Femtosecond （fs） cylindrical vector beams （CVBs） have found use in many applications in recent years. However, the existing rigid generation methods seriously limit its development. Here, we propose a flexible met...Femtosecond （fs） cylindrical vector beams （CVBs） have found use in many applications in recent years. However, the existing rigid generation methods seriously limit its development. Here, we propose a flexible method for generating fs-CVBs with arbitrary polarization order by employing half wave plates and vortex retarders. The polarization state, autocorrelation width, pulse width, and spectrum features of the input and generated CVB pulses are measured and compared. The results verify that the generated CVBs remain in the fs regime with no appreciable temporal distortion, and the energy conversion efficiency can reach as high as 96.5%, even for a third-order beam. As a flexible way to generate fs-CVBs, this method will have great significance for many applications.展开更多
A cross-shaped photonic crystal waveguide formed by a square lattice Al_2O_3 rods array is numerically and experimentally investigated. The band gap of the TE mode for the photonic crystals and transmission characteri...A cross-shaped photonic crystal waveguide formed by a square lattice Al_2O_3 rods array is numerically and experimentally investigated. The band gap of the TE mode for the photonic crystals and transmission characteristics of waveguides are calculated by the plane wave expansion method and the finite element method.We perform the experiments in the microwave regime to validate the numerical results. The measured reflection and transmission characteristics of the photonic crystals show a large band gap between 8.62 and 11.554 GHz（relative bandwidth is 29.34%）. The electromagnetic waves are transmitted stably in the waveguides, and the transmission characteristics maintain a high level in the band gap.展开更多
A novel H-plane cross-shaped circulator based on magneto-photonic crystals is experimentally investigated.The band gap of the TE mode for the photonic crystals is calculated by the plane wave expansion method.The tran...A novel H-plane cross-shaped circulator based on magneto-photonic crystals is experimentally investigated.The band gap of the TE mode for the photonic crystals is calculated by the plane wave expansion method.The transmission characteristics of the circulator are simulated by the finite element method.We perform the experiments in the microwave regime to validate the numerical results.At the central frequency of 10.15 GHz,the measured isolation and insertion loss of the circulator reaches-30.2 and-3.93 d B,respectively.The bandwidth of the circulator is about 550 MHz.The optimal experimental value of isolation is higher than the numerical value.展开更多
基金supported by the National Natural Science Foundation of China(Nos. 61138003, 61427819, 61422506, 61605117, and 61605142)the Science and Technology Innovation Commission of Shenzhen(Nos. KQCS2015032416183980, KQCS201532416183981, and JCYJ20140418091413543)+5 种基金the start-up funding at Shenzhen Universitysupport given by the Leading Talents of Guangdong Province Program(No. 00201505)the Natural Science Foundation of Guangdong Province(No. 2016A030312010)support of Natural Science Foundation of Guangdong Province(No. 2016A030310063)the Project 2016032 supported by the SZU R/D Fundthe Open Fund of the Key Laboratory of Optical Information Science & Technology(Nankai University)
文摘Femtosecond （fs） cylindrical vector beams （CVBs） have found use in many applications in recent years. However, the existing rigid generation methods seriously limit its development. Here, we propose a flexible method for generating fs-CVBs with arbitrary polarization order by employing half wave plates and vortex retarders. The polarization state, autocorrelation width, pulse width, and spectrum features of the input and generated CVB pulses are measured and compared. The results verify that the generated CVBs remain in the fs regime with no appreciable temporal distortion, and the energy conversion efficiency can reach as high as 96.5%, even for a third-order beam. As a flexible way to generate fs-CVBs, this method will have great significance for many applications.
基金supported by the National Natural Science Foundation of China under Grant No.61171006
文摘A cross-shaped photonic crystal waveguide formed by a square lattice Al_2O_3 rods array is numerically and experimentally investigated. The band gap of the TE mode for the photonic crystals and transmission characteristics of waveguides are calculated by the plane wave expansion method and the finite element method.We perform the experiments in the microwave regime to validate the numerical results. The measured reflection and transmission characteristics of the photonic crystals show a large band gap between 8.62 and 11.554 GHz（relative bandwidth is 29.34%）. The electromagnetic waves are transmitted stably in the waveguides, and the transmission characteristics maintain a high level in the band gap.
基金supported by the National Natural Science Foundation of China under Grant No.61171006
文摘A novel H-plane cross-shaped circulator based on magneto-photonic crystals is experimentally investigated.The band gap of the TE mode for the photonic crystals is calculated by the plane wave expansion method.The transmission characteristics of the circulator are simulated by the finite element method.We perform the experiments in the microwave regime to validate the numerical results.At the central frequency of 10.15 GHz,the measured isolation and insertion loss of the circulator reaches-30.2 and-3.93 d B,respectively.The bandwidth of the circulator is about 550 MHz.The optimal experimental value of isolation is higher than the numerical value.
