Liquid nanolaser could enable lab-on-a-chip medical diagnostics

Scientists at Northwestern University (Evanston, IL) have developed a liquid nanoscale laser that is tunable in real time, enabling quick and simple production of different colors. What's more, the technology is inexpensive to produce and operates at room temperature, so it could have utility in a new form of a lab-on-a chip for medical diagnostics.

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The liquid nanolaser the researchers developed is not a laser pointer but a laser device on a chip, explains Teri W. Odom, Board of Lady Managers of the Columbian Exposition Professor of Chemistry in the Weinberg College of Arts and Sciences, who led the work. The laser's color can be changed in real time when the liquid dye in the microfluidic channel above the laser's cavity is changed.

The laser's cavity is made up of an array of reflective gold nanoparticles, where the light is concentrated around each nanoparticle and then amplified. (In contrast to conventional laser cavities, no mirrors are required for the light to bounce back and forth.) Notably, as the laser color is tuned, the nanoparticle cavity stays fixed and does not change; only the liquid gain around the nanoparticles changes.

The nanoscale lasers can be mass-produced with emission wavelengths over the entire gain bandwidth of the dye. Thus, the same fixed nanocavity structure (the same gold nanoparticle array) can exhibit lasing wavelengths that can be tuned over 50 nm, from 860 to 910 nm, simply by changing the solvent in which the dye is dissolved.

Full details of the work appear in the journal Nature Communications; for more information, please visit http://dx.doi.org/10.1038/ncomms7939.

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