Optical path structure of optical fiber hydrophone array based on time division multiplexing technology

Abstract

The invention relates to an optical path structure of an optical fiber hydrophone array based on a time division multiplexing technology. The optical path structure comprises a laser, a 2N-channel time division multiplexing array and a photoelectric detector, the 2N-channel time division multiplexing array comprises 2N-1 2-channel time division multiplexing basic modules; the 2N channel time division multiplexing array is divided into two 2N-1 channel time division multiplexing arrays by a 2N-1 level downlink coupler; all downlink couplers have the characteristic of power equalization; the output end of the laser is connected with the 2N-1-level lower-level coupler through a transmission optical fiber, and the laser is used for inputting an original optical signal into the 2N-channel time division multiplexing array for transmission of 2N optical paths. Compared with a traditional cascade type time division multiplexing optical path, it can be ensured that the number of couplers passed by each stage of time division optical path is completely the same, and downlink couplers have the power sharing characteristic; and due to high path symmetry, the problem of time-division loss inconsistency caused by coupler process deviation is effectively eliminated from the source.

Description

Technical Field

[0001] This invention belongs to the field of fiber optic sensing technology, and particularly relates to an optical path structure of a fiber optic hydrophone array based on time-division multiplexing technology. Background Technology

[0002] With the increasing maturity of fiber optic hydrophone technology and the continuous improvement of application demands, the scale of fiber optic hydrophone arrays is constantly expanding, and the fiber optic transmission distance is extending to hundreds of kilometers. However, the increase in transmission distance and the continuous expansion of fiber optic hydrophone array scale have led to a significant increase in system optical loss. To ensure that the fiber optic hydrophone array can effectively detect weak acoustic signals, it is necessary to minimize optical loss and noise accumulation and improve the transmission signal-to-noise ratio. At the same time, the fiber optic hydrophone system also needs to have high reliability, including redundant design and failure-resistant design, to ensure long-term operation.

[0003] Array loss and its consistency are core performance indicators for fiber optic hydrophone systems. Poor loss consistency directly leads to increased system noise and ultimately limits the system's fundamental detection capability, core positioning accuracy, and overall availability. In traditional time-division multiplexing fiber optic hydrophone arrays, multiple elements share a single fiber, creating a single point of failure risk in the architecture. This makes the overall system reliability highly dependent on the quality of each fiber optic splice, ultimately resulting in poor overall system reliability. Furthermore, the time-division loss of each stage is limited by the splitting ratio of the coupler in the previous stage's optical path. Due to differences in manufacturing processes among different manufacturers, the actual splitting ratio of the devices typically has an error of about 1% to 2%, making it difficult to effectively guarantee the consistency of the array's time-division loss. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides an optical path structure for a fiber optic hydrophone array based on time-division multiplexing technology.

[0005] The technical solution adopted in this invention is:

[0006] Firstly, an optical path structure for a fiber optic hydrophone array based on time-division multiplexing technology is provided, including:

[0007] Laser, 2 N Channel time-division multiplexing array and photodetector;

[0008] 2 N The channel time-division multiplexing array includes 2 N-1 A 2-channel time-division multiplexing basic module;

[0009] The 2-channel time-division multiplexing basic module is divided into two optical paths by a single downlink coupler;

[0010] 2 NThe channel time division multiplexing array consists of 2 N-1 The downlink coupler is divided into two 2-stage couplers. N-1 Channel time-division multiplexing array; 2 N-1 The channel time division multiplexing array consists of 2 N-2 The downlink coupler is divided into two 2-stage couplers. N-2 Channel time-division multiplexing array; cascaded subdivision into a 4-channel time-division multiplexing array is divided into two 2-channel time-division multiplexing basic modules by a two-stage downlink coupler; all downlink couplers have power sharing characteristics;

[0011] The output of the laser is connected to 2 optical fiber. N-1 The lower-level coupler is connected to input the raw optical signal into stage 2. N Channel time-division multiplexing array for 2 N One optical path transmission;

[0012] Photodetector via 2 N The output of the channel time-division multiplexing array receives 2 N The optical signals from the optical paths are synthesized and then converted into electrical signals through photoelectric conversion.

[0013] Furthermore, the 2-channel time-division multiplexing basic module includes:

[0014] The system includes a first-stage downlink coupler, a first-stage fiber optic hydrophone unit, a second-stage fiber optic hydrophone unit, a first-stage fiber optic delay coil, and a first-stage uplink coupler.

[0015] Furthermore, the input of the first-stage downlink coupler is connected to one output of the second-stage downlink coupler to receive the first-stage optical signal;

[0016] The two outputs of the first-stage downlink coupler are connected to the first fiber optic hydrophone unit and the second fiber optic hydrophone unit, respectively, to split the first-stage optical signal into the first optical signal and the second optical signal.

