High-power ultra-dense WDM analog RoF transmission using hollow-core fibers.

Ultra-dense wavelength division multiplexing (WDM) transmission of high-power analog radio-over-fiber (A-RoF) signals over hollow-core fibers (HCFs) is demonstrated for mobile fronthaul networks. The usefulness of ultra-dense WDM transmission using HCFs as a means of A-RoF transmission to many remote units, which will increase significantly in the future, is clarified. Through a comparison with the most widely used standard silica-core single-mode fibers, the impact on the transmission characteristics when changing the channel spacing and fiber input A-RoF signal power is evaluated in detail. Furthermore, by taking advantage of the ultra-low nonlinearity, ultra-dense WDM transmissions of high-power three- and four-channel A-RoF signals are demonstrated with narrower channel spacing than that of the conventional WDM channel grid, and high transmission characteristics are achieved.