Air and silica core Bragg fibers for radiation delivery in the wavelength range 0.6–1.5 μμm

•The laboratory-designed Bragg fibers with silica and air cores of different diameters have been prepared.•We demonstrated the efficient laser radiation delivery in the wavelength range from 600 to 1500 nm.•All fibers have approximately 6 times higher damage threshold intensity (approximately 30 GWcm−2 for the 9-ns-laser pulses at the wavelength of 1064 nm) in comparison with gradient-index fibers.•The lowest attenuation coefficient of 70 dB/km was determined for the 73-μm-air-core fiber at the wavelength of 1064 nm.•All tested fibers exhibited negligible bending losses down to the bend diameter of about 5 cm.

This paper presents fundamental characteristics of laboratory designed and fabricated Bragg fibers with air and silica cores at wavelengths of 632, 975, 1064 and 1550 nm. Fibers with the 26-μμm-silica core and 5- or 73-μμm-air cores in diameters and claddings of 3 pairs of Bragg layers were prepared from one preform. The overall transmittance, attenuation coefficients, coupling losses, bending losses, and damage-intensity thresholds were determined using four continuous-wave laser sources with the maximum output power of 300 mW and a pulsed 9 ns laser with the maximum output energy up to 1 mJ. The lowest attenuation coefficient of about 70 dB/km was determined at 1064 nm with the 73-μμm-air-core Bragg fiber. All fibers have been found to exhibit negligible bending losses down to the bending diameters of 5 cm. In comparison with the conventional gradient optical fiber, all the prepared Bragg fibers have approximately six times higher damage intensity threshold of about 30 GWcm−2 and therefore they are very suitable for high power laser radiation delivery.