Numerical and Experimental Characterization of Radiation Mode of 45° Tilted Fiber Grating

In this paper, we have numerically and experimentally investigated the radiation mode of 45° tilted fiber grating (45° TFG). By introducing the axial distributions into the volume current method, we have established a three-dimensional theoretical model to analyze spatial distributions of the radiation mode of 45° TFG, and measured the radiation mode spatial distributions in experiment. Both numerical and experimental results show that the radiation mode of 45° TFG exhibits an exponential reduction along the fiber axial direction, and a quasi-Gaussian profile along the radial direction of fiber. Additionally, we have also measured the detailed polarization-dependent azimuthal intensity distributions of radiation modes of both s-and p-polarized core modes. The degree of polarization of radiation mode is around 99.886%, which is independent of the length and the polarization extinction ratio of the grating. Moreover, for the first time, we have experimentally observed a very weak p-polarized component existing in the radiation mode, which has matched well with the simulation results

Compact linear polarization spectrometer based on radiation mode shaped in-fiber diffraction grating

We propose a compact linear polarization spectrometer based on the in-fiber polarization-dependent diffraction grating. The beam profile of radiated light of the grating is shaped to be a Gaussian profile to improve the performance of the spectrometer, where the size of the focused light spot is reduced from 44 um to 33 um with the shaped radiation mode of the grating. Based on the experimental results, the proposed spectrometer can achieve 0.05 nm resolution and 115 nm wavelength responding range from 1495 nm to 1610 nm. To verify the performance of the proposed fiber spectrometer, we measure the transmission spectra of an excessively tilted fiber grating, which has a pair of orthogonal polarization transmission spectra. Compared with the traditional measuring method, the proposed fiber spectrometer integrates the polarizing and spectral analyzing functions in the measuring system and achieves the polarization-sensitive spectral analysis, which shows good wavelength consistency and perfect polarization characteristics

Design of loading process tracing and feedback system of coal storage yard

For low supervision efficiency of coal storage yard working, a loading process tracing and feedback system of coal storage yard based on GPS was designed, and design scheme of positioning terminal of loader shipment based on STM32F103VET6 was expounded. In the system, electronic fence is set in coal storage area by use of GPS technology, thus multi coal type storage areas are divided according to distribution of coal types. GPS positioning information of the loaders is uploaded to server real-timely through GPRS network by the positioning terminal, so as to record, analyze and manage loading process data real-timely. The system can be connected to existing coal mine weighing system and weighing data can be forwarded to the positioning terminal real-timely for improving loading efficiency

Investigation on left ventricular multi-directional deformation in patients of hypertension with different LVEF

Abstract Background This study is aimed at investigating myocardial multi-directional systolic deformation in hypertensive with different left ventricular ejection fraction (LVEF), and exploring its contribution to LVEF. Methods One hundred and twenty-three patients with primary hypertension (HT) were divided into group A (LVEF ≥ 55%), group B (45% ≤ LVEF < 50%, or 50% ≤ LVEF < 55% + LVEDVI ≥ 97 ml/m2), and group C (LVEF < 45%). Two-dimensional strain echocardiography (2DSE) including LV longitudinal strain (SL), radial strain (SR) and circumferential strain (SC) were measured. Results SL decreased gradually from group A, B to C (all p < 0.05) while SR and SC were reduced only in group B and C (all p < 0.05). All strain measurements correlated to LVEF, with the strongest correlation in SC (r = −0.82, p < 0.01) and the second in SL (r = −0.76). The diastolic E/e increased from group A, B to C. Conclusions Left ventricular multi-directional deformation correlated well to LVEF in hypertension and particularly SC, indicating that it was SC, not SL or SR, that makes the prominent contribution to left ventricular pump function

In-fiber single-polarization diffraction grating based on radiant tilted fiber grating

In this Letter, we propose an in-fiber single-polarization diffraction grating based on a radiant tilted fiber grating (TFG), in which the s-polarization light could be diffracted from the fiber core to free space with the wavelength-dependent diffraction angle. For the first time, we have presented the theoretical model of angular dispersion of a radiant TFG by employing the Fourier optics analysis method. The angular dispersion of the radiant TFG has been numerically characterized in terms of tilt angle, period, and wavelength. In the experiment, we have measured the diffraction angles and angular dispersion of the radiant TFGs with tilt angles of 41°, 45°, and 47° UV-inscribed into single-mode fiber, where the experimental results matched well with the simulation results. The simulation and experimental results have indicated that the diffraction light of radiant TFGs has a linear polarization state with over 0.99 degree of polarization at the tilt angle range from 41° to 47°