US boffins fire up first silicon laser

A team of US scientists claims to have "made the impossible possible" by creating the world's first directly pumped silicon laser.

The trio of researchers at Brown University, led by engineering and physics professor Jimmy Xu, achieved the feat which has eluded science ever since the first ruby laser was fired up in 1960.

Light emission from silicon has long been considered unattainable because of its crystalline structure. In the past, scientists have chemically altered silicon or smashed it into dust-like particles to generate light emission.

The new laser was tested repeatedly over the course of a year to ensure that it met the classical criteria of a laser, such as threshold behaviour, optical gain, spectral line-width narrowing and self-collimated and focused light emission.

Professor Xu's team achieved its goal by changing the atomic structure of silicon itself. This was accomplished by drilling billions of holes in a small piece of silicon using a nanoscale template. The result: weak but true laser light.

"There is fun in defying conventional wisdom and this work definitely goes against conventional wisdom, including my own," said Professor Xu. However, Professor Xu accepts that currently the "possible is not yet practical".

In order to make his silicon laser commercially viable he explained that it must be engineered to be more powerful and to operate at room temperature, instead of its current working temperature of 200 degrees Centigrade below zero.

Professor Xu pointed out that a material with the electronic properties of silicon and the optic properties of a laser would find uses in the electronics and communications industries, helping to make faster, more powerful computers or fibre-optic networks.

"Every new discovery in science eventually finds an application," he said. " It will just take years of work to develop the technology."

The work was funded by the Defense Advanced Research Projects Agency and the Office of Naval Research.