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In order to improve the sensing precision of fiber Bragg grating sensor and reduce the influence of temperature on the cross-sensitivity of the pressure sensor, a rhombic pressure change sensor with self-temperature-supplementing was proposed. The ANSYS softwave was used to analyze the property of static force and heat of the rhombic structure by the finite element method. The influence of the side length and thickness of rhombic structure on the sensitivity were studied through the mechanism of self-temperature compensation. The side length and thickness of the sensor were determined to be 7mm and 1mm by simulation. At the same time, the simulation experiment also proves that the rhombic structure has the temperature self-compensation, and the final design of the sensor's micro-shape variable can be as low as 7. 9669 X 10-8 mm. Compared with traditional sensors, it can perform temperature compensation and strong anti-interference ability, which can be used in detecting local stress, engineering structural defects, and aerospace sensing. [ABSTRACT FROM AUTHOR]

A design of large-mode area photonic crystal fiber (LMA-PCF) was proposed to improve the non-linear effect of high-power fiber laser, which has the properties as large effective mode area, single mode, passive component, and low loss. The perfect matched layer was set as the boundary condition, and the effect of wavelength and structure on the effective mode area of PCF were analyzed by the finite difference time domain method. Further, a program of LMA-PCF was proposed. The results indicate that the transmission of single mode is obtained. At the wavelength of 1. 064 µm, the effective mode area is able to reach 3118. 4µm², and the non-linear coefficient is only 5. 68 x 10 5m-1 ⋅ W 1 Besides, the confinement loss can be reduced to 4.55 x 10-7 dB ⋅ m 1 Therefore, the high-power and high-beam of laser output is realized. [ABSTRACT FROM AUTHOR]

In order to achieve the effect of pressure sensitization of optical fiber sensor, a photonic crystal fiber structure with high birefringence was designed. The effective refractive index of photonic crystal fiber was calculated by the finite element method when it was applied different stress. Based on the pressure-sensitive characteristics of photonic crystal fiber, the mode of photonic crystal fiber was analyzed. An air hole in the structure was selected and filled with the liquid of specific refractive index. A new pressure sensor was formed by above structures. The pressure sensitivity of the structure was simulated by COMSOL. The simulation results show that the polarization phase sensitivity of photonic crystal fiber sensor increases from 72rad/( MPa ⋅ m) to 128rad/( MPa ⋅ m). The sensitivity is improved by 77. 7% significantly, which contributes to enhance the properties of the sensor. [ABSTRACT FROM AUTHOR]

In order to break the limitation of high Young' s modulus of quartz material on the sensitivity improvement of fiber optic sensor in uniform radial direction, a doped double-core photonic crystal fiber sensing structure was proposed. The circular air holes were arranged on the fiber cladding to form hexagonal lattice. Polymethyl methacrylate was doped into the base-material area surrounded by the air holes on one side of the double-core photonic crystal fiber. The influence of cross-section parameters on sound pressure sensitivity under uniform stress was analyzed by COMSOL and the optimal structure was obtained. At the kPa level, the free spectral width is about 13nm. At the MPa level, the free spectral width is about 2.5465nm. The results show that the sensitivity of x polarized sound pressure is 0.15942nm/kPa at 1550µm. Compared with the Sagnac PCF pressure sensor, the size of this sensor is smaller, and the sensitivity at uniform radial direction is increased about 46. 6 times. This work contributes to the design of the next generation underwater sound pressure sensor. [ABSTRACT FROM AUTHOR]

Based on MSIS90 atmospheric and 3D NeUoG ionospheric models, three types of ionospheric disturbances, i. e. ionospheric storm, traveling ionospheric disturbance (TID) and ionospheric trough were simulated, and their effects on bending angle residual ionospheric errors (RIEs) and temperature accuracy were analyzed. The results show that under high solar activity level, the bending angle RIE and its standard deviation can reach 1.5 μrad and 0.9 μrad, in the impact height range of 35~50 km; 4 μrad and 1.4 μrad, respectively, in the impact height range of 15~35 km. The ionopsheric storm and trough can enlarge the bending angle RIE standard deviations by more than 20 times, and TID can enlarge the bending angle RIE standard deviations by several times. Under the influence of ionospheric disturbances, temperature errors can reach 8 K and can pollute the GPS RO daily-mean and month-mean observations. Hence, it is desirable to develop ionospheric correction algorithms; the temperature outliers caused by ionospheric disturbances should be removed according to ionospheric monitoring results. [ABSTRACT FROM AUTHOR]