2. Femtosecond laser filamentation

Laser technology has evolved considerably over the 2000s. One of the most spectacular breakthroughs has been in the field of short-pulse lasers. Femtosecond lasers are already commercially available and widely used in laboratories and industry. This type of laser emits pulses of the order of tens of femtoseconds duration, at rates ranging from a few hertz to several megahertz. Each pulse contains an energy that can easily reach 10 mJ, or even a few joules in the largest installations. Since the peak power of a pulse is given by the relation P = E/dt, where E is the energy of the pulse and dt its duration, we can see that...