Fig. 1: Structure, mechanism, and optical properties of photonic optomechanical actuator.

a Schematic illustration of the structure of photo-deformable photonic bilayer film. The enlarged image shows the nanostructure of the inverse opal. b Schematics showing the mechanism of photonic-structure-controlled actuation. The photonic structure enhances (PDMS side illumination) or weakens (SIO side illumination) the gold-nanoparticles-driven photothermal conversion by controlling light propagation within the system. c Surface SEM image of SIO obtained from the colloidal crystals composed of polystyrene spheres with a diameter of 300 nm. The inset is a photograph of the as-prepared photonic bilayer film, showing bright green iridescence. The image was collected in the direction perpendicular to the SIO film. d Cross-sectional SEM images of the photonic bilayer film. The enlarged images clearly show the photonic crystal structure displayed by ordered, hollow silk fibroin structure with air holes on the wall (top) and the compactly contacted interface between silk and PDMS (bottom). e Measured and simulated reflectance spectra of the photonic bilayer film and absorbance spectrum of gold nanoparticles. The experimental curve is in agreement with the theoretical calculation. Inset shows a transmission electron microscopy image of the gold nanoparticles. Data for an unstructured SF/PDMS bilayer film is also shown for comparison.