Optical transmission system and method adopting upper and lower sideband transmission for multi-core optical fiber

Abstract

The invention relates to a multi-core optical fiber optical transmission system and method adopting upper and lower sideband transmission, and the system comprises a multi-core optical fiber which is provided with a plurality of fiber cores which are used for transmitting optical signals respectively; the modulator is used for modulating a source signal emitted by the light source into a carrier sideband signal; a filter for filtering the carrier sideband signal into an upper sideband signal and a lower sideband signal; and the multiplexer is used for compounding the upper sideband signal and the lower sideband signal and then respectively distributing the compounded signals to each fiber core of the multi-core fiber. The filter filters a carrier sideband signal output by a modulator into an upper sideband signal and a lower sideband signal. Compared with the prior art, more information can be transmitted in the same frequency spectrum range, the upper sideband signal and the lower sideband signal are separated in frequency, mutual interference between the signals is reduced, different fiber cores transmit the signals of different frequency bands, the physical isolation degree between the signals is increased, and the possibility of signal interference is further reduced.

Description

Technical Field

[0001] The present application relates to the field of optical fiber communication technology, and in particular to an optical transmission system and method using upper and lower sideband transmission in a multi-core optical fiber. Background Art

[0002] In fiber optic communication systems, intensity modulation / direct detection (IM / DD) systems are widely used due to their simple structure and low cost. However, with the continuous increase in data transmission rates, traditional single-core fiber transmission methods can no longer meet the demand. Multi-core fiber (MCF) technology significantly improves transmission capacity and efficiency by integrating multiple cores in a single optical fiber.

[0003] Multi-core fiber transmission technology is a cutting-edge attempt. It designs multiple cores in the cladding structure of an optical fiber. Each core is equivalent to an independent transmission unit, which can realize the independent transmission of multiple signals along different cores in the same optical fiber. This high-density, multi-channel structure has the advantages of low production cost, space saving and high transmission capacity.

[0004] However, the traditional multi-core optical fiber transmission technology is to transmit the same signal on each core at the same time, with the same direction and frequency band. This method has certain limitations. Since each core is transmitting the same signal, if the cores are close together, the signals between the cores may interfere with each other.

[0005] When the number of fiber cores increases, the cladding thickness of the optical fiber may be relatively reduced, which leads to an increase in the limiting loss and bending loss of the optical fiber, further affecting the transmission distance and quality of the signal. If all the fiber cores transmit the same signal on the same frequency band, the frequency band utilization will be reduced. This is because, although multi-core optical fiber can provide more transmission channels, if all channels are transmitting the same signal, the transmission capacity of these channels is not actually fully utilized. Summary of the invention

[0006] The embodiments of the present application provide an optical transmission system and method for a multi-core optical fiber using upper and lower sideband transmission to solve the problem in the related art that the direction and frequency band of multi-core optical fiber transmission signals are the same, resulting in mutual interference between signals between fiber cores.

[0007] A first aspect of an embodiment of the present application provides an optical transmission system using a multi-core optical fiber with upper and lower sideband transmission, including:

[0008] A multi-core optical fiber, wherein the multi-core optical fiber has multiple cores, and the multiple cores are used to transmit optical signals respectively;

[0009] A modulator, the modulator is used to modulate the source signal emitted by the light source into a carrier sideband signal;

[0010] A filter, the filter being used to filter the carrier sideband signal output by the modulator into an upper sideband signal and a lower sideband signal;

[0011] A multiplexer is used to multiplex the upper sideband signal and the lower sideband signal and distribute them to each core of the multi-core optical fiber respectively.

[0012] In some embodiments: further comprising a demultiplexer connected to a multi-core optical fiber, the demultiplexer being used to separate optical signals of each core;

[0013] The demultiplexer is connected to a photodetector, and the photodetector is used to convert the optical signal output by the demultiplexer into an electrical signal.

