Optical performance monitoring (OPM) is used for managing high capacity dense wavelength division multiplexing (DWDM) optical transmission and switching systems in Next Generation Networks (NGN). OPM involves assessing the quality of data channel by measuring its optical characteristics without directly looking at the transmitted sequence of bit

Bit

A bit is the basic unit of information in computing and telecommunications; it is the amount of information stored by a digital device or other physical system that exists in one of two possible distinct states...

s. It is a potential mechanism to improve control of transmission and physical layer fault management in optical transmission systems.

In optical communications, typical roles for optical performance monitoring include ensuring correct switching in reconfigurable optical add-drop multiplexer

Reconfigurable optical add-drop multiplexer

In fiberoptics, a reconfigurable optical add-drop multiplexer is a form of optical add-drop multiplexer that adds the ability to remotely switch traffic from a WDM system at the wavelength layer. This is achieved through the use of a Wavelength selective switching module...

s, setting levels for dynamic equalization of the gain of optical amplifier

Optical amplifier

An optical amplifier is a device that amplifies an optical signal directly, without the need to first convert it to an electrical signal. An optical amplifier may be thought of as a laser without an optical cavity, or one in which feedback from the cavity is suppressed...

s, and providing system alarms and error warning for lost or out of specification optical channels.

The optical component used for this purpose in DWDM networks is known as optical performance monitor (OPM) or optical channel monitor (OCM), which measures channel power, wavelength, and optical signal-to-noise ratio (OSNR) for each channel.