Chen, Y.H. Appl. Phys. B (2009) 95: 757. doi:10.1007/s00340-009-3477-0
The properties and applications of omnidirectional and independently tunable defect modes in fractal photonic crystals containing single-negative materials are demonstrated. The proposed fractal structures can produce as many defect modes as desired by adjusting its structural parameters. The interaction effect between the defect states of such fractal structures is avoided, so the frequency of each defect mode can be tuned independently. Furthermore, these defect modes inside the zero effective-phase gap are insensitive to the incident angle. With perfect transmission, mode controllability and omnidirectional compatibility, these structures open a promising way for designing omnidirectional multichannel filters with specific channels.