Intermodal group velocity engineering for broadband nonlinear optics [article]

Jeff Demas, Lars Rishøj, Xiao Liu, Gautam Prabhakar, Siddharth Ramachandran
2018 arXiv   pre-print
Interest in the nonlinear properties of multi-mode optical waveguides has seen a recent resurgence on account of the large dimensionality afforded by the platform. However, a perceived fundamental limitation of intermodal parametric interactions - that they are impractically narrowband - has yet to be solved. Here we show that by engineering the relative group velocity within the discrete spatial degree of freedom, we can tailor the phase matching bandwidth of intermodal parametric
more » ... s. We demonstrate group-velocity-tailored four-wave mixing between the LP_0,4 and LP_0,5 modes of a multi-mode fiber with unprecedented gain bandwidths (>60 nm at 1550 nm). As evidence of the technological utility of this methodology, we seed this process to generate a high-peak-power wavelength-tunable fiber laser in the Ti:Sapphire wavelength regime. More generally, with the combination of intermodal interactions, which dramatically expand the phase matching degrees of freedom for nonlinear optics, and intermodal group velocity engineering, which enables tailoring the bandwidth of such interactions, we showcase a platform for nonlinear optics that can be broadband while being wavelength agnostic.
arXiv:1806.02902v1 fatcat:zj7vy4khczhhtnvalow2dqxkaa