On campus, more than 30 fraternity buildings are connected
to the core network by OM1 multimode fibers that
were deployed many years ago. The demand for increased
throughput involved 38 multimode optical links. These
multimode fibers, ranging in length from 400 to 1,100
meters (1,310 to 3,610 feet), were unable to transmit
information at the required rate of 10 Gb/s.
Recabling can be complex. Most of the cable ducts
were no longer available and the operational constraints
were too great to implement the project. Recabling would
have been a very costly solution to this problem. The network
managers of this university, being intently focused
on technological innovation, were attracted
to the MPLC technology shown at the 2018 BICSI Winter
Conference and Exhibition in Orlando, Florida. Georgia
Tech ultimately adopted MPLC technology to meet
its broadband requirements using its existing multimode
links (Figure 5). The center launching modal adapters
were installed and implemented as shown in Figure 6.
For lengths under 800 meters (875 yards), the center
launching modal adapter was installed at just one end of
the optical fiber pair to the network core. The equipment
was spliced to existing multimode fiber undergoing the
upgrade. Since the multimode connectors have eccentricity
tolerances of a few micrometers, it was
1
1
January/February/March 2020 I 23
FIGURE 5: Georgia Tech campus illustration showing
multimode fiber links and the network core with installed
MPLC-based modal adapters.1
your own devices (BYOD); and increased digital content
to support online student learning that improves the
students’ experience via innovative teaching tool platforms,
TV/video services, and campus social networking.
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Optical
connector
9
10 Gb/s
transceiver
7
3
4
2
5 5
1
3
MODAL
ADAPTER
7
9
FIGURE 6: Georgia Tech’s MPLC-based modal adapter implementation scheme.2
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10 Gb/s
transceiver
MMF link
>800 m and <10000 m
Fusion
splice MMF link <800 m
SMF
patchcord
SMF
patchcord
Patch panel
SMF
patchcord
Tx
Tx
Tx
Tx
Tx
Rx
Rx
Rx
Tx
Rx
Rx
Rx
Rx 12
11 12
11
10
8
6 6
1
2
2
2
4
8
10
Rx
Network core Remote buildings
MODAL
ADAPTER
10 Gb/s
transceiver
10 Gb/s
transceiver
10 Gb/s
transceiver
10 Gb/s
transceiver
10 Gb/s
transceiver
Tx
Tx
10 Gb/s
transceiver
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