Determination of the duration of a mid-infrared single-cycle light bullet from the structure of induced plasma channels or color centers

A method based on recording of the light-field amplitude of the pulse in the spatial structure of induced plasma channels or tracks of color centers in a transparent dielectric is proposed to determine the duration and phase of intense mid-infrared single-cycle femtosecond pulses. The track structure is recorded and detected in a single interaction of the studied pulse with the medium in which it is nonlinearly compressed. The modulation depth of the track profile is uniquely related to the number of oscillations of the light field under the envelope of the propagating pulse, which allows determining the pulse duration. The estimated duration of the mid-infrared light bullet in LiF is less than 10 fs. The duration of the laser bullet determined by the proposed method is compared with autocorrelation and cross-correlation measurements.