Practical Kramers-Kronig Phase Retrieval FIR Filter With the Gibbs Phenomenon

Kramers-Kronig (KK) receiver shows strong feasibility since the phase can be extracted from detected intensity through Hilbert transform (HT). To reduce complexity and make HT more suitable for practical KK system, approximated as finite impulse response (FIR) filter, i.e., HT-FIR filter. However, Fourier series expansion of filter suffers oscillations around discontinuities further results in an unsatisfactory in-band flatness, which is so-called Gibbs phenomenon. In experiment simulation, we found that performance system using strongly impaired due to phenomenon, by roll-off factor shaping frequency gap between direct-current (DC) component one edge signal spectrum, carrier-to-signal power ratio (CSPR), tap number digital upsampling rate. We have systematically investigated retrieval computational considering phenomenon adoption rather than used previous works without conclude there optimal rate when used, closely related five aspects mentioned above. carried out a transmission 112-Gbit/s 16-QAM over 1920-km with Raman fiber amplifier investigate limit receiver. The experimental show 9-tap 84-GHz (3- sps ), signals transmitted same distance HT, up 1440-km bit error (BER) below 20% soft-decision forward correction threshold.