Two-dimensional materials have become the focus of research for their photoelectric properties, and are employed as saturable absorption materials. Currently, the challenge is how to further improve the modulation depth of saturable absorbers (SAs) based on two-dimensional materials. In this paper, three kinds of WSe2 films with different thicknesses are prepared using the chemical vapor deposition method. The nonlinear optical responses of the WSe2 films including the nonlinear saturable absorption and nonlinear refractive index are characterized by the double-balanced detection method and Z-scan experiments. Different modulation depths are successfully obtained by controlling the thickness of the WSe2 films. We further incorporate them into an all-fiber laser to generate mode-locked pulses. The mode-locked fiber lasers with a pulse duration of 185 fs, 205.7 fs and 230.3 fs are demonstrated when the thickness of the WSe2 films is measured to be 1.5 nm, 5.7 nm and 11 nm, respectively. This work provides new prospects for WSe2 in ultrafast photonic device applications.
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http://dx.doi.org/10.1039/C8NR00471D | DOI Listing |
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December 2024
Zhejiang University, Hangzhou, 310027, China.
ACS Nano
September 2024
Department of Electrical Engineering, Stanford University, Stanford, California 94305, United States.
Semiconducting transition metal dichalcogenides (TMDs) are promising for high-specific-power photovoltaics due to their desirable band gaps, high absorption coefficients, and ideally dangling-bond-free surfaces. Despite their potential, the majority of TMD solar cells to date are fabricated in a nonscalable fashion, with exfoliated materials, due to the lack of high-quality, large-area, multilayer TMDs. Here, we present the scalable, thickness-tunable synthesis of multilayer WSe films by selenizing prepatterned tungsten with either solid-source selenium at 900 °C or HSe precursors at 650 °C.
View Article and Find Full Text PDFJ Synchrotron Radiat
September 2024
Department of Chemical and Materials Engineering, New Uzbekistan University, Tashkent, Uzbekistan.
The simulation of EXAFS spectra of thin films via ab initio methods is discussed. The procedure for producing the spectra is presented as well as an application to a two-dimensional material (WSe) where the effectiveness of this method in reproducing the spectrum and the linear dichroic response is shown. A series of further examples in which the method has been employed for the structural determination of materials are given.
View Article and Find Full Text PDFSmall Methods
September 2024
Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA.
Autonomous systems that combine synthesis, characterization, and artificial intelligence can greatly accelerate the discovery and optimization of materials, however platforms for growth of macroscale thin films by physical vapor deposition techniques have lagged far behind others. Here this study demonstrates autonomous synthesis by pulsed laser deposition (PLD), a highly versatile synthesis technique, in the growth of ultrathin WSe films. By combing the automation of PLD synthesis and in situ diagnostic feedback with a high-throughput methodology, this study demonstrates a workflow and platform which uses Gaussian process regression and Bayesian optimization to autonomously identify growth regimes for WSe films based on Raman spectral criteria by efficiently sampling 0.
View Article and Find Full Text PDFACS Appl Mater Interfaces
May 2024
Microelectronics Research Center, Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, Texas 78758, United States.
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