Abstract: A process and apparatus for the modulation and amplification of light beams having at least one input light beam (8) supplied to at least one Fabry-Perot resonator having at least one resonance mode, and defined by two mirrors (M1,M2) and produced by stacking layers on a substrate (4). At least one of the layers form an active medium (6) able to amplify the input light beam by stimulated emission, the wavelength thereof being around the resonance of the resonator and the density of free charge carriers in the active medium being varied in such a way as to make the latter sometimes absorbent and sometimes an amplifying with respect to the input beam and thus obtain at least one output light beam (10) whose intensity is modulated and amplified relative to the input beam. Application to optical telecommunications and to optical interconnections.