Pérez Benito, ÓscarHernández Rueda, Francisco JavierMartínez Maestro, LauraNoordam, Marc L.Kuipers, L.Weigand Talavera, Rosa María2024-04-052024-04-052023-06-152330-402210.1021/acsphotonics.3c00353https://hdl.handle.net/20.500.14352/1027732023 Acuerdos transformativos CRUENowadays, the accurateand full temporal characterization of ultrabroadbandfew-cycle laser pulses withpulse durations below 7 fs is of great importance in fields of sciencethat investigate ultrafast dynamic processes. There are several indirectmethods that use nonlinear optical signals to retrieve the complexelectric field of femtosecond lasers. However, the precise characterizationof few-cycle femtosecond laser sources with an ultrabroadband spectrumpresents additional difficulties, such as reabsorption of nonlinearsignals, partial phase matching, and spatiotemporal mismatches. Inthis work, we combine the dispersion scan (d-scan) method with atomicallythin WS2 flakes to overcome these difficulties and fullycharacterize ultrabroadband laser pulses with a pulse duration of6.9 fs and a spectrum that ranges from 650 to 1050 nm. Two-dimensionalWS(2) acts as a remarkably efficient nonlinear medium thatoffers a broad transparency range and allows for achieving relaxedphase-matching conditions due to its atomic thickness. Using mono-and trilayers of WS2, we acquire d-scan traces by measuringthe second-harmonic generation (SHG) signal, originated via laser-WS2 interaction, as a function of optical dispersion (i.e., glassthickness) and wavelength. Our retrieval algorithm extracts a pulseduration at full-width half-maximum of 6.9 fs and the same spectralphase function irrespective of the number of layers. We benchmarkand validate our results obtained using WS2 by comparingthem with those obtained using a 10-mu m-thick BBO crystal. Ourfindings show that atomically thin media can be an interesting alternativeto micrometer-thick bulk crystals to characterize ultrabroadband femtosecondlaser pulses using SHG-d-scan with an error below 100 as (attoseconds).engAttribution 4.0 Internationalhttp://creativecommons.org/licenses/by/4.0/journal articlehttps://pubs.acs.org/doi/10.1021/acsphotonics.3c00353open access535Ultrabroadband femtosecond lasersd-scan2D materialsTransition metal dichalcogenidesSecond-harmonic generationNnonlinear opticsWS2Óptica (Física)2209 Óptica