Northwestern University Researchers Create Nanolaser That Can Change Colors Like A Chameleon

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Getting inspiration from chameleons, a team of researchers at the Northwestern University has created a robust, tunable nanolaser that can change colors.

A nanolaser is a tiny laser with nanoscale dimensions. These lasers can be modulated quickly and, combined with their small footprint, which makes them ideal for on-chip optical computing. Their intense optical fields also enable the enhancement effect in non-linear optics or surface-enhanced-Raman-scattering.

According to Northwestern research team, their new nanolaser is reversible and demonstrates a high sensitivity to strain, thereby making it suitable for use in responsive optical displays in smartphones and televisions, multiplexed optical communication, wearable photonic circuits, and ultra-sensitive sensors that measure strain.

A chameleon can change the color of its skin from turquoise to pink to orange to green by controlling the spacing of nanocrystals on its skin.

The nanolaser developed by the Northwestern research team features periodic arrays of metal nanoparticles on a stretchable, polymer matrix. According to researchers, the nanolaser platform can “preserve its high mode quality by exploiting hybrid quadrupole plasmons as an optical feedback mechanism.” When the matrix stretches, the nanoparticles are pulled farther apart (when it contracts, the nanoparticles come closer together). As a result, the wavelength of the light emitted from the laser changes, thereby changing its color.

Researchers state that increasing “the size of metal nanoparticles in an array can introduce ultrasharp lattice plasmon resonances with out-of-plane charge oscillations that are tolerant to lateral strain.”

“By patterning these nanoparticles onto an elastomeric slab surrounded by liquid gain, we realized reversible, tunable nanolasing with high strain sensitivity and no hysteresis.”

“Chameleons can easily change their colors by controlling the spacing among the nanocrystals on their skin, which determines the color we observe,” said Teri W. Odom (associate director of Northwestern’s International Institute of Nanotechnology), Charles E. and Emma H. Morrison Professor of Chemistry in Northwestern’s Weinberg College of Arts and Sciences.

“This coloring based on surface structure is chemically stable and robust.”

“Hence, by stretching and releasing the elastomer substrate, we could select the emission color at will,” Odom said.

George C. Schatz, Charles E. and Emma H. Morrison served as the corresponding authors of the paper, while Danqing Wang, a graduate student in Odom’s laboratory, served as the paper’s first author.

The detailed findings of the study titled “Stretchable Nanolasing from Hybrid Quadrupole Plasmons,” which was supported by the National Science Foundation and the Vannevar Bush Faculty Fellowship from the U.S. Department of Defense, were published in the journal Nano Letters.