Car engines could soon be fired by lasers instead of spark plugs, researchers say. A team at the Conference on Lasers and Electro-Optics will report on 1 May that they have designed lasers that could ignite the fuel/air mixture in combustion engines.

The approach would increase efficiency of engines, and reduce their pollution, by igniting more of the mixture.The team is in discussions with a spark plug manufacturer.

Spark plugs only ignite the fuel mixture near the spark gap, reducing the combustion efficiency, and the metal that makes them up is slowly eroded as they age.

A team from Romania and Japan has now demonstrated a system that can focus two or three laser beams into an engine's cylinders at variable depths.

That increases the completeness of combustion and neatly avoids the issue of degradation with time.However, it requires that lasers of high pulse energies are used; just as with spark plugs, a great deal of energy is needed to cause ignition of the fuel.

"In the past, lasers that could meet those requirements were limited to basic research because they were big, inefficient, and unstable," said Takunori Taira of the National Institutes of Natural Sciences in Okazaki, Japan.

The team has been developing a new approach to the problem: lasers made of ceramic powders that are pressed into spark-plug sized cylinders. Unlike the delicate crystals typically used in high-power lasers, the ceramics are more robust and can better handle the heat within combustion engines.

The team is in discussions to commercialise the technology with Denso, a major automobile component manufacturer.