The first low-energy optical transistor component heralds a new era of 'photonic' technology

Optical circuits use light instead of electricity, making them faster and more energy-efficient than electrical systems. Scientists at Ecole Polytechnique Federale de Lausanne have developed a first building-block for photonic 'transistors' that requires record-low energy to operate. The device is a big step forward in the development and implementation of optical circuits.

Unlike electronic circuits, optical, or "photonic", circuits work with light rather than electricity, which makes them 10 to 100 times faster. They are also more energy-efficient because they show lower heat loss, better signal-to-noise ratios and are less susceptible to interference. Used especially for communications (e.g. fiber optics), optical circuits may use tiny optical cavities as 'switches' that can block or allow the flow of light, similarly to transistors in electronics. EPFL scientists have now fabricated and experimentally tested a silicon-based 'photonic crystal nanocavity' (PCN) that requires an unprecedentedly low amount of energy to operate as a switch. The findings, which have significant implications for the future of optical technologies, are published in a paper that features on the cover of Applied Physics Letters.