Third-order nonlinearity-enabled ultrafast photonic diode based on a SnS&CAS tandem absorber

In this work, we developed a high-speed photonic diode based on third-order nonlinearity of tin sulfide nanosheets (SnS NSs) and copper antimony sulfide quantum dots (CAS QDs). The transmission characteristics of this photonic diode are simulated by nonlinear transmission model and experimentally validated by Z-Scan and P-Scan techniques. Significant non-reciprocal transmission is observed, with a maximum non-reciprocal factor (NRF) of 5.78 dB. Furthermore, the diode demonstrates ultrafast response time less than 1 ps at the VIS-NIR band, enabling optical modulation up to hundreds of gigahertz. This work lays a theoretical and experimental foundation for designing novel photonic devices based on stacked low-dimensional materials.