400 Gb LAYER-1 CONNECTIVITY:
Total Cost of Ownership for Singlemode
Optical Fiber Based Infrastructure
INTRODUCTION
Over the last decade, optical Ethernet based LAN connectivity has evolved
rapidly, generating several options with each serving a specific set of
applications. Today, the industry is deploying 100G (Gb) connectivity,
especially in medium to large data centers; some of the hyperscale data centers
are already planning for 400 Gb in the next few years. There are several
options for providing 400 Gb data center connectivity1. Broadly, the optical
transceiver architectures for singlemode optical fiber connectivity can be
categorized into two: one based on parallel optics where multiple lower speed
signals are transmitted via independent fibers; the other architecture is based
on wavelength division multiplexing where multiple optical fiber channels
with wavelength diversity are multiplexed and transmitted over single fiber.
The most popular devices for 100 Gb connectivity are PSM4 (parallel single
mode – four lane)2 and CWDM4 (coarse wavelength division multiplexing
– four lane).3
January/February 2019 I51
By Mike Connaughton, RCDD
and Rakesh Sambaraju