Long Optical Path Lengths by A Compact and Robust Chaotic Optical Multi-Pass Cavity

Web Published:

Princeton Docket # 08-2414


Typical optical gas sensors utilize multipass cells to probe molecular species by absorption spectroscopy.  Existing multipass cells are usually costly, large, and lack robustness, which limits their use for portable systems.  Princeton researchers have designed and fabricated a highly compact and robust optical cavity, which is composed of essentially a single reflective surface formed by two quadrupolar-shaped half-shells that are securely attached to each other.  The cavity can effectively focus the beam when light bounces repeatedly off the cavity surfaces, resulting in a negative Liapunov exponent.  This enables the chaotic multipass cavity to be more robust against vibrations or misalignment of the cavity shells.  The cavity can support an optical path length up to 15.5 meters with limited beam divergence in a 68 cm3 cavity volume.  Thus, this work established a novel design principle for multipass systems that employ a compact single surface to generate long optical paths.



·         Trace gas detection

·         Optical amplifiers

·         Optical delay lines



·         Simple structure

·         High mechanical/temperature stability

·         Low manufacturing cost



D. Qu, Z. Liu and C. Gmachl. A Compact Asymmetric Chaotic Optical Cavity with Long Optical Path Lengths. Applied Physics Letters, vol. 93, p 014101-1-014101-3 (2008).

D. Qu and C. Gmachl. Quasichaotic optical multipass cell. Phys. Rev. A 78, 033824 (2008).

D.Qu and C. Gmachl. Modeling and Design of a Highly Compact Chaotic Cavity for Optical Gas Sensing Applications. Proc. IEEE Sensor. (2007)


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
Dongxia Qu
Claire Gmachl