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Updated: Aug 21, 2026

Direct Imaging of Laser-driven Ultrafast Molecular Rotation
Published on: February 4, 2017
Starch-based second-harmonic-generated collinear frequency-resolved optical gating pulse characterization at the
Ivan Amat-Roldán1, Iain G Cormack, Pablo Loza-Alvarez
1Ultrafast Imaging Group, ICFO-Institut de Ciències Fotòniques, Jordi Girona, 29, Nexus II, 08034 Barcelona, Spain. ivan.amat@icfo.es
Abstract:
We report the use of starch as an ideal nonlinear medium with which to perform collinear frequency-resolved optical gating measurements of ultrashort pulses at the focal plane of a high-numerical-aperture (NA) lens. We achieved these measurements by simply sandwiching starch granules (suspended in water) between two coverslips and placing them within the focal plane of a high-NA lens. The natural nonlinear characteristics of starch allow the correct phase matching of pulses at the focal plane of a high-NA lens at different wavelengths. This elegant arrangement overcomes all the complexity and problems that were previously associated with pulse characterization within a multiphoton microscope.

