  Over the past decade, the rogue wave debate has stimulated the comparison of
predictions and observations among different branches of wave physics,
particularly between hydrodynamics and optics, in situations where analogous
dynamical behaviors can be identified, thanks to the use of common universal
models. Although the scalar nonlinear Schroedinger equation (NLSE) has
constantly played a central role for rogue wave investigations, moving beyond
the standard NLSE model is relevant and needful for describing more general
classes of physical systems and applications. In this direction, the coupled
NLSEs are known to play a pivotal role for the understanding of the complex
wave dynamics in hydrodynamics and optics. Benefiting from the advanced
technology of high-speed telecommunication-grade components, and relying on a
careful design of the nonlinear propagation of orthogonally-polarized optical
pump waves in a randomly birefringent telecom fiber, this work explores, both
theoretically and experimentally, the rogue wave dynamics governed by such
coupled NLSEs. We report, for the first time, the evidence of a group of three
dark rogue waves, the so-called dark three-sister rogue waves, where
experiments, numerics, and analytics show a very good consistency.
