DWDM Fundamentals, Components, and Applications
This leading-edge resource provides comprehensive, up-to-date coverage of the principles, technologies, standards, and applications of dense wavelength division multiplexing (DWDM).
TABLE OF CONTENTS DWDM Fundamentals, Components, and Applications
6.6: Space Switches
6.6 Space Switches
The space-switch cross-connects (or interconnects [50]) fibers connected to the optical node without regard to the attributes of the optical signals. It can be used for traffic routing, reconfiguration, and restoration at the fiber level.
Used with wavelength (or waveband) division demultiplexer/multiplexers and/or static routers it allows wavelength (or waveband) switching.
6.6.1 Crossbar Switches
A fully optical space switch can be realized as a very simple crossbar configuration (Figure 6.6) with three stages that consist of an area of passive splitters, a matrix of controllable on/off switches, and an area of combiners. With N fiber inputs and N fiber outputs it needs N (1 to R) splitters, N R on-off switches, and R (N to 1) optical combiners. In such a device, the output power is only 1/NR without taking into account any practical losses. High bit-rate hybrid crossbar switches using electrical/optical/electrical (E/O/E) conversion have been proposed.
Figure 6.6: Typical crossbar switch architecture.
For example, a cross-bar switch, using the free space optical fan-out of a 8 8 VCSEL array, providing 64 replicas of 64-bit serial optical input signals generated by the VCSEL array was reported in [51 54]. A full evaluation of this system is continuing at the time of this writing.
6.6.2 Routers/Selectors Switches and Benes Switches
Large switch matrices can be built using simple y-branched 1 2 switches. For example the 4 4 switch of Figure 6.7 consists of four switchingunit areas interconnected by three wiring units. This component can be...
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