  MoTe$_2$ monolayers and bilayers are unique within the family of
van-der-Waals materials since they pave the way towards atomically thin
infrared light-matter quantum interfaces, potentially reaching the important
telecommunication windows. Here, we report emergent exciton-polaritons based on
MoTe$_2$ monolayer and bilayer in a low-temperature open micro-cavity in a
joint experiment-theory study. Our experiments clearly evidence both the
enhanced oscillator strength and enhanced luminescence of MoTe$_2$ bilayers,
signified by a 38 \% increase of the Rabi-splitting and a strongly enhanced
relaxation of polaritons to low-energy states. The latter is distinct from
polaritons in MoTe$_2$ monolayers, which feature a bottleneck-like relaxation
inhibition. Both the polaritonic spin-valley locking in monolayers and the
spin-layer locking in bilayers are revealed via the Zeeman effect, which we map
and control via the light-matter composition of our polaritonic resonances.
