Broadband ultrafast photoresponse of 1D and 2D semiconductors

Abstract

Carbon nanotubes (CNTs) and transition metal dichalcogenides (TMDCs) are representative one-dimensional (1D) and two-dimensional (2D) semiconductors. Both materials have been widely employed in the generation and modulation of ultra-short light waves. While the number of reports on pulsed laser demonstrators is on the rise, the understanding of the exact physical mechanisms governing the nonlinear optical response remains a subject less well studied and understood. Nanotube chirality inhomogeneity, defective states and ambient effects in TMDCs also pose further experimental challenges in fully resolving the photophysics of these low-dimensional materials. Here, we combine several ultrafast nonlinear optical characterization techniques performed over broad spectral range (covering the important range extending from visible to the mid-infrared) to resolve the intrinsic photoresponse of 1D and 2D semiconductors. The unique optical responses revealed from our findings provide important new design guidelines for 1D and 2D semiconductor based nonlinear optical devices.