Author Affiliations
Abstract
1 College of Advanced Interdisciplinary Studies, National University of Defense Technology, Changsha 410073, China
2 Nanhu Laser Laboratory, National University of Defense Technology, Changsha 410073, China
Radio frequency/microwave-directed energy sources using wide bandgap SiC photoconductive semiconductors have attracted much attention due to their unique advantages of high-power output and multi-parameter adjustable ability. Over the past several years, benefitting from the sustainable innovations in laser technology and the significant progress in materials technology, megawatt-class output power electrical pulses with a flexible frequency in the P and L microwave wavebands have been achieved by photoconductive semiconductor devices. Here, we mainly summarize and review the recent progress of the high-power photonic microwave generation based on the SiC photoconductive semiconductor devices in the linear modulation mode, including the mechanism, system architecture, critical technology, and experimental demonstration of the proposed high-power photonic microwave sources. The outlooks and challenges for the future of multi-channel power synthesis development of higher power photonic microwave using wide bandgap photoconductors are also discussed.
high-power photonic microwave wide bandgap photoconductive semiconductor devices linear modulation multi-parameter adjustable microwave generation multi-channel power synthesis Chinese Optics Letters
2024, 22(1): 012501
Shuailin Liu 1,2,3Bin Zhang 1,2,3,*Yuanzhuang Bu 1,2,3Desheng Zhao 1,2,3[ ... ]Jing Hou 1,2,3,*
Author Affiliations
Abstract
1 College of Advanced Interdisciplinary Studies, National University of Defense Technology, Changsha, China
2 Nanhu Laser Laboratory, National University of Defense Technology, Changsha, China
3 Hunan Provincial Key Laboratory of High Energy Laser Technology, Changsha, China
We report a Yb-doped all-fiber laser system generating burst-mode pulses with high energy and high peak power at a GHz intra-burst repetition rate. To acquire the uniform burst envelope, a double-pre-compensation structure with an arbitrary waveform laser diode driver and an acoustic optical modulator is utilized for the first time. The synchronous pumping is utilized for the system to reduce the burst repetition rate to 100 Hz and suppress the amplified spontaneous emission effect. By adjusting the gain of every stage, uniform envelopes with different output energies can be easily obtained. The intra-burst repetition rate can be tuned from 0.5 to 10 GHz actively modulated by an electro-optic modulator. Optimized by timing control of eight channels of analog signal and amplified by seven stages of Yb-doped fiber amplifier, the pulse energy achieves 13.3 mJ at 0.5 ns intra-burst pulse duration, and the maximum peak power reaches approximately 3.6 MW at 48 ps intra-burst pulse duration. To the best of our knowledge, for reported burst-mode all-fiber lasers, this is a record for output energy and peak power with nanosecond-level burst duration, and the widest tuning range of the intra-burst repetition rate. In particular, this flexibly tunable burst-mode laser system can be directly applied to generate high-power frequency-tunable microwaves.
burst-mode laser fiber laser high peak power high pulse energy High Power Laser Science and Engineering
2023, 11(6): 06000e81
Li Jiang 1,2,3Jinming Wu 1,2,3Rui Song 1,2,3,*Zilun Chen 1,2,3[ ... ]Jing Hou 1,2,3,*
Author Affiliations
Abstract
1 College of Advanced Interdisciplinary Studies, National University of Defense Technology, Changsha, China
2 Nanhu Laser Laboratory, National University of Defense Technology, Changsha, China
3 Hunan Provincial Key Laboratory of High Energy Laser Technology, National University of Defense Technology, Changsha, China
The random distributed-feedback fiber laser (RFL) is a new approach to obtain a high-power stable supercontinuum (SC) source. To consider both structure simplification and high-power SC output, an innovative structure achieving a kilowatt-level SC output in a single-stage RFL with a half-open cavity is demonstrated in this paper. It consists of a fiber oscillator, a piece of long passive fiber and a broadband coupler, among which the broadband coupler acting as a feedback device is crucial in SC generation. When the system has no feedback, the backward output power is up to 298 W under the pump power of 1185 W. When the feedback is introduced before the pump laser, the backward power loss can be reduced and the pump can be fully utilized, which could promote forward output power and conversion efficiency significantly. Under the maximum pump power of 1847 W, a 1300 W SC with spectrum ranging from 887 to 1920 nm and SC conversion efficiency of 66% is obtained. To the best of our knowledge, it is the simplest structure used for high-power SC generation, and both the generated SC output power and the conversion efficiency are highest in the scheme of the half-opened RFL output SC.
