Physicists claim smallest semiconductor laser
The researchers say the development is a breakthrough for emerging photonic technology with applications from computing to medicine.
"We have developed a nanolaser device that operates well below the 3-D diffraction limit," said Chih-Kang "Ken" Shih, professor of physics at the University of Texas, in a statement. "We believe our research could have a large impact on nanoscale technologies."
Shih and his colleagues reported in this week’s issue of the journal Science the first operation of a continuous-wave, low-threshold laser below the 3-D diffraction limit. When fired, the nanolaser emits a green light. The laser is too small to be visible to the naked eye.
Researchers say miniaturization of semiconductor lasers is key for the development of faster, smaller and lower energy photon-based technologies, such as ultrafast computer chips; highly sensitive biosensors for detecting, treating and studying disease; and next-generation communication technologies. Such photonic devices could use nanolasers to generate optical signals and transmit information, and have the potential to replace electronic circuits. But the size and performance of photonic devices have been restricted by what’s known as the three-dimensional optical diffraction limit, the researchers say.
The new device is constructed of a gallium nitride nanorod that is partially filled with indium gallium nitride, according to the researchers. Both alloys are semiconductors used commonly in LEDs. The nanorod is placed on top of a thin insulating layer of silicon that in turn covers a layer of silver film that is smooth at the atomic level, the researchers said.
According to a statement issued by the University of Texas, Shih’s lab has been developing the material for more than 15. The "atomic smoothness" is the key to building photonic devices that don’t scatter and lose plasmons, which are waves of electrons that can be used to move large amounts of data, according to the statement.
"Atomically smooth plasmonic structures are highly desirable building blocks for applications with low loss of data," Shih said.
Nanolasers like the one developed in Shih’s lab are seen as an important building block for developing chips with fully on-chip communication systems. This would prevent heat build up and information loss that can be associated with passing data between multiple chips.
"Size mismatches between electronics and photonics have been a huge barrier to realize on-chip optical communications and computing systems," said Shangjr Gwo, a professor at National Tsing Hua University in Taiwan, and a former doctoral student of Shih’s.