• Special Issue
  • Fibres for High Power Lasers
  • 11 Article (s)
kW-class high power fiber laser enabled by active long tapered fiber
Chen Shi, Hanwei Zhang, Xiaolin Wang, Pu Zhou, and Xiaojun Xu
Compared with traditional uniform fibers, tapered fiber has numerous unique advantages, such as larger mode area, higher pump absorption, suppression to nonlinear effects, and maintaining good beam quality. In this manuscript, we have constructed an all-fiberized fiber amplifier which is based on a piece of ytterbium-doped tapered double-clad fiber (T-DCF). The fiber amplifier is operated under continuous wave (CW) regime at 1080 nm wavelength. The factor of the amplifier at 1.39 kW output power is . The maximum output power of the system reached 1.47 kW, which, to the best of our knowledge, is the highest output power of long tapered fiber based fiber laser system. Our result successfully verifies the potential of power scalability and all-fiberized capability of long tapered fiber, and the performance of our system can be further enhanced by fiber design optimization.
High Power Laser Science and Engineering
  • Publication Date: Apr. 23, 2018
  • Vol.6 Issue, 2 02000e16 (2018)
High pulse energy fiber/solid-slab hybrid picosecond pulse system for material processing on polycrystalline diamonds
Wei Chen, Bowen Liu, Youjian Song, Lu Chai, Qianjin Cui, Qingjing Liu, Chingyue Wang, and Minglie Hu
We demonstrate an all polarization-maintaining (PM) fiber mode-locked laser seeded, hybrid fiber/solid-slab picosecond pulse laser system which outputs , 10 ps pulses at the central wavelength of 1064 nm. The beam quality factors in the unstable and stable directions are 1.35 and 1.31, respectively. picosecond pulses at the central wavelength of 355 nm are generated through third harmonic generation (THG) by using two (LBO) crystals, in order to get better processing efficiency on polycrystalline diamonds. The high pulse energy and beam quality of these ultraviolet (UV) picosecond pulses are confirmed by latter experiments of material processing on polycrystalline diamonds. This scheme which combines the advantages of the all PM fiber mode-locked laser and the solid-slab amplifier enables compact, robust and chirped pulse amplification-free amplification with high power picosecond pulses.
High Power Laser Science and Engineering
  • Publication Date: Apr. 25, 2018
  • Vol.6 Issue, 2 02000e18 (2018)
Power scaling on tellurite glass Raman fibre lasers for mid-infrared applications
Tianfu Yao, Liangjin Huang, Pu Zhou, Bing Lei, Jinyong Leng, and Jinbao Chen
The power scaling on mid-infrared Raman fibre lasers (RFLs) is in demand for applications in health, environment and security. In this paper, we present the simulated laser behaviours of the tellurite glass RFLs pumped by 300-W Tm-doped fibre lasers (TDFLs) at for the first time. By combining the advantages of the TDFLs and tellurite fibre, the output power at has reached over hundreds of watts by first-order Raman shift. Moreover, the cascaded RFLs have been demonstrated with a wavelength extension greater than and output power of tens of watts. To maximize the output power and the slope efficiency of the RFLs, we further analyse the interaction between the Raman gain and cavity loss, which are determined by fibre length and output reflectance of the laser cavity.
High Power Laser Science and Engineering
  • Publication Date: May. 23, 2018
  • Vol.6 Issue, 2 02000e24 (2018)
Numerical modeling of the thermally induced core laser leakage in high power co-pumped ytterbium doped fiber amplifier
Lingchao Kong, Jinyong Leng, Pu Zhou, and Zongfu Jiang
We propose a novel model to explain the physical process of the thermally induced core laser leakage (TICLL) effect in a high power co-pumped ytterbium doped fiber (YDF) amplifier. This model considers the thermally induced mode bending loss decrease and the thermally induced mode instability (TMI) in the coiled YDF, and is further used to reproduce the TICLL effect in the high power co-pumped step-index fiber amplifier. Besides, the TICLL effect in the co-pumping scheme and counter-pumping scheme is compared. The result proves that the TICLL effect is caused by the combined effect of the thermally induced mode bending loss decrease and the TMI, and could be mitigated by adopting the counter-pumping scheme. To our best knowledge, this is the first theoretical explanation of the TICLL effect in high power fiber amplifier.
