| 摘要 |
A single-mode fiber laser (66) that provides increased power. The fiber laser (66) includes a fiber ribbon (30) having a plurality of parallel waveguides (10). Each waveguide (10) includes a rectangular shaped core (12) that has a relatively thin dimension in one direction and a relatively wide dimension in an orthogonal direction. A step-index cladding (14, 16) is provided in the thin direction to limit the propagation of light in the core (12) to a single mode in that direction. Mode filters (18, 20) are provided adjacent the ends of the core (12) in the thickness direction and the various propagation modes in the core (12) enter the mode filters (18, 20). The mode filters (18, 20) guide the desirable single-mode back into the core (12) and reject the other modes away from the core (12). Light absorbing layers (22, 24) are provided adjacent the mode filters (18, 20) and opposite the core (12) to absorb the undesirable propagation modes of light. Therefore, the main propagation mode in the core (12) is a single low order mode, but the cross-sectional area of the core (12) is increased to provide more power. Each of the cores (12) in the ribbon (30) are optically pumped form the side by a bar (40) of diode arrays (42) positioned at strategic locations along the length of the ribbon (30) relative to the waveguides (10). Various transmission gratings (48) and/or reflection gratings (50) can be provided within a ribbon jacket (32) to launch the optical pump light down the waveguide (10). The ribbon (30) can be wrapped around a mandrel (68) and a cooling fluid can be introduced through the mandrel (68) to cool the ribbon (30) during laser operation.
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