Femtosecond self-focusing dynamics measured by three-dimensional phase-retrieval cross correlation

Tai Wei Yau, Chau Hwang Lee, Jyhpyng Wang

Research output: Contribution to journalArticlepeer-review

8 Scopus citations


We use a phase-retrieval cross-correlation technique to analyze the spatiotemporal field evolution of self-focused ultrashort pulses. The technique features a new phase-retrieval algorithm based on functional differentiation. Its sensitivity, rapid convergence, and temporal nonreciprocality enable reliable three-dimensional waveform reconstruction. At less than the critical power, the experiments verify conventional description of self-focusing and give a direct proof of the Kerr-lens mode-locking mechanism. In contrast, for pulses with peak power much more than the critical power, nearly uniform self-focusing and quasi-stable single-filament trapping to a universal beam diameter were observed. The trapping can be explained by the saturation of the nonlinear refractive-index change at Δn ∼ 7 × 10-5. The saturation is verified by an independent cross-polarization modulation measurement.

Original languageEnglish
Pages (from-to)1626-1635
Number of pages10
JournalJournal of the Optical Society of America B: Optical Physics
Issue number9
StatePublished - Sep 2000


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