Photonic band gaps deliver the goods

It is hard to imagine a better way of transporting light than using an optical fibre. By surrounding a transparent fibre core with a second material that has a lower refractive index, light in the inner core is trapped by total internal reflection. In silica-based optical fibres, light can propagate in this way with low losses over global distances. However, an alternative way of transmitting light was suggested in 1995 by Philip Russell and co-workers (now at the University of Bath) that proposed trapping light in a fibre with a hollow core using a “photonic band gap”. Such fibres might outperform normal optical fibres because light trapped in their hollow core travels through a tenuous gas, rather than a solid glass. Now Charlene Smith and co-workers at Corning Inc in New York have reported a dramatic decrease in the observed optical losses in this new form of fibre (Nature 424 657–659).