[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Optimisation of Dispersion Flatness in Nanostructured Core Fibres

摘要： Nanostructured optical fibres allow to obtain an arbitrary profile of refraction index in the core. These fibres are composed of several thousands of rods with diameter smaller than incident wavelength. Their optical performance is described with the Maxwell-Garnett effective medium theory. A modification of nanorods distribution or doping level in nanorods allow controlling of chromatic dispersion, polarization and modal properties of the nanostructured fibres. We study an influence of additional microrings in the core on fibre dispersion characteristics. We consider a fibre composed of pure silica nanorods and silica nanorods highly doped with Ge (concentration of GeO2 equals 20% mol). Modification of core internal structure affects electric field distribution in the fundamental mode, and consequently results in changes of its dispersion characteristics. We show that flat, all-normal dispersion characteristics (≈ 2.5 ps/nm/km) in wavelength range from 1.3 up to 2.15 μm can be achieved in the optimized structure. Moreover, within these limits, 1.5 μm to 1.9 μm range was revealed to be ultra-flat (≈ 0.2 ps/nm/km). In contrast to already reported in the literature similar fibres, proposed design is based on fused silica glasses, exhibits spectrally broader and more flat dispersion profile, it is an all-solid construction and it has the effective mode area equal 13μm2 for λ=1.55μm wavelength. Thanks to such characteristics, the fiber allows free from higher order distortions light propagation of highly confined broadband optical pulses, what might find applications in ultrafast optics, or dispersion management systems.