Power scaling of dispersive wave generation in higher angular order modes

Higher-order modes in optical fibers allow power scaling of nonlinearities thanks to the large core area; to date, research in step-index fibers has focused on Bessel modes ( L P 0, m ). However, the central intensity peak of such modes causes dielectric damage at the input facet, restricting the input pulse energy and preventing full use of this power scaling technique. In this work, we demonstrate that using higher angular order modes ( L P >0, m ) without a center spot can significantly mitigate the damage limitation, finding that modes in the center of the mode matrix are stable and best suited for dispersive wave generation. With this approach, we demonstrate dispersive wave generation from a 1030nm pump to 580-660nm with pulse energies of 2-7.4nJ, to 780nm with a pulse energy of 9.5nJ (0.6MW estimated peak power), and to 690nm with 5.1nJ (0.24MW). These results establish that modes featuring higher angular as well as radial order may be the most viable route to extending high-energy nonlinear frequency conversion in multimode fibers.