high conversion efficiency high-power supercontinuum random fiber laser single-stage structure High Power Laser Science and Engineering
2023, 11(6): 06000e80
江丽 1,2,3宋锐 1,2,3,*侯静 1,2,3,**陈胜平 1,2,3[ ... ]韩凯 1,2
1 国防科技大学前沿交叉学科学院，湖南 长沙 410073
2 国防科技大学南湖之光实验室，湖南 长沙 410073
3 国防科技大学高能激光技术湖南省重点实验室，湖南 长沙 410073
高功率可见光至近红外波段的超连续谱光源在光电对抗、光学相干层析成像和高光谱激光雷达等方面具有广泛的应用前景。最近几年，涌现了一些用于产生高功率超连续谱光源的新方法，推动了高功率超连续谱光源的进一步发展。本文从主振荡功率放大结构、随机光纤激光器结构以及多路非相干合成这三种用于高功率超连续谱产生的主流方案出发，着重介绍了近年来有代表性的高功率可见光至近红外波段超连续谱光源的研究进展，并综合分析了这三种方案的优缺点以及未来的发展潜力。
非线性光学 高功率光纤超连续谱 渐变折射率多模光纤 光子晶体光纤 随机光纤激光器 多路非相干合成 光学学报
2023, 43(17): 1719001
朱晰然 1,2,3张斌 1,2,3,*陈子伦 1,2,3赵得胜 1,2,3[ ... ]侯静 1,2,3
1 国防科技大学 前沿交叉学科学院，湖南 长沙 410073
2 国防科技大学 南湖之光实验室，湖南 长沙 410073
3 国防科技大学 高能激光技术湖南省重点实验室，湖南 长沙 410073
中红外超荧光光源具有光谱范围宽、空间相干性好、时域稳定性高等特点，应用前景广泛，但受限于中红外侧面泵浦合束器，目前普遍利用空间结构泵浦产生。文中根据拉锥光纤侧面耦合的原理，在125 μm包层直径的无源双包层氟化物光纤上实现了中红外光纤侧面泵浦合束器的研制，该合束器泵浦光耦合效率达82.3%，可承受的最大泵浦功率达87.5 W。通过在中红外增益光纤上制得侧面泵浦合束器，实现了全光纤中红外超荧光光源产生，前后向输出的中红外超荧光最高功率和为91.09 mW （后向输出53.67 mW，前向输出37.42 mW），输出光谱范围从2702 nm覆盖至2830 nm。在中红外超荧光总输出功率为33.03 mW时，获得了108 nm的最宽20 dB带宽。文中实现的中红外全光纤超荧光光源克服了以往空间泵浦复杂度高、调节难的问题，对推动中红外超荧光光源的进一步功率放大具有重要意义。
中红外光纤光源 超荧光光源 侧面泵浦合束器 氟化物光纤 mid-infrared fiber source superfluorescent fiber source side-pumping combiner fluoride fiber 红外与激光工程
2023, 52(5): 20230101
1国防科技大学前沿交叉学科学院，湖南 长沙 410073
中国激光
2023, 50(11): 1116002
Author Affiliations
Abstract
1 College of Advanced Interdisciplinary Studies, National University of Defense Technology, Changsha 410073, China
2 Nanhu Laser Laboratory, National University of Defense Technology, Changsha 410073, China
3 Key Laboratory of Atmospheric Optics, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China
A monolithic visible supercontinuum (SC) source with a record average output power of 204 W and a spectrum ranging from 580 nm to beyond 2400 nm is achieved in a piece of standard telecom graded-index multimode fiber (GRIN MMF) by designing the pumping system. The influence of the GRIN MMF length on the geometrical parameter instability (GPI) effect is analyzed for the first time, to the best of our knowledge, by comparing the SC spectral region dominated by the GPI effect under different fiber lengths. Our work could pave the way for robust, cost-effective, and high-power visible SC sources.
