Fast phase retrieval for broadband attosecond pulse characterization

Abstract

Efficient characterization method for broadband attosecond pulses has become more and more essential, since attosecond pulses with bandwidth spanning few-hundreds electron-volts have been generated. Here we propose a fast phase retrieval algorithm for broadband attosecond pulse characterization with an omega oscillation filtering technique. We introduce a new error function to improve the accuracy of the retrieved phases. More importantly, it can be solved by the steepest descent methods with iterative algorithm, which is much faster than genetic algorithm adopted previously. An experimental spectrogram for isolated attosecond pulses with photon energy covering 52–127 eV and a pulse width of 71 as was successfully retrieved with this method as demonstrated. The proposed technique will help provide real-time feedback on atto-chirp compensation for ultrashort isolated attosecond pulse generation.