The outcomes of the project include the demonstration of new mode-locking mechanisms in quantum cascade lasers (QCLs) in the mid-infrared spectral range and the explanation of the physical mechanisms that determine the formation of multimode spectra of QCLs and frequency combs.  Its results establish the foundation for a novel and highly promising approach to produce ultrashort pulses and frequency combs in the mid-infrared range and provide new and fundamental understanding of mode competition in QCLs, in order to find ways to engineer these lasers to be broadband mid-infrared frequency combs. Such frequency combs will enable extremely fast chemical detection and identification, which has broad applications in environmental trace gas monitoring, pharmaceutical quality monitoring, and remote detection of explosives or other dangerous substances, to name a few. In the past several years, due to effort by the groups involved in the project and other groups, QCLs have emerged as a potential source of phase-coherent frequency combs and mode-locked pulses, both in the mid-IR and in the terahertz range. The project has also resulted in significant advancement in laser physics and nonlinear optics. A new coherent operation regime of QCLs has been demonstrated, studied and utilized. Therefore, the project results are transformative and have substantially advanced the state-of-the art.

The broader impacts of the project are wide-ranging. Benefits of mid-infrared spectroscopy with QCL frequency combs will be substantial. Such sources are emerging as key elements for many important applications ranging from mid-infrared spectroscopy, remote sensing, and imaging to laser metrology, material processing, laser therapy and laser surgery. The important advances of this project will lead to higher performance, compact, robust QCL solutions for the above applications.

The project has also provided strong enhancement of education and training opportunities in applied physics and engineering. The combination of theoretical studies of laser physics fundamentals, design of laser devices, and experimental effort on device fabrication, testing, and optical measurements offered a unique educational environment for all personnel involved in the project. Knowledge and techniques developed during research was incorporated into courses at TAMU and Harvard and disseminated through publications, conference presentations, and the research groups’ websites. Substantial outreach activity showcasing mid-infrared imaging technology demonstrations was carried out at Texas A&M Physics and Engineering Festivals in 2012-2015, numerous popular lectures for K-12 students and undergraduate students, and high school physics teachers – participants of the Mitchell Institute Physics Enhancement Program at TAMU in 2012-2015. In addition this work had led to the development of industry connections with leading QCL companies, including Daylight Solutions, Thorlabs, and Adtech, as well as MIT Lincoln Labs, all of which are interested in comb operation of QCLs. Collaborations were initiated with the laser spectroscopy group of Nobel Laureate Ted Hänsch at the Max Planck Institute for Quantum Optics (MPQ) in Garching, Germany, with exchanges of students and researchers between Harvard and MPQ. Another highly productive collaboration was established with the European Laboratory of Nonlinear Spectroscopy based in Florence, Italy, which led to joint papers.  The cross-fertilization of knowledge between research groups both academic and industrial, as well as the shared resources pooled by bringing these various groups together, has created important breakthroughs in knowledge, with fruitful collaborations to continue for years to come.

Last Modified: 09/03/2015
Modified by: Alexey A Belyanin