摘要：

An optical fiber, having a fiber cladding and a fiber core doped with laser active material, is embedded in an optical waveguide core having a refractive index almost equal to that of the optical fiber cladding, and pumping light is guided, in a side pumping manner, from the semiconductor laser via the light-guiding section. The guided pumping light is absorbed by the laser active material, as it propagates and moves around in the optical waveguide core in a fixed direction. Because the optical waveguide core is ring-shaped and enclosed by the optical waveguide cladding having a low refractive index, the rest of the guided pumping light propagates and moves around in the optical waveguide core again. Therefore, a laser active material in the optical fiber core can be pumped efficiently.

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