Ultra-low-loss on-chip zero-index materials

Zero-index media: ultra-low loss Calculations suggest that a new design of engineered medium can simultaneously yield a refractive index of zero and low optical loss at the telecommunications wavelength of 1550 nm. The development could lead to applications in nonlinear and quantum optics benefiting from an infinite coherence length. The approach of Tian Dong and coworkers from China and the US is to embed an array of silicon pillars (about 180 nm in radius and 1100 nm high) into a matrix of silicon dioxide to create a Dirac-cone photonic-crystal slab. Importantly, if the pillar height is chosen correctly any upwards and downwards radiation out of the slab can be made to destructively interfere thus reducing propagation loss to a level of 0.15 dB/mm. The slab should be possible to fabricate using standard processes.