Laser set to carve a nano niche in 3D

US researchers have developed a laser capable of carving materials in 3D on a nanometre scale never achieved before.

The breakthrough will make nanomachining with extraordinary precision as easy as cutting a shape out with scissors, claim the researchers from the University of Michigan.

The laser can carve sharp-edged features down to 20nm in materials, such as quartz, sapphire and silicon, said Alan Hunt, assistant professor at the Department of Biomedical Engineering and an associate director at the Centre for Ultrafast Optical Science.

‘We have a very powerful way to really control the structure on the nanoscale, in a much more direct way than is currently possible. It’s a microscopic milling machine,’ said Hunt.

The potential applications are broad, and will benefit all nanomaterial manufacturing from microelectronics to MEMS (microelectromechanical systems), said Hunt. The US-based researchers hope to apply the technology to microfluidics, or ‘lab-on-a-chip’ technology and intracellular nanosurgery.

Unlike other techniques, such as electron beam lithography, the laser carves in 3D and below the surface if the material is transparent.It works by using femtosecond pulses – blasts of light a quadrillionth of a second long. The beam is focused as small as possible, in the order of a micron, over the area to be cut, either on the surface or within the material. If the pulse energy is set precisely, a smaller, more intense central portion of the spot, like a bullseye on a dartboard, exceeds the required threshold to cut the material. This ensures only a small section of the material is cut.

‘We found we could go far further than the physics predicted. We don’t know what our limits are at this point but so far everything we’ve tried has worked,’ said Hunt.

The smallest cut achieved by the team was just 15nm across – around 100 atoms, he claimed.