Information regarding deformations in large and complex systems is necessary in the prediction of structural failures caused by un-natural flexural occurrences. Sensing systems which are used to predict shapes, in order to develop a global surface picture require high precision and lower time lag. In this work, a unique bio-inspired training mechanism for support vector regression is presented for shape sensing in structures mounted with Fiber Bragg Gratings. Experimental validation was carried out on a simply supported beam, loaded at different positions and an aircraft wing model for different types of bending. The resulting deflections at specified locations along the length of the beam and on both surfaces of the wing were interpreted from the wavelength shifts of the corresponding Fiber Bragg Gratings through the specially modified Support Vector Regression. The method has shown high accuracy, low computational requirements and enhanced prediction times. The proposed bio-inspired training method has also been compared with two conventional training methodologies.

In this manuscript, we demonstrate high-power, narrow-linewidth linearly polarized fiber laser with excellent beam quality through compact one-stage amplification scheme. By employing a single-mode–multimode–single-mode structure seed laser, a linearly polarized Yb-doped fiber laser with narrow linewidth and high output power is achieved. This laser, when used as a master oscillator, can be capable of suppressing the ASE in the process of power amplification. Thus, only one-stage amplification structure is used to scale up the laser power, and linearly polarized output with a polarization extinction ration of 14 dB, a narrow linewidth of 0.3 nm and an output power of 1018 W are achieved. Moreover, due to the good beam quality of seed laser and the well-designed amplifier stage, the beam quality of the output laser is near-diffraction-limited with $M_{x}^{2}\sim 1.18$ and $M_{y}^{2}\sim 1.24$ at the maximum power, and without mode instability occurring.

A fiber Bragg grating (FBG) sensor system which can simultaneously measure the point-wise, out-of-plane and in-plane dynamic displacements is proposed. A demodulation system based on the fiber Bragg grating filter is used. The steady-state responses of particle motions of a piezoceramic plate measured by the FBG out-of-plane and in-plane displacement sensors are simultaneously compared with those obtained by a laser Doppler vibrometer (LDV) and a surface-mounted FBG strain sensor, respectively. The integration of the FBG displacement sensor with a dynamic signal analyzer (FBG-DSA) forms a measurement system which has the ability to acquire the frequency response of a piezoceramic plate. An LDV-DSA system and an impedance analyzer are used to compare the results obtained from the dynamic signal analyzer combined with the out-of-plane FBG sensor (OFBG-DSA) and the in-plane FBG sensor (IFBG-DSA), respectively. The experimental results of the impulse excitation as well as the random excitation of the piezoceramic plate are also presented. To explain the experimental results, an optical full-field measurement technique called amplitude-fluctuation electronic speckle pattern interferometry (AF-ESPI) and FEM numerical calculations are also used to provide full-field vibration mode shapes of the piezoceramic plate. These results indicate that the proposed displacement sensor system has the multiplexing capability to measure the dynamic displacements up to 45kHz.