July 23, 2013
Researchers Demonstrate Leap Forward In Optical Coating Technology
University of Vienna
Although it may not be immediately obvious, the mechanical properties of optical components have a significant impact on the performance of lasers employed in precision sensing applications. Currently, the mechanical damping of such components, and the inherent mechanical fluctuations they generate, present a roadblock to further advancement of ever more precise measurements of time and space. For the past decade, researchers in the precision measurement community have been searching for a solution that allows for the development of high-reflectivity mirrors with simultaneously high mechanical quality. Now an international collaboration of scientists from Vienna, Austria and Boulder, Colorado, USA has demonstrated a novel technology for producing mirrors with a tenfold reduction in mechanical loss. The work, reported in Nature Photonics, represents an entirely new approach for generating high-quality optical coatings, key components of state-of-the art laser systems for precision measurement.
The mirror technology described in the manuscript promises to accelerate progress in the development of narrow linewidth laser sources for use in precision measurement systems, spanning time keeping with optical atomic clocks, as well as fundamental physics research involving precision tests of relativity, cavity quantum electrodynamics, and quantum optomechanics. Moreover, leveraging advanced semiconductor production techniques, there is a clear path to implementing large area crystalline coatings in astronomical endeavors, such as gravitational wave detectors. According to Professor Ye, "The development of highly phase coherent optical sources is a key technology that impacts a vast range of scientific explorations. In our own lab, we are able to demonstrate the most stable optical atomic clock thanks to these narrow linewidth lasers, and the progress is marching on!"
"The collaboration with Jun's group was fantastic," states Garrett Cole, who, along with Wei Zhang, is the lead author on the work. "They not only had the courage to take on an unproven technology, but also the ability to tackle a tremendously difficult task: quickly achieving thermally limited noise performance with their characterization system and verifying the high mechanical quality of our mirrors." Following this initial demonstration, the scientists are already hard at work to further improve the technology. Going forward, they plan to combine their novel coatings with the previously demonstrated single-crystal silicon cavity developed by researchers at JILA and PTB in Braunschweig, Germany (see "The World's Most Stable Laser," September 2012. In combination, an all crystalline cavity (comprising crystalline coatings, substrates, and spacer) would enable world-record stability and hence a new milestone in laser technology.
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