11-575: Arrayed waveguide gratings ( AWG ) are commonly used as optical (de)multiplexers in wavelength division multiplexed (WDM) systems. These devices are capable of multiplexing many wavelengths into a single optical fiber , thereby increasing the transmission capacity of optical networks considerably. The devices are based on a fundamental principle of optics , which states that light waves of different wavelengths do not interfere linearly with each other. This means that, if each channel in an optical communication network makes use of light of
22-400: A fiber patch panel or by optical switches which direct the wavelengths to the multiplexer or to drop ports. The multiplexer multiplexes the wavelength channels that are to continue on from demultiplexer ports with those from the add ports, onto a single output fiber. All the lightpaths that directly pass an OADM are termed cut-through lightpaths , while those that are added or dropped at
33-470: A fundamental principle of optics , which states that light waves of different wavelengths do not interfere linearly with each other. This means that, if each channel in an optical communication network makes use of light of a slightly different wavelength, then the light from many of these channels can be carried by a single optical fiber with negligible crosstalk between the channels. The AWGs are used to multiplex channels of several wavelengths onto
44-415: A single optical fiber at the transmission end and are also used as demultiplexers to retrieve individual channels of different wavelengths at the receiving end of an optical communication network. Conventional silica -based AWGs, as illustrated in the figure above, are planar lightwave circuits fabricated by depositing layers of doped and undoped silica on a silicon substrate . The AWGs consist of
55-488: A slightly different wavelength, then the light from many of these channels can be carried by a single optical fiber with negligible crosstalk between the channels. The AWGs are used to multiplex channels of several wavelengths onto a single optical fiber at the transmission end and are also used as demultiplexers to retrieve individual channels of different wavelengths at the receiving end of an optical communication network. Conventional silica -based AWGs, as illustrated in
66-403: A specific type of optical cross-connect . A traditional OADM consists of three stages: an optical demultiplexer , an optical multiplexer , and between them a method of reconfiguring the paths between the demultiplexer, the multiplexer and a set of ports for adding and dropping signals. The demultiplexer separates wavelengths in an input fiber onto ports. The reconfiguration can be achieved by
77-582: Is a device used in wavelength-division multiplexing (WDM) systems for multiplexing and routing different channels of light into or out of a single-mode fiber (SMF). This is a type of optical node, which is generally used for the formation and the construction of optical telecommunications networks . "Add" and "drop" here refer to the capability of the device to add one or more new wavelength channels to an existing multi-wavelength WDM signal, and/or to drop (remove) one or more channels, passing those signals to another network path. An OADM may be considered to be
88-713: The OADM node are termed added/dropped lightpaths . An OADM with remotely reconfigurable optical switches (for example 1×2) in the middle stage is called a reconfigurable OADM (ROADM). Ones without this feature are known as fixed OADMs. While the term OADM applies to both types, it is often used interchangeably with ROADM. Physically, there are several ways to make an OADM. There are a variety of demultiplexer and multiplexer technologies including thin film filters, fiber Bragg gratings with optical circulators , free space grating devices and integrated planar arrayed waveguide gratings . The switching or reconfiguration functions range from
99-479: The figure above, are planar lightwave circuits fabricated by depositing layers of doped and undoped silica on a silicon substrate . The AWGs consist of a number of input (1) and output (5) couplers, a free space propagation region (2) and (4) and the grating waveguides (3) . The grating waveguides consists of many waveguides, each having a constant length increment (ΔL). Optical add-drop multiplexer An optical add-drop multiplexer ( OADM )
110-432: The manual fiber patch panel to a variety of switching technologies including microelectromechanical systems (MEMS), liquid crystal and thermo-optic switches in planar waveguide circuits. Although both have add/drop functionality, OADMs are distinct from add-drop multiplexers . The former function in the photonic domain under wavelength-division multiplexing , while the latter are implicitly considered to function in
121-416: The traditional SONET/SDH networks. Arrayed waveguide grating Arrayed waveguide gratings ( AWG ) are commonly used as optical (de)multiplexers in wavelength division multiplexed (WDM) systems. These devices are capable of multiplexing many wavelengths into a single optical fiber , thereby increasing the transmission capacity of optical networks considerably. The devices are based on
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