Integrated Nyquist transmitter for data rates up to 100 Gbps

Abstract

In order to keep pace with the increasing data traffic, the next generation of optical server connections in a data center requires data rates of 400 Gbps at 100 Gbps per channel. Data center applications require highly integrated, low-cost solutions with very low power consumption and a very small package size. This can be achieved by co-integration of photonic and electronic function blocks. Optical signal processing with Nyquist pulses makes it possible to achieve very high data rates even at relatively low optical and electrical bandwidths. Nyquist pulses have the property of no inter-symbol interference and exhibit a rectangular spectrum, enabling transmission at the maximum possible symbol rate for a given bandwidth. Additionally, with one or two coupled modulators, pulse sequences with three or four times the RF-bandwidth of the single modulator can be achieved. This method neither requires a mode locked source, nor any other complicated equipment. Thus, the generation of Nyquist pulse sequences by integrated modulators is a very promising candidate for the integration on a silicon photonics platform. Within the proposed system modulators, receivers and electronics have only a bandwidth of 12.1 GHz, leading to Nyquist pulses with a bandwidth of 36.3 GHz that are modulated by PAM4 to reach a data rate of 72.6 Gbit/s. By interconnecting several such systems on one chip, the targeted 400 Gbit/s can be achieved in a single common transceiver module. Preliminary simulation results show the data transmission with low bit error rates.