In the process of engineering wiring and fiber optic terminal operation, it is inevitable to encounter situations where the fiber optic cable or jumper tail fiber is not long enough or worn and broken. How should we handle this?
First, let’s take a look at the optical fiber structure:
- Fiber core: The central part, where light waves propagate through the fiber core
- Cladding: Surrounding the fiber core, with a refractive index lower than that of the fiber core, serving as optical isolation
- Coating: maintain fiber strength while isolating certain external forces
To ensure that two optical fibers are connected well, it is necessary to ensure that the core layers are aligned with each other and match well together, no matter fiber type or size. Here we mainly introduce three commonly used fiber optic connection methods.
1. Fiber splice fusion connection (hot melt)
This method involves heating and melting the front end of a glass fiber to bond two fibers together.
According to the different connection methods, fusion splicing can be divided into two types: “core to center method” and “fixed V-groove to center method”.
The core to core center method uses a microscope to position the core to match and connect the central axis. This method is suitable for single core optical fibers.
The fixed V-groove adjustment method is to arrange the optical fibers in high-precision V-grooves of the fixed V-groove and fuse them using the surface tension generated during melting. This method is mainly used for simultaneously connecting multiple core wires (such as ribbon cables), and due to technological advancements, high-precision positioning and fusion can be achieved.
The advantage of fusion splicing is that compared with other methods, the connection loss is about 0.01-0.05dB lower, and the ribbon fibers can be connected together. According to the performance of the fusion splicer, it will automatically melt and check the connection loss, so it is recommended to use it when improving the connection accuracy. However, fusion splicers are expensive and require regular maintenance and charging for mobile operations.
The fusion method will use various fiber optic tools such as fiber fusion splicer, fiber optic cleaver, cable stripping pliers, alcohol, dust-free paper, heat shrink splicing sleeve, etc. Our company can provide individual products or complete fiber optic tool kits. If you have any requirements, please click on the link below and place an order.
2. Mechanical joint connection (cold joint)
Mechanical joint connection, also known as cold joint, is mainly used for fiber optic fast connectors. It is to insert the stripped bare optical fiber into the mechanical joint component, so that the two optical fibers are in contact with each other, and the optical signal is smoothly transmitted through the fiber matching liquid inside, then lock the fiber. And each optical node requires a quick connector.
Because it no need power supply, so the working time is only seconds, and no need large fiber optic tools like fusion splicer, easy to operate, lower costs, and is suitable for field operations.
However, the mechanical connection loss is approximately 0.2-0.5dB, greater than that of fusion splicing, and there is a possibility of malfunction.
Yingda provide various types of fiber optic field installation connectors, as well as corresponding tools: fiber optic cleaver, dust-free paper kimtech wipes, alcohol bottles, laser pen, power meters, fiber optic cable stripping pliers, drop cable strippers, fiber optic tool kit in bag or box, etc.
3. Coupling connection
Coupling is mainly a method of connecting using fiber optic adapters. Unlike permanent connection methods such as fusion welding and cold joint, which cannot be installed or removed once connected coupling can be easily installed or removed through connectors after operation, and various types of interface can be selected like SC LC FC ST E2000, MPO MTP,etc. And the ability to repeat use and directly connect to the device is an advantage that other methods do not have.
However, although coupling is easy to operate, the coupling loss is also relatively high about 0.1-0.2dB, depending on the type of connector and fiber. At the same time, the connector is prone to dust and fingerprints when put on and off, so it must be cleaned with a cleaning kits.
Furthermore, there are two types of connectors, male and female. If both are male, the conversion adapter must be connected to either of the interface. Then we need hybrid adapters.
Yingda can provide various adapters, including regular adapters, hybrid adapters, shutter adapters, and bare fiber adapters. We can meet different customer needs and provide various connector cleaning tools such as cleaning pens, cleaning cassette box, cleaning sticks, dust-free paper, alcohol bottles, etc.
4 Reasons for Fiber Optic Connection Loss
When connecting optical fibers, the cores of the two fibers must face each other. Incorrect positioning will result in loss of fiber optic connection, making it impossible to transmit light in a stable manner. Fiber optic connection loss mainly occurs in the following four situations, so be careful when connecting.
1. Axis misalignment
If the optical axis of the fiber is not aligned, connection loss may occur. The value obtained by multiplying the square of the axis deviation by 0.2 is the connection loss of a universal single-mode fiber.
2. Angle offset
When connecting optical fibers, if the angle of the optical axis deviates, connection loss will occur. On the other hand, when cutting optical fibers, please note that if the cross-section is too angled, the tilt of the fiber will increase during the fusion process.
3. Gap
If the tip of the optical fiber cannot be firmly connected and form a gap, it may lead to connection loss.
4. Reflection
If there is a gap at the end of the optical fiber, the difference in refractive index between the fiber and air will cause reflection, resulting in connection loss. The maximum loss is about 0.6 dB.
Precautions for hot melt connection of optical fibers
1. Don’t forget to insert the protective cover (heat shrink tube)
Insert a protective sleeve to protect the exposed optical fiber during fusion splicing. Clean the fiber optic coating on one side of the insertion sleeve with gauze soaked in alcohol beforehand, taking care not to let dust enter the interior. The protective sleeve cannot be inserted after that, so it must be inserted at the beginning.
2. Be careful when handling cut optical fibers
After cutting the fiber optic cable, if it touches or touches the cross-section, it may cause poor connection. After cutting, it is important to handle with care and not apply additional loads.
3. Conduct discharge test before melting
In order to minimize the connection loss of the fusion splicer, it must be melted with an appropriate discharge power. Perform discharge testing before fusion and set appropriate discharge power. There are various types of fiber optic connections, each with different characteristics. Not only are the connection methods and costs different, but the size of the connection loss will also vary, so please choose the appropriate connection method according to your needs and budget. If you have any questions about connecting optical fibers, please contact us.
