RESUMO
This work presents designed and fabricated silica few-mode optical fiber (FMF) with induced twisting 10 and 66 revolutions per meter, core diameter 11 µm, typical "telecommunication" cladding diameter 125 µm, improved height of quasi-step refractive index profile and numerical aperture 0.22. Proposed FMF supports 4 guided modes over "C"-band. We discussed selection of specified optical fiber parameters to provide desired limited mode number over mentioned wavelength range. Some results of tests, performed with pilot samples of manufactured FMF, are represented, including experimentally measured spectral responses of laser-excited optical signals, that comprise researches and analysis of few-mode effects, occurring after fiber Bragg grating writing.
RESUMO
We present experimental results of birefringence property measurements for two types of negative curvature anti-resonant hollow-core fibers (AR-HCFs). Both AR-HCFs have a core of 50 µm in diameter, providing an effective area of the fundamental guided mode larger than 1000µm2. Measurements were carried out at wavelengths of 2.25, 2.35, and 2.45 µm. The obtained results demonstrate that both fiber types have birefringence axes that do not correspond to core symmetry axes. The proposed technique for the birefringence axes orientation measurement could be applied to other kinds of HCFs at various wavelengths.
