678771 event 1733437603 1733437690 <![CDATA[Ph.D. Proposal Oral Exam - Anjan Goswami]]> Title:  Ultrafast Hot Electron Dynamics for Transient Symmetry-Breaking

Committee: 

Dr. Cai, Advisor   

Dr. Peterson, Chair

Dr. Zhang

]]> The objective of the proposed research is to investigate mechanisms for breaking symmetry in optical responses using hot carrier dynamics in a transient manner. Hot electrons generated by non-radiative decay of plasmonic modes exhibit a spatial profile that mirrors the electric field enhancement of plasmonic nanoresonators. By controlling the incident light's polarization, the near-field profile can be manipulated to break material symmetries optically at ultrafast timescales. Three research projects are designed to explore these symmetry-breaking phenomena: breaking mirror symmetry, and inversion symmetry. The first project leverages inhomogeneous hot carrier generation to create ultrafast transient chirality, which is extended in the next project to GHz frequencies through vibrational modes induced by asymmetric thermal stress. The final project involves injecting hot carriers into an electron-accepting material having inversion symmetry to modulate second harmonic generation, eventually enabling investigation of quantum tunneling by introducing a high potential barrier between a metallic nanoresonator and the electron-accepting material. These investigations aim to establish foundational techniques for using hot carriers to explore symmetry-breaking mechanisms in optical systems.

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