Optical components are broadly divided into two categories: active and passive. Active components are used in optical networks to generate, amplify or convert an optical signal. Transmitters, amplifiers and receivers are considered to be active components within an optical network. Passive components are used to guide, mix, filter, route, adjust and stabilize optical signals transmitted through an optical network without the need for power generation. They include:
Attenuators: components that adjust the power distribution among different wavelengths in a light signal. Of particular interest are Variable Optical Attenuators (or VOAs) that allow the system operator to vary the level of attenuation at different wavelengths.
Couplers: components used to split and combine light.
WDMs and DWDMs: components used to split and combine wavelengths.
OADMs: components used to insert or remove one or more wavelengths or channels from a light signal.
Optical isolators: components used to eliminate reverse transmission of light down a fiber.
Optical switches: components used to select the fiber path down which an optical signal is transmitted.
DiCon also uses the term dynamic passive components to refer to passive components that are combined with some form of intelligence to enable automatic configuration or re-configuration. Examples of dynamic passive components include Optical Cross-Connect Switch Matrices (or OXCs), ROADMs (Re-configurable OADMs), and Dynamic Gain/Power Equalizers (one or more VOAs combined with optical monitoring to automatically set attenuation or absolute power levels).