A 20-node fiber-grating-based wireless sensor network is proposed and experimentally demonstrated. Each sensor node is integrated with the light source, 1-3 FBG sensing probes, wavelength demodulation, and wireless communication module. Via self-organized clusters and low energy adaptive clustering hierarchy (LEACH) route protocols, the sensor nodes are able to exchange sensing data with the control center, and the maximum communication radius of a sensor node is over 170 m. The sensor node is battery-powered with a survival lifetime of up to 120 days at a network refresh rate of 5 minutes.

In this paper, the mode coupling mechanism of tilted fiber Bragg gratings (TFBGs) is briefly introduced at first. And a general review on the fabrication, theoretical and experimental research development of TFBGs is presented from a worldwide perspective, followed by an introduction of our current research work on TFBGs at the Institute of Modern Optics, Nankai University (IMONK), including TFBG sensors for single-parameter measurements, temperature cross sensitivity of TFBG sensors, and TFBG-based interrogation technique. Finally, we would make a summary of the related key techniques and a remark on prospects of the research and applications of TFBGs.

提出了光纤光栅啁啾化传感概念和传感机理,将光纤光栅微观分解为栅区长度范围的许多具有独立感知能力且彼此关联的有效作用子栅集,表述了有效作用子栅集与待测环境场空间梯度分布之间的对应关系,从而较好地解释了光纤光栅啁啾谱产生的内在机理。理论推导并实验验证了光栅啁啾谱各谱参量(波长、带宽和反射光强)与待测环境场(温度和应变)之间的对应关系,为利用单一光纤光栅实现多参量同时区分测量、任意非均匀空间分布场传感提供了科学有效的解决方法。

The characteristics of coherent coupling in Mach-Zehnder erbium-doped fiber laser cavity are experimentally studied. By virtue of a seemly controlling of length difference between two interferometric arms, the obtained comb-like spectrum of interferometer resonator with a period of 0.06 nm commendably agrees with the theory of self-organization coherence. The coherent output exits from the output mirror of a fiber Bragg grating with 4.5% reflectivity. A high coherent combining efficiency of 94% is obtained. Investigation on characteristics of the leak power opens out self-organization mechanism in Mach-Zehnder composite cavity.

Germanium doping in silica can be used as a method for nonlinearity enhancement. Properties of the enhanced nonlinearity in photonic crystal fiber (PCF) with a GeO2-doped core are investigated theoretically by using all-vector finite element method. Numerical result shows that the nonlinear coefficient of PCF is greatly enhanced with increasing doping concentration, furthermore, optimal radius of the doped region should be considered for the desired operating wavelength.

A flat high gain L-band gain-clamped erbium-doped fiber amplifier (GC-EDFA) by using backward C-band amplified spontaneous emission (ASE) is proposed. It uses two stages of EDFs pumped forward as gain media, and a broadband chirp fiber Bragg grating (CFBG) to reflect the backward C-band ASE back into the loop to control the gain, which avoids spectral-hole and relaxation oscillation due to no controlling laser exists. Compared with other similar GC-EDFAs, the proposed structure has higher and flatter clamped gain in L-band because of its optimal structure -- the length of EDFs and pump power, pump scheme, etc.. The gain is above 23 dB, the bandwidth of 3 dB is more than 36 nm, and the input signal saturation power arrives -15 dBm.