Antiresonant Hollow-Core Inline Fiber Polarizer

The unique characteristics of hollow core fibers lead to low non-linearity and reduced sensitivity to environmental influences, making them attractive platform for designing inline fiber optic devices. Among these, an inline fiber polarizer would be most desired for applications such as gyroscopes, interferometric sensors and telecommunication. Hollow-core fiber polarizers, demonstrated to date, suffer from high insertion loss (>5 dB) for the pass polarization, and typically require tens of meters long nested antiresonant fiber to achieve a meaningful polarization extinction ratio (PER) >20 dB. We report a novel approach that makes use of intricate modal loss spectrum within a resonant band of single-ring antiresonant fiber to realize the first high-performance, discrete hollow-core fiber polarizer. The compact device comprising only 6 cm long fiber offers a high PER of >25 dB with <1 dB transmission loss for the pass polarization. In the present form, the polarizing action takes place over 14 nm and 7 nm bandwidth in the 2 μm and 1 μm wavelength range, but the simplicity of design principles makes it straightforward to shift the operating wavelengths to practically any wavelength band. The device can be fusion spliced with a standard antiresonant hollow-core fiber and a large mode area solid-core fiber with splice loss of 0.14 dB and 0.45 dB respectively. Complete integration of the proposed device into an all hollow-fiber setup would lead to a total insertion loss of 1.3 dB including both input and output splicing, which is the lowest for a discrete hollow-core fiber polarizer reported so far. The results encourage the development of other hollow-core fiber components by exploiting the unique characteristics cultivated in a resonant band of an antiresonant fiber.