Ultra-highly sensitive optical gas sensors based on chemomechanical polymer-incorporated fiber interferometer.

We demonstrate a novel optical sensor for use in explosive gas detection, having a simple structure, ultrahigh sensitivity, room-temperature sensing/refreshing operation, and no local power requirements. The sensor relies on a fiber Fabry-Pérot interferometer prepared using poly(4-vinylpyridine), which induces cavity expansion upon absorption of nitrobenzene, thereby shifting the phase matching conditions of the resonating modes. An estimated sensitivity limit as low as 5 ppb was achieved.