Masters of Light Garner Nobel

Three “masters of light” considered the fathers of fiber optics and digital imaging were honored today with the 2009 Nobel Prize in Physics by the Royal Swedish Academy of Sciences.

Charles K. Kao received half of the $1.4 million prize for his discovery that led to a breakthrough in fiber optics.

As early as the 1920s scientists were researching how to guide light through glass fibers for image transmission, with the motivation being medicine (gastroscope), defense (flexible periscope, image scrambler) and even early television. The problem was that the glass fibers available were leaky and didn’t transmit much light. Also, each time the fibers touched each other, or when the surface of the fibers was scratched, light was led away from the fibers.

At the beginning of the 1950s, it was discovered that cladding the fibers would help light transmission by facilitating total internal reflection. The invention of the laser in the 1960s provided an ideal light source for optical communication, but the fiber itself was poor – only 1 percent of light got transmitted in 20 meters of fiber.

Kao’s 1966 breakthrough was in discovering that the fiber needed to be made of a higher purity glass, with single-mode fibers presented as the best transmission medium. Kao pointed to fused silica as the material having the purity required, but the problem was that the material has a high melting temperature, and its fabrication and manipulation were not easy.

Most labs first tried to draw fibers using other types of glass, without much success, but then in 1970 Corning succeeded in making low-loss fused silica fibers using chemical vapor deposition. They doped titanium in the fused silica core and used pure fused silica in the cladding.

Other advances over the years have led to modern optical fibers with more than 95 percent light left after 1 km propagation. Today, optical fibers facilitate global broadband communication by carrying almost all telephone and data – text, music, images and video – traffic.

“The Nobel has never been given out for applied sciences before. This is very, very unexpected,” Kao was quoted as saying after the announcement. “Fiber optics has changed the world of information so much in these last 40 years. It certainly is due to the fiber optical networks that the news (of the award) has travelled so fast.”

If all of the glass fibers that wind around the globe were unraveled, the result would be a single thread more than 1 billion kilometers long – enough to encircle the globe more than 25,000 times – and is increasing by thousands of kilometers every hour, the academy said in awarding the prize.

Kao, a British and US citizen, served as director of engineering at Standard Telecommunication Laboratories in Harlow, England, and vice chancellor at the Chinese University of Hong Kong, before retiring in 1996.

Splitting the other half of the award are Willard S. Boyle and George E. Smith, Bell Laboratories inventors of the first successful imaging technology using a digital sensor, a charge-coupled device (CCD), which eliminated the need to capture images on film. The CCD is a silicon plate about the size of a stamp that holds millions of photocells sensitive to light.

When they first started brainstorming their CCD idea in the lab in 1969, their intent was to fulfill Bell Labs’ desire that they create better electronic memory. Instead, they created an indispensable part of modern imaging technology. Boyle and Smith revolutionized photography by exploiting the photoelectric effect, through which light is transformed into electric signals. (Albert Einstein received the Physics Nobel in 1921 for his theories on photoelectric effect.)

Smith, a US citizen, took out 30 patents during his time at Bell Labs (1959-1986) and served as head of the VLSI Device department.

Boyle, a Canadian and US citizen, who began working at Bell Labs in 1953, had many important discoveries under his belt by the time he helped develop CCD as executive director of the communication sciences division, such as the first continuous red light laser. In the 1960s he was among the scientists who worked to put a man on the moon in July 1969. Boyle retired from Bell Laboratories in 1979.

Bell Labs researchers Willard Boyle (left) and George Smith (right) are shown in 1974 with the charge-coupled device (CCD), which transforms patterns of light into useful digital information and is the basis for many forms of imaging, including camcorders and satellite surveillance. (Photo: Alcatel-Lucent/Bell Labs)

In 1970, about a year after their invention, Smith and Boyle demonstrated a CCD in a video camera for the first time. In 1972, Fairchild Semiconductor constructed the first image sensor with 100 x 100 pixels, which entered production a few years later. In 1975, Boyle and Smith themselves constructed a digital video camera of a sufficiently high resolution to manage television broadcasts.

It would not be until 1981 before the first camera with built-in CCD appeared on the market. Five years later, in 1986, the first 1.4-megapixel image sensor (1.4 million pixels) arrived, and in 1995 the first fully digital photographic camera appeared. Camera manufacturers around the world quickly caught on, and soon the market was flooded with ever smaller and cheaper products.

Not only is Boyle and Smith's CCD technology used today in photography, but it is also considered an irreplaceable tool in many fields of research, including medical imaging and astronomy. Images from the Hubble space telescope would not be possible without the CCD.

During a news conference held to announce the award, Boyle said via telephone that imaging other planets was the greatest achievement of his work. "We saw for the first time the surface of Mars. It wouldn't have been possible without our invention," he said.

Lately the CCD has been challenged by another technology, CMOS, invented at about the same time. Both make use of the photoeffect, but while the electrons gathered in a CCD march in line in order to be read out, every photocell in a CMOS is read out on site. CMOS consumes less energy so batteries last longer, and has also been less expensive, but with its higher noise levels and loss of image quality it is not sufficiently sensitive for many advanced applications. It is used in photography, such as in cell phones.

Three years ago, CCD breached the limit of 100 megapixels, and although the image quality is not only dependent on the number of pixels, surpassing this limit is seen to have brought digital photography a further step into the future. There are those that predict that the future belongs to CMOS rather than to CCD, but others maintain that the two technologies will continue to supplement each other for a long time.

The Nobel will be presented Dec. 10 at a ceremony in Stockholm.

For more information, visit: http://nobelprize.org