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| We report on the first hollow-core fiber (HCF) whose fundamental transmission band covers almost the whole visible spectral window starting from 440 nm. This HCF, in the form of nodeless structure (NL-HCF), exhibits unprecedented optical performance in terms of low transmission attenuation of 80 dB/km @ 532 nm, broad transmission bandwidth from 440 nm to 1200 nm, low bending loss of 0.2 dB/m @ 532 nm under 8 cm bending radius and single mode profile. When launched to high power picosecond laser systems at 532 nm, the fiber, exposed to ambient air, could easely deliver a 80 ps, 58 MHz, 32 W average power laser pulse with no damage and a 20 ps, 1 kHz high energy laser pulse with a damage threshold in excess of 144 microjoule at fiber output. A proof-of-concept experiment on Raman spectroscopy in ambient air shows the significance of this broadband visible guiding HCF for interdisciplinary applications in nonlinear optics, ultrafast optics, lasers，spectroscopy, biophotonics, material processing, etc. |
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| Keywords:optoelectronics and laser technology; photonic crystal fiber; hollow-core anti-resonant fiber; ultrafast beam delivery |
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