100 Gbaud On–Off Keying/Pulse Amplitude Modulation Links in C-Band for Short-Reach Optical Interconnects

Abstract

We experimentally evaluate the high-speed on–off keying (OOK) and four-level pulse amplitude modulation (PAM4) transmitter’s performance in C-band for short-reach optical interconnects. We demonstrate up to 100 Gbaud OOK and PAM4 transmission over a 400 m standard single-mode fiber with a monolithically integrated externally modulated laser (EML) having 100 GHz 3 dB bandwidth with 2 dB ripple. We evaluate its capabilities to enable 800 GbE client-side links based on eight, and even four, optical lanes for optical interconnect applications. We study the equalizer’s complexity when increasing the baud rate of PAM4 signals. Furthermore, we extend our work with numerical simulations showing the required received optical power (ROP) for a certain bit error rate (BER) for the different combinations of the effective number of bits (ENOB) and extinction ratio (ER) at the transmitter. We also show a possibility to achieve around 1 km dispersion uncompensated transmission with a simple decision feedback equalizer (DFE) for a 100 Gbaud OOK, PAM4, and eight-level PAM (PAM8) link having the received power penalty of around 1 dB.

Advances in Optical Fiber Communications

“…Lastly, in even-shorter-reach scenarios of data center interconnections only up to a few hundred meters, Ozolins and coworkers [10] show up to 100 GBaud capacity over 400 m using OOK and PAM-4 modulation and a monolithically integrated, externally modulated laser with 100 GHz 3 dB bandwidth. Equalizer complexity is also taken into account, studying its evolution as a function of the baud rate.…”

Joint WDM and OAM Mode Group Multiplexed Transmission Over Conventional Multimode Fiber

“…The quantity of computation and traffic on the data center interconnection network is growing due to the introduction of new machine learning (ML) applications, new web services, and search engines [1], [3]. As a result, maintaining bandwidth scalability is a prime task that research and technology development community are investigating realizing low-cost, short-reach optical connectivity for intra-data center links [4], [5]. Multimode fibers (MMFs) are frequently used in short-reach intra-and inter-data center (IDC) interconnects for distances up to a few km because of their cost-effective transceivers [6].…”

Error probability of Mode Vector Modulation optically-preamplified direct-detection receivers

“…To satisfy the first two specifications, direct-detection optical receivers are currently preferred to coherent optical receivers. To increase spectral efficiency, binary intensity modulation (IM) is gradually replaced by M -ary pulse amplitude modulation (M -PAM) [5]- [8].…”