Institute of Photonics Technology, Jinan University, Guangzhou 510632, China.
Opt Lett. 2012 Jul 1;37(13):2649-51. doi: 10.1364/OL.37.002649.
We present fiber Bragg grating fabricated in rectangular microfiber for temperature-independent refractive index (RI) measurement. The grating has two Bragg peaks due to the high geometrical birefringence of the rectangular microfiber. The two peaks present different RI responses because the modes along the orthogonal polarizations have different energy fractions in terms of evanescent field outside the silica microfiber and hence the light/liquid interaction strength are different. In contrast, they exhibit identical temperature sensitivities because most mode energy is confined in the microfiber and the thermal-optic effect of silica dominantly determines the temperature response. As a result, temperature-independent RI sensing can be realized by monitoring the wavelength separation between the two peaks.
我们提出了一种在矩形微光纤中制作的光纤布拉格光栅，用于实现温度不敏感的折射率（RI）测量。由于矩形微光纤的高几何双折射，光栅具有两个布拉格峰。由于沿正交偏振的模式在二氧化硅微光纤外的消逝场中具有不同的能量分数，因此光/液体相互作用强度不同，这两个峰呈现出不同的 RI 响应。相比之下，它们表现出相同的温度灵敏度，因为大部分模式能量被限制在微光纤中，而二氧化硅的热光效应主要决定了温度响应。因此，可以通过监测两个峰之间的波长间隔来实现温度不敏感的 RI 传感。
