Ring Resonator-Based Optical Hydrogen Sensor

We have proposed and demonstrated numerically a ultra-small and highly sensitive hydrogen sensor, based on micro ring resonator with a footprint size as small as 4x4 mu m(2). With a palladium or platinum hydrogen sensitive layer coated on the inner surface of the micro ring resonator, the device is highly sensitive to the low hydrogen concentration variation and the sensitivity is at least one magnitude order larger than the optical fiber-based hydrogen sensor. We have also investigated the tradeoff between the portion coverage of palladium/platinum layer and the sensitivity. The width of the hydrogen sensitive layer is also studied and the minimum feature width is determined to be the length of the ring waveguide evanescent wave. This ultra-small optical hydrogen sensor will be promising to realize highly compact sensor with integration capability for applications on hydrogen fuel economy.