A theoretical model for multimode fibers to benefit high-power lasers and telecommunications
A theoretical model for multimode fibers to benefit high-power lasers and telecommunications lead image
For decades, single-mode fibers have dominated fiber optic technologies, but recent advances in fiber communications have revived interest in multimode structures. Multimode fibers are instrumental in short-distance telecommunication links and could be key in implementing high-power lasers. However, because of the periodic way beams propagate along a graded-index fiber, geometric parametric instabilities often occur, thus producing new harmonics. A new study presents a comprehensive theory capable of describing the geometric parametric instabilities in nonlinear graded-index multimode fibers.
“Now we have developed an ab-initio theory that explains what is going on in nonlinear multimode fibers,” said Helena Lopez-Aviles, a co-author on the paper. “With this we can modify and tailor the spectrum and gain in a particular system.”
The research found that this process could be described through a Hill’s equation that can be systematically solved using a Floquet approach. The results show how unstable spectral domains associated with geometric parametric instabilities can be altered by increasing the optical power injected into a multimode fiber. More importantly, the team found that the instability sidebands can move closer to the pump wavelength as the input power increases. While this effect has been previously observed in experiments, the underlying process was still not fully understood.
These findings may lead to significant advances in high-power laser technologies, since an increase in power in multimode fiber systems could also lead to higher spectral gains. Furthermore, these results suggest that the laser’s spectrum can be further extended into the visible regime, thus further enriching the infrared portion of the spectrum.
Source: “A systematic analysis of parametric instabilities in nonlinear parabolic multimode fibers,” by H. E. Lopez-Aviles, F. O. Wu, Z. Sanjabi Eznaveh, M. A. Eftekhar, F. Wise, R. Amezcua Correa, and D. N. Christodoulides, APL Photonics (2018). The article can be accessed at https://doi.org/10.1063/1.5044659 .
