Nonlinear optical performance of few-layer molybdenum diselenide as a slow-saturable absorber

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

doi:10.1364/PRJ.6.000674

Journals >Photonics Research >Volume 6 >Issue 7 >Page 674 > Article

Photonics Research
Vol. 6, Issue 7, 674 (2018)

Nonlinear optical performance of few-layer molybdenum diselenide as a slow-saturable absorber

Gaozhong Wang^1、2、†, Guangxing Liang^1、†, Aidan A. Baker-Murray², Kangpeng Wang^2、4, Jing Jing Wang², Xiaoyan Zhang³, Daniel Bennett², Jing-Ting Luo^1、5, Jun Wang³, Ping Fan^1、*, and Werner J. Blau²

Author Affiliations

¹Shenzhen Key Laboratory of Advanced Thin Films and Applications, College of Physics and Energy, Shenzhen University, Shenzhen 518060, China

²School of Physics and the Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), Trinity College Dublin, Dublin 2, Ireland

³Key Laboratory of Materials for High-Power Laser, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China

⁴e-mail: wangkangpeng@msn.com

⁵e-mail: luojt@szu.edu.cn

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DOI: 10.1364/PRJ.6.000674 Cite this Article Set citation alerts

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): 674 Copy Citation Text

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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.

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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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).

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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$T_{0}$ (%)	$α_{0}$ ( ${cm}^{- 1}$ )	$α_{NL}$ (cm/GW)	$Im χ^{(3)}$ (esu)	$T_{\max}$ (%)	$Δ T$ (%)	$A_{ns}$ (%)	$I_{S}$ ( $MW / {cm}^{2}$ )	$σ_{e} / σ_{g}$
47.8	5.22	−0.017	$- 0.98 \times 10^{- 14}$	55.2	7.4	44.8	39.37	0.81
34.9	6.51	−0.044	$- 2.50 \times 10^{- 14}$	55.0	15.1	45.0	234.75	0.57

Table 1. NLO Performance of Few-Layer MoSe2 Used as a Slow-Saturable Absorber

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$α_{0}$ ( ${cm}^{- 1}$ )	$D_{1}$ (%)	$D_{2}$ (%)	$τ_{1}$ (ps)	$τ_{2}$ (ps)	$σ$ (fs)
5.22	82.9	17.1	2.16	210.13	95
6.51	89.8	10.2	2.22	226.27	161

Table 2. 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