Downhole optical signal transmission system and method

Abstract

The application relates to the technical field of optical signal processing, in particular to an underground optical signal transmission system and method. The system comprises an optical signal generating device, which is used for generating an optical signal in an X polarization direction and transmitting the optical signal to a polarization state regulating device through a polarization maintaining optical fiber; the polarization state regulating device is used for adjusting the polarization state of the optical signal to obtain a candidate optical signal and transmitting the candidate optical signal to a total reflection device; the total reflection device is used for performing total reflection on the candidate optical signal to obtain a total reflection optical signal; and the total reflection optical signal is transmitted to a signal processing unit through a polarization maintaining optical fiber; and the signal processing unit is used for performing polarization state detection on the total reflection optical signal to obtain target polarization state information of the total reflection optical signal. The system reduces the problems of damage and attenuation of the optical signal and improves the reliability and stability of the whole system.

Description

Technical Field

[0001] This invention relates to the field of optical signal processing technology, and more specifically to a downhole optical signal transmission system and method in the field of optical signal processing technology. Background Technology

[0002] In downhole operations, with the continuous development of intelligent mining technology, the demand for high-speed and accurate transmission of large amounts of data is becoming increasingly urgent. Traditional electrical signal transmission methods face many challenges in the complex downhole environment, such as severe electromagnetic interference and limited transmission bandwidth. In contrast, optical signal transmission, with its advantages of high bandwidth and low loss, has gradually become a research hotspot for downhole data transmission.

[0003] However, in the related technologies, the optical signal transmission optical path structure in wells is not good in terms of high temperature resistance, reflection efficiency and stability in the signal reflection stage, which results in large transmission loss and attenuation of optical signals, thus reducing the accuracy of polarization state detection of optical signals. Summary of the Invention

[0004] The purpose of this invention is to provide a downhole optical signal transmission system and method, and the specific technical solution adopted is as follows: In a first aspect, embodiments of the present invention provide a downhole optical signal transmission system, the system comprising: An optical signal generating device is used to generate an optical signal in the X-polarization direction and transmit it to a polarization state control device through a polarization-maintaining fiber. The polarization state modulation device is used to adjust the polarization state of the optical signal to obtain a candidate optical signal, and transmit the candidate optical signal to the total internal reflection device; The total internal reflection device is used to perform total internal reflection on the candidate optical signal to obtain a total internal reflection optical signal; and transmits the total internal reflection optical signal to the signal processing unit through a polarization-maintaining fiber. The signal processing unit is used to perform polarization state detection on the total internal reflection light signal to obtain the target polarization state information of the total internal reflection light signal.

[0005] Secondly, embodiments of the present invention provide a downhole optical signal transmission method, the method comprising: Generates light signals in the X-polarization direction; The polarization state of the optical signal is adjusted to obtain a candidate optical signal; The candidate optical signal is subjected to total internal reflection to obtain a total internal reflection optical signal; The polarization state of the total internal reflection light signal is detected to obtain the target polarization state information of the total internal reflection light signal.

[0006] This invention offers the following advantages: In a downhole signal transmission system, an X-polarized optical signal is generated by an optical signal generating device and transmitted to a polarization-maintaining fiber to a polarization-state modulation device. The polarization-state modulation device then adjusts the polarization state of the optical signal to obtain a candidate optical signal, which is transmitted to a total internal reflection device. This allows the candidate optical signal to be totally reflected, resulting in a totally reflected optical signal. This total internal reflection makes the totally reflected optical signal sent to the signal processing unit more accurate, reducing signal damage and attenuation. Finally, the signal processing unit detects the polarization state of the totally reflected optical signal to obtain the target polarization state information. Because the signal processing unit receives the totally reflected optical signal with high accuracy, the target polarization state information detected by the signal processing unit is also highly accurate, thereby improving the reliability and stability of the entire system. Attached Figure Description

[0007] To more clearly illustrate the technical solutions and advantages in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0008] Figure 1 This is a schematic diagram of the composition structure of a downhole optical signal transmission system provided in related technologies; Figure 2 This is a schematic diagram of the composition structure of a downhole optical signal transmission system provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of another component structure of a downhole optical signal transmission system provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of another component structure of a downhole optical signal transmission system provided in an embodiment of the present invention; Figure 5 This is a schematic diagram of the composition structure of the signal processing unit provided in an embodiment of the present invention; Figure 6 This is a schematic diagram illustrating the implementation process of a downhole optical signal transmission method provided in an embodiment of the present invention; Figure 7 This is a schematic diagram of the structure of a computer device provided in an embodiment of the present invention. Detailed Implementation

[0009] To further illustrate the technical means and effects adopted by the present invention to achieve its intended purpose, the following detailed description, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation, structure, features, and effects of a downhole optical signal transmission method proposed according to the present invention. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments may be combined from any suitable form.