[0017] The first optical signal enters the first fiber optic hydrophone unit, and the second optical signal enters the second fiber optic hydrophone unit.

[0018] Furthermore, the output of the second fiber optic hydrophone unit is connected to the first-stage fiber optic delay coil;

[0019] The preset delay of the first-stage fiber delay coil is T.

[0020] Furthermore, the first-stage uplink coupler is connected to the output end of the first fiber optic hydrophone unit and the first-stage fiber optic delay coil, and is used to synthesize the optical signal passing through the first fiber optic hydrophone unit and the optical signal passing through the second fiber optic hydrophone unit and the first-stage fiber optic delay coil to obtain a first-stage synthesized optical signal.

[0021] Furthermore, the first fiber optic hydrophone unit and the second fiber optic hydrophone unit are symmetrically arranged on both sides of the primary downlink coupler.

[0022] The beneficial effects achieved by this invention are as follows:

[0023] The optical path structure of a fiber optic hydrophone array based on time-division multiplexing technology includes a laser, 2 N Channel time-division multiplexing array and photodetector; 2 N The channel time-division multiplexing array includes 2 N-1 A 2-channel time-division multiplexing basic module; the 2-channel time-division multiplexing basic module is divided into two optical paths by a single downlink coupler; 2 N The channel time division multiplexing array consists of 2 N-1 The downlink coupler is divided into two 2-stage couplers. N-1 Channel time-division multiplexing array; 2 N-1 The channel time division multiplexing array consists of 2 N-2 The downlink coupler is divided into two 2-stage couplers. N-2 A channel time-division multiplexing array; cascaded subdivision into a 4-channel time-division multiplexing array is divided into two 2-channel time-division multiplexing basic modules by a two-stage downlink coupler; all downlink couplers have power-sharing characteristics; the laser output is connected to a 2-channel time-division multiplexing array via a transmission fiber. N-1 The lower-level coupler is connected to input the raw optical signal into stage 2. N Channel time-division multiplexing array for 2 N One optical path transmission; the photodetector passes through 2 N The output of the channel time-division multiplexing array receives 2 N The optical signals from each optical path are synthesized and converted into electrical signals through photoelectric conversion. Compared with traditional cascaded time-division multiplexed optical paths, this invention can ensure that the number of couplers traversed by each stage of the time-division optical path is exactly the same, and that the downlink couplers all have power-sharing characteristics; the high path symmetry effectively eliminates the problem of inconsistent time-division losses caused by coupler process deviations from the source;

[0024] The first and second fiber optic hydrophone units are symmetrically positioned on both sides of the first-stage downlink coupler, enabling optical path matching between the two optical signals output by the coupler, thereby further ensuring the array's loss performance and channel consistency. Attached Figure Description

[0025] Figure 1 This is a diagram of the optical path structure of the 8TDM array of the present invention;

[0026] Figure 2 This is a diagram of the optical path structure of the 2TDM basic module of the present invention;

[0027] Figure 3 This is a diagram of the optical path structure of a traditional 8TDM array.

[0028] The attached figures are labeled as follows:

[0029] 1 is a three-stage downlink coupler, 2 and 5 are two-stage downlink couplers, 3, 4, 6 and 7 are all one-stage downlink couplers, 10 is a three-stage uplink coupler, 9 and 13 are two-stage uplink couplers, 8, 11, 12 and 14 are all one-stage uplink couplers, 15, 16 and 17 are transmission optical fibers, 18 is an optical fiber fusion splice, 19 is a one-stage optical fiber delay coil, 20 is a two-stage optical fiber delay coil, and 21 is a three-stage optical fiber delay coil. Detailed Implementation

[0030] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0031] In this invention, 2 N The channel time-division multiplexing array contains 2 N-1 A basic 2-channel time-division multiplexing module, for ease of demonstration, is shown below. Figure 1 The array uses N=3, which is four 2-channel time-division multiplexing (2TDM) basic modules to form an 8TDM array.

[0032] like Figure 1 As shown, this embodiment of the invention provides an optical path structure for a fiber optic hydrophone array based on time-division multiplexing technology, including:

[0033] Laser, 2 N TDM array and photodetector; specifically, N=3;

[0034] 2 N TDM arrays include 2 N-1 One 2TDM basic module;

[0035] The 2TDM basic module is divided into two optical paths by a single downlink coupler;

[0036] 2 N TDM array consists of 2 N-1 The downlink coupler is divided into two 2-stage couplers. N-1 TDM array; 2 N-1 TDM array consists of 2 N-2 The downlink coupler is divided into two 2-stage couplers. N-2 TDM array; cascaded subdivision into a 4TDM array is divided into two 2TDM basic modules by a two-level downlink coupler; all downlink couplers have power sharing characteristics; specifically, all downlink couplers are 50% couplers;

[0037] The output of the laser is connected to 2 optical fiber. N-1 The lower-level coupler is connected to input the raw optical signal into stage 2.N TDM array performs 2 N One optical path transmission;

[0038] Photodetector via 2 N The output of the TDM array receives 2 N The optical signals from the optical paths are synthesized and then converted into electrical signals through photoelectric conversion.