[0014] In some embodiments: the modulator comprises an optical input terminal, an optical output terminal and an electrical radio frequency port;

[0015] The optical input end is connected to the light source output end and is used to perform phase modulation on the source signal emitted by the light source to generate a carrier sideband;

[0016] The optical output end is connected to the filter;

[0017] The electrical radio frequency port is connected to a microwave signal source, which serves as a signal source of the modulator and outputs a radio frequency signal.

[0018] In some embodiments: the filter comprises a high-pass filter, the high-pass filter is used to filter out the lower sideband signal and output the upper sideband signal;

[0019] and a low-pass filter, wherein the low-pass filter is used to filter out the upper sideband signal and output a lower sideband signal.

[0020] In some embodiments: the multi-core optical fiber further includes an outer cladding coated on the periphery of each of the cores, and a coating layer coated on the periphery of the outer cladding, and the refractive index of the outer cladding is lower than the refractive index of the core.

[0021] In some embodiments: the refractive index n1 of the core is 1.46, and the refractive index n2 of the outer cladding is 1.43.

[0022] In some embodiments: the coating layer includes an inner coating layer and an outer coating layer, the inner coating layer is a soft acrylic resin, and the outer coating layer is a hard acrylic resin.

[0023] In some embodiments: among the multiple cores of the multi-core optical fiber, one core is located in the middle of the multi-core optical fiber as the middle core, and the remaining cores are evenly distributed around the middle core as the outer cores, and the line connecting the middle core and two adjacent outer cores forms an equilateral triangle structure.

[0024] A second aspect of an embodiment of the present application provides a method for optical transmission using a multi-core optical fiber with upper and lower sideband transmission, the method using an optical transmission system using a multi-core optical fiber with upper and lower sideband transmission as described in any of the above embodiments, including:

[0025] The source signal emitted by the light source is sent to the modulator, and the modulator modulates the source signal into a carrier sideband signal;

[0026] The carrier sideband signal output by the modulator is input into a filter, and the filter filters the carrier sideband signal into an upper sideband signal and a lower sideband signal;

[0027] The upper sideband signal and the lower sideband signal are input into a multiplexer, and the multiplexer combines the upper sideband signal and the lower sideband signal and distributes them to each core of the multi-core optical fiber respectively;

[0028] The upper sideband signal and the lower sideband signal are transmitted along each core in the multi-core optical fiber, thereby reducing the crosstalk between the upper sideband signal and the lower sideband signal.

[0029] In some embodiments: further comprising:

[0030] The upper sideband signal and the lower sideband signal outputted from each core of the multi-core optical fiber are inputted into a demultiplexer, and the demultiplexer separates the optical signals of each core;

[0031] The demultiplexer transmits the optical signal to the photodetector, and the photodetector converts the optical signal output by the demultiplexer into an electrical signal.

[0032] The beneficial effects of the technical solution provided by this application include:

[0033] The embodiment of the present application provides an optical transmission system and method for a multi-core optical fiber using upper and lower sideband transmission. Since the optical transmission system for the multi-core optical fiber using upper and lower sideband transmission of the present application is provided with a multi-core optical fiber, the multi-core optical fiber has multiple cores, and the multiple cores are used to transmit optical signals respectively; a modulator, which is used to modulate the source signal emitted by the light source into a carrier sideband signal; a filter, which is used to filter the carrier sideband signal output by the modulator into an upper sideband signal and a lower sideband signal; a multiplexer, which is used to compound the upper sideband signal and the lower sideband signal and distribute them to each core of the multi-core optical fiber respectively.

