【講座題目】Probing Light-Matter Interactions in Polar Semiconductor Materials

【講座時(shí)間】2017年12月5日（星期二）15:00

【講座地點(diǎn)】北京校部主樓B606

【主 講 人】熊啟華 教授

【主講人簡(jiǎn)介】

熊啟華是南洋理工大學(xué)數(shù)理科學(xué)學(xué)院和電氣電子工程學(xué)院雙聘教授。他1997年本科畢業(yè)于武漢大學(xué)物理系，2006年于賓夕法尼亞州立大學(xué)獲得博士學(xué)位，師從Peter C. Eklund教授。2006-2009年在哈佛大學(xué)Charles Lieber研究組從事博士后研究。2009年加入南洋理工大學(xué)， 2014年獲得終身教職，2016年升正教授。他于2014年起擔(dān)任數(shù)理科學(xué)學(xué)院副院長(zhǎng)主管科研, 研究生教學(xué)，2017年起主要負(fù)責(zé)教職事務(wù)。熊教授的主要研究領(lǐng)域是以穩(wěn)態(tài)和瞬態(tài)光譜學(xué)為主要實(shí)驗(yàn)手段，以光和物質(zhì)相互作用為研究主題, 著重研究低維半導(dǎo)體納米材料基于光子-聲子-電子耦合作用的物理機(jī)制和量子調(diào)控。在《自然》及子刊, 《納米通訊》，《先進(jìn)材料》等一系列國(guó)際知名雜志上發(fā)表了180多篇文章， 并被世界知名雜志及大眾媒體所報(bào)道，總引用次數(shù)超過(guò)6500余次，H-因子48。獲新加坡物理學(xué)會(huì)納米科技獎(jiǎng)（2015），新加坡國(guó)立研究基金NRF Investigatorship獎(jiǎng)（2014）等。

【內(nèi)容簡(jiǎn)介】

The interaction of light with matter gives rises to a wide range of linear and nonlinear phenomena that we are familiar with, such as absorption and scattering, spontaneous or stimulated emission, and second harmonic generation. In polar semiconductors, the electromagnetic field of light polarizes the matter leading to the formation of elemental excitations such as excitons and exciton polaritons, due to long-range dipolar force as well as additional coupling to the optical fields. In this talk, I will first introduce the background of exciton, exciton polaritons and the electron/exciton-longitudinal optical phonon (LOP) interactions in semiconductors. I will then present the first fluorescence laser cooling of semiconductors based on cadmium sulfide nanoribbons, enabled by enhanced strong exciton-LOP coupling at nanoscale. In zinc telluride nanoribbons, resolved-sideband Raman cooling of LOPs can be realized with a similar physical picture of cavity optomechanics, in which the excitonic mode was utilized to assist the photoelastic Raman scattering from the LOPs. By detuning the laser pumping, the dipole oscillation of the LOPs is photoelastically attenuated (enhanced) to a colder (hotter) state, corresponding to the laser cooling of amplification of the LOPs respectively. Finally, I will introduce our recent work on strong light-matter coupling in all-inorganic perovskite crystals embedded in optical microcavities. Those prototype semiconductors have exceptionally large exciton binding energy, strong oscillator strength and facile epitaxy-free growth. Room temperature exciton polariton lasing can be realized, which was unambiguously evidenced by a superlinear power dependence, macroscopic ground state occupation, blueshift of ground state emission, and the build-up of long-range spatial coherence, suggesting considerable promise of room temperature polariton devices and coherent light sources extending from the ultraviolet to near infrared range. Future work will be briefly discussed, with a particular interest on transient spectroscopy investigations of semiconductors.