Method and device for generating isolated ultrashort electromagnetic pulses

A method for generating isolated ultra-short electromagnetic pulses of duration shorter than 100 ps (IR2), comprising the following steps:

• directing onto a surface (SC) of a target (CEC) in the condensed state a first laser pulse (IL1) at an oblique angle of incidence and with p-polarization, said first laser pulse having a first wavelength (2), corresponding to a first optical period (T1), and a normalized peak amplitude greater than or equal to 1, whereby a plasma mirror (MPR) oscillating at relativistic velocity is generated on the surface of the target;
• and
• directing onto said surface of the target, in correspondence with said plasma mirror, a second laser pulse (IL2) having a second wavelength, shorter than the first wavelength, and a duration (τ2) shorter than or equal to the first optical period (T1), the second laser pulse being spatially and temporally superposed with the first laser pulse;
• whereby the second laser pulse, reflected by the plasma mirror, undergoes a shift of its wavelength and a modification of its duration.