2D TiS₂ Layers: A Superior Nonlinear Optical Limiting Material

TLDR

High‑power lasers demand efficient optical limiting materials for eye and sensor protection, yet 2D transition metal dichalcogenides have only recently been explored for this purpose and their limiting performance has lagged behind benchmarks such as fullerene and graphene. The study investigates the optical limiting performance of TiS₂ nanosheets using optical and photoacoustic z‑scan techniques. The enhanced nonlinear response arises from simultaneous two‑photon absorption and induced excited‑state absorption. TiS₂ nanosheets achieve 77 % nonlinear optical limiting with 73 % linear transmittance, outperforming other 2D dichalcogenides, graphene, and C₆₀, and photoacoustic z‑scan indicates the limiting is dominated by nonlinear absorption rather than scattering, demonstrating the potential of 2D dichalcogenides as highly efficient low‑fluence optical limiters.

Abstract

Abstract The advancement in high power lasers has urged the requisite of efficient optical limiting materials for both eye and sensor protection. The discovery of atomically thin 2D transition metal dichacogenides with distinctive properties has paved the way for a variety of applications including optical limiting. Until recently, the optical limiting effect exhibited by 2D materials is inferior to the benchmark materials fullerene (C 60 ) and graphene. This article reports the optical limiting activity of the 2D transition metal dichalcogenide, titanium disulfide (TiS 2 ) nanosheets, using optical and photoacoustic z‐scan techniques. The 77% nonlinear optical limiting exhibited by the TiS 2 sheets with 73% linear‐transmittance is superior to that of any other existing 2D dichalcogenide sheets, graphene, and the benchmark optical limiting material, C 60 . The enhanced nonlinear response is attributed to the concerted effect of 2‐photon and the induced excited state absorptions. By using photoacoustic z‐scan, a unique tool developed to determine the nonlinear optical limiting mechanism in materials, it is found that the optical limiting exhibited by TiS 2 2D sheets and graphene are mainly due to nonlinear absorption rather than scattering effects. These results have opened the door for 2D‐dichalcogenide‐materials‐based highly efficient optical limiters, especially at low fluences.