Wisconsin Alumni Research Foundation

Information Technology
Information Technology
More Efficient Semiconductor Lasers
WARF: P140047US01

Inventors: Luke Mawst, Dan Botez, Thomas Earles, Jeremy Kirch, Christopher Sigler

The Wisconsin Alumni Research Foundation (WARF) is seeking commercial partners interested in developing quantum cascade lasers that can operate in the desired symmetric mode without the need for phase shifters or complex optics.
Quantum cascade lasers (QCLs) are semiconductor lasers that provide light in the mid- and far-infrared wavelength ranges. They are designed so that the generated light is transverse-magnetic (TM) polarized. They can be made using first-order distributed feedback gratings. While this design provides desirable single-mode emission, the lasers are edge-emitting (i.e., laser light is emitted from a cleaved facet).

To eliminate the need for cleaved facets (which are expensive and complex to manufacture), second-order distributed feedback gratings may be used instead. However, these QCLs generally operate in an antisymmetric longitudinal mode, resulting in a double-lobe, far-field pattern. To achieve a desired single-lobe beam pattern, a phase shifter may be used. Still, problems include inefficiency and low potential for continuous-wave (CW) operation at high output powers.
The Invention
UW–Madison researchers have taken a new approach and developed QCLs configured for symmetric longitudinal mode (single-lobe beams) with no loss in efficiency. Instead of relying on phase shifters, the new lasers work by suppressing undesired antisymmetric longitudinal modes.

The lasers are made of layers of cladding, metal (such as gold or silver) and indium phosphide-based semiconductor material. The interface of the metal and semiconductor layers forms a corrugated, second-order distributed feedback grating, which absorbs the undesired antisymmetric longitudinal modes. This configuration eliminates the need for cleaved facets.
  • Medical imaging
  • Materials processing
  • Remote sensing and infrared countermeasures
  • Free-space optical communications
Key Benefits
  • Increased outcoupling efficiency and high output power CW operation
  • No cleaved facets
  • No phase shifters or complex gratings
  • Easier and cheaper to manufacture
Stage of Development
The new lasers emit single-lobe, far-field beam patterns and a wavelength in the range of about 4 to 5 microns.
Additional Information
For More Information About the Inventors
  • Sigler C., Kirch J.D., Earles T., Mawst L.J., Yu Z. and Botez D. 2014. Design for High-Power, Single-Lobe, Grating-Surface-Emitting Quantum Cascade Lasers Enabled by Plasmon-Enhanced Absorption of Antisymmetric Modes. Appl. Phys. Lett. 104, 131108.
For current licensing status, please contact Jeanine Burmania at [javascript protected email address] or 608-960-9846