Characterization of weak deep ultraviolet pulses using cross-phase modulation scans.

Temporal pulse characterization methods can often not be applied to deep ultraviolet (DUV) pulses due to the lack of suitable nonlinear crystals and very low pulse energies. Here, a method is introduced for the characterization of two unknown and independent laser pulses. The applicability is broad, but the method is especially useful for pulses in the DUV, because pulse energies on the picojoule scale suffice. The basis is a spectral analysis of the two interfering DUV pulses, while one of the pulses is phase shifted by an unknown visible-infrared (VIS-IR) pulse via cross-phase modulation. The pulse retrieval is analytic, and the fidelity can be checked by comparing the complex-valued data trace with the retrieved trace.