"In the present dissertation work, the spectral and temporal features of actively Q-switched erbium-doped fiber lasers are reported. These features were investigated for two common laser configurations: for the linear Fabry-Pérot cavity with a pair of fiber Bragg gratings as reflectors, and for onedirectional ring cavity without spectrally selective elements. It is shown that in both configurations the spectral width of sub-pulses, forming a Q-switch pulse, depends on the sub-pulse number, the spectrum of the most powerful sub-pulse is much broader than those of the rest, less powerful ones. In the case of the ring laser, the optical spectra of sub-pulses shift to the Stokes side while increasing a sub-pulse’s number. Possible reasons for such laser spectral dynamics will be discussed. We also report properties of the intensity noise of actively Q-switched erbium-doped fiber lasers implemented in these two configurations. We demonstrate that the types of photon noise statistics of Q-switched pulses in these two lasers are dramatically different (Poissonian or Bose-Einstein), revealing a crucial role of the cavity’s spectral selectivity. To determine the type of experimental statistics in terms of photon noise distribution, a detailed modeling is performed. Finally, the noisy Qswitched pulses are employed as a pump for generating broadband supercontinuum in telecom fiber, which affects their noise statistics."