China
Africa
Explore chapters and articles related to this topic
Optical Ring Metropolitan Area Networks
Published in Partha Pratim Sahu, Advances in Optical Networks and Components, 2020
SONE/SDH ring is used in an optical network infrastructure today for a MAN [12,13]. In a SONET ring network, WDM contributes a point-to-point bandwidth transmission technology. The SONET system’s hierarchical TDM schemes permit a high-speed OC-N channel to accommodate multiple OC-M channels (where M is smaller than or equal to N). The ratio of N to the smallest value of M carried by the network is defined as grooming ratio. Electronically controlled add–drop multiplexers (ADMs) are used to add/drop traffic at intermediate nodes to/from the high-speed channels. In a SONET ring network, an ADM is required for a wavelength at every node to add/drop traffic in that wavelength. The use of ADM is expensive as the same number of ADMs is needed at every network node since traffic assigned to a wavelength is only by passing an intermediate node. With the emerging optical components such as OADM (also referred to as wavelength ADM (WADM)), a node bypasses most of the wavelength channels optically and drops only the wavelengths having the traffic destined to the node. Figure 1.1 shows the architecture of a typical node in a SONET/WDM ring network. Since there is no need to add or drop any of its time slots, they are optically by passed at the node. For other wavelengths (λ2 and λ3) where at least one time slot needs to be added or dropped, an electronic ADM is used.
Thermo-Optic Devices
Published in Kenichi Iga, Yasuo Kokubun, Encyclopedic Handbook of Integrated Optics, 2018
An optical add/drop multiplexer (OADM), which adds and drops incoming and outgoing channels according to their wavelengths in WDM systems, is important in photonic networks. The OADM was constructed by combining an AWG and PLC-type TO switches. The PLC-type TO switch in the OADM node has two functions. One is high-isolation switching for the add/drop operation. The switch must have a high extinction ratio in order to avoid any crosstalk-induced degradation in the bit error rate. The other requirement is a VOA function for level equalization at each channel. Any power deviation among the WDM channels degrades the signal-to-noise ratio for weaker power channels while high power channels suffer waveform distortion induced by fiber nonlinearity [11].
Switching Systems: Architecture and Performances
Published in Iannone Eugenio, Telecommunication Networks, 2017
Referring to a two fiber ring network, an OADM interfaces both the fibers and is able to add/drop optical channels from both the fibers. Thus, the principle scheme of an OADM can be depicted as in Figure 7.39 where a simple OCh-P ring is shown with four OADM nodes and the path of an OCh is represented both in the working (w) and in the protection (p) fiber.
All-optical programmable array logic unit using semiconductor optical amplifier-based polarization switch
Published in Journal of Modern Optics, 2022
Manas Kumar Garai, Mrinal Kanti Mandal, Sisir Kumar Garai
The operational mechanism of the proposed PAL unit is based on: Routing of frequency by an optical add/drop multiplexer (ADM)Polarization rotation of the probe beam-based switching action of SOA.