Bandwidth:   A measure of the information carrying capacity of a communication channel.  Velocity and the wavelength are both factors in determining the bandwidth in fiber optic cable.

Decibel (dB):  Ten Bells.  It is a ratio of power measurements that can be represented by the formula 10 log P2/P1.  Optical power and attenuation (loss) is most often measured in dB.

Fiber Optics:  Transmission of signals through thin strands of glass or plastic fiber.

Frequency:  Expressed in Hertz (Hz) it is the number of wave cycles per second.

Micron (um):  One-millionth of a meter. (0.000001m)

Multi-Mode Fiber:   Fiber that conducts light in a number of patterns.  When a light pulse enters the fiber core, some goes straight down the fiber while the rest scatters, refracting and reflecting at various angles off of the junction of the core and the cladding.  The effect of the dispersion of the light means that different portions of the light pulse will reach the receiver at different time intervals.  Multi-mode fiber has larger core diameters, typically in the 50 to 200 micron range.

Nanometer (nm):  One-billionth of a meter. (0.000000001m)

Optical Attenuation or Optical Dynamic Range or Optical Loss Budget or Optical Power Budget:  Loss of optical power as it travels any distance through fiber. Loss can be attributed to inherent impurities in the core, cladding or at the cable ends. Extreme bends in the cable, length of cable, or the type of connectors used in splicing or connecting to components can also lead to loss. Attenuation is measured in decibels (dB's) per kilometer.

Reflection:  The action of light bouncing off of a surface.

Refraction:  The bending of light as it meets the junction of two surfaces.

Single-Mode Fiber:   Fiber that conducts light in one pattern, straight down the fiber.  Data rates and distances are increased due to the fact that most of the light source travels down the core of the fiber with very little dispersion.  Single-mode fiber has small core diameters in the 5 to 10 micron range.

SMA Connector:  A type of fiber optic connector that is secured with a threaded ring.

ST* Connector: A type of fiber optic connector with an aligning slot and stud for more repeatable connections.  It requires a push/quarter-turn to be secured, much like a BNC connector.

Topology:  Network configuration or layout which may be either wire or fiber or both.  A network that connects one single point to another is often called a Point-to-Point system.  If that network continues on to another location and maybe then another, and so on, it is referred to as a Daisy-Chain.  If the last point in a daisy-chain is routed back to the first point in the chain it is then a Ring configuration.  A Star network is one that radiates from one single point to multiple points.  A network topology may consist of one of these topologies or a combination.

Wavelength:   The length of one cycle of frequency measured as a distance.  In fiber it is mainly used to indicate the portion of the light spectrum that is being sent down the fiber.   Systems using glass fibers use infrared light in wavelengths of 850 to 1550 nanometers.

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