[0010] In the description of the embodiments of the present invention, unless otherwise stated, " / " means "or". For example, A / B can mean A or B. The "and / or" in the text is merely a description of the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist simultaneously, and B exists alone. In addition, in the description of the embodiments of the present invention, "multiple" means two or more.

[0011] Hereinafter, the terms "first" and "second" are used for descriptive purposes only and should not be construed as implying or suggesting relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature.

[0012] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0013] In some embodiments, key technological bottlenecks still exist in downhole optical signal transmission. On the one hand, the high-temperature environment downhole poses a serious threat to the normal operation of lasers. The materials and structures of conventional lasers are prone to performance degradation at high temperatures. For example, high temperatures can cause deformation of the optical resonator structure inside the laser, reduce the quantum efficiency of the active region material, and make heat dissipation difficult, making it impossible for the laser to stably emit high-quality optical signals or even to operate, thus cutting off the source of optical signal transmission. On the other hand, although high-temperature resistant quantum dot lasers can maintain a certain operating state in high-temperature environments, they have significant shortcomings in high-speed signal propagation. The special physical mechanism of quantum dot lasers can cause problems such as complex carrier dynamics and limited modulation bandwidth during high-speed modulation, making it difficult to meet the signal transmission rate requirements of complex downhole operations for real-time transmission of large amounts of data.

[0014] Furthermore, the optical path structure for downhole optical signal transmission in related technologies also has some limitations. For example, in the signal reflection stage, the commonly used fiber optic loop structure may have room for improvement in terms of high-temperature resistance, reflection efficiency, and stability. Figure 1As shown, laser 101 generates an X-polarized optical signal, which is transmitted to PZT through polarization-maintaining fiber to adjust the polarization state of the optical signal. The optical signal after polarization adjustment is then transmitted to signal processing unit 103 through optical fiber loop 102. Due to the limitations of optical fiber loop 102, the accuracy of the optical signal transmitted to signal processing unit 103 is low.

[0015] Based on this, embodiments of the present invention provide a downhole optical signal transmission system that can effectively overcome the influence of high-temperature environments on lasers, achieve high-speed signal transmission from high-temperature resistant quantum dot lasers, and optimize the optical path structure to improve overall system performance. The specific solution of the downhole optical signal transmission system provided by the present invention is described in detail below with reference to the accompanying drawings. Please refer to... Figure 2 The document presents a schematic diagram of the composition of a downhole optical signal transmission system according to an embodiment of the present invention. The system 200 includes: The optical signal generating device 201 is used to generate an optical signal in the X-polarization direction and transmit it to the polarization state control device through a polarization-maintaining fiber.

[0016] Here, the optical signal generating device 201 can be implemented using a laser. The laser generates an X-polarized optical signal. The working principle of this downhole optical signal transmission system is based on the polarization characteristics of light, precisely controlling the optical signal. The system begins with a laser, which, as a light source, has high polarization specificity, emitting linearly polarized light at any angle. This beam of light with a specific polarization angle then enters a polarization-maintaining fiber. The polarization-maintaining fiber can simultaneously support the stable transmission of light in both X and Y polarization directions. Moreover, in the absence of external interference, the polarization-maintaining fiber can effectively maintain the initial polarization state of the light, allowing the X-polarized light emitted from the laser to be transmitted in the fiber with extremely low loss and extremely high polarization fidelity. In some possible implementations, multiple polarization-maintaining fibers can be used to transmit the optical signal in parallel to improve transmission efficiency.

[0017] The polarization state modulation device 202 is used to adjust the polarization state of the optical signal to obtain a candidate optical signal and transmit the candidate optical signal to the total internal reflection device.

[0018] Here, the polarization state control device 202 can be implemented using lead zirconate titanate piezoelectric ceramic (Pb(Zr1-xTiO3), PZT). When the optical signal is successfully transmitted to the PZT in the polarization-maintaining fiber, the PZT becomes the core element for controlling the polarization state of the light. When the non-polarization-maintaining fiber placed on the wall of the housing is not compressed, its polarization state remains unchanged; for example, it remains in the X direction, just as it does when transmitted in the polarization-maintaining fiber. However, once the PZT compresses the non-polarization-maintaining fiber placed on the wall of the housing, the refractive index of the fiber changes, which in turn causes a change in the polarization angle of the optical signal, for example, from the original X polarization angle to the Y polarization angle.

[0019] In some possible implementations, the polarization state modulation device 202 includes: a first piezoelectric ceramic, a second piezoelectric ceramic, and a third piezoelectric ceramic; wherein: The first piezoelectric ceramic is used to adjust the phase difference of the propagation of the optical signal in two orthogonal directions based on a first pressure, so as to convert the optical signal into linearly polarized light.

