A major breakthrough in technology for photonic computers

The construction of a logic gate in which the logic state can be changed by a pulse of light instead of applying a voltage can mean the beginning of the end of current electronics and high chance of the Nobel Prize for scientists who developed the new technology.

The essence of the development is a logic switch created through the use of cadmium sulphide nanostructures on silicon substrate.

To make the switch, the scientists used a pair of nanowires; two such switches formed a NAND gate. During the test, pulses of laser light changed the output state in accord with the logic of the gate.
The most difficult and spectacular achievement was the 1,1 -> 0 state, when two "1" input signals resulted in "0" output - one light pulse blanked the other!

The basic switch is made of two nanowires, two such switches form a NAND gate

 Possible combinations of logic states

NAND gates enable realization of all logic functions. The development of "optical" NAND gate may open the way for the construction of advanced integrated circuits, operating with optical signals, instead of electric charges.

The new technology may revolutionize ICT industry. Optical integrated circuits used in photonic computers should use less energy, be almost completely resistant to electromagnetic interference, and - perhaps most important - be much faster.
The introduction of photonic computers will also accelerate the development of optical fiber technology, currently hampered by comparatively expensive and inefficient media converters (from electrical to optical and optical to electrical form).

One of the scientists, professor Ritesh Agarwal, University of Pennsylvania, said that the research brings us closer to "a future where consumer electronics become consumer photonics."

 On-chip laser light source made of CdS nanowire

source: www.upenn.edu

Photonics is a field of science that combines electronics, ICT and optics to develop techniques and devices that use light for information processing. Photonics can be understood as analogous to electronic science, with photons as the basic information carriers, instead of electrons. The origins of this field of science are associated with the invention of laser in 1960, development of the first semiconductor light emitters in the early 1960s, and emergence of fiber optic technology in the mid-1970s.