Highly Power-Efficient Quantum Cascade Lasers with Ultra-Strong Coupling Injection

Web Published:

Princeton Docket # 09-2561


The transport of electrons from the injector ground level to the upper laser level in the active region of a QC laser significantly influences the laser performance.  The stronger the coupling between these two levels, the faster electrons can be transferred into the active region, the better is the performance of the device.  In conventional QC laser designs, the injection barrier between the injector and the active region has the greatest thickness resulting in a tunnel coupling of approximately 4-8meV.  


Princeton researchers have employed a novel "ultra-strong coupling" strategy, by utilizing a much thinner injection barrier, and created an ultra-strong coupling of roughly 20meV, close to the width of intrinsic transition broadening.  The resulting laser is highly power-efficient.  Specifically, the experimental laser achieved 50% power efficiency, while the best previously reported result was 34%.



·         Mid-infrared sensor systems for:

o   Environmental trace gas sensing

o   Medical diagnostics

·         Mid-infrared light source for:

o   Infrared counter-measures

o   Free-space communication



·         High output power

·         High power efficiency

·         Enabling compact, portable, power-efficient, and low-cost systems



P.Q. Liu, A.J. Hoffman, M.D. Escarra, K.J. Franz, J.B. Khurgin, Y. Dikmelik, X.J. Wang, J.Y. Fan, and C.F. Gmachl. ¿Highly power-efficient quantum cascade lasers¿, Nature Photonics 4(2) 95 ¿ 96 (2010)


Principal Investigator

Clair Gmachl, Eugene Higgins Professor of Electrical Engineering and Director of MIRTHE, is the principle inventor for these QC laser technologies.  Her research group is working on the development of new quantum devices, especially lasers, and their optimization for sensor systems and their applications in environment and health.  Among the numerous honors Professor Gmachl has received are Election to Austrian Academy of Sciences as Corresponding Member Abroad (2008), MacArthur Fellow (2005), and Popular Science Magazine's list of Brilliant 10 (2004).


Intellectual Property status

Patent protection is pending.

Patent Information:
For Information, Contact:
John Ritter
Princeton University
Qiang Liu
Anthony Hoffman
Matthew Escarra
Kale Franz
Claire Gmachl
Jacob Khurgin
Yamac Dikmelik