[0034] Therefore, the multi-core optical fiber of the present application uses the filter of the optical transmission system of upper and lower sideband transmission to filter the carrier sideband signal output by the modulator into an upper sideband signal and a lower sideband signal. More information can be transmitted within the same spectrum range, thereby maximizing the spectrum utilization. The upper sideband signal and the lower sideband signal can be reused on the same spectrum resource, reducing the occupancy of a single signal frequency band. At the same time, the separation of the upper sideband signal and the lower sideband signal in frequency reduces the mutual interference between the signals, and different fiber cores transmit signals of different frequency bands, so that the physical isolation between the signals is increased, further reducing the possibility of signal interference. The present application not only improves the frequency band utilization, but also reduces signal interference, and improves transmission efficiency and system reliability. Through the structure of the multi-core optical fiber, the transmission of the upper sideband signal and the lower sideband signal is carried out simultaneously, and efficient data transmission is achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0036] Figure 1 A structural block diagram of an optical transmission system according to an embodiment of the present application;

[0037] Figure 2 A schematic cross-sectional view of a multi-core optical fiber according to an embodiment of the present application;

[0038] Figure 3 A schematic longitudinal cross-sectional view of a multi-core optical fiber according to an embodiment of the present application;

[0039] Figure 4 Schematic diagram of upper sideband signal and lower sideband signal in an embodiment of the present application.

[0040] Reference numerals:

[0041] 1. Multi-core optical fiber; 2. Modulator; 3. Filter; 4. Multiplexer; 5. Light source; 6. Demultiplexer; 7. Photodetector; 8. Microwave signal source; 11. Fiber core; 12. Outer cladding; 13. Coating; 31. High-pass filter; 32. Low-pass filter; 111. Intermediate core; 112. Outer core. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0043] The embodiments of the present application provide an optical transmission system and method for multi-core optical fibers using upper and lower sideband transmission, which can solve the problem in the related art that the directions and frequency bands of multi-core optical fibers transmitting signals are the same, resulting in mutual interference between signals between fiber cores.

[0044] See also Figures 1 to 4 As shown, the first aspect of the embodiment of the present application provides an optical transmission system using a multi-core optical fiber with upper and lower sideband transmission, including:

[0045] A multi-core optical fiber 1 has a plurality of cores 11, and the plurality of cores 11 are used to transmit optical signals respectively; for example, the multi-core optical fiber 1 has eight cores 11, and the first four cores 11 can be used to transmit upper sideband signals, and the last four cores 11 can be used to transmit lower sideband signals. The upper sideband signal (USB) is the high-frequency part of the transmission signal, and the lower sideband signal (LSB) is the low-frequency part of the transmission signal. Which cores transmit the upper and lower sideband signals can be determined according to specific circumstances, and the main principle is to ensure transmission efficiency while increasing transmission capacity.

[0046] Modulator 2, which is used to modulate the source signal emitted by the light source 5 into a carrier sideband signal; the modulator 2 processes the source signal emitted by the light source 5 to make it suitable for channel transmission. Generally speaking, the source signal contains a DC component and a lower frequency component, which is called a baseband signal. The baseband signal is often not used as a transmission signal. Therefore, the baseband signal must be converted into a signal with a very high frequency relative to the baseband frequency to be suitable for channel transmission.

[0047] Filter 3 is used to filter the carrier sideband signal output by the modulator into an upper sideband signal and a lower sideband signal. In radio communications, a sideband is a frequency band higher or lower than the carrier frequency, and the power contained is the result of modulation. The sideband consists of all Fourier analyses of the modulated signal outside the carrier. All forms of modulation produce sidebands. Figure 4 As shown, amplitude modulation of the carrier signal usually results in two image sidebands.

[0048] The signal components above the carrier frequency constitute the upper sideband (USB), and the signal components below the carrier frequency constitute the lower sideband (LSB). The spectrum structure of the upper sideband is the same as the original modulated signal, and the lower sideband is the mirror image of the upper sideband. Filter 3 separates the upper sideband signal and the lower sideband signal to filter the carrier sideband signal output by modulator 2 into the upper sideband signal and the lower sideband signal respectively.

[0049] The multiplexer 4 is used to multiplex the upper sideband signal and the lower sideband signal and distribute them to each core 11 of the multi-core optical fiber 1. The multiplexer 4 combines the light waves of the upper sideband signal and the lower sideband signal together, and each upper sideband signal and the lower sideband signal are distributed to one core 11 of the multi-core optical fiber 1. In this way, multiple signals can be transmitted simultaneously in one multi-core optical fiber, improving the transmission efficiency, and the multiplexed optical signal is transmitted through the multi-core optical fiber 1.

