Theoretical MMF bandwidth
gain according to launching
conditions (extract from
IEEE 802.3aq study)
Perfect center launching
(Multi-Plane Light Conversion)
Offset launching
(Mode conditioning patchcord + Electronic Dispersion Compensation)
MMF Bandwidth gain
0 Light launching conditions
FIGURE 4: Multimode Fiber (MMF) bandwidth gain comparison between perfect center launching (MPLC) and offset launching.
22 I ICT TODAY
Exposed cables
easily disrupted
Temporary new projector
distance too great for
passive HDMI cable
transparent to wavelength and can operate in the O-band
(1300 nm window) or C-band (1500 nm window) range
with standard singlemode transceivers at 1 Gb/s, 10 Gb/s
or even higher. Intrinsic loss of such a modal adapter is
less than 2 dB and does not add transmission power
penalty. Considering the linear losses of optical fibers
at these high wavelengths and the sensitivity of singlemode
standard transceivers, the overall optical budget of
the link remains sufficient to transmit information over
long distances and to cover the requirements for all types
of LANs that need their legacy multimode fiber cabling
infrastructure upgraded.
CASE STUDY: UPGRADING THE
CONNECTIVITY OF FRATERNITY
HOUSES AT GEORGIA TECH
The Georgia Institute of Technology, also known as
Georgia Tech, is a public research university located in
Atlanta, Georgia. This university strives to provide highspeed
connection to fraternity houses on campus in
order to provide students with high quality services,
such as robust Wi-Fi coverage with increased wireless
access points (WAPs); high quality wired internet access
in the face of increased data traffic in the era of bring
complete light shaping with very little loss through
a succession of transverse phase profiles similar to very
complex optical lenses. The technology shapes a laser
beam (light from a transceiver) in such a way that each
mode within the multimode optical fiber can be independently
and precisely excited. Today, MPLC technology
is used to increase the transmission capacity and to
achieve bandwidth gains of existing multimode fibers by
performing perfect center launching on legacy multimode
fibers (Figure 4). By overcoming speed and distance limitations,
up to 100 Gb/s can be carried over an existing multimode
infrastructure up to several kilometers. There are
solutions adapted to different topologies that allow for
a progressive and flexible evolution of the legacy network
optical infrastructure, compatible with any 62.5/125 μm
or 50/125 μm multimode fiber types (i.e., OM1 to OM5).
Because this technology consists solely of optical
elements, the solutions are passive (e.g., no energy
consumption, no supervision) and operate at the physical
layer level, which makes them transparent to the commu-
nication protocol and modulation format used. There is
no need for EDC or complex digital processing at the
reception of the transmission; simple detection systems,
such as direct detection, are sufficient. This technique is
MPLC enables flexible and complete light shaping with very little loss through
a succession of transverse phase profiles similar to very complex optical lenses.