Chaos on a chip

[Sean McGrath]

-------- Original Message --------

Subject: Physics News Update 810

PHYSICS NEWS UPDATE
The American Institute of Physics Bulletin of Physics News
Number 810   30 January 2007 by Phillip F. Schewe, Ben Stein, Turner
Brinton, and Davide Castelvecchi                     www.aip.org/pnu

[...]

CHAOS ON A CHIP.  For the first time physicists have shown that well
structured chaos can be initiated in a photonic integrated circuit.
Furthermore, this represents the first time scientists have been
able to study optical chaos at gigahertz rates.
The output of a semiconductor laser is normally regular.  However,
if certain laser parameters are tweaked, such as by modulating the
electric current pumping the laser or by feeding back some of the
laser’s light from an external mirror, the overall laser output will
become chaotic; that is, the laser output will be unpredictable.  To
make the chaos even more dramatic (and exploitable) Mirvais Yousefi
and his colleagues at the Technische Universiteit Eindhoven (in the
Netherlands) use paired lasers, lasers built very close to each
other on a chip in such a way that each affects the operation of the
other.  The Eindhoven chip, using the paired-laser
mutual-perturbation approach to triggering chaos, is the first to
exhibit chaos directly-revealing telltale strange attractors on
plots of laser power at one instant versus laser power at a slightly
later instant-rather than indirectly through recording laser spectra.
Looking ahead to the day when opto-photonic chips are covered with
thousands or millions of lasers, the Eindhoven approach could allow
troubleshooters to pinpoint the whereabouts of misbehaving
lasers---not only that but possibly even exploit localized chaotic
effects to their advantage.
According to Yousefi (m.yousefi at tue.nl) other possible uses for
chip-based chaos will be the business of encryption, tomography, and
possibly even in the establishment of multi-tiered logic protocols,
those based not on just on the binary logic of 1s and 0s but on the
many intensity levels corresponding to the broadband output of the
chaotic laser system. (Yousefi et al., Physical Review Letters, 26
January 2007; text at www.aip.org/physnews/select )

[...]

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