Control of Nonlinear Properties of van der Waals Materials

<p>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<br />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.</p>

Name thesis:degree_name

Doctor of Philosophy

Level thesis:degree_level

Doctoral

Discipline thesis:degree_discipline

Physics

Grantor

The Graduate School and University Center of The City University of New York

Year dc:date.available

2022

Author dc:creator

• Bushati, Rezlind

Advisor dc:contributor.advisor

• Vinod Menon

Committee members dc:contributor.committeemember

• Andrea Alu
• Alexander Khanikaev
• Gabriele Grosso
• Li Ge

• Condensed Matter Physics
• Optics
• Quantum Physics
• Light-matter interactions
• spectroscopy
• nonlinear optics
• van der waals materials

Repository record dc:identifier

https://academicworks.cuny.edu/gc_etds/5020

OAI identifier oai:identifier

oai:academicworks.cuny.edu:gc_etds-6146