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Two-photon based pulse autocorrelation with CdSe nanoplatelets

Quick, Michael T.; Owschimikow, Nina; Khan, Ali Hossain; Polovitsyn, Anatolii; Moreels, Iwan; Woggon, Ulrike; Achtstein, Alexander W.

FG Nichtlineare Optik

We investigate broadband two-photon absorption autocorrelators based on II–VI semiconductor nanoplatelets as an alternative to common second harmonic generation based techniques. As compared to bulk materials the exceptionally high enhancement of two-photon absorption in these 2D structures results in very efficient two-photon absorption based autocorrelation detected via PL emission. We compare the results with TPA autocorrelation in CdS bulk as well as SHG based autocorrelation in β-barium borate. We show that CdSe nanoplatelet based autocorrelation can exceed the efficiency of conventional methods by two orders in magnitude, especially for short interaction length, and allows a precise pulse-width determination. We demonstrate that very high two-photon absorption cross sections of the nanoplatelets are the basis for this effective TPA autocorrelation. Based on our results with II–VI nanoplatelets efficient broadband autocorrelation with more than ∼100 nm bandwidth and very high sensitivity seems feasible.