200 Gb/s PAM4 modulator design without DAC for inter Data-Centre Communication.

This paper demonstrates a four-level pulse amplitude modulated (PAM4) signal without any digital to analog conversion by controlling the polarization of the continuous-wave laser signal applied to the two parallel placed Mach–Zehnder modulators. In this way, up to 200 Gbps, the PAM4 signal has been successfully generated and transmitted over an 80 km distance with a quality factor of 23.9 dB. The dispersion in optical fiber limits the data-transmission distance, which is reduced by controlling the chromatic dispersion using a dispersion compensated fiber. For long-distance transmission, polarization mode dispersion also comes into the picture due to its polarization dependency and degrades the signal's quality, which is reduced by controlling the polarization rotator just before the DCF fiber. The proposed system is also suitable for inter data-center communication due to its 80 km distance data transmission with such a high bit rate and Q-factor. [ABSTRACT FROM AUTHOR]