Ultrafast nonlinear optical response of layered violet phosphorus for femtosecond noise-like pulse generation

Abstract

As a new member of two-dimensional (2D) phosphorene, 2D layered violet phosphorus (VP) has unique optoelectronic properties and good environmental stability, showing its huge advantages in optoelectronic applications. In this paper, the ultrafast nonlinear optical (NLO) properties of layered VP nanosheets at 1 µm band were explored, which exhibit an obvious saturable absorption response with a modulation depth of ∼1.97%. Meanwhile, the fast and slow carrier lifetimes of VP nanosheets at 1µm band were also determined as 295.9 fs and 2.36 ps, respectively, which are much shorter than that of most reported 2D materials. The excellent saturable absorption response combined with ultrashort carrier lifetimes indicate the prospect of layered VP nanosheets as a fast saturable absorber (SA) for ultrafast laser modulation. Then we demonstrated a Yb-doped fiber laser based on the VP-deposited taper-shaped fiber (TSF) SA, which delivers stable Q-switched mode-locked (QSML) pulses, dual-wavelength mode-locked pulses and 404-fs noise-like pulses. This work fully demonstrates the great potential of 2D VP materials for 1 µm ultrashort laser pulse generation.

High Ambipolar Mobility and Long-Range Carrier Transport in Violet Phosphorus Nanosheet

“…As photoinduced absorption is due to the excited state absorption instead of ground state bleaching, such broadband transient absorption reveals that VP is a promising lasing semiconductor material to realize population inversion readily. 22 The carrier dynamics at the two PA peaks under different pump fluence are shown in Figure S2a−d in the Supporting Information. The photogenerated carrier dynamics at PA1 and PA2 are fitted well by using a double-exponential decay convoluted with a Gaussian function (details in Supporting Information Section S2).…”