Our research group is working on the development of new quantum devices, especially lasers, and their optimization for systems applications ranging from sensors to optical communications.
Our special focus is currently on Quantum Cascade (QC) lasers, a novel type of semiconductor injection laser based on electronic intersubband transitions in the conduction band of a coupled quantum well heterostructure. Quantum wells are only few atomic layers thick slivers of one type of semiconductor material interleaved with another type of semiconductor, the barrier. Many performance features of the lasers, e.g. their emission wavelength in the mid- to far-infrared, power, or modulation capabilities, are designed into the device by choice of the quantum well and barriers thicknesses. Think ~ 500 quantum wells; think creativity!
Current projects include the development of high temperature, high power QC lasers for sensing of explosives and toxic chemicals. Widely tunable, monolithic and external cavity, QC lasers are being developed for optical sensors in environmental and medical applications. While our group is focused mainly on the development of the lasers, we maintain strong collaborations with many expert spectroscopists in academia, government and industrial labs, who are building sensor systems. Another application of QC lasers is in mid-infrared free-space optical wireless communication. Our team is developing lasers for this purpose, and conducts research into some of the fundamental, physical layer issues of long-wavelength optical wireless communication.
Recently, we have developed a new kind of QC laser, capable of simultaneously acting as pump laser and resonant nonlinear optical medium. We have demonstrated efficient second harmonic generation, and are quickly expanding our efforts to other nonlinear optical effects. We are looking into the development of electronic-Raman QC lasers, as well as difference frequency generation and parametric down-conversion. Our ultimate goal is to generate an efficient non-classical semiconductor light source. In the process, we will also develop detection systems capable of measuring the photon statistics of mid-infrared light. With the development of efficient photon-pair sources, we will venture into the field of applied quantum communication and secure communication.
Aside from the fundamental work on QC lasers, our group is also conducting experimental research on chaotic and quasi-chaotic optical resonators. Our goal is the exploitation of the theoretical concepts of "wave chaos", developed by Prof. Narimanov, OOE, for high impact real-world applications.
Our group's working style is collaborative and open. Expect to work hard, and expect to have a lot of fun, too! Device modeling on the computer, device fabrication in the PRISM facilities, and optical device characterization in our labs take up about the same amount of time (~ 30 %) of the work week, with ~ 10 % reserved for scientific writing etc.
In the future, we are planning to develop a material synthesis effort, centered around III-V and/or group-IV crystal growth, that plays well into our above described projects, and will also open up a wider range of development opportunities for innovative optical quantum devices.