[0050] The multi-core optical fiber of the embodiment of the present application uses the filter 3 of the optical transmission system of upper and lower sideband transmission to filter the carrier sideband signal output by the modulator 2 into an upper sideband signal and a lower sideband signal. More information can be transmitted within the same spectrum range, thereby maximizing spectrum utilization. The upper sideband signal and the lower sideband signal can be multiplexed on the same spectrum resource, reducing the occupancy of a single signal frequency band.

[0051] At the same time, the separation of the upper sideband signal and the lower sideband signal in frequency reduces the mutual interference between the signals. Different fiber cores 11 transmit signals of different frequency bands, which increases the physical isolation between the signals and further reduces the possibility of signal interference. The present application not only improves the frequency band utilization, but also reduces signal interference, and improves transmission efficiency and system reliability. Through the structure of the multi-core optical fiber 1, the upper sideband signal and the lower sideband signal are transmitted simultaneously, achieving efficient data transmission.

[0052] In some alternative embodiments: See Figure 1 As shown, the embodiment of the present application provides an optical transmission system using upper and lower sideband transmission in a multi-core optical fiber, and the optical transmission system also includes a demultiplexer 6 connected to the multi-core optical fiber 1, and the demultiplexer 6 is used to separate the optical signals of each core 11. The demultiplexer 6 is connected to a photodetector 7, and the photodetector 7 is used to convert the optical signal output by the demultiplexer 6 into an electrical signal.

[0053] At the output end of the multi-core optical fiber 1, the optical signal first passes through the demultiplexer 6, which separates the signals in different fiber cores 11 and restores them to the original multiple independent signals. The demultiplexed signal is sent to the photodetector 7. The photodetector 7 converts the optical signal into an electrical signal by detecting the change in light intensity.

[0054] The converted electrical signal needs further processing, such as amplification, filtering, etc., to improve the signal quality. The processed electrical signal is usually a radio frequency (RF) signal, which is output through the RFout port for subsequent electronic system use or further processing.

[0055] In some alternative embodiments: See Figure 1 As shown, the embodiment of the present application provides an optical transmission system using upper and lower sideband transmission in a multi-core optical fiber, wherein the modulator 2 of the optical transmission system comprises an optical input end, an optical output end, and an electrical radio frequency port. The optical input end is connected to the output end of the light source 5 to perform phase modulation on the source signal emitted by the light source 5 to generate a carrier sideband.

[0056] The optical output end is connected to the filter for outputting the carrier sideband. The electrical RF port is connected to a microwave signal source 8, which serves as the signal source of the modulator 2 and outputs a RF signal. The electrical RF port receives a RF signal from an external microwave signal source 8, which is a data source and is used to modulate the intensity of the source signal output by the light source 5. The RF signal is then fed into the modulator 2, where the modulator 2 changes the intensity of the light according to the data signal to be transmitted. The data is encoded by changing the intensity of the light, i.e., intensity modulation.

[0057] In some alternative embodiments: See Figure 1 As shown, an embodiment of the present application provides an optical transmission system using a multi-core optical fiber and adopting upper and lower sideband transmission. The filter 3 of the optical transmission system includes a high-pass filter 31, which is used to filter out the lower sideband signal and output the upper sideband signal; and a low-pass filter 32, which is used to filter out the upper sideband signal and output the lower sideband signal.

[0058] In some alternative embodiments: See Figure 2 and Figure 3 As shown, the embodiment of the present application provides an optical transmission system of a multi-core optical fiber using upper and lower sideband transmission, and the multi-core optical fiber 1 of the optical transmission system also includes an outer cladding 12 coated on the periphery of each core 11, and a coating layer 13 coated on the periphery of the outer cladding 12, and the refractive index of the outer cladding 12 is lower than the refractive index of the core 11. The refractive index n1 of the core 11 is about 1.46, and the refractive index n2 of the outer cladding 12 is about 1.43.

