The threshold of a laser-induced breakdown of air is determined experimentally and theoretically. We find that the ionization of air has two steps: the first step is a multi-photon ionization process, which provides enough “seed electrons” to initiate the
When using normalized dispersion method for the dispersion design of photonic crystal fibers (PCFs), it is vital that the group velocity dispersion of PCF can be seen as the sum of geometrical dispersion and material dispersion. However, the error induced
Optical angular momentum (OAM)-based structured light beams provide an additional degree of freedom for practical applications ranging from optical communication to laser-based material processing. Many techniques exist for generating such beams within la