Decoding coherent information in femtosecond shaped laser pulses

We report here an experimental demonstration of a pulse decoding technique from spectral analysis of femtosecond pulses. This technique is based on a single-step Fourier domain inversion algorithm and shows the impact of the spectral window function on the retrieval of the signal pulse. Using two femtosecond laser pulses at 780 and 1560 nm from a fibre laser, we have shown that even when the spectral content of the reference pulse is far from a narrow band limit (as much as a quarter of its entire spectral content for our conditions), the single-step retrieval analysis using spectral windowing in the Fourier domain works efficiently. The enhanced signal levels possible due to the wider spectral window are critical in the unambiguous description of laser pulses, which would have potential application in the retrieval of comparatively weak and complex ultra-short pulses as is often needed in pulse shaping applications and coherent optical communications.