Direct Observation of Degenerate Two-Photon Absorption and Its Saturation in WS<sub>2</sub> and MoS<sub>2</sub> Monolayer and Few-Layer Films

Wang

et al. 2016

Opt. Mater. Express

Self Cite

Size dependence of the saturable absorption (SA) property for black phosphorus (BP) was investigated. Three types of BP dispersions with different sizes were prepared using the liquid phase exfoliation method. By fitting the Z-scan data with the analytical solution of the propagation equation, the SA coefficients NL α and the imaginary part of the third order optical susceptibility (3) Im χ are compared at two specific wavelengths, one above the bandgap of the BP monolayer at 515 nm and another between the bandgaps of the monolayer and bulk at 1030 nm. A figure of merit (FOM, |Imχ (3) /α 0 |, α 0 linear absorption) was employed to assess the SA performance of the three different dispersions. The FOM, about (2.1 ± 0.3) × 10 −14 esu cm at 515 nm, hardly depends on the size and hence the layer number of the dispersed BP nanosheets, whereas that at 1030 nm decreases from (1.14 ± 0.20) × 10 −14 to (0.50 ± 0.02) × 10 −14 esu cm when the size of the nanosheets becomes smaller. Zhang, G. S. Duesberg, and J. Wang, "Direct observation of degenerate two-photon absorption and its saturation in WS 2 and MoS 2 monolayer and few-layer films," ACS Nano 9(7), 7142-7150 (2015). 26. K. Wang, Y. Feng, C. Chang, J. Zhan, C. Wang, Q. Zhao, J. N. Coleman, L. Zhang, W. J. Blau, and J. Wang, "Broadband ultrafast nonlinear absorption and nonlinear refraction of layered molybdenum dichalcogenide

Section: Methodssupporting

confidence: 87%

Size-dependent saturable absorption and mode-locking of dispersed black phosphorus nanosheets

Wang

et al. 2016

Opt. Mater. Express

Self Cite

“…The values obtained for different wavelengths are listed in Table 1. Compared to previous works, the values of the FOM are approximately two orders of magnitude larger than that of graphene ~5 × 10 −15 esu cm, graphene oxide ~4.2 × 10 −15 esu cm46, reduced graphene oxide ~0.36 × 10 −15 esu cm47, and MoS 2 /NMP dispersions ~1.06 × 10 −15 esu cm20, one order of magnitude larger than that of multilayer MoS 2 (25–27 layers) ~1.1 × 10 −14 esu cm and WS 2 (18–20 layers) ~2.16 × 10 −14 esu cm19, and close to that of monolayer WS 2 ~ 1.1 × 10 −13 esu cm19. Our results indicate that the Bi 2 Te x Se 3−x nanosheets possess a fascinating NLO response in an ultra-broadband.…”

Section: Resultsmentioning

confidence: 98%

“…Meanwhile, inspired by the progress of NLO applications of TI materials1617181920, NLO research into TIs has attracted a great deal of interest. Zhang et al 212223.…”

mentioning

confidence: 99%

Ultra-broadband Nonlinear Saturable Absorption for Two-dimensional Bi2TexSe3−x Nanosheets

Wang

Liu

Yuan

et al. 2016

Sci Rep

We report the ultra-broadband nonlinear optical (NLO) response of Bi2TexSe3−x nanosheets produced by a facile solvothermal method. Our result show that the extracted basic optical nonlinearity parameters of Bi2TexSe3−x nanosheets, αNL, Imχ(3), and FOM reach ~104 cm/GW, ~10−8 esu and ~10−13 esu cm, respectively, which are several orders of magnitude larger than those of bulk dielectrics. We further observed the excitation intensity dependence of the NLO absorption coefficient and the NLO response sensitivity. The mechanisms of those phenomena were proposed based on physical model. The wavelength dependence of the NLO response of Bi2TexSe3−x nanosheets was investigated, and we determined that the Bi2TexSe3−x nanosheets possess an ultra-broadband nonlinear saturable absorption property covering a range from the visible to the near-infrared band, with the NLO absorption insensitive to the excitation wavelength. This work provide fundamental and systematic insight into the NLO response of Bi2TexSe3−x nanosheets and support their application in photonic devices in the future.

“…[14,15] Two-dimensional (2D) materials, such as graphene, transition-metal dichalcogenides (TMDs), topological insulators, and black phosphorus (BP), have been reported to have excellent NLO performances. [25][26][27][28] Nanocomposites of MoS 2 and CNTs have been investigated widelyi na pplications such as energy storagea nd hydrogen evolution. [22][23][24] Compared to graphene with zero-band gap and BP with easy oxidation and deliquenscence, MoS 2 is semiconducting and has good chemical stability.I th as been confirmed that MoS 2 nanosheets have excellent third-order NLO performance over ab road wavelength range from visible( Vis) to near infrared (NIR) region with versatile optical mechanisms, such as saturable absorption (SA), two-photon absorption (TPA), and nonlinear scattering (NLS).…”

Section: Introductionmentioning

confidence: 99%

MoS₂/Carbon Nanotube Core–Shell Nanocomposites for Enhanced Nonlinear Optical Performance

Selkirk

et al. 2017

Chemistry A European J

Self Cite

Nanocomposites of layered MoS and multi-walled carbon nanotubes (CNTs) with core-shell structure were prepared by a simple solvothermal method. The formation of MoS nanosheets on the surface of coaxial CNTs has been confirmed by scanning electron microscopy, transmission electron microscopy, absorption spectrum, Raman spectroscopy, and X-ray photoelectron spectroscopy. Enhanced third-order nonlinear optical performances were observed for both femtosecond and nanosecond laser pulses over a broad wavelength range from the visible to the near infrared, compared to those of MoS and CNTs alone. The enhancement can be ascribed to the strong coupling effect and the photoinduced charge transfer between MoS and CNTs. This work affords an efficient way to fabricate novel CNTs based nanocomposites for enhanced nonlinear light-matter interaction. The versatile nonlinear properties imply a huge potential of the nanocomposites in the development of nanophotonic devices, such as mode-lockers, optical limiters, or optical switches.