High-temperature wave thermalization spoils beam self-cleaning in nonlinear multimode GRIN fibers

In our experiments, we reveal a so-far unnoticed power limitation of beam self-cleaning in graded-index nonlinear multimode optical fibers. As the optical pulse power is progressively increased, we observed that the initial Kerr-induced improvement of the spatial beam quality is eventually lost. Based on a holographic mode decomposition of the output field, we show that beam spoiling is associated with high-temperature wave thermalization, which depletes the fundamental mode in favor of a highly multimode power distribution. (c) 2023 Optica Publishing Group

Automated summary

In our experiments, we discover a previously unnoticed power limitation in beam self-cleaning in graded-index nonlinear multimode optical fibers. As the optical pulse power increases, the initial improvement of spatial beam quality is lost due to high-temperature wave thermalization, depleting the fundamental mode and leading to a highly multimode power distribution.