Birefringent, low loss, and broadband semi-tube anti-resonant hollow-core fiber

are demonstrated. This achieved loss is more than one order of magnitude lower than the previously reported birefringent AR-HCF and the bandwidth is one order of magnitude broader than the reported birefringent photonic bandgap hollow-core fiber (PBG-HCF) with the same loss level. The polarization extinction ratio (PER) reaches the ∼20 dB level in a 90 m-long fiber under >25 cm bending radius. Combined with the single mode and low dispersion features, the developed semi-tube AR-HCF may find a variety of applications in frequency metrology, interferometric fiber gyroscopes, and long-baseline stellar interferometry.