Wisconsin Alumni Research Foundation

Analytical Instrumentation, Methods & Materials
Analytical Instrumentation Methods Materials
Semiconductor Lasers with Doping Gradients in Optical Confinement Areas to Increase Laser Efficiency
WARF: P03391US

Inventors: Dan Botez

The Wisconsin Alumni Research Foundation (WARF) is seeking commercial partners interested in developing a highly efficient, aluminum-free semiconductor laser.
Overview
Current semiconductor lasers are 45 to 50 percent efficient. Lowering the voltage needed for lasing to occur could increase the electrical-to-optical power conversion efficiency significantly.
The Invention
UW–Madison researchers have developed a highly efficient, aluminum-free semiconductor light-emitting source that is particularly suited for high-power diode lasers of one-watt continuous wave (CW) output or higher. This device is grown on a semiconductor substrate and includes, in transverse section, an active region layer containing quantum wells, where the laser light is generated; optical confinement layers on either side of the active region layer; and cladding layers, one that is p-type doped and the other n-type doped, outside the confinement layers. The layers on either side of the active region layer confine the light emitted by the laser to the active region.

What makes this aluminum-free semiconductor device unique is the presence of a doping gradient in the layers surrounding the active region. Doping is heaviest in the confinement layers adjacent to the active region and quantum wells, and decreases toward the cladding layers. This doping profile creates an electric field that significantly increases the transport speed of injected carriers (i.e., electrons and holes), thereby reducing the non-ohmic voltage drop across the core of the device and greatly increasing laser efficiency. In addition, these doping profiles do not introduce a large free carrier absorption (FCA) penalty because the device is aluminum-free.
Applications
  • Telecommunications
  • Fiber optics
  • Laser pumping
Key Benefits
  • Could potentially increase laser efficiency (efficiency of converting electrical to light energy) to 80 percent from the current range of 45 to 50 percent
  • Particularly suited for high power diode lasers of one-watt CW output or higher
  • Doping profile could also be applied to asymmetric transverse waveguides, such as those used in high, single-mode power devices (e.g., ARROW-type lasers)
Additional Information
For More Information About the Inventors
For current licensing status, please contact Jeanine Burmania at [javascript protected email address] or 608-960-9846

WARF