<p>An amplifier or laser using the stimulated Raman diffusion effect comprises a light guide (6) , and a light pump (10) for producing a pump wave. In order to increase amplification efficiency, the light guide comprises a core structure that includes at least one optically active component that presents an electron transition energy corresponding to a wavelength that is close to the wavelength of the pump wave while nevertheless not being identical thereto. The invention is applicable to optical transmission systems.</p>
