An optical splitter is a component used to build a PON network. It is a passive device that connects the OLT and the ONU, and its function is to distribute downstream data and aggregate upstream data. An optical splitter has one upstream optical interface and a number of downstream optical interfaces. The optical signal arriving at the upstream optical interface is distributed to all downstream optical interfaces for transmission, and the optical signal arriving at the downstream optical interfaces is distributed to the single upstream optical interface for transmission. The only difference is that when the optical signal passes from the upstream optical interface to the downstream optical interfaces, the optical signal strength / optical power decreases; the same applies when it passes from the downstream optical interfaces to the upstream optical interface. The optical signal strength delivered by each downstream optical interface may be identical or may differ.
Working principle: when a single-mode fiber carries an optical signal, the optical energy is not entirely concentrated in the core; a small portion propagates through the cladding close to the core. In other words, if the cores of two fibers are close enough, the mode field of the light traveling in one fiber can enter the other fiber, and the optical signal is redistributed between the two fibers.
Optical splitter loss calculation • Optical power loss is related to the number of optical branches (each 1:2 split produces ~3.5 dB of loss) • The amount of optical power loss determines the transmittable distance • Bandwidth vs. cost: the average available bandwidth per household depends on the split ratio; the larger the split ratio, the lower the OLT cost shared per household.
Types of Optical Splitters
According to differences in manufacturing processes, optical splitters fall mainly into two categories: the FBT type (fused biconical taper splitter) and the PLC type (planar lightwave circuit power splitter). Fused biconical taper technology bundles two or more fibers together and then melts and draws them on a tapering machine. During drawing, the coupling and split ratio of each fiber is monitored; once the required split ratio is reached, the melting and drawing stops. One end retains a single fiber (the others are cut off) as the input end, while the other end serves as the multi-channel output end.
Process Principle of FBT-Type Optical Splitters
Planar lightwave circuit technology is based on optical integration technology. It uses semiconductor processes to fabricate optical waveguide branching devices, and the splitting function is completed on the chip.
Process Principle of PLC-Type Optical Splitters
By application scope, optical splitters can be divided into: box-type splitters, tray-type splitters, rack-mounted splitters, wall-mounted splitters, and so on. Box-type splitters are mainly used inside ODF frames in equipment rooms and inside optical cable distribution boxes.
Box-Type Optical Splitter
Tray-type splitters can only be installed in ODF frames in equipment rooms or in optical cable distribution boxes. Tray-type splitters Rack-mounted splitters can only be installed in standard racks. Wall-mounted splitters are installed on walls and can be installed in corridors and hallways.
