In the passive optical network of FTTH(fiber to the home), there is no doubt that fiber optic splitter plays a key role. It accomplishes the fact that multiple users are able to share the same PON(passive optical network) interface and get the higher network performance in. Fiber optic splitter is generally installed between the OLT(optical line terminal) of PON and ONT(optical network terminal). This article is going to give a detailed explanation about how fiber optic splitters distribute the optical signals in FTTH.
Fiber optic splitter in FTTH
How does fiber optic splitter work?
There are two kinds of fiber optic splitters called FBT splitter and PLC splitter. FBT splitter and PLC splitter have different ways to distribute the optical signals but basically, they work against a similar principle. By changing the coupling degree of the evanescent field among fibers and the radius of fibers, the fiber optic splitters accomplish the different amounts of distribution. On the contrary, multiple light signals could be merged into one by fiber optic splitter.
Fiber optic splitters are normally specified with the distribution specification of optical power, which is briefly written as M*N or M: N. M stands for input fiber paths, N stands for output fiber paths. In FTTH network construction, the selection of distribution specification is quite important.
PLC splitter or FBT splitter, which to choose?
Even though they have a similar working principle, but a deeply consideration or research is also necessary when choosing a fiber optic splitter to deploy your network. Because they are equipped with respective typical features from appearance, performance as well as price. In below form, they show the obvious differences in multiple aspects.
|Parameter||PLC splitter||FBT splitter|
|Wavelength range||1260-1650 nm||Single/double/three windows|
|Splitting ratio||Even distribution||Even or uneven distribution|
|Sensitivity of wavelength||low||high|
With the extensive use of FTTH network, for the sake of providing more customers with better network performance, PLC splitter has been adopted as the first choice in FTTH network deployment due to its advantage of more optical paths and evenly splitting.
Optical splitting construction of FTTH network
There are two ways to deploy optical splitting in PON network, centralized splitting and cascaded splitting. Centralized splitting is a way that fiber optic splitter is distributed inside the fiber distribution box and one end is directly connected with the center office by a single fiber, another end is connected with multiple ONTs in users ’end via multiple fibers. The splitting ratio of optical splitter in centralized splitting is normally 1:32 or 1:64. This way is suitable for city or downtown where users are centered.
Cascaded splitting is a way that two groups of fiber optic splitters build a cascaded connection between OLT and ONU. The first stage splitter is located around the center office and with 1×4 optical splitter deployed. The second stage splitters are normally placed in the end of users, where multiple 1×8 optical splitters are equipped. This way is suitable for a sparsely populated village or other like places.
To conclude the two ways of splitting in FTTH, the primary splitting has the main advantage of high flexibility, low operating cost, and convenient maintenance. And the secondary splitting features faster profits, low input cost. Both ways are able to support high performance, but we need to select the proper way for splitting construction in terms of actual application and purpose.
Splitting ratio design of FTTH network
1: N（N=2~64） or 2: N（N=2~64） splitter is the quite commonly used one in PON. Here “N” stands for the number of output ports. Fiber optic splitters with different splitting ratios play different roles in FTTH network. In addition to the above mentioned 1×32 or 1×64 optical splitter for primary splitting, and the 1×4 or 1×8 optical splitter for secondary splitting, it is also recommended to use 1×32 optical splitter if OLT is far away from ONU, and 1×64 optical splitter is more applicable if there is a short distance between OLT and ONU.
splitting ratio affects the transmission distance
What needs attention for fiber optic splitters in FTTH construction?
the location of fiber optic splitter
In FTTH construction, fiber optic splitter is not suggested to be placed inside the center office. Generally, put it in an outdoor optical distribution box where users concentrate.
Mostly, an outdoor place where is close to users is appropriate for concentrated splitting, considering investment protection and the future expansion of fiber optic splitters. In other words, the number of fiber optic splitter is flexible according to the number of users, so it is important to consider the enough space for expansion before designing concentrated splitting.
Finding a proper location for fiber optic splitters can make the whole FTTH construction efficient. What you can benefit from it includes:
- Greatly save the investment to fiber optic cables which connect the center office to fiber distribution box. Take an example of a 24-fiber optical cable. If place the optical splitter in central office, this fiber optic cable as the connection between center office and fiber distribution box is only able to serve for 24 houses. While if the optical splitter is placed outdoor, the fiber optic cable is able to cover 1536 houses as 1:64 splitting ratio by connecting the center office to the outdoor optical splitter.
- Save the space of central office and improve the management of devices and components.
Significance of PLC splitter in FTTH
In the passive optical network of FTTH, fiber optic splitters enable multiple users to share the same PON. And it provides a cost-effective optical splitting solution as it adopts the planar lightwave circuit technology. Different with FBT splitter, PLC splitter offers better performance and efficiency with various favorable packages. There are many popular types of PLC splitters in fiber optic network deployment, such as bare PLC splitter, Miniature Tubular optical splitter, ABS Cartridge Optical Splitter, Pallet Optical Splitter, Rack Optical Splitter, LGX Optical Splitter and Miniature Plug-in PLC splitter.
Fiber optic splitter offers a relatively simple way of optical splitting for FTTH network. To sum up, there are 3 key points for constructing an efficient optical splitting system in FTTH network, selecting a high-quality fiber optic splitter, finding a proper location to place fiber optic splitter, deploying an efficient splitting way. Among which, an effective fiber optic splitter provides a good basic in the whole system, so it is always recommended by experienced buyers to get them in the reputable suppliers like Cozlink. And also importantly, when deploying the fiber optic splitters, not only the application environment should be taken into your account, and the technical performance of optical splitter should be able to allow the future expansion.