Long range laser propagation: power scaling and beam quality issues

2010 ◽  
Author(s):  
Willy L. Bohn
Keyword(s):  
Long Range ◽  
Beam Quality ◽  
Power Scaling ◽  
Laser Propagation ◽  
Quality Issues ◽  
Propagation Power

scholarly journals Mitigation of stimulated Raman scattering in kilowatt-level diode-pumped fiber amplifiers with chirped and tilted fiber Bragg gratings

2019 ◽  
Vol 7 ◽  
Author(s):  
Meng Wang ◽  
Le Liu ◽  
Zefeng Wang ◽  
Xiaoming Xi ◽  
Xiaojun Xu
Keyword(s):  
Raman Scattering ◽  
Fiber Lasers ◽  
Stimulated Raman Scattering ◽  
Beam Quality ◽  
Average Power ◽  
Fiber Amplifiers ◽  
Maximum Output ◽  
Power Scaling ◽  
Diode Pumped ◽  
Stimulated Raman

The average power of diode-pumped fiber lasers has been developed deeply into the kW regime in the past years. However, stimulated Raman scattering (SRS) is still a major factor limiting the further power scaling. Here, we have demonstrated the mitigation of SRS in kilowatt-level diode-pumped fiber amplifiers using a chirped and tilted fiber Bragg grating (CTFBG) for the first time. The CTFBG is designed and inscribed in large-mode-area (LMA) fibers, matching with the operating wavelength of the fiber amplifier. With the CTFBG inserted between the seed laser and the amplifier stage, an SRS suppression ratio of ${\sim}10~\text{dB}$ is achieved in spectrum at the maximum output laser power of 2.35 kW, and there is no reduction in laser slope efficiency and degradation in beam quality. This work proves the feasibility and practicability of CTFBGs for SRS suppression in high-power fiber lasers, which is very useful for the further power scaling.

Yb3+-doped rod-type amplifiers with local adiabatic tapers for peak power scaling and beam quality improvement

Laser Physics ◽  
2017 ◽  
Vol 27 (10) ◽  
pp. 105103 ◽  
Author(s):  
Yuan Zhu ◽  
Tina Eschrich ◽  
Martin Leich ◽  
Stephan Grimm ◽  
Jens Kobelke ◽  
...  
Keyword(s):  
Quality Improvement ◽  
Peak Power ◽  
Beam Quality ◽  
Power Scaling

Ion-Focused Propagation of Relativistic Electron Beam in the Self-Generated Plasma in the Atmosphere

2022 ◽  
Author(s):  
Hao Jian-Hong ◽  
Xue Bi-Xi ◽  
Zhao Qiang ◽  
Zhang Fang ◽  
Fan Jie-Qing ◽  
...  
Keyword(s):  
Electron Beam ◽  
Relativistic Electron ◽  
Long Range ◽  
Relativistic Electron Beam ◽  
Beam Quality ◽  
Pulse Length ◽  
Space Environment ◽  
Long Distance ◽  
Particle In Cell ◽  
Neutral Gas

Abstract It is known that ion-focused regime can effectively suppress the expansion of relativistic electron beam (REB). By using particle in cell-Monte Carlo collision (PIC-MCC) method, the propagation of REBs in neutral gas is numerically investigated. The numerical results demonstrate that the beam body is charge neutralization and a stable IFR can be established. As a result, the beam transverse dimensions and longitudinal velocities keep close to the initial parameters. We also calculated the charge and current neutralization factors of REBs. Combined with envelope equations, we obtained the variations of beam envelopes, which agree well with the PIC simulations. However, both the energy loss and instabilities of REBs may lead to a low transport efficiency during long-range propagation. It has been proved that decreasing the initial pulse length of REBs can avoid the influence of electron avalanche. Using parts of REB pulses to build a long-distance IFR in advance can improve the beam quality of subsequent pulses. Further, a long-distance IFR may contribute to the implementation of long-range propagation of REBs in the space environment.

scholarly journals Novel constant-cladding tapered-core ytterbium-doped fiber for high-power fiber laser oscillator

2021 ◽  
Vol 9 ◽  
Author(s):  
Yun Ye ◽  
Xianfeng Lin ◽  
Xiaoming Xi ◽  
Chen Shi ◽  
Baolai Yang ◽  
...  
Keyword(s):  
Fiber Laser ◽  
Output Power ◽  
High Power ◽  
Stimulated Raman Scattering ◽  
Beam Quality ◽  
Maximum Output Power ◽  
Maximum Output ◽  
Power Scaling ◽  
Laser Oscillator ◽  
Optical Efficiency

Abstract Power scaling based on traditional ytterbium-doped fibers (YDFs) is limited by optical nonlinear effects and transverse mode instability (TMI) in high-power fiber lasers. Here, we propose a novel long tapered fiber with a constant cladding and tapered core (CCTC) along its axis direction. The tapered-core region of the fiber is designed to enhance the stimulated Raman scattering (SRS) threshold and suppress higher-order mode resonance in the laser cavity. The CCTC YDF was fabricated successfully with a modified chemical vapor deposition (MCVD) method combined with solution doping technology, which has a cladding diameter of 400 μm and a varying core with a diameter of ~24 μm at both ends and ~31 μm in the middle. To test the performance of the CCTC fiber during high-power operation, an all-fiber laser oscillator based on a CCTC YDF was investigated experimentally. As a result, a maximum output power of 3.42 kW was achieved with an optical-to-optical efficiency of 55.2%, although the TMI effect was observed at an output power of ~3.12 kW. The measured beam quality (M2 factor) was ~1.7, and no sign of the Raman component was observed in the spectrum. We believe that CCTC YDF has great potential to simultaneously mitigate the SRS and TMI effects, and further power scaling is promising by optimizing the structure of the YDF.

Beam Quality Issues in Copper Vapour Lasers

1996 ◽  
pp. 241-254 ◽  
Author(s):  
D. J. W. Brown ◽  
D. W. Coutts
Keyword(s):  
Beam Quality ◽  
Quality Issues
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