The growing demand for complex photonic systems and platforms continues to push for exploring new optical geometries, concepts and material systems to achieve sophisticated and unprecedented functionalities. These, on the other hand, require a deeper understanding and precise control of the interaction of light with material. One particular research activity of great interest to modern technology, enabling applications in computing, communication, sensing and detection, and bio-imaging, is the development of efficient coherent light sources that can provide emission at wavelengths beyond those obtained by conventional lasers. Nonlinear wave-mixing processes, by which light of different colors can intermix to produce new colors, are often the strategy pursued. The implementation of these nonlinear light sources requires stringent physical conditions dictated by the conservation of photon momentum. This poses serious limitations on the design and, to date, impede the utilization of many highly nonlinear materials such as semiconductors as nonlinear light sources. This project will explore theoretically and experimentally novel strategies to overcome these difficulties by engineering the optical losses in the photonic structures to control the nonlinear wave-mixing process, creating irreversible energy conversion from input photons (pump photons) to signal photons with the desired wavelength (color). This will enable the practical implementation of new chip-scale light sources toward applications in healthcare, information technology and sensing. Synergistically, this project includes outreach activities aiming at increasing the diversity and talent pool of future scientists and engineers in photonics. The team will organize participatory activities, lab open houses, and research training opportunities for graduate, undergraduate, and high school students, with a focus on students from underrepresented groups.
Part 2: The proposed research will develop an integrated theoretical and experimental platform for developing efficient nonlinear light sources via spectral and spatial engineering of optical losses in wave-mixing processes. Loss engineering enables non-Hermitian phase matching by removing the idler component produced in the process, and thus allowing the use of highly nonlinear materials that do not lend themselves easily to Hermitian phase-matching. This also allows the nonlinear process to take place in such materials without stringent waveguiding, dispersion engineering or quasi-phase matching criteria. The approaches in pursuit of this goal are: 1) Developing a theoretical model and platform to study the impact of loss engineering on the dynamics and efficiency of nonlinear wave-mixing process; 2) Investigating design strategies and experimental techniques to controllably introduce asymmetric loss and gain profiles for wave-mixing; and 3) Demonstrate optical parametric amplification and efficient nonlinear light sources in waveguides and resonators by loss engineering. The structure of non-Hermiticity and its effects on optical processes, if properly understood and controlled, will present an exciting opportunity to explore novel photonic devices and light sources.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
