200 Gbps/Lane IM/DD Technologies for Short Reach Optical Interconnects

Abstract

Client-side optics are facing an ever-increasing upgrading pace, driven by upcoming 5G related services and datacenter applications. The demand for a single lane data rate is soon approaching 200 Gbps. To meet such high-speed requirement, all segments of traditional intensity modulation direct detection (IM/DD) technologies are being challenged. The characteristics of electrical and optoelectronic components, and the performance of modulation, coding and digital signal processing (DSP) techniques are being stretched to their limits. In this context, we witnessed technological breakthroughs in several aspects, including development of broadband devices, novel modulation formats and coding, and high-performance DSP algorithms for the past few years. A great momentum has been accumulated to overcome the aforementioned challenges. In this paper, we focus on IM/DD transmissions, and provide an overview of recent research and development efforts on key enabling technologies for 200 Gbps per lane and beyond. Our recent demonstrations of 200 Gbps short-reach transmissions with 4level pulse amplitude modulation (PAM) and discrete multitone signals are also presented as examples to show the system requirements in terms of device characteristics and DSP performance. Apart from digital coherent technologies and advanced direct detection systems, such as Stokes-vector and Kramers-Kronig schemes, we expect high-speed IM/DD systems will remain advantageous in terms of system cost, power consumption and footprint for short reach applications in the short-to mid-term perspective.

Electroabsorption‐modulated laser as optical transmitter and receiver: status and opportunities

“…Due to the non‐linear EAM transfer function, the drive voltage for each of the quaternary PAM levels was set to a specific value through a 3‐bit digital‐to‐analogue converter (DAC), in order to avoid uneven eye openings that would result in large reception penalties. Higher data rates beyond 200 Gb/s/λ have been achieved by employing signal equalisation in the digital domain [11, 12] or probabilistic shaping in combination with 8‐level PAM [13].…”

Hybrid Coding and Filtering Technique for Optical IM-DD Link With Robustness to Multipath Interference and Bandwidth Limitation

“…Recent years, optical intensity modulation and direct detection (IM-DD) solution exhibits its advantages in short reach optical communication application, with low power consumption and economical implementation [1]. Comparing with coherent detection technique, rate performance of single point-to-point IM-DD link is more limited by channel bandwidth limitation.…”

Experimental Demonstrations of Hybrid OFDM-Digital Filter Multiple Access PONs

“…assive optical networks (PONs) based on intensity modulation and direct detection (IMDD) are attractive for implementation of mobile front-hauls/mid-hauls/back-hauls for 5G and beyond networks [1], [2]. However, significant advances in existing IMDD PONs are envisaged as necessary in order to effectively address the ever-increasing 5G and beyond network-associated demands on low latency, ultra-dense connections and high data rates [3]. In addition, to enable IMDD PON-based 5G and beyond networks to offer end-users fast on-demand heterogeneous services, software-defined networking (SDN) [4], [5] from high network layers down to the physical layer is also desirable to flexibly and dynamically reconfigure the networks in a simple, fast and resource-efficient way.…”