Technical: This collaborative research project at CUNY Queens College and University of Michigan aims to develop a new class of nonlinear optical materials that combine the advantages of organic, inorganic and metallic systems. Composite structures comprising hybridized excitons that have the desirable nonlinear optical properties of large oscillator strength (organic like), low saturation power (inorganic like), and quasiparticles (exciton-plasmon polaritons) that form through the strong interaction between inorganic excitons and plasmons of metal nanoparticles are investigated. The research project is expected to realize these hybridized materials systems through (i) dipole-dipole interaction of the Frenkel and Wannier-Mott excitons at the organic-inorganic interface and (ii) strong coupling between inorganic excitons and plasmons of metal nanoparticles using layered nanocomposite geometry. Nonlinear optical properties and morphology of the materials are investigated using a variety of spectroscopic and structural characterization techniques.
The project addresses basic research issues in a topical area of materials science with high technological relevance. A successful outcome of this research project will make substantial contributions to the field of nonlinear optics by exploring a new class of engineered nonlinear optical materials. Besides potential applications such as efficient all-optical switching elements, imaging, spectroscopy and second harmonic generation, these materials can potentially contribute to the interdisciplinary field of quantum informatics. The collaborative project also trains, creates research opportunities, and helps instill interest in science and engineering for graduate, undergraduate and high school students, from diverse backgrounds and ethnicities.
During the period of the grant, the most important scientific achievement was the demonstration of the formation of hybrid organic-inorganic excitons using light as the medium that binds them (See cartoon). The emergent properties such as enhanced strength of interaction with light of such hybrid states were also demonstrated. Engineered nanomaterials with optoelectronic properties that surpass the naturally existing ones is of immense technological importance. Our specific research program aimed at developing optical materials that combine the advantages of organic, inorganic and metallic materials to realize systems that have superior nonlinear optical properties. The need for efficient nonlinear optical devices is driven by a wide array of applications such as all-optical switches, optical memory, spectroscopy, imaging, slowing of light, ultrashort pulse generation, entangled photon generation, and quantum cryptography. The major drawback of existing nonlinear optical materials is the large optical fluence requirement due to the weak nonlinear optical response of most naturally occurring materials. In this context, the possibility to engineer the nonlinear optical response is highly attractive. From a broader societal perspective, the realization of engineered nanomaterials that can control light-matter interaction is central to the development of (i) efficient energy harvesting systems that can be implemented in solar cells, (ii) high quantum efficiency light emitters for low-cost lighting, and (iii) secure communication systems that rely on principles of quantum mechanics. In addition to the scientific impact, the program also contributed to workforce training and promoting and retaining students from underrepresented communities to participate in the research. The collaborative aspect of the present grant also allowed students from two institutions (U of Michigan and CUNY) with different subject expertise to interact closely and work towards the common scientific goal. Outreach efforts included participation in "world science fair", annual science open house at Queens College, and hosting of high school students to work in the lab during summer months.
