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  5. With second company, laser researchers are seeing new light

With second company, laser researchers are seeing new light

Two professors have formed a startup company to commercialize a nanoscale laser structure that could benefit a wide range of industries. Intraband LLC was co-founded in 2008 by Philip Dunham Reed Professor of Electrical and Computer Engineering Dan Botez and Professor Luke Mawst and has received recent funding from the U.S. Army and Navy Small Business Technology Transfer Programs. Botez and Mawst also have received a grant from the Wisconsin Alumni Research Foundation Accelerator Program, which will support more research toward proving their patented concepts. “We have the ideas and now we’re gradually building toward making these devices a reality,” Botez says.

In the next two years, Botez and Mawst will build a prototype based on their concepts for a novel structure that could yield lasers twice as efficient as current continuous-wave semiconductor lasers emitting in the mid-infrared. These lasers could be used in biomedical devices, environmental monitoring devices, missile avoidance systems and even food packaging processes. This wide range of applications is possible because the researchers have all but eliminated the temperature sensitivity for lasers operating in continuous-wave mode, meaning the laser emits uninterrupted, coherent light.

Mid-infrared semiconductor lasers release most energy as heat rather than light. To overcome this inherent deficiency, researchers have developed a quantum cascade laser structure, where electrons move like a ball falling down a ladder. The “ball” may hit the first couple of steps and emit a quantum unit of light, or photon, each time it falls from one step to the next. Eventually, though, the ball may veer off course and drop off the ladder entirely. This efficiency problem, called carrier leakage, results in heating and poor reliability, which currently is the major barrier to using continuous-wave, quantum-cascade lasers in most industrial applications.

Botez and Mawst have created structures that work more like a set of tiered boxes, with a ball getting caught at each stage of the structure. This ensures the electrons will not fall off the cascade structure, or leak, and thus continue to produce photons efficiently. The new tiered-box structures are called deep-well and tapered-active quantum cascade lasers.

Importantly, Botez and Mawst grow the new structures via a process known as metalorganic chemical vapor deposition, which is suitable for large-scale manufacturing.

Botez and Mawst also are co-founders of the startup Alfalight, and both say this previous experience will help them grow Intraband. “It’s really satisfying to see a concept as a product,” Mawst says.

Sandra Knisely
1/25/2012