为了研究一种星载光纤光栅传感解调系统, 通过高掺锗光纤载氢增敏和优化紫外曝光功率, 实现了栅区长度小于0.5 mm, 反射率大于40%, 3 dB带宽大于5 nm, 反射谱边缘有效线性区域大于2 nm的超短光纤光栅的写制。提出了一种将超短FBG作为传感器件, 利用其光谱线性区进行传感解调的方法。将中心波长位于光谱线性区域的稳频激光入射到超短光纤光栅, 随着超短光纤光栅光谱的漂移, 反射光的功率随之变化。由于稳频激光位于线性区域, 返回光功率与光谱漂移量呈线性关系, 因而可实现传感测量。将该系统用于应变和温度的测量, 结果表明, 光功率随应变、温度变化具有较好的线性关系, 线性度分别为0.997和0.999, 灵敏度分别为54.59 nW/με和230 nW/℃。该方法可用于温度及应变的精确测量, 并且具有结构简单、功耗小、测量空间分辨率高等潜在优势。

To study a fiber grating sensing and demodulation system applied to satellites, ultra-short fiber Bragg gratings with grating length of less than 0.5 mm, reflectivity of over 40%, 3 dB bandwidth of over 5 nm, and the edge linear region of the reflection spectrum of over 2 nm were fabricated by the hydrogen enrichment of high germanium fiber and optimization of UV exposure power. A novel method was proposed to transmit the ultra-short FBG as a sensor and demodulate it by using its spectral linear region in this paper. The frequency stabilized laser whose central wavelength was located in the spectral linear region was incident on the ultra-short fiber grating. The reflected optical power changed with the drift of the ultra-short fiber grating spectrum. As the frequency stabilization laser was located in the linear region, the reflected optical power was linearly related to the spectral drift, so that the sensing measurement could be realized. Using the system for strain and temperature measurements, the experimental results show that the optical power has a good linear relationship with strain and temperature, and the linearity is 0.997 and 0.999, the sensitivity is 54.59 nW/με and 230 nW/℃, respectively. The method can be used for accurate measurement of temperature and strain, and has the potential advantages of simple structure, low power consumption and high measurement spatial resolution.