Parallel options suitable
for 100G on dedicated fiber, limited distances
4 X 25G and 10X10G have
been proposed
4x 25G VCSEL WDM likely
candidate for client-side optics (achievable with CMOS)
Negative service provider
reaction to parallel networking solutions in MAN/WAN
Non-scalability of
capacity: multiple waves to manage, ROADM port exhaust
Serial options – new technology
to improve propagation, spectral efficiency
Trading speed for
complexity – starting at 112 Gb/sec
Polarization multiplexing – divide by
2
Each polarization carries a
56 Gb/s signal
Phase coding – e.g.: Four
phase states
Four phases encode two info
bits
Symbol rate cut in half to
28 Gbaud/sec