The polarization mode dispersion (PMD) is a difficult phenomenon to compensate in the optical fiber. Its reduction can be achieved by the spinning process that provokes the rotation of the birefringence axes of the fiber inciting a coupling of its modes that is controlled at the time of its manufacture. In this work, the Jones Matrix Eigen-Analysis method (JME) is used to characterize the spun fibers to evaluate their PMD and to prove that it is distinctly lower than the standards fibers PMD. Furthermore, the differential group delays (DGD) of spun fibers is determined using the photon counting optical time-domain reflectometry (C-OTDR) method. The obtained results are compared with those found in the JME method. It is noted that the two methods yield practically identical values. The determination of the beat length and the spin period of spun fibers are carried out using the polarization-sensitive optical frequency-domain reflectometer (POFDR).
In this work, an angular sensor using optical fiber is achieved. The principle of attenuation of the intensity of the luminous wave in the optical fiber (curved to deduct the angle of curvature) is used. A mechanical system controlled by a PC is conceived to simulate the articulation of a human being in order to test the optical sensor on the during various angular displacements of the articulation. According to the variation of this attenuation, a measure of angle is deducted. This process may offer a useful technique for use in functional rehabilitation, which requires a quantification of the angular kinematics of movements.
pler is related to the coupling coefficient. The size reduction ratios against minimum line width with different parameters are shown in Figures 1 and 2. SIMULATED AND MEASURED RESULTSTo validate the proposed procedure, a miniaturized 6-dB ring coupler operated at 1 GHz is fabricated and measured. The substrate is FR4 with r ϭ 4.2 and h ϭ 1.6 mm. If the minimum line width is 0.2 mm, the maximum impedance will be 148.67⍀, leading to the minimum size reduction ratio of 0.28. Figure 3 shows the layout of the original 6-dB ring coupler and the reduced version with 12 open stubs. It is noted that the line widths of the original ring coupler are different so as to control the coupling coefficient. In contrast, the line widths of the reduced ring coupler on the circumference are all equal to 0.2 mm, the minimum line width. Figure 4 shows the photograph of the manufactured reduced ring coupler. The frequency responses of these two ring couplers, simulated using Ansoft Serenade, are compared with the results measured by using Agilent 8720ES in Figure 5. In this figure, the discontinuity effects, including T-junction and open end, are considered and compensated. Good agreement between the simulated and measured results at the operation frequency is found, with the exception of the return loss, because it is sensitive to line width and the minimum line width is influenced severely by the manufacturing precision. CONCLUSIONThe size-reduction limit of a ring coupler with restricted minimum line width that is miniaturized by connecting multiple open stubs is derived. The limits of size-reduction ratios of different parameters have been checked. According to the predicted minimum size, a reduced ring coupler has been designed and fabricated in order to validate the proposed procedure. ABSTRACT: The measure of the chromatic dispersion of the optic fibers used in telecommunications networks and high-speed systems is very useful because it permits chromatic-dispersion compensators to be conceived across the wavelength range of interest. The modulationphase-shift method is used to measure chromatic dispersion in a standard single-mode fiber for telecommunication between 1200 and 1600 nm, by measuring the variation of the modulation phase of the transmitted signal modulated by a radio frequency signal, relative to the transmitted signal in a short reference fiber, modulated by the same signal. We verify the reduction of the thermal transitions in the measurement setup and fiber under test, while covering the spool of the fiber.
The purpose of this work consists in a comparative study between block matching search algorithms, used in video images motion estimation. Exploiting the temporal correlation between two successive sequence frames we can reduce enormously the memory space needed for image registration. In this context, we have applied and compared different algorithms of search used in block matching technique. These algorithms include full search algorithm, three steps search algorithm, new three steps search algorithm, four steps algorithm, diamond search algorithm and minimum search algorithm. The performance of an algorithm is a compromise between the pick signal to noise ratio and the computing search time of the algorithm.
In fact proposed method is more accurate than past methods of determining range from phase difference between two millimeterwave signals properly spaced in frequency. CONCLUSIONSA 77-GHz six-port interferometer for FMCW collision-avoidance radar is presented. Range and speed are determined by evaluating the slope of instantaneous phase of beat signal. Simulation results provide comparison of present range dispersion with those obtained in literature. Range measurements derived from slope of instantaneous phase of baseband beat signal is found to be more accurate than method of determining range from phase difference between two millimeter-wave signals properly spaced in frequency. Proposed method of correcting DC offset and amplitude imbalance for six-port interferometer FMCW with phase/frequency discriminator avoids use of complicated calibration method using network analyzer.
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