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Optical parametric oscillator (OPO) is an important mid-infrared coherent light source. Two-dimensional (2D) transition metal dichalcogenide (TMDC) with nonlinear absorption of near-infrared-wavelength light is expected to be a prospective modulating switch for OPO’s fundamental laser. In this work, firstly, the characteristics of a home-made 3.5nm-thick tungsten disulfide (WS2) sample are measured and analyzed. The nonlinear transmission is figured and fitted, revealing the performance of WS2’s saturable absorption. Then, the output characteristics of WS2 saturable absorber (SA) modulated solid-state laser are measured experimentally. Although the photon energy of 1.06 μm-wavelength laser is less than the bandgap energy of 3.5nm WS2, the sample still exhibits the saturable absorption. This may be attributed to the mechanisms of defect-induced absorption, coexistence of states, edge-state of material, two-photon absorption, etc. Secondly, combined with active acousto-optic (AO) modulator, the active and passive Q-switched OPO with idler-light oscillation are implemented, and the nanometer pulse-width mid-infrared pulse is obtained. The implementation of AO modulator is to manage the regular switching time to reduce the pulse peak-to-peak vibration of fundamental light and improve the peak power. The optimal characteristics of WS2 for OPO are studied. Based on the saturable absorption characteristics, the output pulse is compressed by 60%, the peak power is improved by 191%, and the stability of pulse train is improved by 79.62%. Especially, the insertion of WS2 nanosheet could alleviate the “output saturation and drop” phenomenon in singly active-Q-switched OPO. This phenomenon may origin from the uneven refrigeration of KTA. Because the saturable absorption effect of WS2 can significantly reduce the transverse area of Gaussian beam, it can alleviate the temperature gradient distribution of KTA and optimize the output characteristics. Finally, based on the nonlinear transmittance curve measured for WS2, the absorption cross section of ground state and excited state are calculated to be1.732 × 10–17 cm2 and 4.758 × 10–19 cm2, respectively, and the lifetime of excited-state energy level and the initial population density of ground state are evaluated to be 400.6 μs and 1.741 × 1022 cm–3, respectively, by considering the inhomogeneous-broadening mechanism and unsaturated absorption under large signal. The rate equations of layered-WS2 modulated optical parametric oscillator are solved. This study shows the optimization effect of 2D TMDC on nonlinear conversion of laser, especially the mitigation of thermal effect. At the same time, it provides a parameter basis for the dynamic simulation of two-dimensional material modulated laser.
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Keywords:
- layered transition metal dichalcogenide /
- mid-infrared optical parametric oscillator /
- dynamical equation /
- saturable absorption cross section
[1] Loparo Z E, Ninnemann E, Ru Q, Vodopyanov K L, Vasu S S 2020 Opt. Lett. 45 491Google Scholar
[2] 郝倩倩, 宗梦雨, 张振, 黄浩, 张峰, 刘杰, 刘丹华, 苏良碧, 张晗 2020 物理学报 69 184205Google Scholar
Hao Q Q, Zong M Y, Zhang Z, Huang H, Zhang F, Liu J, Liu D H, Su L B, Zhang H 2020 Acta Phys. Sin. 69 184205Google Scholar
[3] Ashik A S, O’Donnell C F, Kumar S C, Ebrahim-Zadeh M, Tidemand-Lichtenberg P, Pedersen C 2019 Photonics Res. 7 783Google Scholar
[4] Wang J, Zhao S, Yang K, Li D, Li G, An J 2007 J. Opt. Soc. Am. B 24 2521Google Scholar
