Recent advances in mid-infrared ultrafast fiber laser technology
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摘要:
中红外波段覆盖重要的分子吸收区与多个大气透射窗口,该波段的超快激光器在多个领域具有广泛应用。基于光纤的中红外超快激光器近年来在激光发射与传输、超快脉冲产生与应用等方面发展迅速,为中红外波段超快激光开辟了新的研究手段与应用领域。综述了近十年来中红外超快光纤激光器的发展概况,介绍了近年来中红外波段的激光传输与增益手段。其中,重点回顾了近年来中红外超快脉冲产生技术的研究进展及其代表性工作,包括非线性偏振旋转、可饱和吸收体以及频移反馈锁模技术。此外,还介绍了中红外超快脉冲的压缩放大技术与超连续谱产生应用。最后讨论并总结了中红外超快光纤激光器面临的挑战与可能的发展方向。
Abstract:Mid-infrared region ranging from 2.5 μm to 25 μm covers absorption lines of most molecules and multiple atmospheric windows. The ultrafast lasers operating in this waveband have vast applications in many fields. In recent years, significant progress has been made in the area of mid-infrared fiber-based ultrafast lasers in terms of long waveband emission and ultrafast pulse generation, which enables many unexplored reseaches and novel applications. In this paper, we reviewed the development of mid-infrared ultrafast fiber lasers over the last decade. Starting with the fiber materials and the gain medium used for mid-infrared emission, we focused on the current mode-locking methods and their representative progress for mid-infrared fiber lasers including nonlinear polarization rotation, saturable absorbers and frequency shifted feedback technique. Then we briefly discussed the mid-infrared pulse post-modification and typical applications including few-circle pulses and supercontinuum generation. Finally, the critical challenges the mid-infrared ultrafast fiber lasers are currently facing and the possible routines for further development were summarized.
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Key words:
- mid-infrared /
- ultrafast laser /
- fiber laser /
- mode-locking technology /
- few-circle pulse /
- supercontinuum
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图 4 (a-d) 2.8 μm非线性偏振旋转锁模[29]。(a) 系统结构;(b) 直接输出光谱与重建光谱;(c) 自相关迹;(d) 二次谐波信号光谱;(e-g) 3.5 μm非线性偏振旋转锁模光纤激光器[32]。(e) 系统结构;(f) 输出光谱;(g) 自相关迹
Figure 4. (a-d) 2,8 μm nonlinear polarization rotation based mode-locking[29]. (a) Experimental configuration; (b) direct and reconstructed output spectra; (c)autocorrelation trace; (d) second harmonic signal spectrum. (e-g) 3.5 μm nonlinear polarization rotation based mode-locking[32]. (e) Experimental setup; (f) pulse spectrum; (g) autocorrelation trace
图 8 (a-d)基于非线性压缩的70 fs脉冲产生[34]。(a) 系统结构;(b) 输出光谱;(c) 压缩前的自相关迹;(d) 压缩后的自相关迹。(e-h) 基于啁啾脉冲放大和高阶孤子压缩的15.9 fs脉冲产生。(e) 系统结构;(f) 种子光谱和放大后的脉冲光谱;(g) 压缩后脉冲光谱;(h) 恢复的脉冲波形及其相位
Figure 8. (a-d) 70 fs pulses generation via nonlinear compression[34]. (a) Experimental setup; (b) output spectra; (c) autocorrelation trace before compression; (d) autocorrelation trace after compression. (e-h) 15.9 fs pulses generation via chirped pulse amplification and high order soliton self-compression[33]. (e) Experimental setup; (f) spectra of seed and amplified pulse; (g) spectrum of compressed pulse; (h) retrieved temporal intensity and phase of compressed pulse
表 1 中红外被动调Q光纤激光器性能比较
Table 1. Comparison of results of mid-infrared fiber lasers Q-switched by various saturable absorbers
saturable absorber doped rare-earth elements wavelenth/nm duration/ns frequency/kHz SNR/dB power/mW reference graphene Er3+ 2783 1670 37 30 62 [53] SESAM Er3 2791 1680 47.6 50 317 [54] Bi2Te3 Ho3+ 2979.9 1370 81.96 37.4 327.4 [55] BP Er3+ 2779 1180 63 − 485 [56] SESAM Er3+ 2783 315 146.3 − 1010 [57] Bi2Te3 Er3+ 2791 1300 92 36 856 [58] WS2 Ho3+/Pr3+ 2867 1670 131.6 40.5 48.4 [59] Fe2+:ZnSe Er3+ 2779 742 102.9 41 822 [60] Fe2+:ZnSe Er3+ 2780 430 160.8 39 873 [61] GNS Er3+ 2800 536 125 44 454 [62] SWCNT Ho3+/Pr3+ 2837~2892 1460 131.6 40 55.8 [63] PbS Dy3+ 2710~3080 795 166.8 33 252.7 [64] MoS2 Er3+ 2754 806 70 40 140 [65] MXene Er3+ 2798 730 99.5 33.1 80 [66] Sb Er3+ 2800 1700 28.8 36.2 59 [52] PtSe2 Ho3+/Pr3+ 2865 620 238.1 30 93 [67] Fe3O4 Dy3+ 2931 1250 123 35 111 [68] InSe Er3+ 2791 423 253 43.7 712 [69] SNR: single-to-noise ratio; BP: black phosphorus; SWCNT: single-walled carbon nanotube -
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