Selectively gas-filled anti-resonant hollow-core fibers for broadband high-purity LP11 mode guidance

An anti-resonant hollow-core fiber capable of propagating the LP11 mode with high purity and over a wide wavelength range is proposed and demonstrated. The suppression of the fundamental mode relies on the resonant coupling with specific gas selectively filled into the cladding tubes. After a length of 2.7 m, the fabricated fiber shows a mode extinction ratio of over 40 dB at 1550 nm and above 30 dB in a wavelength range of 150 nm. The loss of the LP11 mode is measured to be 2.46 dB/m at 1550 nm. We discuss the potential application of such fibers in high-fidelity high-dimensional quantum state transmission.