Hollow-core conjoined-tube fiber for penalty-free data transmission under offset launch conditions.

Three types of hollow-core fibers, i.e., photonic-bandgap fiber, negative-curvature fiber, and conjoined-tube fiber, are compared in terms of data transmission performance. Their group velocity dispersions and group indices are measured in detail by using low-coherence interferometry. Whilst all three fibers show good performance with an optimized central launch, they behave differently under offset launch for 10 Gbit/s on-off keying transmission. We use a Q-factor analysis method to gain insight into the data transmission over a hollow-core fiber. The low-loss, low-intermodal crosstalk conjoined-tube fiber shows great resilience to bending and offset launch compared to the other two hollow-core fibers, enabling genuine penalty-free data transmission in realistic environments.