Optical mode converters are essential for enhancing the capacity of optical communication systems. However, fabrication errors restrict the further improvement of conventional mode converters. To address this challeng...Optical mode converters are essential for enhancing the capacity of optical communication systems. However, fabrication errors restrict the further improvement of conventional mode converters. To address this challenge, we have designed an on-chip TE0–TE1mode converter based on topologically protected waveguide arrays. The simulation results demonstrate that the converter exhibits a mode coupling efficiency of 93.5% near 1550 nm and can tolerate a relative fabrication error of 30%. Our design approach can be extended to enhance the robustness for other integrated photonic devices, beneficial for future development of optical network systems.展开更多
Thousands of orbit tracks of space objects are collected by a radar each day,and many may be from uncatalogued objects.As such,it is an urgent demand to catalogue the uncatalogued objects,which requires to determine w...Thousands of orbit tracks of space objects are collected by a radar each day,and many may be from uncatalogued objects.As such,it is an urgent demand to catalogue the uncatalogued objects,which requires to determine whether two or more un-correlated tracks(UCTs)are from the same object.This paper proposes to apply the Lambert problem to associate two radar-measured orbit tracks of LEO and HEO objects.A novel method of position correction is proposed to correct the secular and short periodic effects caused by the J_2 perturbation,making the Lambert problem applicable to perturbed orbit tracks.After that,an orbit selection method based on the characteristics of residuals solves the multiple-revolution Lambert problem.Extensive experiments with simulated radar measurements of LEO and HEO objects are carried out to assess the performance of the proposed method.It is shown that the semi-major axis can be determined with an error less than 200 m from two tracks separated by 4 days.The true positive(TP)rates for associating two LEO tracks apart by less than 6 days are 94.2%.The TP rate is still at 73.1%even for two tracks apart by 8–9 days.The results demonstrate the strong applicability of the proposed method to associate radar measurements of uncatalogued objects.展开更多
基金Project supported by the National Undergraduate Training Projects for Innovation and Entrepreneurship (Grant No. 5003182007)the National Natural Science Foundation of China (Grant No. 12074137)+1 种基金the National Key Research and Development Project of China (Grant No. 2021YFB2801903)the Natural Science Foundation from the Science,Technology,and Innovation Commission of Shenzhen Municipality (Grant No. JCYJ20220530161010023)。
文摘Optical mode converters are essential for enhancing the capacity of optical communication systems. However, fabrication errors restrict the further improvement of conventional mode converters. To address this challenge, we have designed an on-chip TE0–TE1mode converter based on topologically protected waveguide arrays. The simulation results demonstrate that the converter exhibits a mode coupling efficiency of 93.5% near 1550 nm and can tolerate a relative fabrication error of 30%. Our design approach can be extended to enhance the robustness for other integrated photonic devices, beneficial for future development of optical network systems.
基金support from the National Natural Science Foundation of China(Grant No.41874035)the Natural Science Foundation of Hubei province,China(Grant No.2020CFB396)the Fundamental Research Funds for the Central Universities,China(Grant No.2042021kf0001)。
文摘Thousands of orbit tracks of space objects are collected by a radar each day,and many may be from uncatalogued objects.As such,it is an urgent demand to catalogue the uncatalogued objects,which requires to determine whether two or more un-correlated tracks(UCTs)are from the same object.This paper proposes to apply the Lambert problem to associate two radar-measured orbit tracks of LEO and HEO objects.A novel method of position correction is proposed to correct the secular and short periodic effects caused by the J_2 perturbation,making the Lambert problem applicable to perturbed orbit tracks.After that,an orbit selection method based on the characteristics of residuals solves the multiple-revolution Lambert problem.Extensive experiments with simulated radar measurements of LEO and HEO objects are carried out to assess the performance of the proposed method.It is shown that the semi-major axis can be determined with an error less than 200 m from two tracks separated by 4 days.The true positive(TP)rates for associating two LEO tracks apart by less than 6 days are 94.2%.The TP rate is still at 73.1%even for two tracks apart by 8–9 days.The results demonstrate the strong applicability of the proposed method to associate radar measurements of uncatalogued objects.
