Engineers 'lose' to reap laser gains

Engineers at Washington University in St. Louis have shown a new way to reverse or eliminate energy loss in optical systems by, ironically, adding loss to a laser system to actually reap energy gains.

In other words, they have invented a way to win by losing.

Energy loss in optical systems such as lasers is a chief hindrance to their performance and efficiency and it occurs on an ongoing, frustrating basis.

To help laser systems overcome loss, operators often pump the system with an overabundance of photons or light packets to achieve optical gain.

"But the beauty of this work is in how we came to provide new schemes and techniques to engineer a physical system by controlling loss," said Lan Yang, associate professor in electrical and systems engineering.

Light intensity is a very important parameter in optical systems.

New research provide a new route to increase light intensity by modulating loss in the system.

"Instead of the standard method of adding more energy into the system, we are offering a more energy-efficient method," he added.

"Too much of something can be really detrimental. If you pump in more energy to get more laser intensity, and it's too strong, you can get a sudden drop in the laser performance," concluded research scientist Sahin Kaya Ozdemir.

In addition to lasing improvements, the findings could lead to new schemes and techniques for controlling and reversing the effects of loss in various other physical systems, such as in photonic crystal activities, plasmonic structures and meta-materials.

The results were published in the journal Science.