IEEE Photonics Journal | |
Experimental Study of 5-kW High-Stability Monolithic Fiber Laser Oscillator With or Without External Feedback | |
Hanwei Zhang1  Xiaoming Xi1  Xiaojun Xu1  Baolai Yang1  Pu Zhou1  Yun Ye1  Xiaolin Wang1  Chen Shi1  | |
[1] College of Advanced Interdisciplinary Studies, National University of Defense Technology, Changsha, China; | |
关键词: Fiber lasers; laser oscillators; stimulated Raman scattering; transverse mode instability; external feedback; | |
DOI : 10.1109/JPHOT.2019.2923709 | |
来源: DOAJ |
【 摘 要 】
In this paper, we construct a high power monolithic fiber laser oscillator based on a commercial ytterbium-doped fiber with core/inner cladding diameter of 25/400 μm. The output performances of the fiber oscillator are experimentally investigated in the conditions of either with or without an external feedback. In the presence of external feedback, a very strong stimulated Raman scattering (SRS) (~9 dB below the signal light) emerges at the output power of ~3.56 kW, where the onset of the transverse mode instability (TMI) limits further power scaling. By large angle cleaving the signal arm of the forward combiner to avoid external feedback, the maximum output power of 5.07 kW is achieved with no sign of TMI. The Raman stokes light is ~35 dB below the signal light and the M2 factor is measured to be ~1.6. To directly characterize its power stability and engineering capability, the fiber oscillator is tested for continuous 5-h operation at ~5.07 kW with power fluctuation less than 0.42%. During the test process, the output power, spectrum, beam quality, and temporal signal perform excellent stability. The experimental results reveal that thresholds of SRS and TMI strongly depend on the external feedback in high power fiber oscillators.
【 授权许可】
Unknown