Fiber Optic Splitter is the Component in Passive Optical Network
Fiber optic splitter is also called fiber optical coupler, beam splitter, passive optical splitter. Used to split optical fibers and their signals. It is a connection device of multiple input ends and output ends, which can realize the coupling, branching and distribution of optical signals in the optical network system, and is the most important part of the optical fiber link. M×N is commonly used to indicate that an optical splitter has M inputs and N outputs. For example, a 1×4 Fiber Optic Splitter means 1 input and 4 outputs.
Fiber optic splitters allow us to design flexible and scalable network topologies, create fault-tolerant networks, and make efficient use of fiber optic transport. Redundancy is easily considered with fiber splitters, increasing fault tolerance through aggregation switches or path redundancy.
Fiber optic splitter is the reversible transmission
Fiber optic splitter can divide a main light source into 1-N optical paths out
Synthesize 1-N optical paths into one main light source through Fiber optic splitter and recover
How the Fiber optic splitter works
The signal from the aggregation switch is sent along a single fiber, and when it reaches the passive optical splitter, mirrors and glass in the assembly split the light into two or three or more fibers. These are fully passive network components, which means they require no power, no climate control, and no maintenance.
When an optical signal is transmitted in a single-mode fiber, the light energy cannot be completely concentrated in the core to propagate, and a small amount of light energy is propagated near the fiber cladding. In general, when the cores of two optical fibers are close enough, the optical signal transmitted in one optical fiber can enter the other optical fiber, that is, the optical signal can be redistributed in the two optical fibers, which is the origin of fiber optic splitter.
For example, a 1×4 fiber optic splitter can distribute the optical signal in one fiber to four fibers in equal proportion. In fact, in simple terms, 1000Mbps bandwidth is evenly distributed to four households, and each household can use a network with 250Mbps bandwidth.
Features of fiber optic splitters
- Connectable: PC Connector, UPC Connector, APC Connector
- Multi-port design, the length and diameter of the fiber optic cable can be customized
- There are multiple splitting ratios, from 1:99 to 50:50
- Can terminate FC, SC, ST, LC and MU connectors
- Can use single-mode fiber, multi-mode fiber and single-mode PM fiber
Types of fiber optic splitter
- Fiber optic splitter can be divided into FBT Splitter and PLC Splitter according to the principle.
- FBT Splitter fused taper products are produced by side-splicing two or more optical fibers.
- The PLC Splitter planar waveguide type is a micro-optical component type product. It uses photolithography technology to form optical waveguides on a dielectric or semiconductor substrate to achieve branch distribution functions.
For more details on fiber optic splitter, view articles: What is FBT Splitter，What is PLC Splitter，FBT Splitter vs PLC Splitter
According to the packaging method, there are 5 types of fiber optic splitters in the market
Blockless fiber optic splitter
Steel tube fiber optic splitter
ABS box fiber optic splitter
Rack mounted fiber optic splitter mounts in a standard rack
Mini Plug-in PLC Splitter
According to the transmission mode of light in the optical fiber, the splitter can be divided into single mode splitter and multimode splitter
Single mode splitters are made with two single-mode fibers, and multimode splitters are made with multimode fibers. PLC planar waveguide splitter is full-band, and single mode is generally used in the full-wave communication band of 1260nm–1620nm.
The multimode fiber works in the 0.85μm wavelength window or the 1.3μm wavelength window, which is called a single window optical splitter (the single window of the taper splitter only allows this fixed wavelength to pass, and the dual window is two wavelengths); Or work in these two wavelength windows at the same time, which is called a dual window optical splitter. Which window the fiber is suitable for is mainly determined by its bandwidth index.
Tips: In fiber optic communications, the light used is light in the infrared region, where the wavelength of light is greater than that of visible light. In fiber optic communications, typical wavelengths are 800 to 1600 nm, with the most commonly used wavelengths being 850 nm, 1310 nm and 1550 nm.
Application of Fiber Optic Splitter
Optical fiber splitters are generally used between optical line terminals and optical network terminals of passive optical networks, and are suitable for EPON, GPON, BPON, FTTX, FTTH, etc. to connect MDF and terminal equipment to distribute optical signals.
The general architecture of FTTH is: OLT (computer room central office) – ODN (passive optical network distribution system) – ONU (user end), in which the optical splitter is applied in the ODN to realize that multiple end users share the same one PON interface. In the PON structure, when the distribution of buildings is scattered and irregular, such as the distribution of villas, the distance is far, and the density of users is low, the centralized light splitting method can make full use of resources and cover the surrounding area.
In a passive optical network, only one optical fiber splitter may be used, or multiple optical fiber splitters may be used together to split optical signals.
ODN is an optical distribution network, which is the optical transmission physical channel between OLT and ONU. Its main function is to complete the bidirectional transmission of optical signals. It is usually composed of optical fiber cables, optical connectors, optical splitters, and supporting equipment for installing and connecting these devices, the most important component of which is the beam splitter. There are two main types of optical distribution network (ODN) splitting modes: primary splitting and secondary splitting.
The structure of primary splitting is OLT-optical splitter-ONU, and the optical splitters from OLT to ONU are all parallel.
When using primary splitting, the splitter is generally set at the intersection of the wiring and light. The structure of Secondary splitting is OLT-optical splitter 1-optical splitter 2-ONU, and the optical splitter from OLT to ONU is cascaded. When secondary splitting is used, the first-level splitter is generally set at the intersection of the wiring light, and the second-level splitter is generally set at the fiber splitting box.
Primary splitting can only be connected to one splitter. Generally, a splitter with a large number of splits is used, such as 1:32 or 1:64. Secondary splitting generally uses a 1:8 or 1:16 splitter at the primary splitting point, and a 1:4 or 1:8 splitter at the secondary splitting point.
Typically, primary splitting solutions are used in congested downtown or town areas to reduce costs and ease maintenance of Optical Distribution Network (ODN) nodes. On the other hand, secondary splitting solutions are used in roadside or rural locations to cover a wide range of ODN nodes, saving resources and saving money.
4 important performance indicators of fiber optical splitter
There are four main performance indicators that are used to judge the quality of an optical splitter: insertion loss, return loss, splitting ratio, and isolation.
Insertion loss refers to the dB number of each output relative to the input light loss, and its mathematical expression is: Ai=—10lg Pouti/Pin. The smaller the value of Insertion loss, the better the performance of the optical splitter.
Return loss is the DB number of the total optical power of all output ports relative to the input optical power loss.
The additional loss is an indicator that reflects the quality of the device manufacturing process, and reflects the inherent loss of the device manufacturing process. The smaller the loss, the better.
Splitting ratio is the output power ratio of each output port of the fiber splitter. The splitting ratio of the fiber optic splitter is related to the wavelength of the transmitted light, and the wavelength must be indicated when ordering the fiber optic splitter.
Isolation refers to the isolation ability of a certain optical path of a fiber optic splitter to optical signals in other optical paths. Among the above indicators, the isolation degree is more significant for the optical splitter. In practical system applications, devices with an isolation degree of more than 40dB are often required, otherwise, the performance of the entire system will be affected.
However, other parameters such as uniformity, directivity and PDL polarization loss can also have a significant impact on the overall performance of the device.