The interaction of light with matter capable of light absorption and emission is of fundamental and long-standing scientific and technological interest. This interaction can be enhanced by using miniature optical cavities made of two mirrors, in which light repeatedly bounces back and forth while traversing the absorbing medium. This structure forms the basis of the laser. Organic dyes, commonly used for making lasers, exhibit particularly enhanced behavior when placed in ultrasmall optical cavities, often exemplified by unusually large color changes. This project addresses nonlinear optical effects in optical cavities smaller than the wavelength of light, in which the aforementioned enhancements are particularly strong. The optical cavities coupled with the special optical materials exhibiting these exceptionally strong interactions can be dynamically controlled, and, as a result, the optical performance of these systems. The phenomena addressed in this project have potential applications in optical information processing and communications, and in such technologies as holographic displays. The graduate and undergraduate students involved in this project are also involved in mentoring and outreach programs for students from underrepresented groups in the inner cities in northeast Ohio.
Ultrastrong coupling between photons and excitons in microcavities containing organic dyes and semiconductors has been recently observed at room temperature. The unusually strong interactions dovetail with the robust nonlinear optical responses of the same materials. This provides a new and promising hybrid material for photonics. This project explores the nonlinear optical properties of organic materials as active elements in nanoscale low-Q optical cavities in the regime of strong and ultrastrong photon-exciton coupling of cavity polaritons. In this regime, the physics of quantum cavity electrodynamics describes significant changes in the spectral dispersion of the composite structure. Contributions to the AC Stark effect is the focus of studies implying particular attention to spectral response of the nonlinear optical interaction and manipulation of the spectrum by varying the cavity resonance, for example, by angle tuning. Well-studied organic glass forming nonlinear optical materials incorporated into metal mirror cavities of low-Q are being investigated, experimentally and theoretically, in a number of cavity configurations to determine their nonlinear optical response for the optical Kerr effect, third harmonic generation and photorefraction.
