Graphene-dispersed polymer waveguide for efficient formation of mode-locked lasers at extremely low graphene concentration

Abstract

Graphene-functioned mode-locked lasers have been the key elements in ultrafast optical data management. However, most conventional graphene mode-rely on deleterious transferred graphene that inefficiently interacts with the evanescent field of the propagating light. We demonstrate a polymer waveguide that contains reduced graphene oxide (rGO) particles to induce “direct” interaction with a significantly improved efficiency at an rGO concentration of 8 × 10−4 wt%. By confirming the nonlinear saturable absorption and dispersion stability of the rGO crystals hosted in a commercially available polymer matrix by only a solution process, we obtained a femtosecond fiber laser passively functioned by the waveguide. The resultant laser displays a center wavelength, spectral width, repetition rate, extinction ratio, and temporal pulse duration of 1561.8 nm, 9.5 nm, 2.35 MHz, 83.19 dB, and 690 fs, respectively.