Researchers have invented a tiny laser -- a thousand times thinner than a single human hair -- that is capable of functioning inside living tissues without harming them, an advance that could improve diagnosis and treatment for neurological disorders like epilepsy.
The laser, developed by researchers at Northwestern and Columbia Universities in the US, is just 50 to 150 nanometres thick.
The study, published in the journal Nature Materials, noted that the laser can fit and function inside living tissues, and could be used to sense disease characteristics in tissues, or in treating deep-brain neurological disorders like epilepsy.
The nanolaser, according to the researchers, is specifically promising for imaging living tissues.
The laser is made mostly of glass, which the researchers said made it biocompatible.
Traditionally, according to the researchers, nanolasers were much less efficient than macroscopic ones, and used shorter wavelengths, such as ultraviolet (UV) light.
"This is bad because the unconventional environments in which people want to use small lasers are highly susceptible to damage from UV light, and the excess heat generated by inefficient operation," said P. James Schuck, co-author from Columbia University's School of Engineering.
But the new laser, they said, can be excited with longer wavelengths of light and emit at shorter wavelengths.
"Longer wavelengths of light are needed for bioimaging because they can penetrate farther into tissues than visible wavelength photons," said Teri Odom, who co-led the research from Northwestern University in the US.
Odom added that shorter wavelengths of light are often desirable at those same deep areas.
"Our nanolaser is transparent but can generate visible photons when optically pumped with light our eyes cannot see," said Odom.
The researchers added that the nanolaser is an optically clean system that can effectively deliver visible laser light at penetration depths that are normally accessible to longer wavelengths.
The new laser, according to the researchers, can operate in extremely confined spaces such as microprocessors, which make it valuable for ultra-fast and low-power electronics.
Odom said that the continuous wave, and low-power characteristics of the new laser could open numerous new applications, especially in biological imaging.
According to Schuck, the new tiny lasers can operate at powers that are orders of magnitude smaller than observed in any existing laser.
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