Coherent spectroscopy, including multidimensional approaches, overcomes the effects of inhomogeneous broadening and can reveal coupling between resonances, effects that occur in semiconductors due to structural disorder in nanostructures and many-body effects.
Multi-dimensional coherent spectroscopy (MDCS) has become an extremely versatile and sensitive technique for elucidating the structure, composition, and dynamics of condensed matter, atomic, and molecular systems. The appeal of MDCS lies in its ability to resolve both individual-emitter and ensemble-averaged dynamics of optically created excitations in disordered systems. When applied to semiconductors, MDCS enables unambiguous separation of homogeneous and inhomogeneous contributions to the optical linewidth, pinpoints the nature of coupling between resonances, and reveals signatures of many-body interactions. In this review, we discuss the implementation of MDCS to measure the nonlinear optical response of excitonic transitions in semiconductor nanostructures. Capabilities of the technique are illustrated with recent experimental studies that advance our understanding of optical decoherence and dissipation, energy transfer, and many-body phenomena in quantum dots and quantum wells, semiconductor microcavities, layered semiconductors, and photovoltaic materials.
Abstract Optical multidimensional coherent spectroscopy provides information about the structure and excitation dynamics in a broad range of material systems. This book focuses on systems of interest in physics, including atomic vapors, semiconductor nanostructures and two-dimensional materials. An introduction to ultrafast spectroscopy and the fundamental concepts of multidimensional coherent spectroscopy applies to all material systems. Relevant experimental implementations, including phase-stabilized crossed-beams, frequency-tagged fully-collinear, three-dimensional and frequency-comb based methods. The use of the method to study atomic vapors, semiconductor quantum wells, semiconductor quantum dots and two-dimensional materials are described in separate chapters. The final chapters survey the use of the method in some other areas and speculate on future directions.
Abstract Multidimensional coherent optical spectroscopy (MDCS) is an elegant and versatile tool to measure the ultrafast nonlinear optical response of materials. Of particular interest for semiconductor nanostructures, MDCS enables the separation of homogeneous and inhomogeneous linewidths, reveals the nature of coupling between resonances, and is able to identify the signatures of many-body interactions. As an extension of transient four-wave mixing (FWM) experiments, MDCS can be implemented in various geometries, in which different strategies can be used to isolate the FWM signal and measure its phase. I review and compare different practical implementations of MDCS experiments adapted to the study of semiconductor materials. The power of MDCS is illustrated by discussing experimental results obtained on semiconductor nanostructures such as quantum dots, quantum wells, microcavities, and layered semiconductors.
Optical spectroscopy using ultrafast light pulses has undergone a revolution in the last decade due to the introduction and development of multidimensional coherent techniques. These methods build on established coherent spectroscopic techniques, such as photon echoes, but go beyond them by correlating the coherent dynamics during two time periods. The resulting multidimensional spectra have a number of advantages including disentangling congested spectra, revealing coupling between resonances, and removing the effects of inhomogeneous broadening. Similar ideas are currently being used for imaging. The papers in this 'focus on' collection document some of the current areas of activity in these fields.