Intersubband All-Optical Switching and Optically-Pumped Light Emission with III-Nitride Quantum Wells

Trustees Of Boston University, Boston

Investigators

Abstract

Intersubband All-Optical Switching and Optically- Pumped Light Emission with III-Nitride Quantum Wells 0622102 Dr. Roberto Paiella Boston University Intellectual merit: Intersubband transitions in semiconductor quantum structures offer several remarkable features for device applications, such as great design flexibility, ultrafast relaxation lifetimes, and large optical nonlinearities. So far they have been primarily employed in mid- and far-infrared optoelectronic devices; however, their basic features are also ideally suited to ultrafast nonlinear optical switching at fiber-optic-communications wavelengths - a key ingredient of future all-optical networking for which no adequate device technology yet exists. A promising material system with large enough conduction-band offsets for near-infrared intersubband transitions is that of GaN/AlGaN quantum wells. The investigators have proposed several novel all-optical-switching techniques based on III-nitride intersubband systems, including the use of coupled quantum wells and Coulomb effects for cross-absorption modulation, polarization switching based on the optical Kerr effect, cross-gain modulation in the presence of optical pumping, and wavelength conversion by Raman scattering. This project will focus on the design, material development, and demonstration of these devices; optically pumped emitters and lasers based on the same platform will also be investigated, as a key step towards the development of near-infrared quantum cascade lasers. Broader impacts: The proposed all-optical switches have the potential for a revolutionary impact in the field of information technology, by enabling the development of ultra-broadband communication networks. Furthermore this project will promote education through the training of students in a variety of disciplines, ranging from epitaxial growth, to quantum engineering, to ultrafast and nonlinear optics, to optical communications. Proposed educational activities include (I) the development of an undergraduate course on quantum mechanics for device engineers, (II) the development of a graduate course on semiconductor quantum structures and photonic devices, (III) the creation of a journal club and associated website on advanced GaN-based devices, and (IV) the engagement and mentoring of students - including undergraduates and high-school interns - in the proposed research. This grant will also provide salary support for a female Ph.D. candidate. Finally, this work will advance the general state of knowledge in the broad area of nitride heterostructure materials and devices.