RESUMO
We experimentally demonstrate fundamental mode transmission of digital power division multiplexed direct detection - orthogonal frequency division multiplexed (DD-OFDM) signal at 25.3 Gbps in 6.5 GHz bandwidth through a 5.3 km few-mode fiber. We compare the performance of a two-channel digital power division multiplexed (DPDM) signal with DD-OFDM of higher modulation format with the same spectral efficiency in both linear and nonlinear regimes of operation. In the linear regime, the mean bit error rate performance of the two-channel DPDM signal performance is comparable to the DD-OFDM signal with higher-order modulation. In the nonlinear regime, both the constituent signals of the DPDM scheme have similar nonlinear thresholds compared to the DD-OFDM signal with higher-order modulation. DPDM transmission with DD-OFDM over few-mode fiber offers doubling of both split ratio and spectral efficiency over single-mode fibers when used for passive optical networks.
RESUMO
We propose and experimentally demonstrate a method for measuring the differential modal group delay (DMGD) of a few-mode fiber using a Fourier domain mode-locked laser (FDML). We use the fast frequency-swept, wavelength-tunable output of the FDML in order to perform time domain measurements of interference of the modes, which is further postprocessed to extract the DMGD. We demonstrate the measurement of DMGD for a commercial two-mode fiber over the C-band. This method is not limited by the magnitude of DMGD or the number of modes and is minimally affected by time-dependent polarization and mode fluctuations, environmental noise, and spectral resolution of instruments.