Recently physicists have managed to build "attosecond lasers", lasers which emit pulses 10^-18 seconds long, interrupted by much longer periods of darkness (at least 10^-14 seconds). Before them, lasers emitting femtosecond (10^-15 seconds) pulses have been around. Assuming they produce visible light, what colour is it?

Attosecond pulses require loads of bandwidth to produce (many wavelengths).  The fundamental misunderstanding with this problem is that the duration of the pulse is equal to 1/(de Broglie frequency), but in fact there many wavelength components winthin 1 attosecond or any other ultrashort pulse for that matter. The answer to this is more of a solid state physics problem of natural harmonics of crystals used as the lasing medium, etc.
http://www.mpq.mpg.de/lpg/research/attoseconds/attosecond.html

Posted by jake on 2006-11-15 12:41:11