Two-dimensional spectroscopy on a THz quantum cascade structure

Nanophotonics

article

Sergej Markmann¹  Manfred Fiebig²  Giacomo Scalari¹  Jérôme Faist¹  Martin Franckié¹  Shovon Pal²  David Stark¹  Mattias Beck¹ 

[1] Institute of Quantum Electronics;Department of Materials

关键词: 2D spectroscopy;    nonlinear spectroscopy;    quantum cascade laser;    quantum wells;    semiconductors;    THz;    time-resolved spectroscopy;   

DOI  :  10.1515/nanoph-2020-0369

学科分类：社会科学、人文和艺术（综合）

来源: De Gruyter

【 摘 要 】

Understanding and controlling the nonlinear optical properties and coherent quantum evolution of complex multilevel systems out of equilibrium is essential for the new semiconductor device generation. In this work, we investigate the nonlinear system properties of an unbiased quantum cascade structure by performing two-dimensional THz spectroscopy. We study the time-resolved coherent quantum evolution after it is driven far from equilibrium by strong THz pulses and demonstrate the existence of multiple nonlinear signals originating from the engineered subbands and find the lifetimes of those states to be in the order of 4–8 ps. Moreover, we observe a coherent population exchange among the first four intersubband levels during the relaxation, which have been confirmed with our simulation. We model the experimental results with a time-resolved density matrix based on the master equation in Lindblad form, including both coherent and incoherent transitions between all density matrix elements. This allows us to replicate qualitatively the experimental observations and provides access to their microscopic origin.

【 授权许可】

CC BY