Figure 3
From: High-gain far-detuned nonlinear frequency conversion in a few-mode graded-index optical fiber
(a–e) Near-field images of the spectrally filtered peaks indicated by arrows and colored dashed lines in subplot (g). Left sections are experimental measurements, whereas right sections provide corresponding calculated mode distributions. In subplot (e), both calculated LP\(_{0,1}\) and LP\(_{0,2}\) modes are shown. Red line indicates the inner edge of the fluorine-doped trench. (f) Phase mismatch \(\Delta \beta\) calculated for intramodal and intermodal FWM processes (details provided in text). (g) Experimental spectrum recorded at the output of a 70 cm-long fiber segment with an average power of 29.8 mW.
