Wei, LiuMiroshnichenko, AndreyPoulton, ChristopherXu, ZhiyongNeshev, DragomirSukhorukov, AndreyKivshar, Yuri2015-12-13December 59780977565764http://hdl.handle.net/1885/83614We demonstrate a complete spectral gap based on the coupling between forward and backward modes in a symmetric structure composed of four coupled hollow metallic waveguides.Keywords: Backward modes; Hollow metallic waveguides; spectral gap; Symmetric structures; Optical fibers; Waveguides backward mode; coupling; spectral gap20102016-02-24