[5] 于永吉, 陈薪羽, 成丽波, 王超, 吴春婷, 董渊, 李述涛, 金光勇 2015 物理学报 64 224215Google Scholar
Yu Y J, Chen X Y, Cheng L B, Wang C, Wu C T, Dong Y, Li S T, Jin G Y 2015 Acta Phys. Sin. 64 224215Google Scholar
[6] Liu F Q, Xia H R, Pan S D 2007 Opt. Lase. Technol. 39 1449Google Scholar
[7] Zhang H, Zhao J, Yang K, Zhao S, Li T, Li G, Zhao B 2014 IEEE J. Sel. Top. Quant. Electronics 21 79
[8] Yang X, Peng Z, Xie W, Li L 2018 Opt. Lase. Technol. 98 19Google Scholar
[9] 龙慧, 胡建伟, 吴福根, 董华锋 2020 物理学报 69 188102Google Scholar
Long H, Hu J W, Wu F G, Dong H F 2020 Acta Phys. Sin. 69 188102Google Scholar
[10] Tian K, Li Y, Yang J 2019 Appl. Phys. B 125 2125
[11] Su X, Zhang B, Wang Y, Guan H E, Guo L I, Lin N A 2018 Photonics Res. 6 498Google Scholar
[12] Du W, Li H P, Lan C, Li C, Liu Y 2020 Opt. Express 28 11514Google Scholar
[13] Ma Y, Sun H, Ran B, Zhang S, Lv Z 2020 Opt. Lase. Technol. 126 106084Google Scholar
[14] Wang Y, Liu S, Wang J, Wang H, Wang T, Wang Y 2020 IEEE Photonic. Tech. L. 32 831Google Scholar
[15] Niu Z, Feng T, Pan Z, Yang K, Gao K 2020 Opt. Mater. Express 10 752Google Scholar
[16] Wang J, Pang J B, Liu S P 2019 Opt. Express 27 36474Google Scholar
[17] Wang J, Pang J, Liu S, Song P, Xia W 2020 Infrared Phys. Techn. 8 103525
[18] Sun Y, Bai Y, Li D 2018 Opt. Express 25 21037
[19] Oshman M, Harris S 1968 IEEE J. Quantum Elect. 5 206
[20] Kim Y S, Kang S, So J P, Kim J C, Lee C H 2021 Sci. Adv. 7 eabd7921Google Scholar
[21] Li M, Sinev I, Benimetskiy F, Ivanova T, Khanikaev A B 2021 Nat. Commun. 12 1Google Scholar
[22] Ling H, Li R, Davoyan A R 2021 ACS Photonics 8 721Google Scholar
[23] Berkdemir A, Gutiérrez R, Humberto, Botello-Méndez R 2013 Sci. Rep. 3 1755Google Scholar
[24] Cong C, Shang J, Wu X, et al. 2014 Adv. Opt. Mater. 2 131Google Scholar
[25] Peimyoo N, Shang J, Cong C, Shen X, Wu X 2013 ACS Nano. 7 10985Google Scholar
[26] Xu K, Wang Z, Du X 2013 Nanotechnology 24 465705Google Scholar
[27] Liu Z, Amani M, Naimaei S 2014 Nat. Commun. 5 5246Google Scholar
[28] Chen Y, Zhao C, Huang H, Chen S, Tang P, Wang Z, Lu S, Zhang H, Wen S, Tang D 2013 J. Lightwave Technol. 31 2857Google Scholar
[29] Shimony Y, Burshtein Z, Kalisky Y 1995 IEEE J. Quantum Elect. 30 1738
[30] Zhang S, Dong N, Mcevoy N 2015 Acs Nano 9 7142Google Scholar
[31] Wang S, Yu H, Zhang H, Wang A, Wang J 2014 Adv. Mater. 26 3538Google Scholar
[32] Iliev H, Chuchumishev D, Buchvarov I 2010 Opt. Express 18 5754Google Scholar
[33] Yao J Q, Yu Y Z, Wang P, Wang T, Zhang B G, Ding X, Chen J 2001 Chinese Phys. Lett. 18 1214Google Scholar
[34] Zheng J, Zhao S, Wang Q 2001 Opt. Commun. 199 207Google Scholar
[35] 朱雅琛, 兰戈, 李彤, 牛瑞华 2007 激光技术 5 551Google Scholar
Zhu Y S, Lan G, Li T, Niu R H 2007 Laser Technol. 5 551Google Scholar
[36] 卞进田, 孔辉, 徐海萍, 叶庆, 孙晓泉 2021 中国激光 48 249
Bian J T, Kong H, Xu H P, Ye Q, Sun X Q 2021 Chinese J. of Lasers 48 249
[37] Tang Y, Rae C F, Rahlff C, Dunn M H 1997 J. Opt. Soc. Am. B 14 3442Google Scholar
[38] Coehoorn R, Haas C, Dijkstra J 1987 Phys. Rev. B 35 6195Google Scholar
[39] Zhao S, He D, He J 2018 Nanoscale 10 9536
[40] Xiao G, Bass M, Acharekar M 1998 IEEE J. Quantum Elect. 34 2241Google Scholar
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图 3 WS2 SA被动调Q的1.06 μm激光 (a)实验装置; (b)平均输出功率; (c)脉冲宽度; (d)脉冲重复率; (e)峰值功率; (f) WS2调Q、1.06 μm脉冲波形; (g) WS2+AO调Q的1.06 μm脉冲波形, fp = 15 kHz
Figure 3. WS2 SA passively Q-switched 1.06 μm laser: (a) Experimental setup; (b) average output power; (c) pulse width; (d) pulse repetition rate; (e) peak power; (f) temporal pulse train from WS2 Q-switched 1.06μm laser; (g) temporal pulse train from WS2+AO Q-switched 1.06 μm laser, fp = 15 kHz.
