Abstract : Laser sources emitting around 976 nm are used for telecommunications, to pump erbium-doped fiber amplifiers, or to build sources emitting around 488 nm after a non linear conversion. The available power of transverse single-mode sources was lower than 1 W at the beginning of my thesis, and sources with higher powers were studied. We have chose to propose sources based on ytterbium-doped materials. Ytterbium ions present a high emission cross-section at 976 nm. But the absorption at this wavelength is strong, due to the three-level behavior of the transition. An intense pumping at 915 nm is thus necessary to obtain the doped area transparency at 976 nm. We have studied two solutions.
Ytterbium-doped single-mode fibers allowed us to develop efficiency sources, like a spectrally narrowed laser. It has been used to realize a source emitting at 488 nm with a non linear periodically-poled lithium niobate waveguide. In this aim, we have also studied the amplification of a 976-nm laser diode in the doped fiber, and the frequency doubling of this source. To optimize the sources, we have theoretically studied the propagation of beams in the fiber.
Another solution is to use ytterbium-doped KY(WO4)2 crystals. We have demonstrated a high gain at 981 nm under titanium-doped sapphire laser pumping at 931 nm. These sources have been simulated. Nevertheless, laser diode pumping of these crystals is not actually possible, because of the insufficient brightness of laser diode.