[0020] Here, the first piezoelectric ceramic adjusts the phase difference of the optical signal propagating in two orthogonal directions to 90° based on the first pressure, thereby converting the optical signal into linearly polarized light. For example, an optical fiber placed on the wall of a housing will experience stress birefringence when compressed by PZT. The degree of birefringence is related to the applied pressure. For the first PZT (i.e., the first piezoelectric ceramic), to produce a similar... The waveplate effect converts the input light into linearly polarized light.

[0021] The second piezoelectric ceramic is used to adjust the first pressure to obtain a second pressure; and to rotate the linearly polarized light based on the second pressure to obtain an intermediate light signal; Here, the second piezoelectric ceramic, based on the second pressure, adjusts the phase difference of the linearly polarized light propagating in two orthogonal directions to 180°, thereby rotating the linearly polarized light to obtain the intermediate optical signal; for example, the second PZT (i.e., the second piezoelectric ceramic) produces a similar... (in, The function of a waveplate (representing the wavelength of an optical signal) is to rotate the polarization direction of the optical signal by 90° between the fast and slow axes, thereby achieving the function of adjusting the polarization direction of linearly polarized light.

[0022] The third piezoelectric ceramic is used to adjust the second pressure to obtain a third pressure; and based on the third pressure, to adjust the polarization state of the intermediate optical signal to obtain the candidate optical signal.

[0023] Here, the third piezoelectric ceramic adjusts the phase difference of the candidate optical signal propagating in two orthogonal directions to 90° based on the third pressure, so as to adjust the polarization state of the intermediate optical signal and obtain the candidate optical signal.

[0024] In some possible implementations, a third PZT (i.e., a third piezoelectric ceramic) produces a similar effect. The effect of waveplates allows the polarization state of the optical signal to change further from the state after adjustment by the second PZT (i.e., the polarization state of the intermediate optical signal), and ultimately it is possible to adjust the polarization state to any desired polarization state, just like the effect of using two waveplates in succession and a combination of waveplates.

[0025] According to the theory of birefringence, when an optical fiber is subjected to a certain pressure P, a refractive index difference will be generated in the two orthogonal directions of the fiber (fast axis and slow axis). The relationship between this refractive index difference and pressure can be expressed using the material's elastic coefficient. To indicate, that is (Where, n is the original refractive index of the optical fiber). To achieve the first PZT-like... The function of a waveplate is to measure the phase difference generated by light propagating along the fast and slow axes. (This refers to the length of the fiber in the box wall (the compressed part) corresponding to the first PZT, i.e., the length of the first PZT.) (where is the wavelength of the incident light, and n is the original refractive index of the optical fiber), adjust P1 so that The second PZT needs to be produced The waveplate effect is achieved by adjusting the pressure P2 applied to the optical fiber to create a phase difference in the light propagating along the fast and slow axes. The third PZT needs to be produced. The waveplate effect is achieved by adjusting the pressure P3 applied to the optical fiber to create a phase difference in the light propagating along the fast and slow axes. This allows the polarization state of the intermediate optical signal to be adjusted by the phase difference, thereby obtaining the candidate optical signal.

[0026] In practical operation, a precise pressure sensor is needed to monitor the pressure applied by the PZT, combined with a light polarization state detection device. Based on the difference between the detected polarization state and the target polarization state, a feedback control system adjusts the driving voltage of the PZT, thereby adjusting pressures P1, P2, and P3 to achieve precise polarization state control. Thus, through the first, second, and third piezoelectric ceramics, precise adjustment of the polarization state of the optical signal can be achieved.

[0027] The total internal reflection device 203 is used to perform total internal reflection on the candidate optical signal to obtain a total internal reflection optical signal; and to transmit the total internal reflection optical signal to the signal processing unit through a polarization-maintaining fiber.

[0028] Here, the total internal reflection device includes: a surface-coated total internal reflection mirror or a prism with an isosceles right-angled triangle cross-section; wherein: The surface-coated total reflection mirror is used to prepare a metal or multilayer thin film on the surface of a preset material to perform total reflection on the candidate light signal to obtain a total reflection light signal; like Figure 3 As shown, laser 31 generates an X-polarized optical signal, which is transmitted to a PZT via a polarization-maintaining fiber for polarization state adjustment to obtain a candidate optical signal. Then, the candidate optical signal is totally reflected by a total reflection mirror 32, and the totally reflected optical signal is transmitted to the signal processing unit 33 via a polarization-maintaining fiber.

[0029] The prism, with an isosceles right triangle cross-section, is used to perform total internal reflection on the candidate optical signal based on the geometry and refractive index of the prism, so as to obtain a total internal reflection optical signal.

