In this master thesis we study the optical excitation of quasiparticles and two-level fluctuators (TLFs) inside superconducting resonators. Therefore, we measure the properties of superconducting resonators both under continuous and pulsed light irradiation. The findings are attained through measurements of the resonance frequency and phase shift, the change in quality factor and amplitude due to light exposure. The main results are the measurements of the time-dependent behavior of two-level fluctuator and quasiparticle excitation and relaxation processes. Furthermore we compare the influence of a continuous light flux with effects of a change in temperature or microwave probing power.