  $AdS$ plane wave backgrounds are dual to CFT excited states with energy
momentum density $T_{++}=Q$. Building on previous work on entanglement entropy
in these and nonconformal brane plane wave backgrounds, we first describe a
phenomenological scaling picture for entanglement in terms of "entangling
partons". We then study aspects of holographic mutual information in these
backgrounds for two strip shaped subsystems, aligned parallel or orthogonal to
the flux. We focus on the wide ($Ql^d\gg 1$) and narrow ($Ql^d\ll 1$) strip
regimes. In the wide strip regime, mutual information exhibits growth with the
individual strip sizes and a disentangling transition as the separation between
the strips increases, whose behaviour is distinct from the ground and thermal
states. In the narrow strip case, our calculations have parallels with
"entanglement thermodynamics" for these $AdS$ plane wave deformations. We also
discuss some numerical analysis.
