Advancements and Future Trends in Fiber Optic Communication Technology in China
**Current State of Fiber Optic Communications**
1.1 Low Loss and Long Transmission Distances
Compared to conventional communications, fiber optics have significantly lower loss rates, currently as low as 0.2 dB/km. The spacing between optical amplifiers can exceed 100 km, whereas traditional copper cable amplifiers are spaced only a few hundred meters to a few kilometers apart. Therefore, apart from using copper cables from users to small stations, other networks including television and transoceanic networks use fiber optic communications. The advantages of fiber optics in long-distance transmission are very clear, with current communication distances exceeding 10,000 meters.
1.2 Strong Interference Resistance
Compared to other types of cables, fiber optic communications have a distinct advantage—exceptional resistance to electromagnetic interference. The primary use of silicon dioxide in fiber optic communications equipment brings unparalleled benefits due to quartz’s high resistance to corrosion and insulation, thus providing strong interference resistance. Fiber optic communications are not affected by solar flares, ionospheric changes, lightning, or human-made electromagnetic emissions, making them suitable for military applications.
1.3 High Security and Confidentiality
Since fiber optics primarily rely on the principle of total internal reflection for transmission, the optical signals are completely contained within the cladding, making leakage of optical waves rare. Moreover, many fibers within a single cable do not interfere with each other, hence fiber communications have strong interference resistance and very high confidentiality and security. Additionally, fiber optics are light and compact, saving space and making equipment installation very convenient. Furthermore, the raw materials used in manufacturing fiber optic equipment are increasingly abundant, inexpensive, stable, and less affected by environmental temperatures, ensuring a long lifespan. These advantages have broadened the applications of fiber optic technology in everyday life.
**Development Status of Fiber Optic Communication Technology in China**
2.1 Status of Standard Single-Mode Fiber
Fiber optics are categorized into single-mode and multimode fibers. Currently, standard single-mode fibers are the most common type used in everyday life. Single-mode fibers can only transmit one mode of light and require a light source with a narrow spectral width and high stability. As fiber optic technology advances, the transmission distance and information capacity of single-mode fibers continue to increase, and the performance of G652.A fibers can be further optimized and improved. Single-mode fibers conforming to the ITU-T G.654 cutoff wavelength and those conforming to G.653 are improvements on G652.A fibers.
2.2 Development Status of Access Network Cables
Fiber optic access networks, which use fibers as the primary medium for information transmission, are gradually replacing traditional cables and becoming the focus of future development in communication access networks. The development trend in access network cables is characterized by shorter distances, more branching, and frequent branching. Typically, access networks increase network capacity by adding more fiber cores, especially in urban fiber conduits, where internal diameter limitations necessitate increasing the number of fibers and their packing density while reducing cable weight and diameter. Typically, access network fibers use G652 standard single-mode fiber or G652C low-water-peak single-mode fiber, with the former being more widely used in China.
2.3 Development Status of Indoor Cables
Indoor cables are cables formed by technically processing optical transmission carriers (fibers), typically supporting the transmission of voice, data, and video signals. Indoor cables mainly consist of structured cabling and indoor cables, with the former typically used by end-users indoors and the latter placed in central offices or various telecommunications rooms. The design and application of indoor cable structures are complex due to the constraints of building structures and the diversity of cable materials. Although they have lower tensile strength and less protective layering, indoor cables still offer economic, convenient, and effective communication advantages. Indoor cables transmit information quickly and have stable, clear, strong signal quality, good interference resistance, and high information flow capacity.
2.4 Development Status of Communication Cables
Communication cables primarily consist of multiple fiber cores and cladding, forming the cable core and an outer protective layer, and are considered ideal all-dielectric cables for electrical systems. Communication cables rely on electrical currents to transmit signals and have certain advantages in data transmission, though their data capacity is relatively small. ADSS cables, suitable for the electrical communication field because they can be laid independently, are widely used in the renovation of China’s electrical systems, but the product structure and performance of China’s communication cables still need further improvement.
2.5 Development of Plastic Fibers
Plastic fibers are also widely used in China, offering low cost and fast transmission speeds, making them excellent short-distance communication mediums. They mainly utilize the total internal reflection of light or light bouncing within plastic fibers for transmission, therefore having a huge potential market in data transmission systems. Plastic fibers can be used undersea. When laid undersea, the fibers are insulated, and their ends are equipped with lasers, significantly saving costs and reducing corresponding communication charges.
**Future Development Trends of Fiber Optic Communication Technology in China**
3.1 Extremely High Capacity and Long Dist
ances
Technologies capable of extremely high capacity and long-distance transmissions have broad application prospects in China’s communication technology field. Wavelength Division Multiplexing (WDM) technology significantly increases the transmission capacity of fiber optic systems by increasing the number of channels transmitted through a single fiber. Currently, 1.6 Tbit/s WDM systems are extensively commercialized, and the distance for all-optical transmission is also gradually increasing. Optical Time Division Multiplexing (OTDM) technology increases transmission capacity by raising the single-channel speed, currently reaching up to 640 Gbit/s. To further enhance the speed and capacity of fiber optic communications, relying solely on WDM or OTDM technologies is insufficient; a combination of both is necessary to significantly improve the speed and capacity of fibers.
3.2 Intelligent Optical Networks
Intelligent optical networks are an important future direction for the development of fiber optic communication technology in China. Over the past 50 years, information transmission has dominated the field of fiber optic communications. With the rapid development of computer technology, the perfect integration of network and communication technologies has further propelled optical network communication technology towards higher and better directions. Modern optical networks not only facilitate the transmission of information data but also integrate computer control technology, automatic discovery functions, and enhanced self-protection and repair capabilities to truly form intelligent optical networks.