Fiber-optic networks are light-conducting tools that use the principle of total reflection in fibers made of glass or plastic to reach a company or home or computer room. Use switches or other terminals to convert to an ordinary RJ45 network cable to a computer, also called LAN. The IP address is automatically assigned by the switch or other terminal. The internal network IP needs to be set in the background of the terminal. The default is automatic, and no dialing is required.
The width of the frequency band represents the size of the transmission capacity. The higher the frequency of the carrier wave, the greater the bandwidth of the signal that can be transmitted. In the VHF band, the carrier frequency is 48.5 MHz to 300 MHz. With a bandwidth of about 250MHz, it can only transmit 27 sets of TVs and dozens of sets of FM broadcasts. Visible light has a frequency of up to 100000 GHz, more than a million times higher than the VHF band. Although the bandwidth of the fiber is affected due to the different loss of the fiber to different frequencies, the bandwidth in the lowest loss region can reach 30000 GHz. The bandwidth of a single light source accounts for only a small part of it (multi-mode fiber has a bandwidth of about several hundred megahertz, and good single-mode fiber can reach 10 GHz or more), and advanced coherent optical communication can be used to arrange 2000 optical carriers in the 30000 GHz range. Wavelength division multiplexing can accommodate millions of channels.
For optical communication, its technology is basically mature and its business needs are relatively inadequate. Taking the FTTH known as the "broadband access ultimate goal" as an example, its implementation technology EPON has been fully matured, but due to the low bandwidth required for ordinary users to access the Internet, the commercial use of FTTH is limited to some pilot areas. However, in 2006, with the implementation of triple-play services such as IPTV, the bandwidth provided by operators could not meet the requirements of users for high-definition television, and the deployment of FTTH was also put on the agenda. Coincidentally, ASON has flexible control over the transmission network and can provide personalized services to enterprise customers. Many operators have invested heavily in building ASON to develop and maintain corporate customers.
The ultimate goal of the future transmission network is to build an all-optical network, that is, to realize “optical fiber transmission instead of copper transmission” in the access network, metropolitan area network, and backbone network, and to use the fiber optic splice closure, fiber optic boxes, and so on. The backbone network and metropolitan area network have basically all adopted the optic fibre, some areas that the network develops fast, also realized the partial access layer optic fibre to adopt.