A novel dual-negative-refraction (DNR) effect is studied in two types of normal two-dimensional photonic crystals (2DPCs) with hexagonal lattices. Systematical analyses of the band structures and equifrequency surfaces indicate that the DNR may be realized when the overlapping second and third bands with relatively flat shapes and only a slight separation are available at some frequencies close to the band’s peak of 2DPCs. Further simulations have not only confirmed the DNR and corresponding dual-imaging effects in normal 2DPCs with hexagonal lattices but also revealed some relative rules to the dual images. In particular, the thickness as well the cutoff value at terminations of PCs can strongly influence the performance of dual images and even determine whether the dual images would appear. Moreover, a relatively low working frequency is recommended to minimize the distortion degree of dual images.
© 2012 Optical Society of America
Diffraction and Gratings
Original Manuscript: November 10, 2011
Revised Manuscript: February 28, 2012
Manuscript Accepted: March 5, 2012
Published: May 18, 2012
Liyong Jiang, Hong Wu, and Xiangyin Li, "Dual-negative-refraction and imaging effects in normal two-dimensional photonic crystals with hexagonal lattices," Opt. Lett. 37, 1829-1831 (2012)