[0030] like Figure 4 As shown, laser 41 generates an X-polarized optical signal, which is transmitted to a PZT (polarization-maintaining optical transducer) via a polarization-maintaining fiber for polarization state adjustment to obtain a candidate optical signal. Then, the candidate optical signal is subjected to total internal reflection by a total internal reflection prism 42, and transmitted to the signal processing unit 43 via the polarization-maintaining fiber. In this way, by using a total internal reflection prism or mirror to perform total internal reflection on the candidate optical signal, and then transmitting it to the signal processing unit via a polarization-maintaining fiber, the attenuation of the optical signal can be reduced, improving accuracy.

[0031] In downhole optical systems, fiber optic loops are commonly used for optical signal transmission and processing. However, fiber optic loops are prone to bending and breakage, and the attenuation increases with fiber length. This system innovatively uses a total internal reflection structure to replace the fiber optic loop, solving the attenuation problem and avoiding the breakage issue. Total internal reflection structures mainly come in two forms: those with metal or multi-layer thin films deposited on the surface, and those with a prism having an isosceles right-angled triangle cross-section. Surface-coated total internal reflection structures utilize the optical properties of metal or multi-layer thin films on a specific material surface to achieve total internal reflection. This structure offers advantages in downhole applications, including small size, ease of installation in confined spaces, and effective reduction of signal loss during transmission. Prisms, on the other hand, utilize the prism's geometry and refractive index to achieve total internal reflection. Prisms have high reflection efficiency and stability, enabling them to adapt to harsh downhole environments such as high humidity and dust, ensuring stable optical signal transmission. By employing a total internal reflection structure, the potential damage and signal attenuation issues of fiber optic loops in complex downhole environments are overcome, improving the reliability and stability of the entire optical system.

[0032] The signal processing unit 204 is used to perform polarization state detection on the total internal reflection light signal to obtain the target polarization state information of the total internal reflection light signal.

[0033] Here, the signal processing unit undertakes the crucial task of accurately detecting and determining the polarization angle of the light returning from the well. Employing advanced photoelectric detection technology and intelligent algorithms, the unit can quickly and accurately analyze the polarization angle information of the light. After being compressed by the PZT, the light is first split into X and Y directions by the PBS, and then enters its corresponding PD to obtain the magnitude of the X and Y direction light signals. If only the X direction has a light signal and the Y direction has no signal, the signal processing unit outputs a signal of 0; conversely, if only the X direction has no light signal and the Y direction has a signal, the signal processing unit outputs a signal of 1. Through this ingenious design, utilizing the magnitude of the force applied by the PZT, effective monitoring and signal conversion of the light polarization state are achieved, constructing a complete, efficient, and accurate system for the control and detection of the light polarization state. Figure 5 As shown, the signal processing unit 204 includes: a polarizing beam splitter (PBS) 51, photodetectors (PD1 and PD2) and a computing module 52; The polarization beam splitter PBS 51 is used to separate the total internal reflection light signal into polarized light signals in two mutually perpendicular directions.

[0034] Here, the PBS 51 accurately decomposes the input polarized light (i.e., the total internal reflection light signal) into two beams of light along the X and Y directions according to its polarization characteristics. In other words, the original polarized light beam is separated into light rays in two mutually perpendicular directions after passing through the PBS, thus providing light signals in different directions for subsequent processing.

[0035] Photodetectors (PD1 and PD2) are used to convert the polarized light signal into an electrical signal.

[0036] Here, there are a total of two photodetectors (i.e. Figure 5 (PD1 and PD2 are shown). One photodetector is responsible for detecting the intensity of light in the X direction, and the other photodetector is used to detect the intensity of light in the Y direction. Through these two photodetectors, the optical signal can be converted into the corresponding electrical signal, thereby obtaining the specific quantitative values ​​of light in the X and Y directions, which facilitates subsequent numerical calculations and other operations.

[0037] The calculation module 52 is used to determine the target polarization state information of the total internal reflection light signal based on the electrical signal.

[0038] Here, the magnitudes of the light detected by the two PDs in the X and Y directions are first obtained. Then, the tangent function (tan) from trigonometric functions is used for calculation. Specifically, the value of the tan function is calculated (this value is determined based on the ratio of the light magnitudes in the X and Y directions, i.e., tan...). =Y direction light magnitude X-axis light magnitude, here This is the angle with the X direction as the base, and thus the angle with the X direction as the reference. The size. Next, the angle will be established. The correspondence between the size and the numerical range of 0-256. For example, through some linear mapping or pre-defined rules, each angle can be made... The specific value can be uniquely found within the range of 0-256, thus enabling the angle information to be converted into a specific coded value.

