Switch of Optical Nonlinear Absorption in Black Phosphorous

Abstract

Nonlinear absorption of multi-layer black phosphorus nanosheets (BPs) were investigated using open aperture Z-scan method with 6 ns nanosecond laser pulses at 532 nm. It was found that, at lower intensities, BPs behave as saturable absorbers, but at higher intensities a shift from saturable absorption to reverse saturable absorption occurs. The transition process was analyzed in terms of the bleaching of ground-state and the excited-state absorption. We investigate the ultrafast dynamics by using pump − probe technique. The investigation implies that BPs has great potential applications in both mode-locking and optical liming in the visible range for ultrafast laser pulses.

Keywords:

• 2D materials
• BP
• saturable
• reverse saturable

Additional information

Funding

This work was supported by the Heilongjiang Province Natural Science Fund (F2018027), Heilongjiang University Graduate Innovation Fund (YJSCX2018-015HLJU), East University of Heilongjiang Scientific Research Fund (HDFHX170115), East University of Heilongjiang Scientific Research Fund (HDFKY190106).