Resonant modes of linearly coupled multiple fiber laser structures

We have experimentally demonstrated coherent combining of 2 and then 4 fiber lasers,with respectively 99% and 95% combining efficiency. The combining method investigated here isbased on a multi-arm resonator of interferometric configuration. In spite of its interferometricnature, the multi-arm laser operates without significant power fluctuations, even in an unpro-tected environment. This occurs when the arm length difference is large enough to introducespectral modulations of period smaller than the laser bandwidth. We have also experimentallyshown that the combining method is compatible with wavelength tuning. A Mach-Zehnder FiberLaser was tuned over a wide spectral range of 60nm. Theoretically then, we confirm that thecombining method can be scaled to a large number of lasers without decreasing the combiningefficiency.8. A. Shirakawa, T. Sekiguchi, Matsuo, and K.-i. Ueda, “Scalable coherent beam combining offiber lasers,” in Advanced Solid-State Photonics (TOPS Vol. 83), J. J. Zayhowski, Ed., pp.82–84 (Optical Society of America (2003). Also presented at CLEO 2003.Abstract: Not available.9. M. Minden, H. W. Bruesselbach, J. L. Rogers, M. S. Mangir, D. C. Jones, G. J. Dunning, D.L. Hammon, A. J. Solis, and L. Vaughan, “Self-organized coherence in fiber laser array,” inFiber Lasers: Technology, Systems, and Applications: Proceedings of SPIE – Volume 5335, vol.5335, June 2004.Abstract: Self-organized coherence between fiber lasers has been reported both via all-fiber 2x2directional coupler trees and in spatially multi-core fibers. We have taken this a major stepforward, coupling together a number of independent fiber lasers to obtain a spatially and spec-trally coherent far field, with no active length, polarization, or amplitude control. The near fieldoutput comes from a spatial array rather than from a single fiber, making this approach scalableto extremely high power.10. Stephen Wolfram, The Mathematica Book (Cambridge University Press, 1996).