Solvent-stabilized few-layer violet phosphorus and its ultrafast nonlinear optics

Featured with high thermal decomposition temperature and layered structure, violet phosphorus (VP) offers an unparalleled stable allotrope of phosphorus to demonstrate the optoelectronic device and photonics elements with high performance at the nanoscale. Here, we report few-layer and hundreds of nanometer-sized VP with robust stability in different solvents and ambient conditions by ultrasound-assisted liquid phase exfoliation approach. For the first time, the ultrafast carrier dynamics and third-order nonlinear optical response of VP were investigated. Sub-picosecond timescale ultrafast carrier dynamic and ultrafast nonlinear saturable absorption of VP were demonstrated. Our findings demonstrated that VP possessed a promising potential for use in ultrafast nonlinear photonic applications such as saturable absorbers and optical switches.