This is an illustration of the nanoscale semiconductor structure used for demonstrating the ultra-low-threshold nanolaser. A single nanorod is placed on a thin silver film (28 nm thick). The resonant electromagnetic field is concentrated at the 5-nm-thick silicon dioxide gap layer sandwiched by the semiconductor nanorod and the atomically smooth silver film. Credit: Science
at The University of Texas at Austin, in collaboration with colleagues
in Taiwan and China, have developed the world’s smallest semiconductor
laser, a breakthrough for emerging photonic technology with applications
from computing to medicine.
The scientists report their efforts in this week’s Science.
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.
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
have developed a nanolaser device that operates well below the 3D
diffraction limit,” said Chih-Kang “Ken” Shih, professor of physics at
The University of Texas at Austin. “We believe our research could have a
large impact on nanoscale technologies.”
the current paper, Shih and his colleagues report the first operation
of a continuous-wave, low-threshold laser below the 3D diffraction
limit. When fired, the nanolaser emits a green light. The laser is too
small to be visible to the naked eye.
device is constructed of a gallium nitride nanorod that is partially
filled with indium gallium nitride. 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.
Physics graduate student Charlotte Sanders’ research with professor Ken Shih helped develop the world’s smallest nanolaser. She stands here with a molecular beam epitaxy machine that she designed and built in collaboration with the Department of Physics Machine Shop and with assistance from co-author Dr. Jisun Kim. The machine is used to create a smooth silver thin film critical to the function of the laser. Credit: Alex Wang
a material that the Shih lab has been perfecting for more than 15
years. That “atomic smoothness” is 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.
“Atomically smooth plasmonic structures are highly desirable building blocks for applications with low loss of data,” said Shih.
such as this could provide for the development of chips where all
processes are contained on the chip, so-called “on-chip” communication
systems. This would prevent heat gains and information loss typically
associated with electronic devices that pass data between multiple
mismatches between electronics and photonics have been a huge barrier
to realize on-chip optical communications and computing systems,” said
Shangjr Gwo, professor at National Tsing Hua University in Taiwain and a
former doctoral student of Shih’s.
Source: University of Texas at Austin