Third- and fifth-harmonic generation by mid-infrared ultrashort pulses: beyond the fifth-order nonlinearity

Third- and fifth-harmonic generation by ultrashort laser pulses in the mid-infrared (mid-IR) reveals nonlinearoptical effects beyond the fifth-order nonlinearity and enables, because of an extraordinarily long coherence length, efficient multiplex frequency upconversion of ultrashort mid-IR pulses. We show that harmonic generation by midIR pulses provides an access to the key optical constants of gas media, allowing metrology of linear and nonlinearoptical susceptibilities in the mid-IR and offering a tool for the remote sensing of the atmosphere. (C) 2012 Optical Society of America