Determination of temporal correlation of ultrafast laser pulses using phase conjugation

A new time domain single shot conjugation autocorrelator is described. Three beams derived from the same initial laser pulse interact in a nonlinear medium to produce a backward signal wave in a 90° phase conjugate geometry. The pulse duration is determined from the spatial width of the phase conjugate beam emerging from the interaction region. Pulse duration measurements of pulses selected from a YAG laser train show that shorter pulses are generated toward the tail of the pulse train.