What is femtosecond laser? Femtosecond laser is a kind of laser that runs in pulse form, and its duration is very short, only a few femtoseconds. One femtosecond is one thousandth of 1 second, which is thousands of times shorter than the shortest pulse obtained by electronic method, and it is the shortest pulse that human beings can obtain under experimental conditions at present. There is only one word difference between the two surgical methods, but the surgical process is completely different.