[0039] exist Figure 1 In the diagram, S1 is the first fiber optic hydrophone unit, S2 is the second fiber optic hydrophone unit, S3 is the third fiber optic hydrophone unit, S4 is the fourth fiber optic hydrophone unit, S5 is the fifth fiber optic hydrophone unit, S6 is the sixth fiber optic hydrophone unit, S7 is the seventh fiber optic hydrophone unit, and S8 is the eighth fiber optic hydrophone unit.

[0040] 1 is a three-stage downlink coupler, 2 and 5 are two-stage downlink couplers, and 3, 4, 6 and 7 are all single-stage downlink couplers;

[0041] 10 is a three-stage uplink coupler, 9 and 13 are two-stage uplink couplers, and 8, 11, 12 and 14 are all single-stage uplink couplers;

[0042] 15, 16, and 17 all represent transmission optical fibers; 18 represents an optical fiber fusion splice, and the red X mark indicates that the optical fiber fusion splice is broken.

[0043] 19 represents the first-level fiber delay coil, 20 represents the second-level fiber delay coil, and 21 represents the third-level fiber delay coil.

[0044] like Figure 2 As shown, from Figure 1 We will select one 2TDM basic module for explanation, including:

[0045] The system includes a first-stage downlink coupler 3, a first-stage fiber optic hydrophone unit S1, a second-stage fiber optic hydrophone unit S2, a first-stage fiber optic delay coil 19, and a first-stage uplink coupler 8.

[0046] The input terminal of the first-stage downlink coupler 3 is connected to one output terminal of the second-stage downlink coupler 2 to receive the first-stage optical signal;

[0047] The two output terminals of the first-level downlink coupler 3 are connected to the first fiber optic hydrophone unit S1 and the second fiber optic hydrophone unit S2 respectively, and are used to split the first-level optical signal into the first optical signal and the second optical signal.

[0048] The first optical signal enters the first fiber optic hydrophone unit S1, and the second optical signal enters the second fiber optic hydrophone unit S2;

[0049] The output of the second fiber optic hydrophone unit S2 is connected to the first-stage fiber optic delay coil 19.

[0050] The preset delay of the first-level fiber delay coil 19 is T, the delay of the second-level fiber delay coil 20 in the 4TDM array is 2T, and the delay of the third-level fiber delay coil 21 in the 8TDM array is 4T.

[0051] The first-level uplink coupler 3 is connected to the output end of the first fiber optic hydrophone unit S1 and the first-level fiber optic delay coil 19, and is used to synthesize the optical signal passing through the first fiber optic hydrophone unit S1 with the optical signal passing through the second fiber optic hydrophone unit S2 and the first-level fiber optic delay coil 19 to obtain a first-level synthesized optical signal.

[0052] The first fiber optic hydrophone unit S1 and the second fiber optic hydrophone unit S2 are symmetrically arranged on both sides of the first-stage downlink coupler 3.

[0053] To demonstrate the advantages of the present invention, Figure 1 The optical path structure of the 8TDM array shown is similar to that of the TDM array. Figure 3 The optical path structure of the traditional 8TDM array shown is compared and analyzed for array loss, and the following table is obtained:

[0054]

[0055] In Table 1 above, each time division corresponds to an optical path. The optical path loss consistency of the 8TDM array of the present invention is 0.99dB less than that of the traditional 8TDM array, which theoretically ensures the optical path loss consistency of the array.

[0056] It should be noted that, in Figure 1 In the process, when fiber optic splice 18 fails, it only affects the second time slot; the other time slots function normally. Figure 3 In the conventional 8TDM array optical path structure shown, the same fault will cause all subsequent time divisions (the second time division and beyond) to fail, with only the first time division able to maintain operation. Therefore, the optical path structure of the 8TDM array of the present invention demonstrates higher reliability.

