  We study the reflection and transmission properties of a system comprising
two whispering-gallery mode resonators, each containing a Zeeman-split quantum
dot and side-coupled to an optical fiber. Our results demonstrate that
unidirectional reflection and transmission can be achieved by tuning the
coupling strength between the resonators and the optical fiber. Furthermore, we
establish a correspondence between quantum dot energy level resonance
frequencies and the positions of low reflection (transmission) peaks at a phase
shift of {\pi}. This research provides insights for the development of quantum
optical devices like isolators, circulators, and routers.
