Thermometry with germanium-vacancy color center in diamond

In this contribution, we present high-resolution, all-optical thermometry based on ensembles of germanium-vacancy color in diamond. Diamond is transparent, physically and chemically inert material, which make it perfect candidate for back action-free sensing applications. While diamond based thermometry was already realized with nitrogen-vacancy color center, it requires strong microwave emission for its operation, which may be unwanted in many application. The germanium vacancy color center allow microwave free, all-optical approach, which opens a way to produce non-invasive, back-action-free temperature measurements in a wide range of temperatures, from a few to thousand Kelvins.