A tilted fiber Bragg grating (TFBG) hydrogen sensor based on Pd/Au composite nanofilms was proposed. Pd and Au films with thickness of 25 nm and 35 nm were deposited on the surface of TFBG by magnetron sputtering method. Pd is a face centered cubic structure, which is capable of adsorbing hydrogen atoms. Accordingly, the effective refractive index of Pd/Au composite film changes with the variations of hydrogen concentrations, which will change the intensities of cladding modes resonant wavelength in TFBG transmission spectrum. The experimental results illustrated that when the hydrogen concentration changes by 1.02%, the intensity of cladding mode resonant wavelength (1558.4 nm for instance) decreases by 1.628 dB, and the hydrogen concentration sensitivity of 1.597 dB/% was obtained, which is almost 16 times higher than that of the current similar hydrogen sensor. The average response and recovery time were 37 s and 49 s, respectively. In addition, the proposed sensor can be made inherently temperature-insensitive by referencing all wavelengths to the wavelength of the core mode resonance of the grating, which is isolated from the fiber surroundings.

提出了一种基于Pd/Au复合纳米薄膜的倾斜光纤布拉格光栅(TFBG)氢传感器。通过磁控溅射方法在TFBG表面沉积了厚度为25 nm和35 nm的Pd和Au薄膜。Pd是一种面心立方结构，能够吸附氢原子。因此，Pd/Au复合薄膜的有效折射率随着氢浓度的变化而变化，这将改变TFBG透射光谱中包层模谐振波长的强度。实验结果表明，当氢浓度变化1.02%时，包层模谐振波长（例如1558.4 nm）的强度降低1.628 dB，得到1.597 dB/%的氢浓度灵敏度，这几乎是目前同类氢传感器的 16 倍。平均响应时间和恢复时间分别为 37 秒和 49 秒。此外，所提出的传感器可以通过将所有波长参考与光纤环境隔离的光栅纤芯模式谐振的波长，使其固有地对温度不敏感。