Nonlinear optical performance of few-layer molybdenum diselenide as a slow-saturable absorber Download: 695次
1 Shenzhen Key Laboratory of Advanced Thin Films and Applications, College of Physics and Energy, Shenzhen University, Shenzhen 518060, China
2 School of Physics and the Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), Trinity College Dublin, Dublin 2, Ireland
3 Key Laboratory of Materials for High-Power Laser, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China
4 e-mail: wangkangpeng@msn.com
5 e-mail: luojt@szu.edu.cn
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Fig. 1. TEM images showing (a) a few-layer MoSe2 flake and (b) a monolayer MoSe2 flake. The scale bar is 50 nm in (a) and 5 nm in (b). (c) Raman spectrum of the few-layer MoSe2 flakes. (d) AFM image displaying the thickness of a large number of MoSe2 flakes in a ∼5 μm×5 μm area. (e) Statistical thickness distribution of the MoSe2 flakes in as-prepared dispersions.
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Fig. 2. Z-scan results of few-layer MoSe2. The linear absorption coefficients are (a) 5.22 cm−1 and (b) 6.51 cm−1, respectively, which are shown in the insets. The measurements were carried out under irradiation of increasing laser intensity. (c) Schematic of an open-aperture Z-scan. The laser pulses are at a center wavelength of 800 nm, with duration of ∼100 fs and a repetition rate of 100 kHz from a Ti: sapphire mode-locked laser (Coherent, RegA 9000).
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Fig. 3. Experimental (scatters) and fitting (solid lines) degenerate pump-probe traces of few-layer MoSe2 based on an 800 nm laser with pulse duration of ∼100 fs and repetition rate of 100 kHz. The inset in (c) shows the relaxation processes of the excited carriers. The inset in (d) shows degenerate pump-probe setup. An intense beam is employed to pump the materials, while another beam with relatively low intensity, which is delayed by a motorized linear translation stage, is used for probing the excited carriers. These two beams are modulated by an optical chopper at 733 Hz and 422 Hz, respectively. A half-wave plate and a polarizer are utilized to eliminate the coherent spikes.
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Fig. 4. NLO performance of few-layer-MoSe2 analyzed by a slow-saturable absorber model. (a) Experimental (scatters) and fitting (solid lines) transmission as a function of intensity. (b) Corresponding differential absorption converted from (a).
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Table1. NLO Performance of Few-Layer MoSe2 Used as a Slow-Saturable Absorber
(%) | () | (cm/GW) | (esu) | (%) | (%) | (%) | () | | 47.8 | 5.22 | −0.017 | | 55.2 | 7.4 | 44.8 | 39.37 | 0.81 | 34.9 | 6.51 | −0.044 | | 55.0 | 15.1 | 45.0 | 234.75 | 0.57 |
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Table2. Fitting Parameters for the Experimental Differential Transmission of Two Few-Layer MoSe2 Dispersions with the Linear Absorption Coefficients of 5.22 cm−1 and 6.51 cm−1, Respectively
() | (%) | (%) | (ps) | (ps) | (fs) | 5.22 | 82.9 | 17.1 | 2.16 | 210.13 | 95 | 6.51 | 89.8 | 10.2 | 2.22 | 226.27 | 161 |
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Gaozhong Wang, Guangxing Liang, Aidan A. Baker-Murray, Kangpeng Wang, Jing Jing Wang, Xiaoyan Zhang, Daniel Bennett, Jing-Ting Luo, Jun Wang, Ping Fan, Werner J. Blau. Nonlinear optical performance of few-layer molybdenum diselenide as a slow-saturable absorber[J]. Photonics Research, 2018, 6(7): 07000674.