Metal–Dielectric–Metal Metamaterial-Based Hydrogen Sensors in the Water Transmission Window

In this letter, we have numerically proposed design of a novel, efficient, and weather condition independent metal-dielectric-metal metamaterial-based plasmonic hydrogen sensor. In the proposed device, the top and bottom metallic layers are palladium (Pd) nanodisc array and gold thin film, separated by a sandwiched dielectric aluminum oxide layer. The presence of hydrogen reversibly changes Pd to its hydride, which leads to a change in its optical properties. Only 4% (v/v) presence of hydrogen in the air can change optical reflectance from 95% to 14% at 905 nm wavelength, center of first water transmission window, that results for a weather-resistant hydrogen sensor with ~21.3% change in optical response for 1% change in hydrogen concentration with 76.5 s of response time for remote hydrogen sensing.