[0039] In this embodiment of the invention, in the downhole signal transmission system, an X-polarized optical signal is generated by an optical signal generating device and transmitted to a polarization-maintaining fiber to a polarization state control device. The polarization state control device then adjusts the polarization state of the optical signal to obtain a candidate optical signal, which is then transmitted to a total internal reflection device. This allows the candidate optical signal to be totally reflected, resulting in a totally reflected optical signal. This total internal reflection of the candidate optical signal makes the totally reflected optical signal sent to the signal processing unit more accurate, reducing signal damage and attenuation. Finally, the signal processing unit performs polarization state detection on the totally reflected optical signal to obtain the target polarization state information. Because the accuracy of the totally reflected optical signal received by the signal processing unit is high, the accuracy of the target polarization state information detected by the signal processing unit is also high, thereby improving the reliability and stability of the entire optical system.

[0040] In some possible implementations, the downhole optical signal transmission system also includes: a data conversion unit; A data conversion unit is used to convert the input initial encoded data into an initial polarization state control signal based on a preset mapping relationship, and to apply the initial polarization state control signal to the polarization state modulation device; wherein, the preset mapping relationship is used to characterize the correspondence between the polarization angle of the optical signal and the range of encoded values; The polarization state modulation device is further configured to adjust the polarization state of the optical signal based on the initial polarization state control signal to obtain the candidate optical signal; The signal processing unit is also used to restore the target polarization state information of the total internal reflection light signal into target encoded data based on the preset mapping relationship.

[0041] Here, to further improve system performance, a one-to-one correspondence is established between downhole signals and the 0-256 encoding range, constructing a direct mapping relationship between signals and digital codes. Simultaneously, the characteristic of light polarization state is introduced into the encoding system, precisely mapping the polarization angle range of 0-90 degrees to the numerical values ​​of 0-256, thus obtaining a preset mapping relationship. For example, code 0 corresponds to the light signal existing only in the X-polarization direction, while code 256 represents light propagating only in the Y-polarization direction. Through this mapping relationship, the polarization angle of light is endowed with the ability to carry information.

[0042] During the transmission of optical signals downhole, the data conversion unit converts the input initial encoded data into an initial polarization state control signal according to a preset mapping relationship, and applies the initial polarization state control signal to the polarization state modulation device.

[0043] Here, the initial encoded data is the encoded data corresponding to the set target polarization state. By converting the input initial encoded data into an initial polarization state control signal, the polarization state modulation device can adjust the polarization state of the optical signal according to the initial polarization state control signal. That is, the polarization state modulation device adjusts the polarization state of the optical signal based on the initial polarization state control signal to obtain the candidate optical signal; finally, the signal processing unit restores the target polarization state information of the total internal reflection optical signal to the target encoded data based on the preset mapping relationship, thereby improving the transmission efficiency of the optical signal.

[0044] In a specific example, taking 8-bit data transmission, each 8-bit data is assigned a specific polarization state. Specifically, the precise action of PZT on the optical signal achieves the corresponding conversion between polarization state and data. Different degrees of PZT compression cause changes in the polarization angle of the light, thus carrying different data information. Downhole, the data is converted into an optical signal with the corresponding polarization state according to a pre-set correspondence, and then transmitted in polarization-maintaining fiber. At the receiving end, the signal processing unit accurately detects the polarization state of the light and, according to pre-defined encoding rules, reverses the polarization state back to 8-bit data, thereby achieving accurate data transmission and reconstruction. This encoding method fully utilizes the polarization characteristics of light, greatly improving the utilization rate of the optical channel, and also enhancing the anti-interference capability of the signal during transmission. Each 8-bit data is precisely assigned a specific polarization state. The core of this process is the mechanism of PZT's action on light. As a piezoelectric material, PZT undergoes different degrees of mechanical deformation when different voltages are applied, thereby compressing the passing light to different degrees and ultimately changing the polarization angle of the light. By precisely controlling PZT, it is possible to finely adjust the polarization state of light, thereby enabling light to carry specific data information.

[0045] At the downhole transmitting end, the data processing system converts 8-bit data into corresponding polarization state control signals according to pre-set encoding rules. These signals are then applied to the PZT (polarization beam splitter) via a drive circuit. The PZT acts on the light according to the control signals, converting the data into optical signals with the corresponding polarization state, and couples them into optical fibers for transmission. At the receiving end, the signal processing unit uses polarization beam splitters and photodetectors to accurately detect the polarization state of the received optical signal. The detection equipment separates the optical signal according to the polarization direction and converts it into an electrical signal. Through analysis and processing of the electrical signal, the polarization angle of the light is determined. Then, according to pre-set encoding rules, the detected polarization angle is converted back into 8-bit data. This process requires the receiving end's signal processing unit to have high accuracy and stability to ensure accurate reconstruction of the data transmitted from the transmitting end.

