Cover story: Wu LM, Fan TJ, Wei SR, Xu YJ, Zhang Y et al. All-optical logic devices based on black arsenic–phosphorus with strong nonlinear optical response and high stability. Opto-Electron Adv 5, 200046 (2022).

Spatial self-phase modulation (SSPM) in 2D nanomaterials is an optical phenomenon of Kerr nonlinearity that is emerging as an appealing and intriguing research area due to their prominent light processing, modulation, and manipulation abilities. Recently, Professor Han Zhang in 2D materials research group at the Institute of Microscale Optoelectronics of Shenzhen university reported an all-optical phase-modulated system based on 2D black arsenic-phosphorus (B-AsP) to realize the functions of “on” and “off” in all-optical switching. When the controlling light passes through the sample, the refractive index of B-AsP changes due to the Kerr effect, which then inversely modulates the phase of the incident light. According to the spatial cross-phase modulation method, the light field of the signal light will be promoted by the controlling light in order to enhance the phase-shift, which further generates the diffraction rings. Moreover, by using the SSPM method, a 2D B-AsP/SnS₂ hybrid structure is fabricated, and the result illustrates that the hybrid structure possesses the ability of the unidirectional nonlinear excitation, which helps in obtaining the function of spatial asymmetric light propagation in isolators. The initial investigations indicate that 2D B-AsP is applicable for designing optical logical devices, which can be considered as an important development in all-optical information processing.