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Optical Switching Systems and Technologies 147

Long-haul Intra-office Intra-officeLong-haul
Figure 6-13
The WIXC from
Rx P Tx Rx P Tx
Agilent (Agilent)
Rx P Tx Rx P Tx
Rx P Tx Rx P Tx
Rx P Tx Rx P Tx
Optical-layer
Rx P Tx Rx P Tx
Cross-connect
Rx P Tx Rx P Tx
Rx P Tx Rx P Tx
Rx P Tx Rx P Tx
Rx P Tx Rx P Tx

Local Traffic Local Traffic

Source: Agilent

sion.Advances have been made in all-optical wavelength converters,
but even if these devices materialize, they still will be expensive.
The most attractive transparent node architecture is the wave-
length-selective cross-connect (WSXC), which can be constructed out
of a single fabric or several smaller fabrics, as shown in Figure 6-14.
The WSXC operates by switching all the “green” wavelengths
between fibers on one plane, the “blue” wavelengths on another
plane, and so on. A WSXC node with 25 fibers and 160 wavelengths
per fiber requires 160 25 25 switches or a single 4,000 4,000
switch. Slightly larger switches enable dropping and adding of local
traffic, enable some channels to be regenerated, and enable some
channels to move between wavelength planes.
Agilent Technologies, Inc., introduced 32 32 and 32 16 port
switches that use tiny bubbles to deflect light from one path to
another at speeds faster than 10 ms. The technology competes with
MEMS and has the advantage of having no moving parts to lock up
or wear out. It also contains the light within the device, unlike some
MEMS equipment, making it less prone to problems.