Page 151 - Optical Switching And Networking Handbook

07_200023_CH06/Batesx 1/17/01 10:05 AM Page 136

136 Chapter 6

Multiple Choices Available

Among the different choices competing to replace electronic cores are
optical switches based on the following:
Thermal bubble generation in planar waveguides (developed by
Agilent Technologies)

Electro-optic properties of liquid crystals (being developed by
Chorum, Corning, and Spectra-Switch)
The MEMS switches (developed by Nortel Networks, Xros,
Lucent, and others)
Some of these products are ready commercially in low-port-count
(2 to 32 channels) switch configurations. However, it remains uncer-
tain whether they can be extended beyond their current forms. In

addition to the relatively high optical throughput losses of these
devices, the need for temperature control and uncertainties over
long-term aging effects are common causes of concern.
TEAMFLY

Mirror-Mirror on the Wall . . .

In the swift-moving world of optical networking, long-distance oper-
ators are using new technologies to facilitate the rocketing demand
for higher and higher levels of bandwidth. Included in the techno-
logical choices are microelectromechanical systems (MEMS). Based
on MEMS technology, tiny mechanical structures can be made using
processing techniques derived from the integrated circuit (IC) indus-
try. Using micromirrors made of single-crystal silicon, input light
beams are directed to the appropriate output ports to perform the
switching function. MEMS consist of optical switch technology using
microscopic mirrors to route signals from fiber to fiber in a network
cross-connect or node. A typical mirror capability is shown in Figure
6-6. These mirrors are smaller than a pinhead.
Theoretically, the essentially all-optical switch bypasses the need
to convert optical signals to electric signals, as is done with tradi-
tional switches. This was the overall goal to save time and prevent

®
Team-Fly