fibre laser
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2022 ◽  
Vol 11 (1) ◽  
Author(s):  
Zhiyue Zhou ◽  
Zefeng Wang ◽  
Wei Huang ◽  
Yulong Cui ◽  
Hao Li ◽  
...  

AbstractFibre lasers operating at the mid-IR have attracted enormous interest due to the plethora of applications in defence, security, medicine, and so on. However, no continuous-wave (CW) fibre lasers beyond 4 μm based on rare-earth-doped fibres have been demonstrated thus far. Here, we report efficient mid-IR laser emission from HBr-filled silica hollow-core fibres (HCFs) for the first time. By pumping with a self-developed thulium-doped fibre amplifier seeded by several diode lasers over the range of 1940–1983 nm, narrow linewidth mid-IR emission from 3810 to 4496 nm has been achieved with a maximum laser power of about 500 mW and a slope efficiency of approximately 18%. To the best of our knowledge, the wavelength of 4496 nm with strong absorption in silica-based fibres is the longest emission wavelength from a CW fibre laser, and the span of 686 nm is also the largest tuning range achieved to date for any CW fibre laser. By further reducing the HCF transmission loss, increasing the pump power, improving the coupling efficiency, and optimizing the fibre length together with the pressure, the laser efficiency and output power are expected to increase significantly. This work opens new opportunities for broadly tunable high-power mid-IR fibre lasers, especially beyond 4 μm.


Author(s):  
Lea Kraft ◽  
Ralf Petzold ◽  
Rodrigo Suarez-Ibarrola ◽  
Arkadiusz Miernik

Abstract The aim of this work was to compare the fragmentation efficiency of a novel, pulsed Thulium solid-state laser (p-Tm:YAG) to that of a chopped Thulium fibre laser (TFL) and a pulsed Holmium solid-state laser (Ho:YAG). During the fragmentation process, we used a silicone mould to fixate the hemispherical stone models under water in a jar filled with room-temperature water. Each laser device registered the total energy applied to the stone model to determine fragmentation efficiency. Our study examined laser settings with single pulse energies ranging from 0.6 to 6 J and pulse frequencies ranging from 5 to 15 Hz. Similar laser settings were applied to explicitly compare the fragmentation efficiency of all three devices. We experimented with additional laser settings to see which of the three devices would perform best. The fragmentation performance of the three laser devices differed statistically significantly (p < 0.05). The average total energy required to fragment the stone model was 345.96 J for Ho:YAG, 372.43 J for p-Tm:YAG and 483.90 J for TFL. To fragment the stone models, both Ho:YAG and p-Tm:YAG needed similar total energy (p = 0.97). TFL’s fragmentation efficiency is significantly lower than that of Ho:YAG and p-Tm:YAG. Furthermore, we found the novel p-Tm:YAG’s fragmentation efficiency to closely resemble that of Ho:YAG. The fragmentation efficiency is thought to be influenced by the pulse duration. TFL’s shortest possible pulse duration was considerably longer than that of Ho:YAG and p-Tm:YAG, resulting in Ho:YAG and p-Tm:YAG exhibiting better fragmenting efficiency.


Author(s):  
Abhijit Patil ◽  
Rohan Sharma ◽  
Darshit Shah ◽  
Ankit Gupta ◽  
Abhishek Singh ◽  
...  

2021 ◽  
Vol 1135 (1) ◽  
pp. 012008
Author(s):  
Handika Sandra Dewi ◽  
Joerg Volpp ◽  
Jan Frostevarg ◽  
Jukka Siltanen

Abstract Mill scale formed on the surface of hot rolled steels consists of magnetite (Fe3O4), hematite (Fe2O3) and wustite (FeO) layers, which can protect the steels from corrosion and other atmospheric effects. Existence of mill scale on the specimens’ surface has shown to be able to decrease the cut edge quality. Since the mechanism behind influence of mill scale on the laser cutting process is unknown, this work performs direct observation of oxygen laser cutting processes on specimens with and without removed mill scale layers. Oxygen laser cutting processes were carried out using Ytterbium fibre laser 1070 nm along the edge of 20-mm-thick-steel specimens which were attached to a borosilicate glass. Focal point of the laser beam was positioned to be 0.7 mm below the specimens’ surface. A high speed imaging system was arranged to face the glass, recording the cut front and kerf dynamics during cutting processes. It was found that cut front inclination angle increase when the mill scale was removed from the specimens’ surface. This implies that mill scale on the specimens’ surface seem to contribute in increasing the exothermal energy during laser cutting processes.


2021 ◽  
Vol 18 (12) ◽  
pp. 125102
Author(s):  
Marcin Franczyk ◽  
Dariusz Pysz ◽  
Ryszard Buczyński
Keyword(s):  

2021 ◽  
Vol 2075 (1) ◽  
pp. 012003
Author(s):  
N. N. A. A. N Zain ◽  
N. A. H. Jasni ◽  
W. M. F. W Nawawi ◽  
F. Ahmad

Abstract Using a copper-based saturable absorber (SA) and chitin as a biocompatible host polymer, this research effectively demonstrated the production of passive Q-switched in an erbium-doped fibre laser (EDFL). A Q-switched lasing was generated with a 100 kHz repetition rate and a pulse width of 4.60 µs. High pulse energy of 17.19 nJ was generated, with a respective instantaneous peak power of 3.51 mW.


2021 ◽  
Vol 2075 (1) ◽  
pp. 012020
Author(s):  
M F A Rahman ◽  
P H Reddy ◽  
A Ahmad ◽  
A A Latiff ◽  
M F Baharom ◽  
...  

Abstract In this paper, we present a Q-switched fibre laser at 1069 nm which is induced by an 8 cm long Hafnium bismuth erbium co-doped fibre (HBEDF) saturable absorber (SA). The pulsating laser has a maximum repetition rate of 67 kHz at 175 mW pump power. We obtained the narrowest pulse width of 3.48 μs, the maximum pulse energy of 70.2 nJ, the maximum output power of 4.7 mW and the maximum peak power of 20.1 mW. The Q-switched laser is simple and may found practical applications in medicine and remote sensing.


2021 ◽  
Vol 2075 (1) ◽  
pp. 012004
Author(s):  
N N M Rashid ◽  
M Q Lokman ◽  
N A Nordin ◽  
H Yahaya ◽  
F Ahmad

Abstract Silver nanoparticles (AgNP), a novel candidate of noble metal nanoparticles, which has great potential for pulsed laser applications due to strong saturation absorption behaviour. This study demonstrated the passively Q-switched laser operating within an Erbium-doped fibre laser cavity using AgNP saturable absorber (SA). The AgNP was synthesized via the chemical reduction method and the average size of nanoparticles was around 52.39 nm. The AgNP was incorporated with polyvinyl alcohol (PVA) polymer to form an AgNP-PVA composite SA. The proposed experimental works generated single pulse energy and peak power of about 66.14 nJ and 18.71 mW corresponds to the repetition rate and pulse width of 62.89 kHz and 3.32 µs.


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