[0046] In some possible implementations, to further improve the transmission rate, parallel transmission can also be performed through multiple optical fibers. Based on this, the data conversion unit divides the initial encoded data according to the number of optical fibers to obtain multiple divided encoded data. Among them, the multiple divided encoded data correspond one-to-one with the multiple optical fibers. Based on the preset mapping relationship, the multiple divided encoded data corresponding to the multiple optical fibers are converted into multiple initial polarization state control signals. Based on the preset mapping relationship, the signal processing unit converts the multiple initial polarization state control signals into multiple intermediate encoded data, and fuses the multiple intermediate encoded data to obtain the target encoded data.

[0047] To further improve the transmission rate and meet the extremely high reliability requirements of signal transmission in scenarios such as underground mining, this embodiment of the invention employs a scheme of transmitting 32-bit data in parallel using four optical fibers. At the transmitting end, the data conversion unit distributes the 32-bit data into the four optical fibers according to a specific rule. Specifically, the 32-bit data is evenly divided into four groups, resulting in multiple pre-defined coded data sets; each group consists of 8 bits, corresponding to one optical fiber. Each optical fiber converts its corresponding 8 bits of data into an encoding mode based on its polarization state at different angles. For example, the first optical fiber may be responsible for transmitting the high 8 bits of the data, which are then converted into an optical signal with a specific polarization state and transmitted within that fiber.

[0048] At the receiving end, the signal processing unit independently receives, detects, analyzes, and decodes the signal from each optical fiber. The signal processing unit can accurately detect and analyze the polarization state of the optical signal in the corresponding fiber, and uses digital signal processing algorithms to process the electrical signal and extract the polarization state information it carries. Then, according to the encoding rules, the polarization state information is restored to 8 bits of data. Finally, the 8 bits of data decoded by the four processing units are combined to obtain the complete 32-bit data.

[0049] This parallel transmission method not only significantly improves the transmission rate but also provides redundancy and fault tolerance due to the simultaneous transmission of data through multiple optical fibers. When one fiber fails or is interfered with, the other three fibers can still continue transmitting data, ensuring data integrity and reliability. For example, if a fiber experiences signal attenuation or distortion due to underground environmental factors, the receiving end's processing unit can analyze and process the data from the other three fibers, utilizing redundant information to recover the lost or erroneous data, ensuring the accuracy of the final received 32-bit data. Thus, the redundancy and fault tolerance mechanism is particularly important in the complex underground environment, effectively guaranteeing the stability and reliability of signal transmission and meeting the requirements of high-reliability scenarios.

[0050] This invention provides a downhole optical signal transmission method, see [link to relevant documentation]. Figure 6 , combined Figure 6 The steps shown are explained below: 601 generates an X-polarized optical signal.

[0051] Here, a laser is used to generate an X-polarized optical signal, which is then transmitted through a polarization-maintaining fiber.

[0052] 602, The polarization state of the optical signal is adjusted to obtain a candidate optical signal.

[0053] Here, the polarization state of the optical signal is adjusted by PZT to obtain the candidate optical signal.

[0054] 603, Perform total internal reflection on the candidate optical signal to obtain a total internal reflection optical signal.

[0055] Here, the candidate light signal is subjected to total internal reflection by a total internal reflection device to obtain a total internal reflection light signal.

[0056] 604. The polarization state of the total internal reflection light signal is detected to obtain the target polarization state information of the total internal reflection light signal.

[0057] First, the total internal reflection light signal is separated into a first polarized light signal and a second polarized light signal that are perpendicular to each other. For example, a photodetector (PBS) can be used to separate the total internal reflection light signal into two beams of light along the X and Y directions. The light along the X direction is the first polarized light signal, and the light along the Y direction is the second polarized light signal. Next, the first polarized light signal and the second polarized light signal are converted into first electrical signals and second electrical signals, respectively. For example, two photodetectors can be used to convert the first polarized light signal and the second polarized light signal into corresponding electrical signals, thereby obtaining the quantized values ​​of the light in the X and Y directions for subsequent numerical calculations. Finally, based on the first electrical signal and the second electrical signal, the target polarization state information of the total internal reflection light signal is determined. For example, after obtaining the magnitudes of the first electrical signal and the second electrical signal, the polarization angle of the total internal reflection light signal, i.e., the target polarization state information, is calculated using the tangent function (tan) in trigonometric functions.

[0058] In some possible implementations, the polarization angle between the first electrical signal and the second electrical signal is determined based on the first electrical signal. ,Right now The polarization angle is used as the target polarization state information of the total internal reflection optical signal. Thus, by employing a total internal reflection structure to perform total internal reflection on the candidate optical signal, polarization state detection is performed on the total internal reflection optical signal. This overcomes the problems of damage and signal attenuation that fiber optic loops may face in complex downhole environments, improving the reliability and stability of the entire optical system.

