Presentation: Lucem sequimur: Light-matter interaction from the photon perspective
Light is more than a tool for perception - it is the fundamental medium through which we interrogate the physical world, from nanometric structures to the farthest reaches of the cosmos. It also underpins much of modern technology, from global telecommunications and biomedical imaging to emerging optical and photonic computing architectures. In this discussion, we follow the light. Rather than adopting the traditional material-centric view of light–matter interaction, we take a complementary perspective and ask what becomes possible, when the properties of the photon itself, its energy, momentum and spatial extent become the variables we engineer. First, we exploit photon energy. We demonstrate how previously underutilized nondegenerate multiphoton processes can be repurposed to enable efficient broadband optical detection spanning multiple spectral octaves using conventional semiconductor detectors. This approach has enabled a range of new capabilities, including high-speed label-free chemically specific imaging, infrared volumetric imaging, hyperspectral infrared video microscopy and related modalities. Second, we exploit photon momentum, exploring a new photonic regime that emerges directly from the Heisenberg uncertainty principle governing the spatial and momentum degrees of freedom of light. Extreme confinement at nanometric dielectric discontinuities localizes the optical field to dimensions approaching one nanometer, necessarily broadening its momentum distribution. The resulting photonic state contains large-momentum components that can bridge the momentum separation between electronic states, dramatically enhancing optical transitions that are strongly momentum-suppressed in the far field. This picture suggests a fundamentally different route to controlling light–matter interaction: rather than modifying a material to accommodate the photon, we engineer the momentum structure of light while leaving the underlying electronic structure of the material largely unchanged. We refer to the resulting optical fields as momentum-expanded photonic states, in which the spatial extent and momentum distribution of light directly govern the accessibility of electronic transitions. At its core, this work asks a simple question: can we change the optical properties of matter without changing the matter itself?
About the candidate: Dmitry A. Fishman received Ph.D. from University of Groningen (Netherlands) in 2008. Since then, he worked at several universities and national labs across the globe, including Grenoble High Magnetic Field Laboratory (CNRS, France), College of Optics and Photonics at University of Central Florida (USA). Prof. Fishman’s research team in the Department of Chemistry at UC Irvine works at the intersection of optics and condensed matter physics/chemistry – understanding and control of light-matter interaction across times and scales. These studies have enabled several fundamental discoveries and spectroscopic modalities, particularly in chemical sensing and imaging: (a) ultrafast time-resolved imaging beyond diffraction limit through photo-induced force, (b) first observation of single molecule vibration in time, (c) infrared light detection by conventional visible detectors and several label-free chemical sensitive imaging modalities, (d) the development of momentum-expanded photonic states for controlling optical transitions. Through his research programs, Dr. Fishman founded, developed and currently directs Laser Spectroscopy Laboratories at UC Irvine – an advanced scientific hub aimed at research and education in the fields of light-matter interactions, linear and nonlinear optics, physics and chemistry.
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