17 Jun 2002
A tiny solid-state laser, operating at the 1.3 micron wavelength, promises to reduce the cost of high-speed fiber optics connections. It developers claim it is the first of its kind: an electrically-pumped vertical cavity surface emitting laser (VCSEL) grown on a gallium arsenide substrate.
Working through a cooperative research and development agreement (CRADA)with Cielo Communications, Inc., Albuquerque-based Sandia National Laboratories developed the gallium arsenide-based VCSEL, which will be cheaper and easier to build than standard edge emitting lasers used in current high-speed communications. Sandia is a Department of Energy lab managed by Lockheed Martin Corpz.
"This VCSEL will meet the needs of high speed fiber optics connections of the future," says Peter Esherick, manager of the Compound Semiconductor Materials and Processes Department at Sandia. "We expect there to be great excitement over the device - fueled by the rapid expansion of Internet use and craving for faster Internet access."
The new VCSEL is made mostly from stacks of layers of semiconductor materials common in shorter wavelength lasers -aluminum gallium arsenide and gallium arsenide. The Sandia team added to this structure a small amount of the new material, indium gallium arsenide nitride (InGaAsN), which was initially developed by Hitachi of Japan in the mid 1990s. The InGaAsN causes the VCSEL's operating wavelength to fall into a range that makes it useable in high-speed Internet connections.
Esherick says laboratories around the world have been in a "horserace to be the first with the 1.3 micron VCSEL on gallium arsenide substrates." Cielo teamed with Sandia through a CRADA last year to research several compound semiconductor alloys in an effort to find the one that achieved the 1.3 micron goal. In May, Sandia researchers came up with a materials combination and materials growth technique that hit the target. The research findings were submitted to Electronic Letters for publication.
In the VCSEL, laser photons bounce between mirrors grown into the structure and then emit vertically from the wafer surface. VCSELs, which are grown by the thousands on a single wafer, have significant advantages over edge-emitting lasers in the areas of lower manufacturing, packaging, alignment, and testing costs, as well as lower power dissipation and higher reliability.