Annika Dochhan

Solutions for 80 km DWDM Systems

We review currently discussed solutions for 80 km DWDM transmission targeting inter data-center connections at 100G and 400G line rates. PDM-64QAM, PAM4 and DMT are investigated, while the focus lies on directly detected solutions.

Flexible bandwidth 448 Gb/s DMT transmission for next generation data center inter-connects

We experimentally evaluate a flexible DMT system using 4 to 8 50-GHz-grid C-band channels to transmit 448 Gb/s over up to 240 km SSMF. VSB filtering enabled by detuned lasers significantly reduces the impact of chromatic dispersion.

First real-time 400G PAM-4 demonstration for inter-data center transmission over 100 km of SSMF at 1550 nm

Real-time transmission of 400G (8×50G DWDM) PAM-4 signals for data center interconnects up to 100 km SSMF is successfully demonstrated. All channels stay well below the 802.3bj KR4 FEC limit, thus allowing error free transmission.

Investigation of PAM-4 for extending reach in data center interconnect applications

Optical four-level pulse amplitude modulation (PAM-4) is being widely studied for various short-reach optical interfaces, motivated by the need to keep cost structure low, and to increase link capacity despite various constraints in component bandwidth. When considering PAM-4 in applications with reach significantly greater than 10 km, such as in extended data center interconnects which require optical amplification, impairments such as chromatic dispersion, optical filtering, and ASE must be controlled. We investigate and report on requirements of PAM-4 for extended-reach, data center interconnect links.

DSP-enhanced Transmission for 100G+ DWDM Data Center Interconnects

We compare sensitivity to optical noise and chromatic dispersion tolerance of the direct detection modulation formats PAM-4 and DMT as potential cost and power efficient candidates for high-speed data center interconnect applications.

26-Gb/s DMT Transmission Using Full C -Band Tunable VCSEL for Converged PONs

Wavelength division multiplex (WDM) passive optical network (PON) is considered for converged fixed mobile broadband access networking. We propose to utilize low-cost tunable lasers at the remote sites, together with a centralized wavelength locker. Practical implementations require a transparently added downstream signaling channel and upstream per-channel pilot tones for channel tagging and remote wavelength control. We demonstrate, for the first time, 26-Gbps discrete multitone transmission modulated on a low-cost wide tunable vertical surface emitting laser over up to 40 km of standard single-mode fiber. The results confirm that converged fixed mobile WDM-PON systems based on low-cost lasers carrying discrete multitone modulation are a technically viable approach.

Practical Solutions for 400Gbit/s Data Center Transmission

We review three solutions for low-cost data center interconnects with a target reach of up to 80 km. Directly detected DMT, PAM-4 and multi-band CAP are promising modulation schemes, enabling 400 Gbit/s by combining eight channels of 56 Gbit/s.

Multi-Dimensional Modulation Formats for Adaptive Optical Transmission

We review several multi-dimensional modulation formats and present experimental results for a 3-dimensional simplex format, yielding a better OSNR tolerance than DP-BPSK.