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

We have developed the optical sampling four-wave mixing technique applicabl e 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 p rinciple, this new spectroscopic tool provides well timing-controlled two-c olor light pulses for excitation and detection, and also wide observable te mporal range from sub-picoseconds to a few nanoseconds with femtosecond tim e resolution. Various transient processes such as phase relaxation, spin re laxation, and energy relaxation processes can therefore be observed rapidly in the common measurement system. (C) 2000 Elsevier Science B.V. All right s reserved.