Toward Room Temperature Exciton-Polaritonics

Background: Nascent and convergent advances demonstrating polariton transport with new physical phenomena and newly discovered low dimensional optically active materials portends an opportunity to advance the field of polariton physics and engineering into a new paradigm. Exciton-polaritons – mixed eigenstates comprised of light and electron-hole pairs – are typically short-lived excitations common to semiconductors. But in optical microcavities they become the ground state of the system and are stable. These have been utilized to demonstrate a number of possibilities including electrically injected polaritonic lasers and modulators. The promise of exciton-polaritonics is that one may overcome the signal processing speed and efficiency (resistivity) constraints of traditional electronics while maintaining the fabrication and scalability strategies thereof. They can also be controlled both electronically and optically suggesting unique signal processing approaches are possible. Multifunctional input/output regimes involving electron spin, optical polarization, coherence and intensity are possible. In addition, recent research on polaritons in two dimensional materials have shown that device operation at military-level temperatures (up to 85 C) is readily achievable. Two dimensional dichalcogenides such as MoS2, MoSe2, MoTe2, WS2 and WSe2 have very large exciton binding energies on the order of 0.5 eV or more. In addition, cavity polaritons are ripe for unique physical phenomena. Bilayer quantum wells in an optical cavity can support a variety of unique phases of polaritons including polaritons with dipole moments and unique coupling regimes between separate quantum wells. Topologically non-trivial polaritonic states have also been proposed to provide a route to robust transport and interactions. Combining the pursuit of polaritonic engineering and polariton physics with the advances in two-dimensional materials provides a unique scientific opportunity to advance a field of study that can both reveal new physical phenomena and explore opportunities for novel device concepts that function naturally at ambient conditions. 

Objective: The purpose of this MURI, is to discover and systematically explore unique physical phenomena of cavity exciton-polaritons, to illuminate the dynamics of the polaritons, and engineer unique heterostructures to effectively functionalize these phenomena. Particular emphasis should be on the use of materials with very large exciton binding energies (> 0.5 eV) to explore the potential of exciton-polaritonics at ambient conditions. 

Research Concentration Areas: Areas of research may include but are not limited to: (1) theoretical efforts to model and predict exciton-polariton phenomena in a variety of material and heterostructure configurations; (2) synthesis and fabrication of polaritonic structures and optical cavities; (3) studies of the creation, control, and detection of exciton polaritons in those structures; (4) exploration of polariton transport and dynamics, and (5) investigation of the effects of defects, interfaces, and heterostructures on polariton phenomena. 

Anticipated Resources: It is anticipated that awards under this topic will be no more than an average of $1.25M per year for 5 years, supporting no more than 6 funded faculty researchers. Exceptions warranted by specific proposal approaches should be discussed with the topic chief during the white paper phase of the solicitation. 

Research Topic Chiefs:

Dr. Michael Gerhold, 919-549-4357, michael.d.gerhold.civ@mail.mil

Dr. Marc Ulrich, 919-549-4319, marc.d.ulrich.civ@mail.mil