Dissertations, Theses, and Capstone Projects

Date of Degree

9-2022

Document Type

Dissertation

Degree Name

Ph.D.

Program

Physics

Advisor

Vinod Menon

Committee Members

Andrea Alu

Alexander Khanikaev

Gabriele Grosso

Li Ge

Subject Categories

Condensed Matter Physics | Optics | Quantum Physics

Keywords

Light-matter interactions, spectroscopy, nonlinear optics, van der waals materials

Abstract

Van der Waals materials are a broad class of materials that exhibit unique optoelectronic properties. They provide a rich playground for which they can be integrated into current on-chip devices due to their nanometer-scale size, and be utilized for studying fundamental physics. Strong coupling of emitters to microcavities provides many opportunities for new exotic physics through the formation of hybrid quasi-particles exciton-polaritons. This thesis
focuses on exploring and enhancing nonlinearity of van der Waals materials through strongly coupling to microcavities. By taking advantage of the stacking order of TMDs, we show intense second-harmonic generation from bulk, centrosymmetric TMD systems. In addition, due to their large refractive index, they support their own Fabry-Perot modes allowing for the creation of self-hybridized exciton-polaritons. Recent studies have also shown that strain in van der Waals materials can provide new insight, as well as new physics into these systems. Combining strain with microcavities allows for increased nonlinear interactions in monolayer strained TMD polariton systems. Our studies in TMDs strained by circular pillars as well as rectangular pillars allow for easy manipulation of nonlinearity. Antiferromagnets are a recent class of 2D materials that have many exotic optoelectronic and magnetic properties. Our nonlinear polariton spectroscopy studies in strongly coupled NiPS3 show insight into previously unknown properties of spin-correlated NiPS3 excitons. Finally, we study a new material, CrSBr, which is an antiferromagnet with highly anisotropic properties. Moreover, CrSBr provides large tunability of excitonic absorption and emission due to the inter-layer coupling of the exciton-magnon complexes present in the system. Strong coupling of CrSBr allows for tunable exciton-magnon-polaritons, and nonlinear experiments provide a platform for re-writable polariton landscapes. The ability to enhance second-harmonic generation, exciton-exciton interactions, and polariton-polariton interactions paves the way for on-chip integration in addition to providing a platform for investigating new physics in previously unexplored materials.

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