Titanium Diselenide ($TiSe_2$) is a two-dimensional material belonging to the family of transition metal dichalcogenides (TMDs), characterised by a stacking of layers kept together via Van der Waals force. Despite it has been extensively studied over the past decades due to the emergence of a charge density waves (CDW) state, the origin of which remains a topic of ongoing debate. In this thesis, we have employed the time-resolved reflectivity (TRR) technique to monitor the ultra-fast dynamics of the sample following femtosecond laser excitation. After introducing the theoretical principles of the TRR method, the components taking place in the experimental setup and outlining the fundamental properties of the sample, we will present a detailed analysis of the fluence- and temperature-dependent measurements taken under ultra-high vacuum. Our results reveal new insights into the behaviour of coherent phonon modes as a function of time and temperature and shed light on their coupling to the lattice distortion associated with the CDW phase. This study contributes to a new perspective of the nonequilibrium dynamics governing CDW systems and the role of lattice degrees of freedom in their formation and evolution. In parallel, we also developed a UHV chamber featuring five-axis motorized movement and a cryogenic system capable of controlling temperatures from 10K to 300K. This will enable the study of new samples that are highly surface-sensitive, and allow the combination of this technique with ARPES and STM.