How does bending fiber optic cable affect FTTH network performance?

1 Causes and types of bends

Bending fiber optic cable can occur during installation, operation, or maintenance of FTTH networks. Some of the common causes of bending are: improper handling, routing, or splicing of the cable; tight corners, loops, or knots in the cable; external pressure, tension, or vibration on the cable; environmental factors, such as temperature, humidity, or water; and accidental damage, such as cuts, breaks, or kinks. Bending can be classified into two types: macrobending and microbending. Macrobending is when the cable bends at a large radius, usually visible to the naked eye. Microbending is when the cable bends at a small radius, usually invisible to the naked eye, but caused by microscopic irregularities or defects in the cable.

2 Effects of bending on performance

Bending fiber optic cable can affect FTTH network performance by causing bend losses, which are the reduction of optical power or signal strength due to bending. Bend losses can result in lower data rates, higher error rates, or signal degradation or interruption. Bend losses depend on several factors, such as the wavelength, mode, and core size of the fiber; the radius, angle, and length of the bend; and the refractive index profile of the fiber. Generally, bend losses are higher for longer wavelengths, smaller core sizes, tighter radii, larger angles, and longer bends. Bend losses are also higher for single-mode fibers than multimode fibers, and for step-index fibers than graded-index fibers.

3 Measurement and prevention of bend losses

Bending fiber optic cable can be measured and prevented by using various tools and techniques. One of the most common tools for measuring bend losses is an optical power meter, which can measure the optical power or signal strength at different points along the cable. Another tool is an optical time domain reflectometer (OTDR), which can measure the distance, location, and magnitude of bend losses along the cable. To prevent bend losses, some of the best techniques are: using bend-insensitive or bend-optimized fibers, which have a modified refractive index profile or a protective coating to reduce bend losses; using bend limiters or radius clips, which are devices that prevent the cable from bending below a certain radius; using proper cable management systems, such as trays, racks, or ducts, which provide adequate space and support for the cable; and following the manufacturer's specifications and industry standards for the minimum bend radius, which is the smallest radius that the cable can bend without causing significant bend losses.

4 Best practices for installation and maintenance

Bending fiber optic cable can be avoided or minimized by following some best practices for installation and maintenance of FTTH networks. Some of the best practices are: planning and designing the network layout and route before installation, taking into account the cable length, type, and capacity; using proper tools and equipment for handling, routing, and splicing the cable, such as cutters, strippers, cleavers, fusion splicers, and testers; avoiding tight corners, loops, or knots in the cable, and leaving some slack or extra cable for future adjustments or repairs; inspecting and testing the cable before, during, and after installation, and identifying and fixing any bends, breaks, or defects; and performing regular maintenance and monitoring of the network, and replacing or repairing any damaged or degraded cable.