Simultaneous multi-frequency topological edge modes between one-dimensional photonic crystals Choi, Ka Hei ; Ling, C. W. ; Lee, K. F. ; Tsang, Y. H. ; Fung, Kin Hung Abstract Publication: Optics Letters Pub Date: April 2016 DOI: 10.1364/OL.41.001644 Bibcode: 2016OptL...41.1644C