Fig. 2
Bend losses. a An infrared laser beam is coupled into one end of a 180° fiber arc to measure attenuation of light transmitted to other fiber end. The red line represents the refractive index (n) profile along the radial coordinate ρ. Propagation in curved fibers can be mapped into a straight fiber problem with the effective refractive index shown by the blue line. b Transmitted power as a function of the arc curvature radius. Experimental data are shown as circles. Error bars represents the standard deviation between the transmission of 5 arches with same curvature. BPM simulations and analytical prediction are plotted as solid orange and dashed green lines respectively. Inset shows the attenuation coefficient per unit length obtained from transmission data in the main panel. Gray dashed line is a guide to the eye representing the axis α = 0