visible supercontinuum high-power supercontinuum graded-index multimode fiber geometrical parameter instability nonlinear optics Chinese Optics Letters
2023, 21(5): 051403
Desheng Zhao 1,2,3Bin Zhang 1,2,3,*Xiran Zhu 1,2,3Shuailin Liu 1,2,3[ ... ]Jing Hou 1,2,3,*
Author Affiliations
Abstract
1 College of Advanced Interdisciplinary Studies, National University of Defense Technology, Changsha, China
2 Nanhu Laser Laboratory, National University of Defense Technology, Changsha, China
3 Hunan Provincial Key Laboratory of High Energy Laser Technology, Changsha, China
We propose a 2.1 μm high-energy dissipative soliton resonant (DSR) fiber laser system based on a mode-locked seed laser and dual-stage amplifiers. In the seed laser, the nonlinear amplifying loop mirror technique is employed to realize mode-locking. The utilization of an in-band pump scheme and long gain fiber enables effectively exciting 2.1 μm pulses. A section of ultra-high numerical aperture fiber (UHNAF) with normal dispersion and high nonlinearity and an output coupler with a large coupling ratio are used to achieve a high-energy DSR system. By optimizing the UHNAF length to 55 m, a 2103.7 nm, 88.1 nJ DSR laser with a 3-dB spectral bandwidth of 0.48 nm and a pulse width of 17.1 ns is obtained under a proper intracavity polarization state and pump power. The output power and conversion efficiency are 0.233 W and 4.57%, respectively, both an order of magnitude higher than those of previously reported holmium-doped DSR seed lasers. Thanks to the high output power and nanosecond pulse width of the seed laser, the average power of the DSR laser is linearly scaled up to 50.4 W via a dual-stage master oscillator power amplifier system. The 3-dB spectral bandwidth broadens slightly to 0.52 nm, and no distortion occurs in the amplified pulse waveform. The corresponding pulse energy reaches 19.1 μJ, which is the highest pulse energy in a holmium-doped mode-locked fiber laser system to the best of our knowledge. Such a 2.1 μm, high-energy DSR laser with relatively wide pulse width has prospective applications in mid-infrared nonlinear frequency conversion.
High Power Laser Science and Engineering
2023, 11(1): 01000e12
Author Affiliations
Abstract
1 College of Advanced Interdisciplinary Studies, National University of Defense Technology, Changsha, China
2 State Key Laboratory of Pulsed Power Laser Technology, Changsha, China
3 Nanhu Laser Laboratory, National University of Defense Technology, Changsha, China
We report the demonstration of a mid-infrared (MIR) supercontinuum (SC) laser delivering a record-breaking average output power of more than 40 W with a long-wavelength edge up to 3.5 μm. The all-fiberized configuration was composed of a thulium-doped fiber amplifier system emitting a broadband spectrum covering 1.9–2.6 μm with pulse repetition rate of 3 MHz, and a short piece of germania fiber. A 41.9 W MIR SC with a whole spectrum of 1.9–3.5 μm was generated in a piece of 0.2-m-long germania fiber, with a power conversion efficiency of 71.4%. For an even shorter germania fiber (0.1 m), an SC with even higher output power of 44.9 W (corresponding to a conversion efficiency of 76.5%) was obtained, but the energy conversion toward the long-wavelength region was slightly limited. A continuous operation for 1 hour with output power of 32.6 W showed outstanding power stability (root mean square 0.17%) of the obtained SC laser. To the best of the authors’ knowledge, for the first time, this work demonstrates the feasibility of germania fiber on generating a 40-W level MIR SC with high efficiency and excellent power stability, paving the way to real applications requiring high power and high reliability of MIR SC lasers.
fiber laser high power nonlinear optics supercontinuum generation High Power Laser Science and Engineering
2022, 10(6): 06000e36
