Online underwater abscission tracking of the ZnO film deposited on the optical fiber surface employing SPR technology

In this work, an optical fiber surface plasmon resonance (SPR) sensing technology is used to monitor the thickness of zinc oxide (ZnO) film in water online, and then study the hydrophilicity of ZnO film deposited by magnetron sputtering. Experimental results show that the ZnO films deposited on the surface of optical fiber, although different in thickness, will eventually detach from the fiber over time in the water. The surface characteristics of ZnO film before and after being soaked in water are compared to prove the existence of abscission of the film. Additionally, ultraviolet (UV) with different wavelengths and intensities affects the hydrophilicity of ZnO, which benefits from the adsorption of water molecules by more oxygen vacancies generated by photo generated carriers. The ability of 365 nm UV in improving hydrophilicity increases with UV intensity and is much higher than that of 395 nm UV. It has been proved that hydrophilicity affects the performance of ZnO devices, so the proposed method is meaningful for the basic research on surface hydrophilicity and the application of controllable wettability of ZnO films.