This proposal is aimed at: (i) demonstrating a novel THz emitter/source device consisting of orientation patterned (OP) Quasi Phase-matching (QPM) optically nonlinear GaN structures that would be optically pumped by a commercially available high power ultrafast fiber laser, and (ii) establishing a strong foundation at the University of Alabama to enable translation of this THz technology to the marketplace. The proposed approach and device structure consists of designing and implementing a prototype device that yields THz radiation at room temperature when excited by short optical pulses and/or high power CW lasers, with the added benefit of being easily tunable at THz frequencies and able produce coherent THz radiation with narrow bandwidth.
The Broader Impact of the proposed activity stems from the potential of the developed THz source to generate useful non-ionizing Terahertz radiation for medical imaging and, thus, provide an alternative to dangerous x-rays. With the support of the University's Alabama Innovation and Mentoring of Entrepreneur Center, this project will also train and engage students and a postdoctoral researcher in both entrepreneurial thinking and practice. This project will provide a platform for students and the postdoctoral fellow to establish a start-up company to translate the developed THz source technology to the marketplace.
Intellectual merit: The goal of this project is to develop "orientation-patterned quasi-phase-matched" structures based on GaN (a semiconductor material typically used in realizing blue light emitting diodes) that would be suitable to enable a viable high power source for generating Terahertz (THz) electromagnetic waves that operates at room temperature. To generate THz signal, such structures are excited by a compact ultrafast laser emitting at a wavelength of approximately 1550 micrometer (which is the wavelength commonly used in fiber optic based telecommunications and therefore more technologically mature). A deeper fundamental understanding of the optical and electronic characteristics of GaN when traversed by a propagating terahertz wave was gained throughout this project. Methods to achieve orientation-patterning of GaN using AlN and ZrN as intermediate layers were demonstrated. A prototype of GaN based THz source has been investigated. One patent has been filed on the technology associated with this project. Broader impact: The use of electromagnetic waves at terahertz frequencies enables unique opportunities for medical imaging because, unlike x-rays, terahertz radiation is not ionizing, thus not harmful, and exhibits lower scattering. Four undergraduate students (2 Hispanic) were mentored and participated in this project, learning cutting edge Terahertz science and technology as well as entrepreneurship and how to commercialize technology.