[0057] In summary, the beneficial effects achieved by the optical path structure of the fiber optic hydrophone array based on time-division multiplexing technology of the present invention are as follows:

[0058] The optical path structure of a fiber optic hydrophone array based on time-division multiplexing technology includes a laser, 2 N Channel time-division multiplexing array and photodetector; 2 N The channel time-division multiplexing array includes 2 N-1 A 2-channel time-division multiplexing basic module; the 2-channel time-division multiplexing basic module is divided into two optical paths by a single downlink coupler; 2 N The channel time division multiplexing array consists of 2 N-1 The downlink coupler is divided into two 2-stage couplers.N-1 Channel time-division multiplexing array; 2 N-1 The channel time division multiplexing array consists of 2 N-2 The downlink coupler is divided into two 2-stage couplers. N-2 A channel time-division multiplexing array; cascaded subdivision into a 4-channel time-division multiplexing array is divided into two 2-channel time-division multiplexing basic modules by a two-stage downlink coupler; all downlink couplers have power-sharing characteristics; the laser output is connected to a 2-channel time-division multiplexing array via a transmission fiber. N-1 The lower-level coupler is connected to input the raw optical signal into stage 2. N Channel time-division multiplexing array for 2 N One optical path transmission; the photodetector passes through 2 N The output of the channel time-division multiplexing array receives 2 N The optical signals from each optical path are synthesized and converted into electrical signals through photoelectric conversion. Compared with traditional cascaded time-division multiplexed optical paths, this invention can ensure that the number of couplers traversed by each stage of the time-division optical path is exactly the same, and that the downlink couplers all have power-sharing characteristics; the high path symmetry effectively eliminates the problem of inconsistent time-division losses caused by coupler process deviations from the source;

[0059] The first and second fiber optic hydrophone units are symmetrically positioned on both sides of the first-stage downlink coupler, enabling optical path matching between the two optical signals output by the coupler, thereby further ensuring the array's loss performance and channel consistency.

[0060] The above are merely embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of the claims of the present invention pending approval.

Claims

1. An optical path structure for a fiber optic hydrophone array based on time-division multiplexing technology, characterized in that, include: Laser, 2 N Channel time-division multiplexing array and photodetector; The 2 N The channel time-division multiplexing array includes 2 N-1 A 2-channel time-division multiplexing basic module; The 2-channel time-division multiplexing basic module is divided into two optical paths by a single downlink coupler; The 2 N The channel time division multiplexing array consists of 2 N-1 The downlink coupler is divided into two 2-stage couplers. N-1 Channel time-division multiplexing array; the 2 N-1 The channel time division multiplexing array consists of 2 N-2 The downlink coupler is divided into two 2-stage couplers. N-2 Channel time division multiplexing array; cascaded subdivision into a 4-channel time division multiplexing array is divided into two 2-channel time division multiplexing basic modules by a two-stage downlink coupler; all downlink couplers have power sharing characteristics; The output end of the laser is connected to the 2 via a transmission optical fiber. N-1 The lower-level coupler is connected to input the raw optical signal into the 2nd stage. N Channel time-division multiplexing array for 2 N One optical path transmission; The photodetector passes through the 2 N The output of the channel time-division multiplexed array receives 2 N The optical signals from the optical paths are synthesized and then converted into electrical signals through photoelectric conversion.

2. The optical path structure of the fiber optic hydrophone array based on time-division multiplexing technology according to claim 1, characterized in that, The 2-channel time-division multiplexing basic module includes: The system includes a first-stage downlink coupler, a first-stage fiber optic hydrophone unit, a second-stage fiber optic hydrophone unit, a first-stage fiber optic delay coil, and a first-stage uplink coupler.

3. The optical path structure of the fiber optic hydrophone array based on time-division multiplexing technology according to claim 2, characterized in that, The input terminal of the first-stage downlink coupler is connected to one output terminal of the second-stage downlink coupler for receiving the first-stage optical signal; The two outputs of the first-stage downlink coupler are respectively connected to the first fiber optic hydrophone unit and the second fiber optic hydrophone unit, and are used to split the first-stage optical signal into a first optical signal and a second optical signal. The first optical signal enters the first fiber optic hydrophone unit, and the second optical signal enters the second fiber optic hydrophone unit.

4. The optical path structure of the fiber optic hydrophone array based on time-division multiplexing technology according to claim 3, characterized in that, The output of the second fiber optic hydrophone unit is connected to the first-stage fiber optic delay coil; The preset delay of the first-stage fiber delay coil is T.

5. The optical path structure of the fiber optic hydrophone array based on time-division multiplexing technology according to claim 4, characterized in that, The first-stage uplink coupler is connected to the output of the first fiber optic hydrophone unit and the first-stage fiber optic delay coil, and is used to synthesize the optical signal passing through the first fiber optic hydrophone unit and the optical signal passing through the second fiber optic hydrophone unit and the first-stage fiber optic delay coil to obtain a first-stage synthesized optical signal.

6. The optical path structure of the fiber optic hydrophone array based on time-division multiplexing technology according to claim 5, characterized in that, The first fiber optic hydrophone unit and the second fiber optic hydrophone unit are symmetrically arranged on both sides of the first-stage downlink coupler.

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