Fig. 1
From: Graphene’s nonlinear-optical physics revealed through exponentially growing self-phase modulation
Illustration of the setup used for the experiments and its constituents. a Cross-section of the SiO2-core waveguides covered by graphene with poly(methyl methacrylate) (PMMA), and numerically simulated distribution of the electric (E) field intensity. b Top-view microscope image of the SiO2-core waveguides with regions 1–5 covered by, respectively, 220, 440, 660, 880, and 1100 μm-long graphene sections with PMMA (white areas in center). c Temporal power profile and phase profile of the negatively chirped input pulse measured with the frequency-resolved optical gating (FROG) technique (solid curves) and the corresponding fit assuming a quadratic phase profile with C0 = −0.2 and TFWHM,0 = 3 ps (dashed curves). d Waveguide transmission as a function of graphene length as measured (dots) and the corresponding linear fit with slope αeff = 4605 m−1 (dashed curve). e Setup for the transmission and spectral broadening measurements. SMF single-mode fiber, VOA variable optical attenuator, PC polarization controller, OSA optical spectrum analyzer
