ZnO microwire-based fiber-tip Fabry-Prot interferometer for deep ultraviolet sensing

We propose a simple deep ultraviolet (UV) sensor consisting of a conventional single-mode optical fiber capped with a ZnO microwire. The ZnO microwire positioned on the fiber-tip acts as a Fabry-Prot interferometer, of which the reflection spectrum can be employed for UV light monitoring. When ZnO microwire is exposed to UV irradiation, variations in the concentration of photogenerated carriers will result in the change of the refractive index (RI) of the ZnO microwire, and thus interference wavelengths of the proposed device exhibits red-shift with a sensitivity of 0.288 nm/(Wcm-2) under 266-nm deep UV laser irradiation. Meanwhile, a fast response time of 0.56 ms is experimentally obtained. The results may pave a new way for fast responsive, highly spatial-resolved optical fiber UV sensors.