[0059] The core 11 is the central part of the multi-core optical fiber 1 and is the transmission path of light. In the multi-core optical fiber 1, there are multiple such cores 11, and each core 11 can transmit signals independently. The material selection and design of the core 11 are crucial to the performance of the optical fiber. The outer cladding 12 is the material surrounding the core 11, and its refractive index is lower than that of the core 11. This design allows light to be totally reflected in the core 11 and thus propagate in the optical fiber.

[0060] The thickness of the outer cladding 12 also has an important influence on the performance of the multi-core optical fiber 1, for example, reducing microbending losses and additional losses in the outer core. The coating 13 is an outer protective layer of the multi-core optical fiber 1, usually made of a plastic material. The main function of the coating 13 is to protect the multi-core optical fiber 1 from physical damage and environmental influences, such as humidity, temperature changes, etc. In addition, the coating 13 can also provide a certain mechanical strength to prevent the multi-core optical fiber 1 from stretching and bending during installation and use.

[0061] The multi-core optical fiber 1 of the embodiment of the present application includes multiple cores 11, each of which can independently transmit a signal, thereby realizing spatial multiplexing. The optical signal is transmitted along the core 11 in the multi-core optical fiber 1. Due to the low loss characteristics of the multi-core optical fiber 1, the signal can maintain a high quality over a long distance. The coating layer 13 is an acrylic resin material. The acrylic resin can not only provide excellent mechanical protection and resistance to environmental corrosion, but also improve production efficiency through rapid UV curing, while maintaining high flexibility and transparency to support the stable transmission of optical signals. Its low moisture absorption characteristics effectively prevent performance degradation, while protecting the multi-core optical fiber 1 from mechanical damage and environmental influences, ensuring the reliable operation of the multi-core optical fiber 1 under bending and complex conditions.

[0062] The coating layer 13 includes an inner coating layer and an outer coating layer. The inner coating layer is a soft acrylic resin for absorbing mechanical stress and reducing microbending loss; the outer coating layer is a hard acrylic resin for enhancing mechanical strength and wear resistance.

[0063] The working principle of multi-core optical fiber 1 is mainly based on the principle of total reflection of light. The path of light wave transmission is as follows Figure 3 As shown. Each fiber core 11 is surrounded by a high refractive index outer cladding 12. When light is emitted from the fiber core 11 (refractive index n1≈1.46) to the outer cladding 12 (refractive index n2≈1.43), n1>n2. As long as the incident angle is greater than the critical angle of total reflection, the light will be reflected inside the fiber core 11, thereby achieving light guidance. This means that each fiber core 11 can transmit data independently, and the light waves between the fiber cores 11 will not interfere with each other.

[0064] In some alternative embodiments: See Figure 2 As shown, the embodiment of the present application provides an optical transmission system of a multi-core optical fiber using upper and lower sideband transmission. Among the multiple cores 11 of the multi-core optical fiber 1 of the optical transmission system, one core 11 is located in the middle of the multi-core optical fiber 1 as the middle core 111, and the remaining cores 11 are evenly distributed around the middle core 111 as the outer cores 112, and the connecting line of the middle core 112 and the two adjacent outer cores 112 forms an equilateral triangle structure. That is, the distance between two adjacent cores 11 in the multiple cores 11 is the same, preventing the distances between the cores 11 from being large or small, and avoiding signal interference between each other.

[0065] See also Figures 1 to 4 As shown, the second aspect of the embodiment of the present application provides a method for optical transmission using a multi-core optical fiber with upper and lower sideband transmission, the method using a multi-core optical fiber optical transmission system using upper and lower sideband transmission described in any of the above embodiments, including:

[0066] Step 1: Send the source signal emitted by the light source 5 to the modulator 2, and the modulator 2 modulates the source signal into a carrier sideband signal.

