JILA, University of Colorado and National Institute of Standards and Technology, Boulder, Colorado 80309-0440, United States.
J Phys Chem B. 2011 May 12;115(18):5365-71. doi: 10.1021/jp109408s. Epub 2011 Mar 9.
Optical two-dimensional Fourier-transform spectroscopy is used to study the heavy- and light-hole excitonic resonances in weakly disordered GaAs quantum wells. Homogeneous and inhomogeneous broadening contribute differently to the two-dimensional resonance line shapes, allowing separation of homogeneous and inhomogeneous line widths. The heavy-hole exciton exhibits more inhomogeneous than homogeneous broadening, whereas the light-hole exciton shows the reverse. This situation occurs because of the interplay between the length scale of the disorder and the exciton Bohr radius, which affects the exciton localization and scattering. Utilizing this separation of line widths, excitation-density-dependent measurements reveal that many-body interactions alter the homogeneous dephasing, while disorder-induced dephasing is unchanged.
光学二维傅里叶变换光谱学用于研究弱无序 GaAs 量子阱中的重空穴和轻空穴激子共振。均匀展宽和非均匀展宽对二维共振线形状的贡献不同，允许分离均匀和非均匀线宽。重空穴激子的非均匀展宽比均匀展宽更明显，而轻空穴激子则相反。这种情况的发生是由于无序的长度尺度和激子玻尔半径之间的相互作用，这影响了激子的局域化和散射。利用这种线宽的分离，激发密度相关的测量表明，多体相互作用改变了均匀退相，而由无序引起的退相则保持不变。