[0059] Optionally, the transmission medium can be a wired link (e.g., but not limited to, coaxial cable, optical fiber, and Digital Subscriber Line (DSL)) or a wireless link (e.g., but not limited to, Wireless Fidelity (WIFI), Bluetooth, and mobile device networks). It should be noted that the system provided in the above embodiments is only an example illustrating the division of the functional modules described above. In practical applications, the above functions can be assigned to different functional modules as needed, that is, the internal structure of the computer device can be divided into different functional modules to complete all or part of the functions described above. Furthermore, the method embodiments provided in the above embodiments belong to the same concept, and their specific implementation processes are detailed in the method embodiments, and will not be repeated here.

[0060] Figure 7 This is a schematic diagram of the structure of a computer device provided in an embodiment of the present invention. For example, as shown... Figure 7As shown, the computer device 700 includes: a memory 701, a processor 702, and a computer program 703 stored in the memory 701 and running on the processor 702, wherein when the processor 702 executes the computer program 703, the computer device can execute any of the downhole optical signal transmission methods described above.

[0061] Furthermore, this embodiment of the invention also protects a system that may include a memory and a processor. The memory stores executable program code, and the processor is used to call and execute the executable program code to perform a downhole optical signal transmission method provided by this embodiment of the invention. This embodiment can divide the system into functional modules based on the above method example. For example, each module can correspond to a specific function, or two or more functions can be integrated into a single processing module. The integrated module can be implemented in hardware. It should be noted that the module division in this embodiment is illustrative and only represents a logical functional division; other division methods may exist in actual implementation. It should also be noted that all relevant content of each step involved in the above method embodiment can be referenced to the functional description of the corresponding functional module, and will not be repeated here.

[0062] It should be understood that the system provided in this embodiment is used to execute the above-described downhole optical signal transmission method, and therefore can achieve the same effect as the above-described implementation method. When using integrated units, the system may include a processing module and a storage module. When the system is applied to a device, the processing module can be used to control and manage the device's operations. The storage module can be used to support the device in executing mutual program code, etc. The processing module may be a processor or a controller, which can implement or execute various exemplary logic blocks, modules, and circuits described in conjunction with the disclosure of this invention. The processor may also be a combination that implements computing functions, such as a combination of one or more microprocessors, a combination of Digital Signal Processing (DSP) and a microprocessor, etc., and the storage module may be a memory.

[0063] Furthermore, the system provided in the embodiments of the present invention may specifically be a chip, component, or module. The chip may include a connected processor and a memory. The memory stores instructions, and when the processor calls and executes the instructions, the chip can execute the downhole optical signal transmission method provided in the above embodiments. The system, computer-readable storage medium, computer program product, or chip provided in this embodiment are all used to execute the corresponding methods provided above. Therefore, the beneficial effects they achieve can be referred to in the beneficial effects of the corresponding methods provided above, and will not be repeated here.

[0064] Through the above description of the embodiments, those skilled in the art will understand that, for the sake of convenience and brevity, the division of the above functional modules is only used as an example. In practical applications, the above functions can be assigned to different functional modules as needed, that is, the internal structure of the system can be divided into different functional modules to complete all or part of the functions described above. In the embodiments provided by the present invention, it should be understood that the disclosed system and method can be implemented in other ways. For example, the system embodiments described above are merely illustrative. For example, the division of modules or units is merely a logical functional division. In actual implementation, there may be other division methods. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Furthermore, the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces. The indirect coupling or communication connection of the system or unit can be electrical, mechanical, or other forms.

[0065] It should be noted that the order of the above embodiments of the present invention is merely for descriptive purposes and does not represent the superiority or inferiority of the embodiments. The processes depicted in the accompanying drawings do not necessarily require a specific or sequential order to achieve the desired results. In some embodiments, multiple task processing and parallel processing are possible or may be advantageous. The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. The above content is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be covered within the protection scope of the present invention.

