Intensity-dependent transition from saturation absorption to reverse saturable absorption ways in TiSxSe2-x (0 ≤ x ≤ 1)

Abstract

• Different atom ratios of TiS 2-x Se x were regulated by sulfur doping. • A laser intensity-dependent transition from SA to RSA in TiS x Se 2-x nanosheets was observed. • With the increase of S 2− contents in TiS x Se 2-x , the SA effect became weaker while the RSA effect became stronger. The third-order nonlinear effects in the TiS x Se 2-x (0 ≤ x ≤ 1) nanosheets were investigated via the open-aperture (OA) Z-scan technique. An input fluence dependent transition from saturation absorption (SA) to reverse saturable absorption (RSA) ways in TiS x Se 2-x was discovered. Under lower laser intensities, only SA existed in the TiS x Se 2-x . Higher incident laser intensities caused the transition from SA to RSA, due to the competition between ground state absorption and excited state absorption. This unique intensity-dependent absorption transition can be applied in all-optical logic gates, fast optical switch, optical limiter, mode storage.