Optical Networking Best Practices Handbook

Glossary

Absorption:

The portion of optical attenuation in an optical fiber resulting from the conversion of optical power to heat; caused by impurities such as hydroxyl ions in the fiber.

A/B Switch:

A device that accepts inputs (optical or electrical) from a primary path and a secondary path to provide automatic or manual switching in the event that the primary path signal is broken or otherwise disrupted. In optical A/B switches, optical signal power thresholds dictate whether the primary path is functioning and signals a switch to the secondary path until optical power is restored to the primary path.

AC:

Alternating current. An electric current that reverses its direction at regularly recurring intervals.

Acceptance Angle:

The half-angle of the cone within which incident light is totally internally reflected by the fiber core. It is equal to sin⁻¹ (NA), where NA is the numerical aperture.

Active Device:

A device that requires a source of energy for its operation and has an output that is a function of present and past input signals. Examples include controlled power supplies, transistors, LEDs, amplifiers, and transmitters.

A/D or ADC:

Analog-to-digital converter. A device used to convert analog signals to digital signals.

Add/Drop Multiplexing:

A multiplexing function offered in connection with SONET that allows lower-level signals to be added or dropped from a high-speed optical carrier in a wire center. The connection to the add/drop multiplexer is via a channel ...