NEWS & VIEWS 138 nature photonics | VOL 1 | MARCH 2007 | www.nature.com/naturephotonics

H igh-speed optical communication and signal processing depend increasingly heavily on devices known as optical modulators. Th ese devices impart information to light beams as they zip through kilometres of optical fi bres at the heart of telecommunication and data-sharing networks. When a light wave passes through a modulator, its polarization state, intensity or phase can be changed simply by applying an external electric or magnetic fi eld. Th ese fi elds can be encoded with information ranging from a single telephone conversation to thousands of channels of high-defi nition television programmes