To navigate the complex world of fiber optics effectively, it's essential to understand the terminology associated with this technology. In this comprehensive glossary, we'll break down the key terms into specific categories for a better understanding.
Fiber optics, as a universal technology, relies on the metric system for measurement standards. Familiarize yourself with these essential metrics:
Meter: Equivalent to 3.28 feet (or more precisely, 3.28084 feet).
Kilometer: Corresponds to 1000 meters, 3,281 feet, or 0.62 miles.
Micron: Represents 1/1,000,000th of a meter. In the fiber optics industry, it is a common unit of measurement for fibers.
Nanometer: One billionth of a meter, typically used in the fiber optics industry to express the wavelength or frequency of transmitted light.
Watts: A linear measure of optical power, usually expressed in milliwatts (mW), microwatts (*W) or nanowatts (nW).
Before diving into any hands on terminology, it's crucial to understand the fundamental components of fiber optics:
Fiber optics (fo): Light transmission through flexible transmissive fibers for communications or lighting.
Optical Fiber: Thin strands of highly transparent glass or plastic designed to guide light.
Core: The central part of the fiber where light transmission occurs.
Cladding: The outer optical layer that traps and guides light within the core, even through curves.
Buffer Coating or Primary Coating: A protective hard plastic layer on the outer surface of the fiber, guarding against moisture and physical damage.
Mode: A single electromagnetic field pattern (akin to a ray of light) that travels within the fiber.
Multimode Fiber: Featuring a larger core (62.5 or 50 microns) and employed with LED sources for short-distance, lower-speed networks, such as LANs.
Singlemode Fiber: With a much smaller core, about 9 microns, networks, telephony, and CATV with laser sources for long-distance, high-speed applications.
Network: A system of cables, hardware and equipment used for communications.
Jumper cable: A short single fiber cable with connectors on both ends used for interconnecting other cables or testing.
Plastic Optical Fiber (POF): A multimode fiber with a large core (about 1mm) utilized in short, low-speed networks. POF has gained popularity in consumer HiFi and car communication systems.
Graded-Index Fiber: A multimode fiber with a core that has a lower refractive index in the center than at the edges.
Singlemode Fiber: A fiber that supports only one mode.
Edge-Emitting Diode (E-LED): A LED that emits from the edge of the semiconductor chip, producing higher power and narrower spectral width.
Helium-Neon Laser: A type of gas laser that emits a red light beam.
Laser: Light Amplification by Stimulated Emission of Radiation.
Light Emitting Diode (LED): A semiconductor that emits light when current flows through it.
Light Source: The device that provides the light for a fiber optic system.
S/N Ratio: Signal-to-Noise ratio.
Signal: Information-carrying electromagnetic or optical wave.
Faraday Rotation: The rotation of the plane of polarized light in a magnetic field.
Polarization: The orientation of electromagnetic wave vibrations.
Decibels (dB): A unit of measurement of optical power which indicates relative power. A -10 dB means a reduction in power by 10 times, -20 dB means another 10 times or 10 times overall, -30 means another 10 times or 1000 times overall and so on.
dB: Optical power referenced an arbitrary zero level
dBm: Optical power referenced to 1 milliwatt
Optical Loss: The amount of optical power lost as light is transmitted through fiber, splices, couplers, etc, expressed in dB.
Optical Power: is measured in "dBm", or decibels referenced to one miliwatt of power. While loss is a relative reading, optical power is an absolute measurement, referenced to standards. You measure absolute power to test transmitters or receivers and relative power to test loss.
Scattering: The change of direction of light after striking small particles that causes loss in optical fibers and is used to make measurements by an OTDR
Wavelength: A term for the color of light, usually expressed in nanometers (nm) or microns (m). Fiber is mostly used in the infrared region where the light is invisible to the human eye.
Wavelength division multiplexing (WDM): A technique of sending signals of several different wavelengths of light into the fiber simultaneously.
Total internal reflection: Confinement of light into the core of a fiber by the reflection off the core-cladding boundary.
PON (Passive Optical Network): A Passive Optical Network (PON) is a type of telecommunications network that uses fiber-optic cables to distribute signals. Unlike active optical networks, PONs do not require powered equipment for signal transmission, making them more cost-effective and efficient.
GPON (Gigabit Passive Optical Network): GPON (Gigabit Passive Optical Network) is an advanced version of PON that pro