Optical sampling four-wave-mixing experiment for exciton relaxation processes

We have developed the optical sampling four-wave mixing technique applicable to measurements of the ultrafast dynamical processes in liquid and solid materials. The method is examined to reveal the exciton dynamical processes in GaAs quantum wells at low temperatures. By using the optical sampling principle, this new spectroscopic tool provides well timing-controlled two-color light pulses for excitation and detection, and also wide observable temporal range from sub-picoseconds to a few nanoseconds with femtosecond time resolution. Various transient processes such as phase relaxation, spin relaxation, and energy relaxation processes can therefore be observed rapidly in the common measurement system. (C) 2000 Elsevier Science B.V. All rights reserved.