Optical properties of low loss (70 dB/km) hypocycloid-core Kagome hollow core photonic crystal fiber for Rb and Cs based optical applications

Abstract : We report on hypocycloid core shaped hollow-core Kagome fiber with a record loss of 70 dB/km at a spectral range of around 750-850 nm, which is compatible with Cs and Rb based applications. The fiber exhibits a single mode operation in a core diameter as large as $40~ \mu{\rm m}$ , and very low sensitivity to bend. We show experimentally that the bending-loss is limited by coupling between the guiding core mode and the modes in the cladding holes.