Fig. 1. (a) The SEM image of the layered B-AsP. (b) The high resolution TEM (HRTEM) image and the selected area electron diffraction (SAED) pattern of the 2D B-AsP. (c) The AFM image of 2D B-AsP. (d) The height profiles along the red line in (c).

Fig. 2. Band gap structures of the B-As_xP_1-x with different value of “x” (x = 0, 0.25, 0.4, and 0.83).

Fig. 3. (a) The band gap structure of the B-As_xP_1-x (x = 0.4) NSs. (b) The 2D B-AsP NSs dispersions used in our experiment, and the Tyndall effect observed as the laser beams transmitted through the sample. (c) The phase-shift of the incident light caused by the Kerr nonlinearity in 2D B-AsP NSs. (d) Experimental schematic of the SSPM based on the 2D B-AsP NSs dispersions. (e, f) The intensity-dependent diffraction patterns generated from the 2D B-AsP NSs dispersions with the lasers of λ = 532 nm and 671 nm, respectively. (g, h) The nonlinear optical response (R) for the 2D B-AsP NSs dispersions with three repeated measurements at λ = 532 nm and 671 nm, respectively.

Fig. 4. (a) The diffraction patterns excited from the 2D B-AsP NSs dispersions with a high light intensity for consecutive 6 hours. (b) The absorption spectrums for the 2D B-AsP NSs dispersions before and after 6 hours of exposure.

Fig. 5. (a) Experimental schematic of the 2D B-AsP-based all-optical phase modulated system. (b) The phase modulation of controlling light to signal light. (c) The number of diffraction rings modulated by the intensity of controlling light. (d) Result of the all-optical switching based on 2D B-AsP NSs to realize the functions of “on” and “off”. (e) 2D B-AsP NSs all-optical logical gate to achieve the “or” function.

Fig. 6. The unidirectional nonlinear excitation in 2D B-AsP/ SnS₂ hybrid structure to achieve the spatial asymmetric light propagation.