图 6 调Q IOPO的中红外闲频光输出特性 (a), (e)平均输出功率; (b), (f)输出脉冲宽度; (c), (g)峰值功率; (d), (h)输出脉冲序列. (a)—(d) AO单调Q IOPO的输出结果; (e)—(h)WS2 SA+AO 双调Q IOPO的输出结果
Figure 6. Output characteristics of Q-switched IOPOs: (a), (e) Average output power; (b), (f) pulse width; (c), (g) peak power; (d), (h) pulse train; (a)–(d) output of AO Q-switched IOPO; (e)–(h) output of WS2 SA+AO Q-switched IOPO.
图 7 (a)走离角、有效非线性系数与相位匹配角θ的关系; (b) AO单调Q的 1.06 μm基频光的光斑, 高斯光束质量因子
${M}_{x}^{2} = $ $ 3.02,\; {M}_{y}^{2} = 2.19$ , 光束半径为798 μm; (c) WS2+AO双调Q的 1.06 μm基频光的光斑, 高斯光束质量因子${M}_{x}^{2} = 1.69,\; {M}_{y}^{2} = $ $ 1.51$ , 光束半径为451 μmFigure 7. (a) Walk-off angle and deff versus θ; (b) 1.06 μm fundamental-light beam from AO Q-switched laser,
${M}_{x}^{2} = 3.02, $ $ {M}_{y}^{2} = 2.19$ , beam radius of 798 μm; (c) 1.06 μm fundamental-light beam from WS2+AO Q-switched laser,${M}_{x}^{2} = 1.69, $ $ {M}_{y}^{2} = 1.51,$ beam radius of 451 μm.图 8 Ppump = 11.2 W, fp = 15 kHz时, 基频光、闲频光、信号光的时域波形 (a) WS2+AO调Q IOPO的基频光波形; (b) WS2+AO调Q IOPO的闲频光波形; (c) WS2+AO调Q IOPO的信号光波形; (d) AO调Q IOPO的基频光波形; (e) AO调Q IOPO的闲频光波形; (f) AO调Q IOPO的信号光波形
Figure 8. Temporal pulses of fundamental light, idler light, and signal light at Ppump = 11.2 W, fp = 15 kHz: (a) Fundamental pulse from WS2+AO Q-switched IOPO; (b) idler pulse from WS2+AO Q-switched IOPO; (c) signal pulse from WS2+AO Q-switched IOPO; (d) fundamental pulse from AO Q-switched IOPO; (e) idler pulse from AO Q-switched IOPO; (f) signal pulse from AO Q-switched IOPO.
表 1 实验制备3.5 nm WS2 SA可饱和吸收特性的关键参数
Table 1. The key parameters for saturable absorption properties of 2D-WS2 SA.
Parameters Values σg/cm2 1.732 × 10–17 σe/cm2 4.758 × 10–19 τy/μs 400.6 ly/nm 3.5 ny0/cm–3 1.741 × 1022 表 2 速率方程中的其它参数
Table 2. The other parameters in rate equations.
Parameters Meaning Values σ/cm2 Nd:YVO4的受激发射截面 1.3 × 10–18 tAO/ns 声光的开关时间 14 τ/μs Nd:YVO4的受激发射寿命 95 deff/(pm·V–1) KTA的有效非线性系数 4.47 n1 1064 nm激光在 Nd:YVO4
中的折射率2.183 n2 1064 nm激光在 AO中的折射率 1.600 np 1064 nm激光在 KTA中的折射率 1.868 ns 1536 nm激光在 KTA中的折射率 1.854 ni 3467 nm激光在 KTA中的折射率 1.817 -
[1] Loparo Z E, Ninnemann E, Ru Q, Vodopyanov K L, Vasu S S 2020 Opt. Lett. 45 491Google Scholar
[2] 郝倩倩, 宗梦雨, 张振, 黄浩, 张峰, 刘杰, 刘丹华, 苏良碧, 张晗 2020 物理学报 69 184205Google Scholar
Hao Q Q, Zong M Y, Zhang Z, Huang H, Zhang F, Liu J, Liu D H, Su L B, Zhang H 2020 Acta Phys. Sin. 69 184205Google Scholar
[3] Ashik A S, O’Donnell C F, Kumar S C, Ebrahim-Zadeh M, Tidemand-Lichtenberg P, Pedersen C 2019 Photonics Res. 7 783Google Scholar
[4] Wang J, Zhao S, Yang K, Li D, Li G, An J 2007 J. Opt. Soc. Am. B 24 2521Google Scholar
[5] 于永吉, 陈薪羽, 成丽波, 王超, 吴春婷, 董渊, 李述涛, 金光勇 2015 物理学报 64 224215Google Scholar
Yu Y J, Chen X Y, Cheng L B, Wang C, Wu C T, Dong Y, Li S T, Jin G Y 2015 Acta Phys. Sin. 64 224215Google Scholar
[6] Liu F Q, Xia H R, Pan S D 2007 Opt. Lase. Technol. 39 1449Google Scholar
