Multifunctional nonlinear photonic devices based on spatial self-phase modulation in InP nanosheets

Indium phosphide (InP) has high carrier mobility and excellent optoelectronic properties, demonstrating significant potential for applications in optical communications and photodetectors. Its two-dimensional (2D) nanosheets exhibit unique optical nonlinearity due to quantum confinement effects, yet their third-order nonlinear optical properties remain rarely explored. In this work, we prepare and characterize InP nanosheet dispersions, investigate their spatial self-phase modulation (SSPM) behaviors, and demonstrate their applications in multifunctional nonlinear photonic devices. By studying the ring formation dynamics of SSPM patterns, the ring formation time τ_F and the third-order nonlinear susceptibility of monolayer InP nanosheets χ(3)monolayer are found to be about 0.3 s and 10^-9 esu, respectively. The formation mechanism of SSPM primarily arises from the interaction between coherent light and InP nanosheets. Leveraging the superior electronic coherence and photostability of InP nanosheets, four types of nonlinear photonic devices are designed and demonstrated, including all-optical switches, spatially asymmetric light transmitters, photonic diodes, and optical logic gates. This work not only bridges a critical gap in the third-order nonlinear optical research of III-V semiconductor nanomaterials but also opens new avenues for developing high-performance multifunctional nonlinear photonic devices.