Ultraviolet electroabsorption modulators based on III-nitride quantum wells

Trustees Of Boston University, Boston

Investigators

Abstract

ECCS-0725786 Theodore Moustakas Boston University Intellectual merit: This project is aimed at the development of semiconductor optical modulators operating at ultraviolet wavelengths, a family of devices that is currently quite underdeveloped and that has important applications in areas such as non-line-of-sight free-space optical communications, sensing and spectroscopy, and Q-switched pulsed lasers. Recently the investigators have demonstrated a strong electro-optic response at ultraviolet wavelengths based on the quantum-confined Stark effect in GaN/AlGaN quantum wells. Building on these results, the proposed research will address the quantum-well design and device geometry ? including the development of quasi-waveguide and asymmetric-Fabry-Perot modulators ? to optimize key modulator parameters such as contrast ratio, on-state losses, drive voltage, and bandwidth. In addition the investigators plan to demonstrate electroabsorption modulators based on polarization rotation in A-plane GaN/AlGaN quantum wells, where the large in-plane anisotropy of the crystal structure can be exploited to obtain very large single-pass contrast ratios. Finally, the high-speed properties of these devices will be investigated. Broader impacts: The proposed activities will promote education through the training of students in a wide range of disciplines, including quantum-well engineering, semiconductor epitaxial growth, ultraviolet and high-speed optoelectronic device fabrication and testing. To increase the effectiveness and scope of this program, the involvement of undergraduates and high-school interns will be emphasized. A journal club and associated website are also planned to further contribute to the dissemination and exchange of ideas in the important field of III-nitride optoelectronics. Furthermore, the proposed research will lead to the development of novel devices that will expand the realm of applications of ultraviolet optoelectronics, e.g. for optical communications, spectroscopy, and sensing. More in general, this work will advance the state of knowledge in the area of nitride heterostructures (particularly with regards to the fabrication of quantum wells on non-traditional substrate planes and of distributed Bragg reflectors), thereby benefiting other device applications of these materials.