Professor CHAN Che Ting (陈子亭)
Department of Physics and William Mong Institute of Nano Science and Technology
The Hong Kong University of Science and Technology
Abstract: Dirac cone physics has generated considerable interest in recent years and Dirac cones can be found in the dispersion of electronic systems such as graphene as well as photonic systems such as photonic crystals, typically at the Brillouin zone boundary. Materials with a zero refractive index also possess amazing wave manipulation characteristics. We demonstrate here that these two seemingly unrelated classes of materials are actually related. We showed that if we can realize a Dirac cone at the Brillouin zone center of a dielectric photonic crystal, the property of the photonic crystal at the Dirac point frequency can in some cases be mapped to a zero refractive index material using effective medium theory. However, achieving a Dirac cone dispersion at the zone center is difficult because the dispersion is generally quadratic at k=0 which excludes the possibility of Dirac cones. Here, we show by theory, simulation and experiment that we can design and realize zone center Dirac cones in photonic/phononic crystals using the principle of accidental degeneracy and materials with such Dirac cones do behave as if they were zero refractive index materials.
Location: 606 Conference Room
Date and time: September 27th, 2011 16:00-17:00
