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Single Atom Deposition

Biedermann, Grant B.; Chow, Weng W.

We have theoretically and experimentally investigated the possibility of single atom deposition using laser cooled sources. In our theoretical work, we investigated an atom source composed of out-coupling from a Bose-Einstein condensate in a trap. A model was developed for Bose- Einstein-condensate-based devices. To illustrate its application, a 2-well system is studied. The results show interesting and possibly useful differences between operation with coherent (phased-locked) and incoherent (unlocked) population transfer between levels in the two wells. The two modes of operation are governed by an interplay among scattering, energy renormalizations and coupling between wells. In parallel, we have experimentally investigated the possibility of controlled deposition of single cesium atoms onto surfaces using optical tweezers. We have measured the rate limit for translation of single atoms in optical tweezers to be 45 mm/s for stepped translation, and have constructed an apparatus for deposition of single atoms on a sapphire substrate for future work.

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TYPE SAND Report YEAR 2014
OSTIDOI

Investigating the LED's dark side. Novel LED Model Offers New Insights

Compound Semiconductor

Chow, Weng W.

A revolution in lighting is well on its way. Rewind the clock a year or so and the prices of LED bulbs made many shoppers wince. But now it is possible to get a high-quality 60 W equivalent for well under $10, and that’s allowing sales of LED bulbs incorporating chips from the likes of Cree and Philips Lumileds to take off. Although these solid-state bulbs are much more pricey than incandescents, which have largely disappeared from shelves due to legislation, they more than make up for that additional up-front cost with a substantial trimming of the electricity bill. It is a more tricky decision, however, whether it makes more sense to buy an LED bulb or a cheaper compact fluorescent (CFL). In terms of durability, adaptability and environmental impact, the solid-state bulb is the clear winner. But both types of light are similar in the efficiency stakes, and thus the running costs.

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TYPE Journal Article YEAR 2014
OSTI

The Energy Frontier Research Center for Solid-State Lighting Science: Exploring New Materials Architectures and Light Emission Phenomena

Journal of Physical Chemistry C

Coltrin, Michael E.; Subramania, Ganapathi S.; Tsao, Jeffrey Y.; Wang, George T.; Wierer, Jonathan W.; Wright, Jeremy B.; Armstrong, Andrew A.; Brener, Igal B.; Chow, Weng W.; Crawford, Mary H.; Fischer, Arthur J.; Koleske, Daniel K.; Martin, James E.; Rohwer, Lauren E.

Abstract not provided.

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TYPE Journal Article YEAR 2014
OSTIDOI

Single-mode GaN nanowire lasers

Optics Express

Li, Qiming L.; Wright, Jeremy B.; Chow, Weng W.; Luk, Ting S.; Brener, Igal B.; Lester, Luke F.; Wang, George T.

We demonstrate stable, single-frequency output from single, asfabricated GaN nanowire lasers operating far above lasing threshold. Each laser is a linear, double-facet GaN nanowire functioning as gain medium and optical resonator, fabricated by a top-down technique that exploits a tunable dry etch plus anisotropic wet etch for precise control of the nanowire dimensions and high material gain. A single-mode linewidth of ∼0.12 nm and >18dB side-mode suppression ratio are measured. Numerical simulations indicate that single-mode lasing arises from strong mode competition and narrow gain bandwidth. © 2012 Optical Society of America.

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TYPE Journal Article YEAR 2012
ScopusOSTIDOI
Results 51–100 of 183
Results 51–100 of 183