Photo-thermal tuning of graphene oxide films on optical waveguides

The power-sensitive photo-thermal tuning (PTT) of two-dimensional (2D) graphene oxide (GO) integrated on the top surface of silicon nitride (SiN) waveguides is experimentally investigated. For SiN waveguide coating with monolayer GO, the light power thresholds for reversible and permanent GO reduction are measured. There are three reduction stages identified based on the presence of reversible versus permanent reduction. We also compared the PTT induced by a continuous-wave laser and a pulsed laser with the same average power, confirming that the PTT is primarily determined by the average input power.