Figure 1
From: High-gain far-detuned nonlinear frequency conversion in a few-mode graded-index optical fiber
(a) Refractive index profile measured at 0.632 \(\upmu \hbox {m}\) (blue dots) and corresponding fit used for our numerical analysis (dotted line). (b) Fiber attenuation measured by means of the cutback technique (blue) and absorption spectrum of bulk silica (Suprasil F300) from Ref.16 (black dashed line) in the mid-IR. Calculated refractive index (c) and effective mode area (d) of the first three LP\(_{0,m}\) modes with cutoff wavelengths marked with gray dashed lines. (e) Experimental setup for observing far-detuned frequency conversion. P polarizer; \(\lambda /2\) half-wave plate; MO microscope objective.
