title: Highly compact circulators in square-lattice photonic crystal waveguides.
abstract: We propose, demonstrate and investigate highly compact circulators with ultra-low insertion loss in square-lattice- square-rod-photonic-crystal waveguides. Only a single magneto- optical square rod is required to be inserted into the cross center of waveguides, making the structure very compact and ultra efficient. The square rods around the center defect rod are replaced by several right-angled-triangle rods, reducing the insertion loss further and promoting the isolations as well. By choosing a linear-dispersion region and considering the mode patterns in the square magneto-optical rod, the operating mechanism of the circulator is analyzed. By applying the finite-element method together with the Nelder-Mead optimization method, an extremely low insertion loss of 0.02 dB for the transmitted wave and ultra high isolation of 46 dB∼48 dB for the isolated port are obtained. The idea presented can be applied to build circulators in different wavebands, e.g., microwave or Tera-Hertz.
authors.affiliation: THz Technical Research Center, Shenzhen Key Laboratory of Micro-nano Photonic Information Technology, College of Electronic Science and Technology, Shenzhen University, 518060, Shenzhen, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Jin
authors.affiliation: THz Technical Research Center, Shenzhen Key Laboratory of Micro-nano Photonic Information Technology, College of Electronic Science and Technology, Shenzhen University, 518060, Shenzhen, China.
authors.forename: Zhengbiao
authors.initials: Z
authors.lastname: Ouyang
authors.affiliation: THz Technical Research Center, Shenzhen Key Laboratory of Micro-nano Photonic Information Technology, College of Electronic Science and Technology, Shenzhen University, 518060, Shenzhen, China.
authors.forename: Qiong
authors.initials: Q
authors.lastname: Wang
authors.affiliation: THz Technical Research Center, Shenzhen Key Laboratory of Micro-nano Photonic Information Technology, College of Electronic Science and Technology, Shenzhen University, 518060, Shenzhen, China.
authors.forename: Mi
authors.initials: M
authors.lastname: Lin
authors.affiliation: THz Technical Research Center, Shenzhen Key Laboratory of Micro-nano Photonic Information Technology, College of Electronic Science and Technology, Shenzhen University, 518060, Shenzhen, China.
authors.forename: Guohua
authors.initials: G
authors.lastname: Wen
authors.affiliation: THz Technical Research Center, Shenzhen Key Laboratory of Micro-nano Photonic Information Technology, College of Electronic Science and Technology, Shenzhen University, 518060, Shenzhen, China.
authors.forename: Jingjing
authors.initials: J
authors.lastname: Wang
mesh_terms: D017076:Computer-Aided Design; D003460:Crystallization; D020342:Finite Element Analysis; D017785:Photons