THB in emerald slows light to 16 km/s

Dec. 5, 2013
An international team of researchers has induced the “slow-light” phenomenon in emerald via the transient spectral-hole-burning (THB) process.

Researchers from the University of New South Wales (Canberra, Australia), Montana State University (Bozeman, MT), and the National Institute of Chemical Physics and Biophysics (Tallinn, Estonia) have induced the “slow-light” phenomenon in emerald via the transient spectral-hole-burning (THB) process. The group was able to slow light within the emerald down to only 16 km/s. Potential applications include time-resolved spectroscopy, in which spectral-hole widths can be measured as a function of time.

In THB, laser light is used to excite some optical centers in the experimental material from the ground state to an excited state, producing a narrow spectral hole that produces high dispersion at the laser frequency (slow light is often associated with high dispersion). The researchers used a lab-grown pale-green emerald (cooled to 2.2 K) with a path length of 2.5 mm and a polarized external-cavity laser diode emitting at 682.30341 nm, along with a tungsten-halogen bulb, a monochromator, and a photomultiplier tube (PMT) to measure the polarized transmission spectrum. The spectral hole width was measured as a function of time; a pulse delay under a 15.2 mT magnetic field was measured to be 1.54 ±0.2 ns, corresponding to a hole 4.8 ±0.01 MHz wide. Contact Hans Riesen at [email protected].

About the Author

John Wallace | Senior Technical Editor (1998-2022)

John Wallace was with Laser Focus World for nearly 25 years, retiring in late June 2022. He obtained a bachelor's degree in mechanical engineering and physics at Rutgers University and a master's in optical engineering at the University of Rochester. Before becoming an editor, John worked as an engineer at RCA, Exxon, Eastman Kodak, and GCA Corporation.

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