Ultrashort pulse reconstruction using a deterministic phase retrieval method with Gaussian-envelope gates

摘要： A novel scheme of ultrashort pulse characterization is proposed that is capable of reconstructing the complex-valued envelope of a pulse in the time domain by use of a second harmonic generation system with two Gaussian gate pulses. In this scheme, we apply an analytic (noniterative) phase-retrieval method for coherent diffractive imaging in the space domain to the pulse characterization, and so the spectral phase of an unknown pulse can be retrieved from only two spectra of the unknown pulse modulated with a Gaussian gate and its time-shifted Gaussian one. Computer-simulated examples demonstrate that the pulse retrieval is robust. In particular, it is shown that the reconstruction of an unknown pulse using approximate Gaussian gates derived from replicas of the pulse itself is also effective, provided the spectrum of the unknown pulse has a gentle slope within the spectral bandwidth of the gate pulse.