Cascaded geometric parametric process in a tapered air–silica graded-like multimode microstructure fiber

We experimentally study the spatial beam profile and the spectral broadening at the output of a multimode air-silica microstructure fiber taper, used along the direction of an increasing fiber diameter. By using a laser pump at 1064 nm emitting 60 ps Gaussian beam pulses, we observed a competition between Raman beam cleanup and Kerr beam self-cleaning: the multimode frequency conversion process permits to generate spectral sidebands with frequency detuning from the pump that are difficult to obtain in standard graded-index multimode fibers. The generated supercontinuum spans from 500 nm up to 2.5 mu m. (c) 2024 Optica Publishing Group. All rights, including for text and data mining(TDM), Artificial Intelligence (AI) training, and similar technologies, are reserved.