Claims

1. A downhole optical signal transmission system, characterized in that, The downhole optical signal transmission system includes: An optical signal generating device is used to generate an optical signal in the X-polarization direction and transmit it to a polarization state control device through a polarization-maintaining fiber. The polarization state modulation device is used to adjust the polarization state of the optical signal to obtain a candidate optical signal, and transmit the candidate optical signal to the total internal reflection device; The total internal reflection device is used to perform total internal reflection on the candidate optical signal to obtain a total internal reflection optical signal; and transmits the total internal reflection optical signal to the signal processing unit through a polarization-maintaining fiber. The signal processing unit is used to perform polarization state detection on the total internal reflection light signal to obtain the target polarization state information of the total internal reflection light signal; The total internal reflection device includes: a surface-coated total internal reflection mirror or a prism with an isosceles right-angled triangle cross-section; wherein: The surface-coated total internal reflection mirror is used to prepare a metal or multilayer thin film on a preset material surface to perform total internal reflection of the candidate optical signal; or... The prism, with an isosceles right triangle cross-section, is used to perform total internal reflection of the candidate optical signal based on the geometry and refractive index of the prism. The polarization state modulation device includes: a first piezoelectric ceramic, a second piezoelectric ceramic, and a third piezoelectric ceramic; wherein: The first piezoelectric ceramic is used to adjust the phase difference of the propagation of the optical signal in two orthogonal directions based on the first pressure, so as to convert the optical signal into linearly polarized light; The second piezoelectric ceramic is used to adjust the first pressure to obtain a second pressure; and to rotate the linearly polarized light based on the second pressure to obtain an intermediate light signal; The third piezoelectric ceramic is used to adjust the second pressure to obtain a third pressure; and based on the third pressure, to adjust the polarization state of the intermediate optical signal to obtain the candidate optical signal.

2. The downhole optical signal transmission system according to claim 1, characterized in that, The downhole optical signal transmission system further includes: a data conversion unit; The data conversion unit is used to convert the input initial encoded data into an initial polarization state control signal based on a preset mapping relationship, and to apply the initial polarization state control signal to the polarization state modulation device; wherein, the preset mapping relationship is used to characterize the correspondence between the polarization angle of the optical signal and the range of encoded values; The polarization state modulation device is further configured to adjust the polarization state of the optical signal based on the initial polarization state control signal to obtain the candidate optical signal; The signal processing unit is also used to restore the target polarization state information of the total internal reflection light signal into target encoded data based on the preset mapping relationship.

3. The downhole optical signal transmission system according to claim 2, characterized in that, The polarization-maintaining optical fiber includes: multiple optical fibers; The data conversion unit is further configured to divide the initial encoded data according to the number of the multiple optical fibers to obtain multiple divided encoded data; wherein, the multiple divided encoded data corresponds one-to-one with the multiple optical fibers; based on the preset mapping relationship, the multiple divided encoded data corresponding to the multiple optical fibers are converted into multiple initial polarization state control signals. The signal processing unit is further configured to convert the plurality of initial polarization state control signals into a plurality of intermediate encoded data based on the preset mapping relationship, and to fuse the plurality of intermediate encoded data to obtain the target encoded data.

4. The downhole optical signal transmission system according to claim 1, characterized in that, The first piezoelectric ceramic is also used to adjust the phase difference of the optical signal propagating in two orthogonal directions to 90° based on the first pressure, so as to convert the optical signal into linearly polarized light; The second piezoelectric ceramic is also used to adjust the phase difference of the linearly polarized light propagating in two orthogonal directions to 180° based on the second pressure, so as to rotate the linearly polarized light and obtain the intermediate light signal; The third piezoelectric ceramic is also used to adjust the phase difference of the candidate optical signal propagating in two orthogonal directions to 90° based on the third pressure, so as to adjust the polarization state of the intermediate optical signal and obtain the candidate optical signal.

5. The downhole optical signal transmission system according to claim 1, characterized in that, The signal processing unit includes: A polarization beam splitter is used to separate the total internal reflection light signal into polarized light signals in two mutually perpendicular directions; A photodetector is used to convert the polarized light signal into an electrical signal; The calculation module is used to determine the target polarization state information of the total internal reflection light signal based on the electrical signal.

6. A downhole optical signal transmission method, applied to the downhole optical signal transmission system according to any one of claims 1-5, characterized in that, The downhole optical signal transmission method includes: Generates light signals in the X-polarization direction; The polarization state of the optical signal is adjusted to obtain a candidate optical signal; The candidate optical signal is subjected to total internal reflection to obtain a total internal reflection optical signal; The polarization state of the total internal reflection light signal is detected to obtain the target polarization state information of the total internal reflection light signal.

7. The downhole optical signal transmission method according to claim 6, characterized in that, The step of detecting the polarization state of the total internal reflection light signal to obtain the target polarization state information of the total internal reflection light signal includes: The total internal reflection light signal is separated into a first polarized light signal and a second polarized light signal that are perpendicular to each other; The first polarized light signal and the second polarized light signal are respectively converted into a first electrical signal and a second electrical signal; Based on the first electrical signal and the second electrical signal, the target polarization state information of the total internal reflection light signal is determined.

8. The downhole optical signal transmission method according to claim 7, characterized in that, Determining the target polarization state information of the total internal reflection light signal based on the first electrical signal and the second electrical signal includes: Using the first electrical signal as a reference, determine the polarization angle between the first electrical signal and the second electrical signal; Based on the polarization angle, the target polarization state information of the total internal reflection light signal is determined.

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