Thin liquid film as an optical nonlinear-nonlocal medium and memory element in integrated optofluidic reservoir computer

Understanding light-matter interaction enables harnessing physical effects to translate into new capabilities realized in modern integrated photonics platforms. Here, we present the design and characterization of optofluidic components in integrated photonics platform, and numerically predict a series of novel physical effects which rely on thermocapillary-driven interaction between waveguide modes to topography changes of optically thin liquid dielectric film. Our results indicate that this coupling introduces substantial self-induced phase change in a single channel waveguide, transmittance through Bragg grating waveguide and nonlocal interaction between adjacent waveguides. We then employ the self-induced phase change together with the inherent built-in finite relaxation time of the liquid film, to demonstrate that its light-driven deformation can serve as a reservoir computer capable to perform digital and analog tasks, where the gas-liquid interface operates both as a nonlinear actuator and as an optical memory element.