Large-hole-large-spacing holey fibers with a few air holes: Fabrication and measurements of light-delivering properties and optical losses

Silica holey fibers with a core surrounded by a few rings of air holes of a large diameter and pitched by a large spacing are fabricated and characterized in terms of their linear-optical properties (i.e., light-delivering quality and optical losses). An optimal value of the relative hole diameter, 0.52 ± 0.05, is found, which provides a single-mode propagation of the launched laser beam along the fibers in the visible (wavelength 633 nm) and near IR (wavelengths 1310 and 1550 nm) spectral ranges with low (about 10-30 dB/km) transmission losses.