高斯切趾光纤Bragg光栅折射率传感器特性研究

Study on characteristics of refractive index sensor based on Gaussian-apodized fiber Bragg gratings

基于3层结构和双层结构光纤波导理论,对不同腐蚀深度的高斯切趾光纤Bragg光栅(FBG)的基模谐振波长与外部介质折射率(SRI)间的关系进行理论仿真,并通过实验研究其谐振波长、3dB带宽及反射峰强度对SRI的响应特性。实验表明,随着SRI逐渐增大,基模谐振波长向长波方向的移动幅度越来越大,与仿真结果基本吻合;3dB带宽随着SRI的增大越来越窄;反射峰强度随SRI的增大略微减小,但当SRI接近FBG的包层或纤芯折射率时,反射峰强度将迅速降低。这些结果为高斯切趾FBG应用于生物化学传感方面的折射率测量奠定了基础。

Based on the three-layer and double-layer optical fiber waveguide theory,the relation between the fundamental mode resonant wavelength of Gaussian-apodized FBG with different etching depths and the surrounding refractive index（SRI） is numerically analyzed,and experiments are carried out for the response characteristics of fundamental mode resonant wavelength,3 dB bandwidth,and reflection-peak intensity to the SRI.The experimental results show that,as the SRI increases,the movement of resonant wavelength to a longer wavelength grows largely,which is in accordance with the numerical results,and the 3 dB bandwidth become more and more narrow and the reflection-peak intensity only decreases slightly which fells down dramatically as the SRI gets close to the cladding index or core index.These results are useful for the SRI measurement based on Gaussian-apodized FBG in the biochemical sensing applications.