All-optical diode based on asymmetric nonlinear optical absorption in ternary transition metal chalcogenides

As the typical representative of ternary transition metal chalcogenides, CrPS 4 and MnPS 3 exhibit unique light–matter interactions, demonstrating great potential in photonic devices. In this work, we systematically studied the nonlinear optical (NLO) responses of CrPS 4 and MnPS 3 flakes by the I-scan technique. CrPS 4 and MnPS 3 flakes show saturable absorption and reverse saturation absorption excited by fs laser at wavelengths of 600 nm, respectively. Furthermore, utilizing the non-degenerate transient absorption technology, we observed that the fast and slow carrier relaxation times of CrPS 4 at different probe wavelengths were components with constants of about 1.4–3 ps and 490–1420 ps, respectively. Their excellent ultrafast NLO properties imply that they can be applied in photoelectronic fields for advanced and functional devices. Here, we designed and demonstrated an all-optical diode based on a CrPS 4 /MnPS 3 tandem structure by breaking the time-reversal symmetry, and it achieved nonreciprocal transmission of light similar to that of a p-n electron diode.