Fast and Transparent Adaptive Lens Based on Plasmonic Heating

In the current trend toward miniaturization, integrated micro-optical elements play a central role in the development of various applications including high-density data storage and imaging. In these operations, fine alignment and focus adjustment are usually performed mechanically, thus, limiting the accuracy, size and speed of devices. Here, we propose a novel reconfigurable microlens based on the engineering of the temperature distribution induced by a patterned plasmonic surface shined with a resonant near-infrared light. The refractive index change generated in a surrounding thermo-optical material acts as an effective lens whose parameters are remotely adjusted by the control near-infrared light. We demonstrate focal distance tunability of tens of microns with subnanometer accuracy along with time-responses down to 200 μs. The applicability of this photothermal lens is proved in the framework of optical microscopy and adaptive optics.