Nonlinear Optics in Optical Fibers

Since I started my PhD, I had the opportunity to study several different nonlinear phenomena in optical fibers.

Raman scattering in CO₂-filled hollow-core fibers

Understanding the dynamic of Raman scattering in CO₂-filled hollow-core fibers was a nice collaborative project I worked on. When high peak power pulses are launched in such fibers, it is possible to generate a frequency comb with a high repetition frequency (several tens of THz) [OL-19]. On this topic, I studied numerically and experimentally the pressure dependence of CO₂ in the hollow-core fiber, and tried to numerically reproduce as accurately as possible our experimental observations [JOSAB-23].

Figure : Example of spectrum generated when sending 450 ps pulses at 1064 nm with 40 kW of peak power in a 3 m hollow-core fiber filled with 6 bar of CO₂ [OL-19].

Kerr beam self cleaning

I participated in an experimental work to investigate the impact of high peak power pulses sent in a multimode fiber at a wavelength around 1.55 µm. The idea was to study the Kerr beam self cleaning effect in a graded index fiber, and it was found that this effect can be highly efficient when obtained with a few-mode excitation [OE-20].

Figure : Example of self-selection of a LP11 mode when increasing the peak power [OE-20].

Dispersive shock waves

Dispersive shock waves is an interesting phenomenon to broaden the optical spectrum of picosecond pulses. I extensively used this phenomenon to obtain flat electro-optic combs, which is beneficial for spectroscopic applications. I also found an analytical formula that gives the maximum spectral bandwidth one can obtain with this phenomenon [OL-17].

Figure : Spectra obtained after a DCF of different lengths to study the spectral broadening by dispersive shock waves [OL-17].

References

[JOSAB-23] Katarzyna Krupa, Alexandre Parriaux, Guy Millot, and Gil Fanjoux, “Self-similarity in transient stimulated Raman scattering in CO₂-filled hollow-core fiber,” JOSA B 40.3, 637-644 (2023).
DOI: 10.1364/JOSAB.471348

[OE-20] Y. Leventoux, A. Parriaux, O. Sidelnikov, G. Granger, M. Jossent, L. Lavoute, D. Gaponov, M. Fabert, A. Tonello, K. Krupa, A. Desfarges-Berthelemot, V. Kermene, G. Millot, S. Février, S. Wabnitz, and V. Couderc, “Highly efficient few-mode spatial beam self-cleaning at 1.5µm,” Optics Express 28.10, 14333-14344 (2020).
DOI: 10.1364/OE.392081

[OL-19] Katarzyna Krupa, Kilian Baudin, Alexandre Parriaux, Gil Fanjoux, and Guy Millot, “Intense stimulated Raman scattering in CO₂-filled hollow-core fibers,” Opt. Lett. 44, 5318-5321 (2019).
DOI: 10.1364/OL.44.005318

[OL-17] A. Parriaux, M. Conforti, A. Bendahmane, J. Fatome, C. Finot, S. Trillo, N. Picqué, and G. Millot, “Spectral broadening of picosecond pulses forming dispersive shock waves in optical fibers,” Opt. Lett. 42, 3044-3047 (2017).
DOI: 10.1364/OL.42.003044