[0067] Step 2: Input the carrier sideband signal output by the modulator 2 into the filter 3, and the filter 3 filters the carrier sideband signal into an upper sideband signal and a lower sideband signal.

[0068] Step 3: Input the upper sideband signal and the lower sideband signal to the multiplexer 4 . The multiplexer 4 multiplexes the upper sideband signal and the lower sideband signal and distributes them to the cores 11 of the multi-core optical fiber 1 .

[0069] Step 4: The upper sideband signal and the lower sideband signal are transmitted in and along the cores 11 of the multi-core optical fiber 1 to reduce crosstalk between the upper sideband signal and the lower sideband signal.

[0070] Step 5: Input the upper sideband signal and the lower sideband signal output from each fiber core 11 of the multi-core optical fiber 1 to the demultiplexer 6 , and the demultiplexer 6 separates the optical signals of each fiber core 11 .

[0071] Step 6: The demultiplexer 6 transmits the optical signal to the photodetector 7, and the photodetector 7 converts the optical signal output by the demultiplexer 6 into an electrical signal.

[0072] How it works

[0073] The embodiment of the present application provides an optical transmission system and method for a multi-core optical fiber using upper and lower sideband transmission. Since the optical transmission system for the multi-core optical fiber using upper and lower sideband transmission of the present application is provided with a multi-core optical fiber 1, the multi-core optical fiber 1 has multiple cores 11, and the multiple cores 11 are used to transmit optical signals respectively; a modulator 2, the modulator 2 is used to modulate the source signal emitted by the light source 5 into a carrier sideband signal; a filter 3, the filter 3 is used to filter the carrier sideband signal output by the modulator 2 into an upper sideband signal and a lower sideband signal; a multiplexer 4, the multiplexer 4 is used to compound the upper sideband signal and the lower sideband signal and distribute them to each core 11 of the multi-core optical fiber 1 respectively.

[0074] Therefore, the multi-core optical fiber of the present application uses the filter 3 of the optical transmission system of upper and lower sideband transmission to filter the carrier sideband signal output by the modulator 2 into an upper sideband signal and a lower sideband signal. More information can be transmitted within the same spectrum range, thereby maximizing spectrum utilization. The upper sideband signal and the lower sideband signal can be multiplexed on the same spectrum resource, reducing the occupancy of a single signal frequency band.

[0075] The separation of the upper sideband signal and the lower sideband signal in frequency reduces the mutual interference between the signals. Different fiber cores 11 transmit signals of different frequency bands, which increases the physical isolation between the signals and further reduces the possibility of signal interference. The present application not only improves the frequency band utilization, but also reduces signal interference, and improves transmission efficiency and system reliability. Through the structure of the multi-core optical fiber 1, the upper sideband signal and the lower sideband signal are transmitted simultaneously, achieving efficient data transmission.

[0076] In the description of the present application, it should be noted that the terms "upper", "lower", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. Unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be a connection between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to the specific circumstances.

[0077] It should be noted that, in this application, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0078] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. An optical transmission system using upper and lower sideband transmission in a multi-core optical fiber, characterized in that: include: A multi-core optical fiber (1), the multi-core optical fiber (1) having a plurality of fiber cores (11), the plurality of fiber cores (11) being used to transmit optical signals respectively; A modulator (2), the modulator (2) being used to modulate a source signal emitted by a light source (5) into a carrier sideband signal; A filter (3), wherein the filter (3) is used to filter the carrier sideband signal output by the modulator (2) into an upper sideband signal and a lower sideband signal; A multiplexer (4) is used for combining an upper sideband signal and a lower sideband signal and distributing the multiplexed signals to the respective fiber cores (11) of a multi-core optical fiber (1).

2. The optical transmission system of a multi-core optical fiber using upper and lower sideband transmission as claimed in claim 1, characterized in that: It also includes a demultiplexer (6) connected to the multi-core optical fiber (1), wherein the demultiplexer (6) is used to separate the optical signals of each fiber core (11); The demultiplexer (6) is connected to a photodetector (7), and the photodetector (7) is used to convert the optical signal output by the demultiplexer (6) into an electrical signal.

