July 30, 2012

Scientists Develop World’s Smallest Semiconductor Laser

Lee Rannals for - Your Universe Online

A team of international scientists reported in the journal Science that they have developed the world's smallest semiconductor laser.

This development by physicists in the U.S., Taiwan and China is considered a breakthrough for emergence photonic technology, and it has a range of applications from computing to medicine.

Miniaturizing a semiconductor laser is key for developing faster, smaller and lower energy photon-based technologies, such as ultrafast computer chips.

These types of devices could use nanolasers to help generate optical signals and transmit information.  However, the size and performance of photonics devices have been restricted by the three-dimensional optical diffraction limit.

We have developed a nanolaser device that operates well below the 3-D diffraction limit,” Chih-Kang “Ken” Shih, professor of physics at The University of Texas at Austin, said in a press release. “We believe our research could have a large impact on nanoscale technologies.”

The scientists reported the first operation of a continuous-wave, low-threshold laser below the 3D diffraction limit in their paper.  When this laser is fired, it emits a green light, but it is too small to be visible to the naked eye.

The team developed the device using gallium nitride nanorod, which is partially filled with indium gallium nitride.  Both alloys used in the device are semiconductors commonly used in LEDs.  The nanorod is placed on top of a thin insulating layer of silicon that covers a layer of silver film that is smooth at the atomic level.

They said the "atomic smoothness" of the material is key to building photonic devices that do not scatter and lose plasmons.

“Atomically smooth plasmonic structures are highly desirable building blocks for applications with low loss of data,” Shih said in the release.

Nanolasers could help pave the way for the development of chips where all processes are contained on the chip.  This would prevent heat gains and information loss that is associated with electronic devices that pass data between multiple chips.

“Size mismatches between electronics and photonics have been a huge barrier to realize on-chip optical communications and computing systems,” Shangjr Gwo, professor at National Tsing Hua University in Taiwan and a former doctoral student of Shih´s, said in a press release.