Passive photonic diodes based on natural van der Waals heterostructures

Van der Waals heterostructures are composed of stacked atomically thin two-dimensional (2D) crystals to provide unprecedented functionalities and novel physics. Franckeite, a naturally occurring van der Waals heterostructure consisting of superimposed SnS2-like and PbS-like layers alternately, shows intriguing potential in versatile optoelectronic applications. Here, we have prepared the few-layer franckeite via liquid-phase exfoliation method and characterized its third-order nonlinearity and ultrafast dynamics experimentally. We have found that the layered franckeite shows low saturable intensity, large modulation depth and picosecond ultrafast response. We have designed the passive photonic diodes based on the layered franckeite/C60 cascaded film and suspension configuration and found that the passive photonic diodes exhibit stable nonreciprocal transmission of light. The experimental results show the excellent nonlinear optical performance and ultrafast response of the layered franckeite, which may make inroad for the cost effective and reliable high-performance optoelectronic devices.