title: Slow and fast absorption saturation of black phosphorus: experiment and modelling.
abstract: According to the excited-state decay time, a slow saturable absorber model was employed to obtain the ground-state absorption and excited-state absorption cross sections σgsand σesof black phosphorus (BP) nanosheets, which are (1.25 ± 0.07) × 10-16cm2and (2.97 ± 0.21) × 10-17cm2at 515 nm, and (5.95 ± 0.17) × 10-18cm2and (5.19 ± 0.71) × 10-19cm2at 1030 nm, respectively. In comparison, the σgsand σesof MoS2and graphene were also obtained with the same model. The ratio σes/σgsof BP is the smallest (only 0.24 ± 0.03 at 515 nm and 0.09 ± 0.01 at 1030 nm) among the three two-dimensional layered materials both at 515 nm and 1030 nm. Relatively large ground-state transition probability and weak loss of excited-state absorption result in good saturable absorption performance. In comparison with MoS2and graphene, the much lower saturation intensity of BP can be well explained from this perspective.
authors.affiliation: Key Laboratory of Materials for High-Power Laser, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China. jwang@siom.ac.cn.
authors.forename: Saifeng
authors.initials: S
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Materials for High-Power Laser, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China. jwang@siom.ac.cn.
authors.forename: Yuanxin
authors.initials: Y
authors.lastname: Li
authors.affiliation: Key Laboratory of Materials for High-Power Laser, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China. jwang@siom.ac.cn.
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Materials for High-Power Laser, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China. jwang@siom.ac.cn.
authors.forename: Ningning
authors.initials: N
authors.lastname: Dong
authors.affiliation: School of Physics, Trinity College Dublin, Dublin 2, Ireland and CRANN and AMBER Research Centres, Trinity College Dublin, Dublin 2, Ireland.
authors.forename: Kangpeng
authors.initials: K
authors.lastname: Wang
authors.affiliation: School of Physics, Trinity College Dublin, Dublin 2, Ireland and CRANN and AMBER Research Centres, Trinity College Dublin, Dublin 2, Ireland.
authors.forename: Damien
authors.initials: D
authors.lastname: Hanlon
authors.affiliation: School of Physics, Trinity College Dublin, Dublin 2, Ireland and CRANN and AMBER Research Centres, Trinity College Dublin, Dublin 2, Ireland.
authors.forename: Jonathan N
authors.initials: JN
authors.lastname: Coleman
authors.affiliation: Key Laboratory of Materials for High-Power Laser, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China. jwang@siom.ac.cn.
authors.forename: Long
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Materials for High-Power Laser, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China. jwang@siom.ac.cn.
authors.forename: Jun
authors.initials: J
authors.lastname: Wang