IEEE Signal Processing - May 2018 - 14

on implementing nonlinear functions
all-optically, to lift these speed limits,"
he says.
"This technology has applications
in optical communications, high-performance computing, radars/lidars-any
field which needs to process massive
amounts of information at fast speeds,"
Vasilyev observes.
The current version of the multichannel regenerator is designed for "on-off"
modulated signals. However, the telecom
industry is rapidly transitioning toward
more advanced modulation formats,
such as quadrature amplitude modulation, where the information is encoded
in both the amplitude and the phase of
the signal. "Hence, the next logical step
[will be] to combine our technology with
another signal processing technology
also pioneered in our lab-multichannel
phase-sensitive amplification-to build
multichannel regenerators of these advanced modulation formats," Vasilyev says.

Author
John E d w a r d s ( jedwards@john
edwardsmedia.com) is a technology
writer based in the Phoenix, Arizona
area. Follow him on Twitter @Tech
JohnEdwards.

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IEEE Signal Processing Magazine

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May 2018

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SP

IMAGE LICENSED BY INGRAM PUBLISHING

The new nonlinear medium allowed
of times faster than what can be prothe researchers to recently demonstrate
cessed electronically," Vasilyev says.
simultaneous all-optical regeneration of
Until now, all-optical regeneration has
16 WDM channels by a single device-a
only been able to handle only one WDM
number limited only
channel at a time. This
by laboratory conis because the SPM is
Processing signals entirely
always accompanied
in the optical domain opens straints. "It is quite
feasible to simultaneby cross-phase modthe door to terahertz-scale
ously regenerate all
ulation (XPM), an
bandwidth, as opposed to
80-160 WDM chaneffect which causes
the gigahertz-scale levels
nels without increasthe intensity of one
WDM channel to
achievable with electronics. ing the cost, all in a
book-sized device,"
modify the speed of
Vasilyev says. "This multichannel regenlight in the other channels, causing
erator could even potentially shrink to
debilitating interchannel crosstalk and
the size of a matchbox in the future if
nullifying any regeneration benefits.
the nonlinear-optical medium could be
"We have found a solution to this fundaimplemented on a microchip."
mental problem by developing a novel
Processing signals entirely in the
group-delay-managed nonlinear-optical
optical domain opens the door to teramedium, where a strong SPM effect is
hertz-scale bandwidth, as opposed to the
achieved without any XPM crosstalk,"
gigahertz-scale levels achievable with
Vasilyev explains. "This medium is obelectronics. As a result, the approach
tained by splitting a conventional noncan handle much faster, higher-capacity
linear medium, such as an optical fiber,
data streams. "Today, linear signal prointo several short sections separated by
cessing functions, such as filtering
special all-pass phase filters called periand amplification, are already widely
odic-group-delay devices." The combinaused in optical communications," Vasition effectively yields a medium in which
lyev notes. Yet nonlinear functions such
all frequency components of the same
as quantization, compression, limiting,
WDM channel travel at the same speed,
regeneration,and frequency conversion are
ensuring strong SPM, while different
still handled electronically, which re sults
WDM channels travel at very different
in high power consumption and limited
speeds, which dramatically suppresses
processing sp e e d s. "We are working
any interchannel interaction.
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Table of Contents for the Digital Edition of IEEE Signal Processing - May 2018
