Mid-infrared radiation transmission through fluoride glass multimode optical fibers

Measurement of the transmission laser radiation from Q-switched and free-running Er:YAG lasers operating at 2.94 μm through fluoride glass multimode optical fibers of 448, 465 and 620 μm core diameter were performed. Attenuation measurements were obtained as a function of the laser energy input, of the bending angle and of the radius of curvature. The fibers exhibited low attenuation under straight and bent conditions. The output beam quality was also studied using the appropriate beam profiler. The output beam profiles showed a central multi-spiked energy distribution.

► Three fluoride glass multimode optical fibers were evaluated.
► The attenuation under straight and bent conditions is low.
► The output profile had a multimode character.
► The output beam divergence is similar with the beam divergence of other fibers.
► Power densities of 507 MW/cm2 were launched into the fibers.