Dissertation Title: Non-Hermitian optics in a Thin-Film Lithium Niobate Microcavity
Date: 2024/05/17
Dissertation Title: Non-Hermitian optics in a Thin-Film Lithium Niobate Microcavity
Speaker: Jiankun Hou
Time: 14:00, May 17, 2024 (Beijing Time)
Location: 414B, Longbin Building
Abstract
Non-Hermitian theory is a theoretical framework used to describe open systems. It offers a powerful tool in the characterization of both the intrinsic degrees of freedom of a system and the interactions with the external environment. By designing loss, gain and coupling strength in non-Hermitian optical systems, the systems can exhibit parity-time (PT) symmetry and exceptional points (EPs), revealing some counterintuitive behaviors like topological encircling chirality and loss induced lasing. Due to the excellent optical properties of lithium niobate, Thin-Film Lithium Niobate (TFLN) platform provides a rich soil for the study of non-Hermitian photonics. This dissertation investigates intriguing physical phenomena and applications of non-Hermitian optics in a TFLN microcavity. Firstly, a self-induced transparency effect in an optical microcavity with perfect absorption characteristics is introduced. Then the second harmonic generation is found to be greatly enhanced at PT symmetry line. Finally, a reconfigurable subwavelength photorefractive grating within a TFLN optical microcavity is demonstrated, benefitting from the photorefractive effect with a short period equal to half of the wavelength of the incident light, without complex fabrication processes. These findings possess potential applications in diverse non-Hermitian systems, encompassing domains such as acoustics, matter waves, microwaves, and mechanics. Consequently, these pave the way for practical implementations in all-optical signal processing and quantum information.
Biography
Jiankun Hou received the B.S. degree in School of Engineering Sciences from Huazhong University of Science and Technology in 2019. He is currently a Ph.D. candidate at the UM-SJTU Joint Institute, supervised by Prof. Wenjie Wan. His current research interests include whispering gallery mode microresonator, second harmonic generation, non-Hermitian optics, and thin-film lithium niobate.