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您的检索式：作者名="Zengping Su"
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| 1 | Parameter estimation of chirp signal under low SNR显示文摘Aiming at solving the problem of great difficulty and low accuracy existing in parameter estimation of chirp signal under low signal-to-noise ratio(SNR) condition, an algorithm of accurate parameter estimation of chirp signal is proposed. First, the algorithm extracts ridge frequency of chirp signal based on Short Time Fourier Transform. Second, the protruding glitch frequencies are eliminated through median filter with proper size and the smoothing frequencies are obtained corresponding to the time. Third, the frequency time frequencymodulated(FM) line is fitted coarsely by the least-square linear fitting method, and some frequency points are removed, which are far away from the FM line. Repeat the process several times until the sample correlation coefficient of the fitted line is in high degree when the optimum chirp line is fitted out, so chirp rate and initial frequency are obtained. Simulation shows that the correct rate of parameter estimation is very high. When SNR is not less than –17 d B, the correct rate is 100%, and when the SNR is –18 d B, the correct rate is still capable of up to 99%. This algorithm has a lower SNR threshold of about –17 d B. When the SNR is greater than threshold,parameter estimation accuracy is close to Cramer Rao low bound(CRLB), higher than parameter estimation based on the phase field method. Measured data experiments show that the algorithm can reasonably fit the chirp line of measured chirp signal, which better characterizes the FM features of chirp signal. | WANG JinZhen SU ShaoYing CHEN ZengPing | 2015 | Science China(Information Sciences)2015，58，2： | 5 |
| 2 | Arbitrarily polarized bound states in the continuum with twisted photonic crystal slabs显示文摘Arbitrary polarized vortex beam induced by polarization singularity offers a new platform for both classical optics and quantum entanglement applications.Bound states in the continuum(BICs)have been demonstrated to be associated with topological charge and vortex polarization singularities in momentum space.For conventional symmetric photonic crystal slabs(PhCSs),BIC is enclosed by linearly polarized far fields with winding angle of 2π,which is unfavorable for high-capacity and multi-functionality integration-optics applications.Here,we show that by breakingσz-symmetry of the PhCS,asymmetry in upward and downward directions and arbitrarily polarized BIC can be realized with a bilayer-twisted PhCS.It exhibits elliptical polarization states with constant ellipticity angle at every point in momentum space within the vicinity of BIC.The topological nature of BIC reflects on the orientation angle of polarization state,with a topological charge of 1 for any value of ellipticity angle.Full coverage of Poincarésphere(i.e.,-π/4≤X≤4 and-π/2≤ψ≤π/2)and higher-order Poincarésphere can be realized by tailoring the twist angles.Our findings may open up new avenues for applications in structured light,quantum optics,and twistronics for photons. | Haoye Qin Zengping Su Mengqi Liu Yixuan Zeng Man-Chung Tang Mengyao Li Yuzhi Shi Wei Huang Cheng-Wei Qiu Qinghua Song | 2023 | Light(Science & Applications)2023，12，4： | 0 |
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