The fiber optic splitter, known as fiber coupler, is a special fiber optic device with one or more input fibers to distributing optical signals into two or more output fibers at a certain ratio. It is one of the most important passive devices in the optical fiber link, especially applicable to a passive optical network (EPON, GPON, BPON, FTTx, etc.), to connect the MDF (Main Distribution Frame) and the terminal equipment and to achieve the branching of the optical signal. This paper will make an introduction of fiber optic splitter from its features and common types.
The fiber optic splitter comes in a wide range of styles and sizes to split or combine light with minimal loss. All splitters are manufactured in a very simple proprietary process that produces reliable, low-cost devices. Their fiber lengths and/or with terminations of any type are optional. Most splitters are available in 900µm loose tube and 250µm bare fiber. 1×2 and 2×2 couplers come standard with a protective metal sleeve to cover the split. Higher output counts are built with a box to protect the splitting components.
The fiber optic splitter comes in singlemode and multimode fiber modes. Typical connectors installed on the fiber optic splitters are FC or SC type, but many couplers are also compliant with LC, LC/APC, SC, SC/APC, FC, FC/APC, and ST. Because the splitter is a passive device, it is immune to EMI (Electromagnetic Interference), consumes no electrical power and does not add noise to system design. Its passive design is bi-directional and operationally independent of wavelength, constrained only by the physical properties of the PMMA (Poly (Methyl Merthiolate)) fiber core.
According to the technology used to fabricate splitters, there are two common types optical splitters: FBT splitter and PLC splitter. Each type has both advantages and disadvantages when deploying them in a passive optical network.
FBT splitters are fused with a heat source similar to one-to-one fusion splice. The fibers are aligned in a group to create a specific location and length. Heat is applied to the aligned fibers while the fibers are monitored for polarization-dependent loss (PDL), split ration and insertion loss (IL). Once the desired parameters have been met on all fibers, the fusion process stops.
FBT splitters are well-known and are easy to produce, thus reducing cost of production. They can split unequal ratio, either symmetrical or non-symmetrical, according to the needs of real-time monitoring. Besides, FBT splitters can work on three different operating bands, such as 850 nm, 1310 nm and 1550 nm. Due to these benefits, these splitters are widely deployed in passive networks, especially for instances where the split configuration is smaller (1×2, 1×4, etc).
However, FBT splitters are limited in the number of quality splits that can be achieved in a single instance, so several must be spliced together when a larger split configuration is required. Besides, its poor uniformity can not ensure uniform spectroscopic and the insertion loss changes greatly with temperature variation.
PLC (Planar Light-wave Circuit )
PLC splitters use an optical splitter chip to divide the incoming signal into multiple outputs. The chip, either silica or quartz-based, is available in varying polished finishes. It is composed of three layers: a substrate, the waveguide and the lid. Waveguides are fabricated using lithography onto a silica glass substrate, which allows for routing specific percentages of light. The physical appearance of the splitter varies depending on final assembly.
PLC splitters have high quality performance but low failure rate, such as low insertion loss, low PDL, high return loss and excellent uniformity over a wide wavelength range from 1260 nm to 1620 nm. In addition, its compact configuration and small size occupy little space. Different from FBT splitters, PLC splitters split equal splitter rations for all branches. When larger split configurations are required, PLC splitter is a better solution.
However, FBT fabrication process is very complex, thus setting a high technical threshold in application. Besides, they are more expensive than FBT splitters in the smaller ratios.
The fiber optic splitter is a passive device that plays an increasingly significant role in many of optical networks. From FTTX systems to traditional optical networks, fiber splitters provide capabilities that help customers maximize the functionality of optical network circuits. Thus an educated decision regarding splitter selection determines the long-term success and financial viability of a network build.