Ultrashort optical pulse characterization using WS₂ monolayers.

We demonstrate the application of two-dimensional materials for ultrashort optical pulse characterization. Monolayer transition metal dichalcogenides, such as tungsten disulfide (WS₂), possess extraordinarily large second-order nonlinear susceptibility, and due to their atomic thickness, have relaxed phase-matching requirements and, hence, an inherently wide bandwidth. Synthesized monolayer WS₂ triangular islands were used to characterize ultrashort optical pulses at the focal point of an objective lens through second-harmonic generation collinear frequency-resolved optical gating.