The passive optical network does not use power components to divide the signal. Use beam splitter for signal distribution. Different from the manufacturer, each splitter usually divides an optical fiber into 16, 32, or 64 sub-fibers, and some splitters can aggregate a single cable. A beam splitter cannot provide any switching or buffering capabilities; this connection is called a point-to-multipoint link. For such a connection, the user-side optical network terminal must perform some special functions that cannot be implemented by other methods. For example, due to the lack of routing capability, every signal leaving the central office (co) must be broadcast to all users under the same splitter (including those signals that are not expected). Therefore, the optical network terminal filters out the signals expected to other users.
Also, when the beam splitter cannot perform buffering, each individual optical network terminal must work in coordination with a multiplexing system to ensure that the signals leaving the user do not collide at the intersection. Two multiplexing methods can be implemented: wavelength division multiplexing and time-division multiplexing. In wavelength division multiplexing, each user uses a separate wavelength to transmit signals. In time-division multiplexing, users "take turns" to transmit information. In early 2007, only time-division multiplexing was technically feasible. Compared with active optical networks, the advantages and disadvantages of passive optical networks are very obvious. The passive optical network avoids the use of complex outdoor electronic equipment. Passive optical networks also allow the transmission of simple analog TV signals for analog signal broadcasting. However, because each signal must be pushed to all users under the same beam splitter (as opposed to only one signal switching device), the central office must be equipped with a particularly powerful transmission device called an optical terminal (OLT).
In addition, because each user's optical network terminal must transmit all paths to the central office (rather than just to the nearest switching equipment), users cannot be as far away from the central office as an active optical network.
