Nobel Physics Prize - 2009

The Royal Swedish Academy of Sciences has decided to award the Nobel Prize in Physics for 2009 with one half to Charles K. Kao, "for groundbreaking achievements concerning the transmission of light in fibres for optical communication" and the other half jointly to Willard S. Boyle and George E. Smith "for the invention of an imaging semiconductor circuit – the CCD sensor".

Half of the prize is awarded to Charles Kao who made a discovery that led to a breakthrough for fibre-optic communication. Today optical fibres make up the circulatory system that nourishes our information society. Light flows in threads of glass, as thin as a hair, which carries almost all of the telephony and data traffic in each and every direction. Without optical fibres there would be no internet nor broadband. A large share of the traffic is made up of digital images, which constitute the second part of the award. In 1969 Willard S. Boyle and George E. Smith invented the first successful imaging technology using a digital sensor, a CCD (Charge-Coupled Device). The CCD revolutionized photography, as light could now be captured electronically instead of on film.

The image sensor, CCD, is the advanced digital camera's electronic eye. Incoming light releases electrons in the CCD's photocells, the pixels. The more light, the more electrons are collected in the pixels.

The CCD array is read out row by row. Electrons slide off the array onto an electronic conveyor belt and are subsequently translated into digital ones and zeros. This digital form makes it easy to manipulate and transfer the images.

Every pixel is a silicon mini-capacitor built in layers that collects the electrons. A variable electric voltage is used for reading out the pixels. In this simple but ingenious way, almost the entire area of the sensor is used to collect light, creating the high performance of the CCD.