Polarizing Antiresonant Hollow-Core Fiber

Achieving robust single-polarization guidance in hollow-core fibers has remained a longstanding challenge, limiting their integration into precision photonic systems. Here, we report the first experimental realization of a low-loss, polarization filtering antiresonant hollow-core fiber (AR-HCF). Conventional AR-HCFs inherently support degenerate orthogonal polarization modes, making them vulnerable to polarization drift under environmental perturbations. Our dual-ring fiber design introduces polarization-selective resonant coupling to lossy cladding modes, enabling strong polarization filtering without compromising transmission efficiency. The fiber achieves a polarization extinction ratio exceeding 21 dB and a propagation loss as low as 0.15 dB m^-1 over a 10 m fiber length. The design is scalable across wavelength bands and maintains polarization discrimination under mechanical bending, making it highly suitable for applications in fiber-based gyroscopes, quantum optics, and polarization-sensitive nonlinear interactions. This work represents a significant step toward monolithic, polarization-selective hollow-core fiber systems.