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New way to make laser-like beams using 1,000 times less power

Press Trust of India  |  Washington 

Scientists led by an Indian-origin researcher have found a more efficient way to make a coherent laser-like beam, paving way for more compact and energy efficient computers in which lasers replace wires.

University of Michigan researchers have made what is believed to be the first polariton laser that is fuelled by electrical current as opposed to light, and also works at room temperature, rather than way below zero.

"It represents a milestone like none the field has seen since the invention of the most common type of laser - the semiconductor diode - in the early 1960s," researchers claim.

This work could advance efforts to put lasers on computer circuits to replace wire connections, leading to smaller and more powerful electronics. It may also have applications in medical devices and treatments and more.

A polariton is part light and part matter. Polariton lasers harness these particles to emit light. They are predicted to be more energy efficient than traditional lasers.

"The new prototype requires 1,000 times less electricity to operate than its conventional counterpart made of the same material," researchers said.

"For the past 50 years, we have relied on lasers to make coherent light and now we have something else based on a totally new principle," said Pallab Bhattacharya, the Charles M Vest Distinguished University Professor of Electrical Engineering and Computer Science at Michigan.

Polariton lasers don't need a lot of start-up energy to excite electrons and then knock them back down.

"The threshold current can be very small, which is an extremely attractive feature," Bhattacharya said.

He and his team paired the right material - the hard, transparent semiconductor gallium nitride - with a unique design to maintain the controlled circumstances that encourage polaritons to form and then emit light.

The beam they demonstrated was ultraviolet and very low power - less than a millionth of a watt. For context, the laser in a CD player is about one-thousandth of a watt.

The research appears in the journal Physical Review Letters.

First Published: Fri, June 06 2014. 17:19 IST