Open AccessSpatio-spectral metrology at focus of ultrashort lasers: a phase-retrieval approach
Author(s) -
Antonin Borot,
F. Quéré
Publication year - 2018
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.26.026444
Subject(s) - optics , phase retrieval , laser , metrology , fourier transform , focus (optics) , physics , phase (matter) , reference beam , ultrashort pulse , laser beam quality , beam (structure) , materials science , laser beams , quantum mechanics
The complete characterization of an ultrashort laser beam ultimately requires the determination of its spatio-temporal electric field E(x, y, t), or its spatio-spectral counterpart Ẽ(x, y, ω). We describe a new measurement technique called INSIGHT, which determines Ẽ(x, y, ω), up to an unknown spatially-homogeneous spectral phase. Combining this information with a temporal measurement at a single point of the beam then enables the determination of the spatio-temporal field E(x, y, t). This technique is based on the combination of spatially-resolved Fourier-transform spectroscopy with an alternate-projection phase-retrieval algorithm. It can be applied to any reproducible laser source with a repetition rate higher than about 0.1 Hz, relies on a very simple device, does not require any reference beam, and circumvents the difficulty associated with the manipulation of large beam diameters by working in the vicinity of the beam focus. We demonstrate INSIGHT on a 100 TW-25 fs laser, and use the measurement results to introduce new representations for the analysis of spatio-temporal/spectral couplings of ultrashort lasers.