CAREER: Photonics in the Lowest Symmetry Crystals

PART 1: NON-TECHNICAL SUMMARY Controlling the properties of light is critical for creating advanced technologies such as laser imaging, optical biosensors, and quantum optics. These technologies all use carefully prepared light waves to effectively measure or communicate with the world around us. An important part of developing these technologies is developing compact and efficient components which control both direction and orientation of the light. The capabilities of each component are critically determined by the materials used in their construction, and how light interacts with these materials. Notably, by using unconventional materials, scientists can generate new types of light propagation, and make optical components both smaller and more efficient. In this project, the research team will determine how certain classes of crystals can be used to control both direction and orientation of light waves. By coupling light to a class of crystals having a parallelepiped structure, it becomes possible to engineer a unique light-matter interactions not seen in materials with simpler structures. By performing these studies, the principal investigator and team will discover new design paradigms for creating optical components exploiting this class of crystals. A key part of this is developing educational tools which can be used to educate the future photonics workforce on how these materials work and can be utilized. We will specifically work with two different groups – middle school and junior undergraduate students, which typically receive limited education on photonics and the impact on modern technologies. In the former case, we will work closely with middle-school teachers to develop a series of lesson plans to target curriculum relevant skills, including concepts in photonics. Our work with junior undergraduates will then build on this, introducing research-like projects into the curriculum to build key analysis skills required for the future quantum and semiconductor workforces. Those efforts will be distributed online, which will allow teachers nationally to access resources developed as part of this program. PART 2: TECHNICAL SUMMARY The research focuses on understanding how light can propagate in crystals with low crystalline symmetry. Coupling light to materials with inherently low symmetry produces shear polaritons, a phenomenon that can enhance a specific range and orientation of wave vectors; this is not possible in more conventional materials. Similarly, shear polaritons can offer control over the polarization state, including the potential to realize photons with high angular orbital momentum. This wave vector selectivity offers insensitivity to scattering, which would enable the development of high-efficiency devices. However, there is a clear and critical need to better understand the materials in which these form, to leverage their unique chiral properties for photonics with control over directionality and polarization. This study is designed to provide a framework for identifying materials that produce strong shear phenomena, as well as determining how they can be applied in developing future photonic technologies. The utilization of natural crystal systems reduces the requirements for complex nanostructure designs, reducing the cost associated with the new phenomena. The team envision the creation of light sources through long-wave infrared range that emit with high directionality linear, circular, or vortex polarized beams, in the absence of external optics. This will be achieved over three objectives. (i) Create a framework for understanding polariton propagation and scattering in the lowest symmetry crystals, (ii) Demonstrate polaritonic emission in low symmetry excitonic materials for asymmetric photoemission, (iii) Enhance photonic materials education toward the goal of developing a future quantum workforce. By the end of these objectives, the team will have understood the key material and optical properties, which will enable development of technologies based on the unique properties of shear polaritons. This project is jointly funded by the Electronic and Photonic Materials (EPM) program and the Established Program to Stimulate Competitive Research (EPSCoR). 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.