400-G Single Carrier 500-km Transmission With an InP Dual Polarization IQ Modulator

In this letter, we demonstrate experimentally 400-G transmission over 500 km using an InP-based dual-polarization IQ modulator on a single wavelength. The results show that a 56-Gbaud polarization division multiplexed (PDM)-16-quadratic-amplitude modulation (QAM) modulated signal can be transmitted over 500 km at a bit error rate (BER) below the hard decision forward error correcting threshold of 3.8 ×10
^-3
. A 43-Gbaud PDM-64-QAM modulated signal can be transmitted over 320 km with a BER below the soft decision forward error correcting threshold of 2×10
^-2
.