High Power Laser Science and Engineering
  • Publication Date: May. 24, 2018
  • Vol.6 Issue, 2 02000e25 (2018)
Nonlinearity optimization of dissipative-soliton fiber laser for generation of pulses with 350 kW peak power
Han Chi, Bowen Liu, Youjian Song, Minglie Hu, Lu Chai, Weidong Shen, Xu Liu, and Chingyue Wang
We demonstrate a nonlinearity optimization method by altering distribution of passive fibers in a dissipative-soliton mode-locked fiber laser to level up output parameters. In the numerical simulation, we found that the passive fiber segment after gain fiber characterizes the highest average B-integral among fiber segments. By reducing the length of this fiber section and keeping the total passive fiber length as constant, the output pulse energy can be effectively scaled up while maintaining a short dechirped pulse duration, resulting in boosting peak power. With this method, 37-nJ pulses are generated from a dissipative-soliton mode-locked cladding pumped ytterbium-doped single-mode fiber laser in the experiment. The pulse can be dechirped to 66 fs with 350 kW peak power. Moreover, the pulse pedestal is suppressed by a vector-dispersion compressor.
High Power Laser Science and Engineering
  • Publication Date: Jun. 01, 2018
  • Vol.6 Issue, 2 02000e27 (2018)
Investigation on extreme frequency shift in silica fiber-based high-power Raman fiber laser
Jiaxin Song, Hanshuo Wu, Jun Ye, Hanwei Zhang, Jiangming Xu, Pu Zhou, and Zejin Liu
In this paper, we experimentally investigated the extreme frequency shift in high-power Raman fiber laser (RFL). The RFL was developed by using a pair of fiber Bragg gratings with fixed and matched central wavelength (1120 nm) combined with a piece of 31-m-long polarization maintaining (PM) passive fiber adopted as Raman gain medium. The pump source was a homemade high-power, linearly polarized (LP) wavelength-tunable master oscillator power amplifier (MOPA) source with tunable working range (1055–1080 nm). High-power and high-efficiency RFL with extreme frequency shift between the pump and Stokes light was explored. It is found that frequency shift located within 10.6 THz and 15.2 THz can ensure efficient Raman lasing, where the conversion efficiency is more than 95% of the maximal value, 71.3%. In addition, a maximum output power of 147.1 W was obtained with an optical efficiency of 71.3%, which is the highest power ever reported in LP RFLs to the best of our knowledge.
High Power Laser Science and Engineering
  • Publication Date: Jun. 01, 2018
  • Vol.6 Issue, 2 02000e28 (2018)
Development and prospect of high-power Yb3+ doped fibers
Yibo Wang, Gui Chen, and Jinyan Li
Ytterbium-doped fibers have become the optimum gain media of high-power fiber lasers thanks to a simple energy structure, which strongly reduces the excited state absorption, and a low quantum defect and a high optic–optic conversion efficiency, which means the low thermal load. In this paper, we take a review of the current state of the art in terms of doped fibers for high-power fiber lasers, including the development of the fabrication techniques. The research work to overcome the challenges for doped fibers, which affect the stability of output power and beam quality, will be demonstrated. Direction of further research is presented and the goal is to look for a fiber design, to boost single fiber output power, stabilize the laser power and support robust single-mode operation.
High Power Laser Science and Engineering
  • Publication Date: Jul. 11, 2018
  • Vol.6 Issue, 3 03000e40 (2018)
Monolithic high-average-power linearly polarized nanosecond pulsed fiber laser with near-diffraction-limited beam quality
Long Huang, Pengfei Ma, Daren Meng, Lei Li, Rumao Tao, Rongtao Su, Yanxing Ma, and Pu Zhou
An all-fiberized high-average-power narrow linewidth ns pulsed laser with linear polarization is demonstrated. The laser system utilizes a typical master oscillator power amplifier (MOPA) configuration. The stimulated Brillouin scattering (SBS) is effectively suppressed due to the short fiber length and large mode area in the main amplifier, combined with the narrow pulse duration smaller than the phonon lifetime of SBS effect. A maximal output power of 466 W is obtained with a narrow linewidth of 203.6 MHz, and the corresponding slope efficiency is 80.3%. The pulse duration is condensed to be 4 ns after the amplification, corresponding to the peak power of 8.8 kW and the pulse energy of . Near-diffraction-limited beam quality with an factor of 1.32 is obtained at the output power of 442 W and the mode instability (MI) is observed at the maximal output power. To the best of our knowledge, this is the highest average output power of the all-fiberized narrow linewidth ns pulsed fiber laser with linear polarization and high beam quality, which is a promising source for the nonlinear frequency conversion, laser lidar, and so on.
High Power Laser Science and Engineering
  • Publication Date: Jul. 16, 2018
  • Vol.6 Issue, 3 03000e42 (2018)