12/16 Seminar Speech

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Category: Speeches

Created on Tuesday, 10 December 2019 09:52

Last Updated on Monday, 16 December 2019 13:15

Published on Tuesday, 10 December 2019 09:53

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Speaker: Professor Yu-Jung Lu

Topic: Controlling Light-matter Interactions at Nanoscale with Plasmonics: From Spontaneous Emission to Lasing

Speaker：Professor Yu-Jung Lu

Organization：Research Center for Applied Sciences (RCAS), Academia Sinica & Department of Physics, National Taiwan University

Topic：Controlling Light-matter Interactions at Nanoscale with Plasmonics: From Spontaneous Emission to Lasing

Date：10:20 , 2019.12.16

Location：Room 203, College of Engineering

Work Experience：

Academia Sinica / Research Center for Applied Sciences (RCAS) / Assistant Research Fellow

National Taiwan University / Department of Physics / Assistant Professor

Abstract：

In this talk, I will present an overview of my research works in recent five years. My previous works mainly focus on wavelength-tunable on-chip nanoemitters, such as InGaN nano-LEDs and InGaN plasmonic nanolasers. Here, I will specifically present my recent work during my 2-years Postdoc research in Caltech. I have developed a research project focusing on “Gate Tunable Spontaneous Emission Decay Rate of InP Quantum Dots” and “Organo-lead Halide Perovskite Nanolasers”. I have performed electromagnetic simulations to design gate tunable heterostructures for tuning spontaneous emission from quantum dots, which have been also fabricated and experimentally characterized. The idea is by electrically modulating the titanium nitride (TiN) in the designed plasmonic heterostructure, we demonstrated the field-effect modulated spontaneous emission rate of semiconductor quantum dots due to novel electric-field induced refractive index change mechanism. We demonstrate gate tunable spontaneous emission rate of InP quantum dots (QDs) due to bias induced modification of the local density of optical states (LDOS). The modulation is due to the large change in complex dielectric function at TiN/gate dielectric interface in the bias-induced accumulation/depletion layer. The underlying physics is very promising since by using electric-field induced LDOS modulation, not only bias-induced PL quenching but also bias-induced PL enhancing of semiconductor QDs can be observed. Unlike conventional LED structure which require special doping to make p-n junction or complex growth, this work opens the door towards optoelectronic applications that are simple to implement. This LDOS modulation effect provides an insight in development of tunable on-chip optical light sources for potential future application on electrically driven plasmonic nanolasers, ultracompact on-chip optical information processing, electrical controlled single photon emission, and thin film display.