Formation of angular power profile via ballistic light transport in multimode optical fibers with corrugated surfaces -: art. no. 085419

We present experimental results on the light transmission and intermode power exchange in multimode fibers with rough surfaces. The experiments were performed with chemically etched 200-mu m-diameter cores of fused silica fibers that can support up to 700 X 700 guided modes at the wavelength employed, lambda approximate to 0.6 mu m. After propagation through some rough fiber section the mode power profile acquires a Gaussian shape that propagates along the mean axis of the corrugated fiber, with a slowly reducing radius (alpha 1/ root z), and practically without attenuation of the central intensity. These features, and other observed characteristics, are reproduced with a theory that assumes a ballistic regime of light propagation through a one-dimensional slab waveguide, relating the characteristic propagation lengths to parameters of the fiber surface roughness.