PDM-16QAM transmission of 135 GBaud enabled by 120 GSa/s DAC and Tomlinson-Harashima pre-coding.

We experimentally verified that Tomlinson-Harashima (TH) pre-coding for an optical coherent system can enhance the speed of polarization division multiplexing (PDM) 16 quadrature amplitude modulation (QAM) signal to be higher than 135 GBaud with 120 GSa/s digital-to-analog converter (DAC) and electrical/optical/electrical bandwidth of the system narrower than 57 GHz at -30. The improvement of achievable capacity based on the received SNR in optical back-to-back conditions could be obviously observed by comparing the PDM-16QAM signal with and without TH pre-coding. The normalized generalized mutual information of the 135 GBaud PDM-16QAM signal for 120 km standard single mode fiber transmission was much higher than the threshold of error-free operation of a 5/6 code rate of digital video broadcasting satellite second generation low-density parity check forward error correction.

Fast optical channel recovery in field demonstration of 100-Gbit/s Ethernet over OTN using real-time DSP.

A field trial of 100-Gbit/s Ethernet over an optical transport network (OTN) is conducted using a real-time digital coherent signal processor. Error free operation with the Q-margin of 3.2 dB is confirmed at a 100 Gbit/s Ethernet analyzer by concatenating a low-density parity-check code with a OTN framer forward error correction, after 80-ch WDM transmission through 6 spans x 70 km of dispersion shifted fiber without inline-dispersion compensation.