NET 436 optical Network Tutorial Lecture #4 Networks and Communication Department Lab 4

Structure of Fiber-Optic Cables Core Cladding Coating

General Structure of Fiber-Optic Cables

Cladding Cylindrical material made of glass or specialized plastic Central portion of the fiber Light signal carrying the information travels through the core The diameter of the core can range from a couple of micrometers (µm-one millionth of a meter) to a couple of millimeters (mm-one thousandth of a meter) 24-Feb-19 Networks and Communication Department

Jacket Insulates and protects the fiber from physical damage and environmental effects, such as moisture, that might interfere with the inner workings of the cable Usually made of opaque plastic or another type of material 24-Feb-19 Networks and Communication Department

Layered Structure (continued): 24-Feb-19 Networks and Communication Department

Layered Structure: Inner core – glass or plastic fibers at the center that carry laser pulses or an LED light used for data transmission Cladding – a layer of plastic or glass around the fibers that reflects the light back to the core Plastic buffer – an opaque layer that protects the cladding and the core and absorbs any light that escapes Plastic sheath – providing the overall cable protection 24-Feb-19 Networks and Communication Department

Layered Structure (continued): Two types of fiber with different propagation modes: Single-mode fiber: only single mode is permitted small core diameter: 8.3(core)/125(cladding) µm Multi-mode fiber: several modes are permitted large core diameter: 50~62.5(core)/125(cladding) µm 24-Feb-19 Networks and Communication Department

Layered Structure (continued): Glass (silicon dioxide, also called silica) is used usually for optical fibers. An optical fiber consists of core and cladding, having less refractive index. 24-Feb-19 Networks and Communication Department

Propagation modes 24-Feb-19 Networks and Communication Department

Types of Fiber-Optic Cables Single-mode fiber Multi-mode fiber Step index fiber Graded index fiber 24-Feb-19 Networks and Communication Department

Single-mode fiber Dispersion is minimal in the single-mode fibers. The core diameter of a single-mode fiber is less than 10 µm. A typical single-mode optical fiber, showing diameters of the component layers. 24-Feb-19 Networks and Communication Department

Single-mode fiber Very small core diameter, on the order of a few micrometers (μm); less than that of a human hair The cladding diameter is tens of micrometers, making it much larger than the core Single-mode fiber can transmit information at very high data rates across large distances The small diameter restricts only a single mode of light to carry all of the information 24-Feb-19 Networks and Communication Department

Multi-Mode Fiber Has a much larger core diameter, ranging from tens to hundreds of micrometers Used for lower-bandwidth, shorter-distance applications than single-mode fibers Information-carrying capacity is less than that of single-mode fibers due to the physical effects they impose on the signals traveling through them 24-Feb-19 Networks and Communication Department