Nanolaser makes photonic computers possible

German researchers take first steps to produce cost effective optical components

Researchers at the Technical University of Munich have developed a laser one thousand times thinner than a human hair, which they say will be used to make faster and more efficient optical computers in the future.

According to Professor Jonathan Finley, Director of the Walter Schottky Institute at Technical University of Munich (TUM), the miniaturization of electronics is reaching its physical limits.

He said: “Today transistors are merely a few nanometers in size. Further reductions are horrendously expensive. Improving performance is achievable only by replacing electrons with photons, i.e. particles of light.”

Although the first silicon-based photonics chips already exist, the sources of light for the transmission of data must be attached to the silicon in a complicated manufacturing processes.

TUM’s “nanolaser” is transmitted through a gallium arsenide “nanowire” grown on a silicon chip. The production process evaporates a 200 nanometre thick layer of silicon oxide onto the silicon into which tiny holes are etched. The semiconductor nanowires are then grown atom by atom out of the holes.

The process avoids the defects that usually occur because of the different lattice parameters and coefficients of thermal expansion the materials possess. A patent for the technology is pending.

The gallium arsenide nanowire lasers produce infrared light at a predefined wavelength and under pulsed excitation. “In the future we want to modify the emission wavelength and other laser parameters to better control temperature stability and light propagation under continuous excitation within the silicon chips,” said Finley.

The next goal for the team is to create an electric interface for the nanowires to they can be operated under under electrical injection instead of relying on external lasers.

“The work is an important prerequisite for the development of high-performance optical components in future computers,” adds Finley. “We were able to demonstrate that manufacturing silicon chips with integrated nanowire lasers is possible.”