  Two dimensional (2D) semiconductor materials of transition-metal
dichalcogenides (TMDCs) manifest many peculiar physical phenomena in the
light-matter interaction. Due to their ultrathin property, strong interaction
with light and the robust excitons at room temperature, they provide a perfect
platform for studying the physics of strong coupling in low dimension and at
room temperature. Here we report the strong coupling between 2D semiconductor
excitons and Tamm plasmon polaritons (TPPs). We observe a Rabi splitting of
about 54 meV at room temperature by measuring the angle resolved differential
reflectivity spectra and simulate the theoretical results by using the transfer
matrix method. Our results will promote the realization of the TPP based
ultrathin polariton devices at room temperature.
