Elastic plasmonic-enhanced Fabry-Perot cavities with ultrasensitive stretching tunability.

The emerging stretchable photonics field faces challenges like the robust integration of optical elements into elastic matrices or the generation of large opto-mechanical effects. Here we demonstrate the first stretchable plasmonic enhanced and wrinkled Fabry-Perot cavities, which are composed of self-embedded arrays of Au nanostructures at controlled depths into elastomer films. The novel self-embedding process is triggered by the Au nanostructures catalytic activity, which locally increases the polymer curing rate, thereby inducing a mechanical stress that simultaneously pulls the Au nanostructures into the polymer and forms a wrinkled skin layer. This geometry yields unprecedented opto-mechanical effects produced by the coupling of the broad plasmonic modes of the Au nanostructures and the Fabry-Perot modes, which are modulated by the wrinkled optical cavity. As a result, film stretching induces drastic changes in both the spectral position and intensity of the plasmonic enhanced Fabry-Perot resonances due to the simultaneous cavity thickness reduction and cavity wrinkle flattening, thus increasing the cavity finesse. We exploit these opto-mechanical effects to demonstrate new strain sensing approaches, achieving a strain detection limit of 0.006%, i.e., 16-fold lower than current optical strain detection schemes. This article is protected by copyright. All rights reserved.