Wednesday, January 31, 2007

A Quote, the Weather, and Chaos on a Chip

What a lovely quotation for when you are in love. Hopefully it is reciprocated!
I wrote your name in the sky, but the wind blew it away. I wrote your name in the sand, but the waves washed it away. I wrote your name in my heart, and forever it will stay.
Jessica Blade
I got up to a warm -3°! The first time it was not -20° in the morning in almost a week or so! I didn't wear my ear muffs, and I didn't even warm up the car; I just jumped in and drove. The throttle still isn't freezing. I am convinced that Francis fixed it! We were laughing at the copier this morning at how 0°F can seem balmy after a week or two of cold air like we have gotten.

By recess time (10:55 AM), the temperature had risen to +6° so we had a full recess with sledding. I love supervising the sledding hill. The kids have so much fun. I'm surprised, though, that nobody breaks bones! They have built snow jumps and a take-off point that reminds me of bobsled runs. The boy of Ms. Grumpypants fame grooms the sled runs with a passion I would love to see in math class!

A wild snow shower on the drive home with whiteouts and impressive accumulation. Bible Study was cancelled.


COOL STUFF
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@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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