3), the high-power erbium-doped optical fiber amplifier 2 (4), the high-power erbium-doped optical fiber amplifier 3 (5), and the high-power erbium-doped optical fiber amplifier 4 (6) are respectively connected to a coupler 1 (7), a coupler 2 (8), a coupler 3 (9), and a coupler 4 (10). 10), four sideband filters (11) are connected to coupler 1 (7), coupler 2 (8), coupler 3 (9), and coupler 4 (10), each sideband filter (11) is connected to a circulator (13) via a fiber grating (12), the circulator (13) is also connected to a detector (14), and the detector (14) is also connected to a computer (16) via an acquisition card (15); a fiber grating sensor of a low-band wavelength for determining the lowest wavelength position of the sideband filter is provided between the sideband filter (11) and the fiber grating (12); Wherein, the broadband light of different wavelengths and equal intensity from the coupler 1 (7), the coupler 2 (8), the coupler 3 (9) or the coupler 4 (10) is arranged to be converted into light of different wavelengths and different intensities after passing through the sideband filter (11); the light of different wavelengths and different intensities is arranged to be determined to have the intensity of the maximum wavelength of the sideband after passing through the fiber grating (12); the light of different wavelengths and different intensities is arranged to be determined to have the lowest wavelength position of the sideband filter after passing through the fiber grating sensor of the low-band wavelength; The demodulation method of the ultra-high-speed fiber Bragg grating bevel intensity type demodulation device comprises the following steps: step 1, the broadband light source is divided into four parts by a 1*4 fiber splitter; step 2, the broadband light is amplified by a high-power erbium-doped fiber amplifier EDFA; step 3, the amplified broadband light is passed through a 1*4 coupler to divide the optical power into four parts; step 4, through a sideband filter, the broadband light of equal intensity of different wavelengths is converted into light of different intensities corresponding to different wavelengths; step 5, the intensity of the maximum wavelength of the sideband is determined by the fiber Bragg grating, and the fiber Bragg grating sensor of the low-band wavelength is used to Determine the lowest wavelength position of the sideband filter; Step 6, input through circulator 1 port, and output the light of different intensities through circulator 2 port; Step 7, the light reflected back by the fiber grating sensor is input through circulator 2 port; Step 8, output through circulator 3 port, and undergo photoelectric conversion through the detector; Step 9, the electrical signal after photoelectric conversion is collected by an acquisition card; Step 10, the collected data is high-speed solved by the FPGA of the acquisition card; Step 11, the data collected by the acquisition card is transmitted to the computer through the network cable for data processing.

2. The ultra-high-speed fiber Bragg grating bevel intensity type demodulation device according to claim 1, characterized in that: There are 16 sideband filters (11), 16 optical fiber gratings (12), 16 circulators (13), the detector (14) is a 16-channel detector, and the acquisition card (15) is a 16-channel acquisition card.

3. The ultra-high-speed fiber Bragg grating bevel intensity type demodulation device according to claim 1, characterized in that: The coupler one (7), the coupler two (8), the coupler three (9), and the coupler four (10) are all 1*4 couplers.

4. The ultra-high-speed fiber Bragg grating slant-edge intensity demodulation device according to claim 1, characterized in that: The optical fiber splitter (2) is a 1*4 optical fiber splitter.

5. The ultra-high-speed fiber Bragg grating bevel intensity type demodulation device according to claim 3, characterized in that: The coupler 1 (7), coupler 2 (8), coupler 3 (9), and coupler 4 (10) are all replaced by 1*4 optical fiber splitters.

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