An optical sensor system, comprising refractory plasmonic elements that can withstand temperatures exceeding 2500° C. in chemically aggressive and harsh environments that impose stress, strain and vibrations. A plasmonic metamaterial or metasurface, engineered to have a specific spectral and angular response, exhibits optical reflection characteristics that are altered by varying physical environmental conditions including but not limited to temperature, surface chemistry or elastic stress, strain and other types of mechanical load. The metamaterial or metasurface comprises a set of ultra-thin structured layers with a total thickness of less than tens of microns that can be deployed onto surfaces of devices operating in harsh environmental conditions. The top interface of the metamaterial or metasurface is illuminated with a light source, either through free space or via an optical fiber, and the reflected signal is detected employing remote detectors.