A breakthrough device recently created by UCLA researchers is
capable of converting electrical signals 50 times faster than the
best commercially available one, and has promising implications for
more efficient communication systems and for defense against
high-powered electromagnetic bombs.
After eight years of work, Professor Bahram Jalali presented a
modified form of a conventional digitizer at the 2005 American
Physical Society’s March meeting in the Los Angeles
Convention Center, which led to immediate interest in the
development and arrangements for further research.
“As electronic devices become smaller and faster, they
also become more susceptible to outside interference,” Jalali
said.
“In order to make equipment more robust, to shield it from
electromagnetic attacks, you first have to understand what kind of
signals you’re dealing with. Because the pulses we’re
talking about are one-time events and are extremely fast, their
capture and analysis eludes conventional digitizers. That’s
exactly what our technique allows,” he added.
The UCLA team found a method to increase the performance of an
electronic digitizer by using optics to process the signals before
digitizing them. In other words, it allows them to analyze fast
signals by slowing them down first.
The technique may allow physicists to capture and analyze
particle interactions which have important implications in
biochemistry and biology.
RadiaBeam Technologies LLC of Los Angeles already has entered
into licensing negotiations with UCLA and plans to produce a
laboratory tool for high-energy physics research, said Salime
Boucher, president of RadiaBeam, according to a UCLA press
release.
“We see a market for this breakthrough with research
laboratories involved in ultrafast phenomena and transient events,
as well as for future applications by engineering and technology
companies in the communication, chemical engineering and life
science sectors,” Boucher said.
The UCLA researchers have also shown that time-elasticity can be
used to perform time compression and time reversal, which can be
applied to radar systems.
Another realm affected by the development is astronomy. There is
increasing ability to observe gamma rays given off by entities such
as massive black holes and pulsars left over from supernova
explosions.
Digitizers analyze real world analogs by converting these
signals using complex algorithms into discrete signals to be
analyzed.
A continuous real-time signal cannot be held long enough to
record and convert into data. Rather, signals are collected in
discrete values and information in between these samples is left
out.
To distinguish between all signal frequency components and to
reconstruct a signal accurately, one must sample faster than twice
the frequency of the highest frequency component. But sampling fast
for a long time means researchers will have a lot of samples
““ and lots of samples means lots of computation, for which
researchers generally don’t have time.
To help rectify these errors in sampling and to produce a signal
as close to the first as possible, previous research in this area
has concentrated on making digitizers compute faster. But the UCLA
team has slowed them down.
“Imagine you have a flat rubber band and you draw an arrow
on it. The arrow’s length reflects the duration of the event.
When you stretch the rubber band, the arrow is elongated, meaning
that the event now occurs over a longer time ““ in other
words, the event is slowed down in time,” Jalali said.
An optical time dilation processor is used to stretch the time
in which the event occurs. Only after the event is slowed does
sampling and conversion of this signal into electrical data occur.
The time-stretch technique appears to be the most promising in
enabling ultrawideband analog-to-digital conversion of fast
waveforms to be digitized at pico-second intervals.
An additional advantage of the time-stretch digitizer is that it
would be cost effective to produce. The recent advances in silicon
photonics make it possible to integrate the entire digitizer on a
silicon chip, leading to a compact and low-cost solution.