Abstract: A diode laser pumped, power stabilized fiber laser comprising a doted fiber, a pumping light source, as well as entrance and exit side resonator units wherein the entrance resonator unit and/or the exit resonator unit have controllable distances (gaps) to the fiber end faces, which are up to 20 ?m wide. A controllable variation of the gap widths allows for the generation of light emission on a plurality of switchable and simultaneously excited emission wavelengths in the visible and the near infrared ranges.