Real-time measurement of ultrashort laser pulses using principal component generalized projections

Frequency-resolved optical gating (FROG) is a technique to measure ultrashort laser pulses that optically constructs a spectrogram of a laser pulse. A two-dimensional (2-D) phase retrieval algorithm is used to extract the intensity and phase of a pulse from its spectrogram. We have improved a recently presented principal component generalized projections algorithm (PCGPA) making it easier to implement and fast enough to allow real-time inversion of FROG spectrograms. A femtosecond oscilloscope, based on second-harmonic generation (SHG) FROG, that displays the intensity and phase of ultrashort laser pulses in real time utilizing the improved PCGP phase retrieval algorithm is presented.