A local micro-structured long-period fiber grating (LMSLPFG) is proposed and investigated experimentally. The LMSLPFG is fabricated by using hydrofluoric acid (HF) to partially etch a standard long-period fiber grating (LPFG), thereby forming a local defect in the cladding. The theoretical analysis and experimental results show that partially etching will change the effective refractive index modulation in the cladding mode, which equivalently introduces a phase shift into the part of defect and manifests, in the spectrogram, as openning a transmission window between the stopbands, forming two transmission stopbands and one transmission passband. On this basis we study the temperatures and bending characteristics of the two stopbands and one passband. The results show that the temperature sensitivities of the two stopbands and one passband are all approximately 0.05 nm/℃; the bending sensitivity of the passband (2.61 nm/m-1) is less than those of two stopbands (4.71 nm/m-1). Thus by using the sensitive matrix, we can simultaneously measure the curvature and temperature, with only one grating used.

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High phase noise and low phase noise have been consideration in CO-OFDM systems, respectively. The hybrid mitigation algorithm is optimized to approach to high phase noise and low phase noise environment, and a hybrid half-blind phase noise compensation algorithm is proposed, which could be suitable to shifty DFB laser linewidth. 4QAM and 16QAM are used to modulate binary signal. The new proposed phase noise compensation algorithm is considered a mitigation method which has the ability of half-blind self-adaptation. It deduces the coefficient matrix in high and low phase noise compensation matrix and could improve performance under high or low modulation index situation.

The original signals always mix with certain noise through blasting engineering test of underground structure, such as fan noise, environmental noise and mechanical noise. That makes the useful information of signal characteristics hidden in the noise signal to cause major error for the site test. The superposed signals of the original signal got by using numerical simulation and artificial white noise signal were processed through different de-noising methods based on wavelet transform. After the de-noising effects were evaluated by the evaluation standard signal de-noising performance, the best wavelet function, the effective scale of wavelet decomposition, and the threshold estimation rules were got settled on. Finally, the best de-noising method of blasting vibration signal is got to lay the foundation for the underground structure safety evaluation based on the wavelet transform theory.