Ring-assisted large mode area fiber supporting high-power transmission within effective single-mode conditions

Nowadays, the demand for communication capacity has surged, but single-mode fiber (SMF) systems face limitations due to nonlinear effects that restrict signal-to-noise ratio (SNR). To overcome this, mode-division multiplexing (MDM) technology offers increased capacity but requires complex systems, while developing novel SMFs with reduced nonlinearity provides a more feasible solution for commercial SMF systems. IIn this paper, we introduce, to our knowledge, a novel ring-assisted large mode area fiber (RA-LMF) within the effective single-mode condition to address the limitation induced by the nonlinear effect in the SMF. Introducing a resonant ring around the fiber core can extend the core radius to support a 212 μm² large effective area (A_eff) of the fundamental mode with a cladding diameter of 125 μm, which is compatible with the standard SMF. With such a large A_eff, the RA-LMF exhibits a nonlinear input power threshold at least 4 dB higher than the standard G.652 SMF. An orthogonal frequency-division multiplexing (OFDM) transmission of the RA-LMF is conducted to evaluate the communication performance of the fiber, which proves that the high tolerance to the fiber nonlinearity is sustained under different signal modulation formats and baud rates.