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Cut Curiously Precise Holes With Femto-Lasers
paymenow points out "this story at Science News Online about femto-lasers and how their novel 'cutting physics' allows much more precision than previous lasers. The technology is now finding applications in various industries including, biotech, automotive and laser eye surgery."
As a "math/science geek" who is dating an "optics geek" ... i can tell you this "femto-burning" is USELESS for increasing the data storage capacity of DVD/CDs. The constricting factor is the laser's wavelength. The laser's wavefront has a size that is propotional to the wavelength.
/. article on getting 87GB on a disc)
Since a laser can't "see" objects (i.e. read data pits) smaller than the wavelength, computer chips are manufactured using Extreme-UltraViolet (EUV) lasers. However, size and $$$ are the current limiting factors for transitioning EUV to the desktop transition.
Layering seems to be the way to go with getting more data on a disc (see a previous
Sig Nazi- "No Sig for you, come back 1 year."
Increasing the rate of pulses (repetition rate) with the energy per pulse staying the same would indeed increase the thermal (destructive) load on the surrounding material. However, the question is, whether
this increase would be significant. This really depends on where you start from (pulse energy) and what material you are looking at, i.e. on the actual numbers.
However, increasing the repetition rate without reducing pulse energy is not easy. In fact, to get the pulse energy to levels where you can evaporate material you have to reduce the repetition rate.
Usually fs-Lasers are built in the way that there is an "oscillator" that delivers short but weak pulses at a very high repetition rate (around 100 MHz). To get more intense pulses you have to amplify them, which usually results in a lower repetition rate, because for an amplification to take effect you have to apply it for a certain time (sum up several round trips of the pulse in the amplifier).
For example in the laser I'm working with the oscillator delivers 20fs long pulses at 80MHz with each pulse having an energy of 5nJ. These pulses are fed into an "Regenerative Amplifier" that delivers 50fs pulses at 200kHz with each pulse having 5uJ of energy (a factor of 1000 more). The amplifier does this by letting a "seed" pulse from the oscillator run several times through an amplifier medium (a laser crystal) until a maximum pulse energy is reached and the amplified pulse is released to the output. You cannot however amplify every of the 80MHz pulses this way, because the amplifier medium has to regenerate ("charge up") before it can amplify again - that's where the name "regenerative amplifier" comes from.
In some systems you can trade repetition rate for pulse energy, i.e. get more intense pulses by lowering
the repetition rate (giving the amlifying medium more time to regenerate and therby reaching higher "charge" levels), but only in a limited range.