Intermodal Nonlinear Signal Distortions in Multi-Span Transmission With Few-Mode Fibers

Intermodal nonlinear signal distortions in a graded-index three-mode fiber are experimentally investigated in a recirculating loop transmission over distances up to 684 km. Transmitting a 24.5 GBaud 16-quadrature-amplitude-modulated spatial super channel as channel under test together with an interfering channel band that is swept by more than 20 nm across the C-band, we find a Q-factor penalty of 1 dB for the signals in the LP01 mode when the interfering channels are approximately 17 nm separated from the channel under test. We find that the wavelength separation between strongest interacting spectral components is independent of the transmission distance.