Complete Field Characterization of Ultrashort Pulses in Fiber Photonics

We report a simple fiber-implemented technique for complete reconstruction of intensity profile and phase of ultrashort laser pulses based on processing only pulse spectrum and two self-phase modulated spectra measured after a short piece of optical fiber. Its applicability is shown on an example of a fiber optical system in the telecommunication range. A retrieval algorithm in a dispersionless approximation and with considering dispersion effects is developed. The obtained results are confirmed by independent measurements using the second-harmonic generation frequency-resolved optical gating technique and by reconstructing purposely introduced signal features. We also provide estimates demonstrating great opportunities for implementing this technique in all-waveguide optical systems ranging from optical communications to nanophotonics with femtojoule pulses as well as to mid-IR photonics, where specialty fibers with huge optical nonlinearities can be used.