3. An optical transmission system using upper and lower sideband transmission using a multi-core optical fiber as claimed in claim 1 or 2, characterized in that: The modulator (2) comprises an optical input end, an optical output end and an electrical radio frequency port; The optical input end is connected to the output end of the light source (5) and is used to perform phase modulation on the source signal emitted by the light source (5) to generate a carrier sideband; The optical output end is connected to the filter (3); The electrical radio frequency port is connected to a microwave signal source (8), and the microwave signal source (8) serves as a signal source of the modulator (2) and outputs a radio frequency signal.

4. An optical transmission system using upper and lower sideband transmission using a multi-core optical fiber as claimed in claim 1 or 2, characterized in that: The filter (3) comprises a high-pass filter (31), and the high-pass filter (31) is used to filter out the lower sideband signal and output the upper sideband signal; and a low-pass filter (32), wherein the low-pass filter (32) is used to filter out the upper sideband signal and output a lower sideband signal.

5. An optical transmission system using upper and lower sideband transmission using a multi-core optical fiber as claimed in claim 1 or 2, characterized in that: The multi-core optical fiber (1) further comprises an outer cladding (12) coated on the periphery of each of the fiber cores (11), and a coating layer (13) coated on the periphery of the outer cladding (12), wherein the refractive index of the outer cladding (12) is lower than the refractive index of the fiber core (11).

6. The optical transmission system of a multi-core optical fiber using upper and lower sideband transmission as claimed in claim 5, characterized in that: The refractive index n1 of the core (11) is 1.46, and the refractive index n2 of the outer cladding (12) is 1.

43.

7. The optical transmission system of a multi-core optical fiber using upper and lower sideband transmission as claimed in claim 5, characterized in that: The coating layer (13) comprises an inner coating layer and an outer coating layer, the inner coating layer is a soft acrylic resin, and the outer coating layer is a hard acrylic resin.

8. An optical transmission system using upper and lower sideband transmission using a multi-core optical fiber as claimed in claim 1 or 2, characterized in that: Among the multiple fiber cores (11) of the multi-core optical fiber (1), one fiber core (11) is located in the middle of the multi-core optical fiber (1) as an intermediate core (111), and the remaining fiber cores (11) are evenly distributed around the intermediate core (111) as peripheral cores (112), and the connecting line of the intermediate core (111) and two adjacent peripheral cores (112) forms an equilateral triangle structure.

9. A method for optical transmission using upper and lower sideband transmission in a multi-core optical fiber, characterized in that: The method uses a multi-core optical fiber optical transmission system using upper and lower sideband transmission as claimed in any one of claims 1 to 8, comprising: The source signal emitted by the light source (5) is sent to the modulator (2), and the modulator (2) modulates the source signal into a carrier sideband signal; The carrier sideband signal output by the modulator (2) is input into the filter (3), and the filter (3) filters the carrier sideband signal into an upper sideband signal and a lower sideband signal; The upper sideband signal and the lower sideband signal are input into a multiplexer (4), and the multiplexer (4) multiplexes the upper sideband signal and the lower sideband signal and distributes them to each core (11) of the multi-core optical fiber (1); The upper sideband signal and the lower sideband signal are transmitted in each fiber core (11) of the multi-core optical fiber (1) and along each fiber core (11), thereby reducing crosstalk between the upper sideband signal and the lower sideband signal.

10. The optical transmission method using upper and lower sideband transmission in a multi-core optical fiber according to claim 9, characterized in that: Also includes: Inputting the upper sideband signal and the lower sideband signal outputted from each fiber core (11) of the multi-core optical fiber (1) into a demultiplexer (6), the demultiplexer (6) separating the optical signals of each fiber core (11); The demultiplexer (6) transmits the optical signal to the photodetector (7), and the photodetector (7) converts the optical signal output by the demultiplexer (6) into an electrical signal.

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