Single-photodiode 112-Gbit/s 16-QAM transmission over 960-km SSMF enabled by Kramers-Kronig detection and sparse I/Q...

We have experimentally demonstrated a single-photodiode 112-Gbit/s 16-QAM transmission over 960-km standard single mode fiber with Kramers-Kronig (KK) detection and a sparse I/Q Volterra filter (VF). KK detection is used to mitigate the signal to signal beating interference. A novel I/Q VF based on dual-input real-valued Volterra series is proposed to overcome the constraints of non-linear distortions. Two conventional single-input real-valued VFs are employed as a contrast to prove the necessity of I/Q hybrid structure in I/Q VF when the system suffers from severe I/Q imbalance and crosstalk. The proposed I/Q VF brings nearly two order magnitude improvement in BER performance compared with the conventional linear equalizer for back to back case and doubles the transmission distance from 480 km to 960 km at the hard-decision forward error correction threshold of 3.8 × 10^-3. To reduce the complexity of full I/Q VF, a simple ℓ₁ regularization-based least mean square (LMS) algorithm is employed to identify the significant kernels and construct a sparse I/Q VF. Compared with full I/Q VF, the sparse I/Q VF reduces up to 58% complexity at 960 km while having the similar BER performance.