Molecular Photonics in the Strong Coupling Regime

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Light-matter interaction is at the heart of most optical phenomena that we are familiar with such as absorption, emission and scattering. We normally treat these by assuming that light does not significantly modify the underlying electronic states of the material it interacts with. The extreme case where light-matter interaction is so strong that this assumption fails has been coined the strong coupling regime. In this regime, new half-light, half-matter quasiparticles called polaritons emerge. In thin films of organic semiconductors--the same class of materials used in display technologies and low-cost solar cells--polaritons can readily form at room temperature. This Program will study collective quantum phenomena in the strong-coupling regime. It will focus on two distinct regimes, where fascinating physics occur. First, at high densities, polaritons can form a macroscopic quantum state termed a Bose-Einstein condensate. We will engineer a novel type of polariton condensate, based on open-shell molecules that will allow for magneto-optical effects to emerge. In addition, we will use lattices of polariton condensates to simulate a complex phenomenon known as many-body localization. This will allow us to gain further understanding of the barrier between quantum and classical physics. Second, at low densities, the emergence of strong light-matter coupling can modify molecular processes that occur within or between organic molecules. The extent to which these processes can be modified depends strongly on the number of molecules per optical mode in the system. We will investigate modifications of two processes directly relevant to increasing the efficiency of organic light-emitting diodes: reverse intersystem crossing and triplet-triplet annihilation. By engineering nanoscale optical cavities, we will reach a regime where the rates for these processes can be significantly enhanced. The findings from this Program will have direct applications in sensing, optoelectronics and our ability to simulate complex quantum systems. At completion, the Program will have trained 3 PhD, 2 MSc and 5 undergraduate students with a broad skill set in photonics, semiconductor science, quantum technologies and nanofabrication highly needed to support priority areas in Canada's technology industry.