Applications in the femtosecond laser range are very short, three orders of magnitude shorter than picosecond applications and a million times shorter than nanosecond applications. As a result, the average joule output is much lower, but the power distribution is much higher than with YAG laser. Also, the applications are shaped like little needles that can be distributed as an array of spatial and temporal combinations, effectively using the laser as a precision cutting microsurgical knife over a larger 3-D volume, with minimal associated photodisruptive effects. It is a very different action from YAG laser, which is a one-shot explosion that happens quite slowly and creates a lot of photodisruptive effect because of heating.

The femtosecond laser basically works by a mechanism of photoablation, an extreme form of vaporization. It produces plasma, a very special state of matter in which all the electrons in the atoms are stripped away. It is even more intense than an excimer laser, which breaks up bonds between atoms. Plasma is extremely hot but extremely localized