Demonstration of a far-infrared streak camera

An atomic infrared (IR) streak camera is demonstrated that operates in the mid- and far-infrared (l=5-85 mm), well beyond the long wavelength cutoff of convential streak cameras. The temporal and spectral characteristics of the streak camera are determined using the FELIX free-electron laser as the IR light source. The temporal resolution of the streak camera was found to be as short as 1.2 ps. The high sensitivity of the streak camera is demonstrated by single-shot characterization of the IR pulses of FELIX.