Bahl wins grant to explore cooling of solids using light

 

MechSE Assistant Professor Gaurav Bahl was recently awarded a Defense University Research Instrumentation Program (DURIP) grant from the U.S. Department of Defense and the Air Force Office of Scientific Research. 

 

The DURIP award will support his work on Raman spectroscopy and the laser cooling of silicon. 

 

Last year, Bahl and his student Yin-Chung Chen proposed theoretically a new method to cool solids using only light, through the Raman scattering mechanism. This DURIP grant helps fund the construction of a fully custom Raman spectrometer, which will allow them to experimentally verify their theoretical predictions.

 

“The ability to extract heat from a solid by simply shining laser light on it is an amazing possibility,” Bahl said. “To date, this can only be achieved in a particular class of highly transparent glasses doped with rare-earth elements, like ytterbium, erbium, thulium, and holmium, and cannot be extended to all materials.”

 

Laser-induced cooling has the advantage of no moving parts, does not use any liquid refrigerants, and is thus highly suited for vibration-sensitive systems and for space-based applications where liquids are impractical.

 

“Additionally, the ability to route light anywhere using optical waveguides and fibers also opens up the amazing possibility of ‘delivering cooling’ where needed,” Bahl said. 

 

One can visualize the heating and ablation of a material when a strong laser beam shines on it. This mental cartoon commonly appears in the form of laser blasters from science fiction shows, or perhaps even more down to earth, the laser-cutting of metal and plastics in modern factories. In contrast, it is uncommon to shine a laser on an object to refrigerate it instead.

 

Although the scientific community involved in laser-cooling research is still quite small, Bahl said he hopes the field will grow larger as fresh ideas are injected – and this award could help. 

 

The DURIP program funds researchers at universities across the country to advance their work in a variety of technical fields—including materials, structures, and manufacturing science; quantum and nanosciences; computing and networks; electronics, electromagnetics, electro-optics; acoustics; neuroscience; fluid dynamics; robotics and autonomous systems; and ocean, environmental, and life sciences and engineering—all under the broad area of defense research. 

 

The highly competitive awards were granted to 176 university researchers at 96 academic institutions that submitted proposals to the three DoD research offices: the Army Research Office, Office of Naval Research, and Air Force Office of Scientific Research.

 

“This grant is a fantastic boost to our group’s research capabilities,” Bahl said. “The equipment, once constructed, will also help improve our measurement capabilities related to other experiments in our group. We hope that our work will help generate a deeper appreciation of the interactions of laser light with matter, and will also offer a very unique training opportunity to the graduate students in our group.”