Measuring Nonlinearities Under High Dispersion and Loss

Contrary to traditional views considering loss a limiting factor for nonlinear photonics applications, a judicious loss management is currently playing a crucial role in different research areas in nonlinear optics ranging from plasmonics and $\mathcal{PT}$-symmetric systems to pulse propagation in waveguides with 2D materials [1] or dispersive nonlinearities [2]. As this physics relies on interplays between nonlinear, dispersive (or diffractive) and loss (or gain) effects, an accurate measurement of the nonlinear coefficient $\gamma$ cannot disregard either chromatic dispersion $\beta_{2}$ or linear loss $\alpha$, whereas state-of-the-art techniques require dispersionless [3] or lossless waveguides [4]. Moreover, such a measurement would aid theoretical ongoing research in discriminating competing nonlinear models founded on different assumptions [5]. Here we demonstrate a procedure for measuring $\beta_{2}/\gamma$, and hence $\gamma$ if $\beta_{2}$ is available, under conditions where dispersion and loss are comparable to nonlinear effects.