Reconfiguration of microring resonators by liquid adhesion

We present a procedure to reconfigure microring resonators based on liquid surface adhesion. Droplets of organic solvents were deposited over $Si3N4/SiO2$ strip- and slot-waveguide ring resonators, and the transmission spectra were measured several hours after the evaporation of the droplets at room temperature. Our measurements show that the optical properties of the microrings are significantly modified by liquid adhered to the waveguides, persisting even 96 h after bulk evaporation. Liquid-solid interfacial forces slow down liquid evaporation at the nanoscale, enabling permanent photonic configurations. Rewriteability is achieved by removing the adhered liquid with heat.