CAREER:Tailoring Phase Change Materials for Nonvolatile Reconfigurable Optical Phenomena

Nontechnical Description Modern technologies increasingly rely on controlling light on a chip for sensing, communications, and computing. A promising class of materials—called optical phase change materials—can be switched between two stable states, each with different optical properties. This switching can dramatically change how the material slows and absorbs light, enabling reconfigurable devices that can remember their settings without using power to hold them. These materials could enable compact, energy-efficient devices. However, they are currently limited by an incomplete understanding of how their internal structure changes during switching and how those changes affect optical performance. As a result, devices are unpredictable. Key metrics such as cyclability, switching energy, and precise property tuning remain suboptimal. The research explores new compositions to precisely control the material’s internal structure and develops automated measurement platforms that rapidly characterize their response as a function of temperature and heating time. The project further explores new phenomena arising from the properties of phase-change materials in photonic structures and devices, as well as their interactions with other quantum materials. These studies establish the foundations needed to make these materials reliable for future photonic technologies. The aim of educational activities is to train the next generation of photonics professionals through mentoring and research. These activities also support transfer students in materials science and engineering. Technical Description This CAREER project aims to advance the field of optical phase change materials through a materials research-focused approach that includes exploring composition, microstructure, properties, and performance. The principal investigator plans to unlock the full potential of optical phase change materials by shifting the focus from empirical devices to scientifically grounded frameworks capable of addressing the most pressing challenges, such as understanding the connection between their microstructure kinetics and optical properties, the reliance on off-the-shelf materials, and a lack of systematic characterization. To achieve this, the principal investigator proposes a closed-loop approach encompassing four main Thrusts: 1. Exploring new compositions using combinatorial sputtering guided by computational modeling, tailoring structural and physical properties like bandgap, thermo-optical coefficients, and complex refractive index, while identifying design principles. 2. Microstructure engineering as a novel optical modulation paradigm. This includes precise, deterministic control of amorphous-crystalline domains using inverse-designed on-chip microheaters to avoid stochastic nucleation and the development of phase change nanocomposites. 3. High-throughput characterization using wafer-scale photonic integrated circuits for automated mapping of the complex refractive index of ultra-thin phase change materials, and on-chip microheaters to generate temperature-time-transition diagrams to fill a significant data gap in the field. 4. Studying optical phenomena enabled uniquely by the properties and microstructure control of phase change materials. These include reconfigurable dielectric screening, breaking and unbreaking parity-time symmetry in photonic devices, and thermo-optical modulation effects. This research ultimately elucidates fundamental properties-processing-performance relationships that drive the field of optical phase change materials towards high-performance devices and applications entirely rooted in solid material principles. 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. NSF Award ID: 2543468 | Program: 01002930DB NSF RESEARCH & RELATED ACTIVIT,01002627DB NSF RESEARCH & RELATED ACTIVIT,01002829DB NSF RESEARCH & RELATED ACTIVIT | Principal Investigator: Carlos Rios Ocampo | Institution: University of Maryland, College Park, COLLEGE PARK, MD | Award Amount: $417,130 View on NSF Award Search: https://www.nsf.gov/awardsearch/show-award/?AWD_ID=2543468 View on Research.gov: https://www.research.gov/awardapi-service/v1/awards/2543468.html