Scalable antiguided ribbon laser

A new scalable fiber laser approach to phase locking of multiple gain cores in an antiguided structure is described and modeled. In essence, the waveguide comprises a periodic sequence of gain-loaded and no-gain segments that has a uniform refractive index (referred to as the ribbon) encapsulated within a reduced-index cladding region. Our calculations reveal that the constant-index profile within the ribbon structure provides optimal mode discrimination; the refractive index must be constant within +/-0.001 to ensure single-mode operation for a five-core design. One-dimensional and two-dimensional calculations are pursued to support the design criteria. Slight periodic variation in the refractive index of the ribbon laser leads to the emergence of a photonic bandgap, in analogy to so-called holey fibers. Our constant-index design, together with the periodic gain profile, may be described as a photonic metal. (C) 2002 Optical Society of America.