Institute of Information Photonics Technology and College of Applied Sciences, Beijing University of Technology, Beijing 100124, P.R. China.
Small. 2012 Jun 25;8(12):1937-44. doi: 10.1002/smll.201102290. Epub 2012 Apr 4.
A polarization-independent optical sensor is created by fabricating a concentric gold ring grating with a period of 900 nm on the end facet of an optical fiber. The sensing function of this miniaturized device is realized by sending white light as a probe to the gold rings and collecting the response signal in the back-reflection through the optical fiber. A pronounced peak due to the Rayleigh anomaly of the gold ring grating is observed in the reflection spectrum, the center wavelength of which is sensitive to the change in the environmental refractive index of the fiber end facet. Theoretical analysis not only shows excellent agreement with the experimental results, but also gives insights into the mechanisms of this kind of sensor. Using the center position of the Rayleigh peak as the response signal, a high sensitivity dλ/dn of 900 nm per unity refractive index is realized for this sensor and a resolution of Δn/n ≈ 1% is demonstrated in preliminary experiments. The sensitivity is solely determined by the period of the grating.
一种偏振无关的光纤光学传感器，是通过在光纤端面制作一个周期为 900nm 的同心金环光栅来实现的。该小型化器件的传感功能是通过将白光作为探针发送到金环，并通过光纤收集背反射中的响应信号来实现的。在反射光谱中观察到由于金环光栅的瑞利异常而产生的明显峰值，其中心波长对光纤端面环境折射率的变化敏感。理论分析不仅与实验结果吻合得很好，而且还深入了解了这种传感器的工作机制。该传感器使用瑞利峰的中心位置作为响应信号，其单位折射率的灵敏度达到了 900nm/RIU，在初步实验中证明了分辨率为 Δn/n ≈ 1%。该灵敏度仅由光栅的周期决定。
