Femtosecond asymmetric multi-pulse shaping via spectral intensity modulation

In this study, we experimentally validate the intensity optimization iterative Fourier transform algorithm (IO-IFTA). This method derives spectral intensity modulation patterns in combination with spectral phase control to achieve enhanced waveform shaping precision. We apply the modulation patterns obtained from IO-IFTA in a spatial light modulator-based pulse-shaping system to generate asymmetric double pulses. The designed intensity modulation suppressed unwanted higher-order pulses and reduced the pulse duration by approximately 11%, improving agreement with the target waveform. Quantitative analysis further confirmed the superiority of IO-IFTA, showing an 89.6% reduction in deviation from the target peak intensity ratio compared to the case without intensity modulation. These findings provide a promising approach to achieving high-precision pulse shaping, which is essential for advanced ultrafast optical applications.