[7] Zhang H, Zhao J, Yang K, Zhao S, Li T, Li G, Zhao B 2014 IEEE J. Sel. Top. Quant. Electronics 21 79
[8] Yang X, Peng Z, Xie W, Li L 2018 Opt. Lase. Technol. 98 19Google Scholar
[9] 龙慧, 胡建伟, 吴福根, 董华锋 2020 物理学报 69 188102Google Scholar
Long H, Hu J W, Wu F G, Dong H F 2020 Acta Phys. Sin. 69 188102Google Scholar
[10] Tian K, Li Y, Yang J 2019 Appl. Phys. B 125 2125
[11] Su X, Zhang B, Wang Y, Guan H E, Guo L I, Lin N A 2018 Photonics Res. 6 498Google Scholar
[12] Du W, Li H P, Lan C, Li C, Liu Y 2020 Opt. Express 28 11514Google Scholar
[13] Ma Y, Sun H, Ran B, Zhang S, Lv Z 2020 Opt. Lase. Technol. 126 106084Google Scholar
[14] Wang Y, Liu S, Wang J, Wang H, Wang T, Wang Y 2020 IEEE Photonic. Tech. L. 32 831Google Scholar
[15] Niu Z, Feng T, Pan Z, Yang K, Gao K 2020 Opt. Mater. Express 10 752Google Scholar
[16] Wang J, Pang J B, Liu S P 2019 Opt. Express 27 36474Google Scholar
[17] Wang J, Pang J, Liu S, Song P, Xia W 2020 Infrared Phys. Techn. 8 103525
[18] Sun Y, Bai Y, Li D 2018 Opt. Express 25 21037
[19] Oshman M, Harris S 1968 IEEE J. Quantum Elect. 5 206
[20] Kim Y S, Kang S, So J P, Kim J C, Lee C H 2021 Sci. Adv. 7 eabd7921Google Scholar
[21] Li M, Sinev I, Benimetskiy F, Ivanova T, Khanikaev A B 2021 Nat. Commun. 12 1Google Scholar
[22] Ling H, Li R, Davoyan A R 2021 ACS Photonics 8 721Google Scholar
[23] Berkdemir A, Gutiérrez R, Humberto, Botello-Méndez R 2013 Sci. Rep. 3 1755Google Scholar
[24] Cong C, Shang J, Wu X, et al. 2014 Adv. Opt. Mater. 2 131Google Scholar
[25] Peimyoo N, Shang J, Cong C, Shen X, Wu X 2013 ACS Nano. 7 10985Google Scholar
[26] Xu K, Wang Z, Du X 2013 Nanotechnology 24 465705Google Scholar
[27] Liu Z, Amani M, Naimaei S 2014 Nat. Commun. 5 5246Google Scholar
[28] Chen Y, Zhao C, Huang H, Chen S, Tang P, Wang Z, Lu S, Zhang H, Wen S, Tang D 2013 J. Lightwave Technol. 31 2857Google Scholar
[29] Shimony Y, Burshtein Z, Kalisky Y 1995 IEEE J. Quantum Elect. 30 1738
[30] Zhang S, Dong N, Mcevoy N 2015 Acs Nano 9 7142Google Scholar
[31] Wang S, Yu H, Zhang H, Wang A, Wang J 2014 Adv. Mater. 26 3538Google Scholar
[32] Iliev H, Chuchumishev D, Buchvarov I 2010 Opt. Express 18 5754Google Scholar
[33] Yao J Q, Yu Y Z, Wang P, Wang T, Zhang B G, Ding X, Chen J 2001 Chinese Phys. Lett. 18 1214Google Scholar
[34] Zheng J, Zhao S, Wang Q 2001 Opt. Commun. 199 207Google Scholar
[35] 朱雅琛, 兰戈, 李彤, 牛瑞华 2007 激光技术 5 551Google Scholar
Zhu Y S, Lan G, Li T, Niu R H 2007 Laser Technol. 5 551Google Scholar
[36] 卞进田, 孔辉, 徐海萍, 叶庆, 孙晓泉 2021 中国激光 48 249
Bian J T, Kong H, Xu H P, Ye Q, Sun X Q 2021 Chinese J. of Lasers 48 249
[37] Tang Y, Rae C F, Rahlff C, Dunn M H 1997 J. Opt. Soc. Am. B 14 3442Google Scholar
[38] Coehoorn R, Haas C, Dijkstra J 1987 Phys. Rev. B 35 6195Google Scholar
[39] Zhao S, He D, He J 2018 Nanoscale 10 9536
[40] Xiao G, Bass M, Acharekar M 1998 IEEE J. Quantum Elect. 34 2241Google Scholar
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