Accession Number : ADP007851

Title :   Femtosecond Gain Dynamics in Semiconductors,

Corporate Author : SANDIA NATIONAL LABS ALBUQUERQUE NM

Personal Author(s) : Fu, W. S. ; Poirer, G. E. ; Bryan, R. P. ; Klem, J. F. ; Olbright, G. R.

Report Date : 22 MAY 1992

Pagination or Media Count : 4

Abstract : The fundamental study of semiconductor gain dynamics is crucial to the understanding of electron-hole-pair excitation dynamics and semiconductor lasers. While there have been numerous experimental and theoretical investigations of absorption dynamics, relatively few dynamical gain studies have been reported. One of the first time-resolved gain measurements examined focused primarily on hot-carrier relaxation in wide GaAs quantum wells (QWs). In this paper we describe the complete temporal evolution of gain in narrow GaAs/A1O.45 Ga0.55As quantum wells. Using femtosecond pump/probe spectroscopy we have measured the development and subsequent decay (recovery) of gain (absorption). We present a detailed investigation of the exciton bleaching followed by gain buildup and decay. These optical nonlinearities are discussed in terms of phase-space filling, screening and thermalization of carriers. The observed ultrafast (< 400 fs) gain decay is explained in terms of plasma-expansion.

Descriptors :   *EXCITONS, *GALLIUM ARSENIDE LASERS, ABSORPTION, DECAY, DYNAMICS, ELECTRONS, EXCITATION, EXPANSION, FILLING, GAIN, MEASUREMENT, PAPER, PHASE, PROBES, RECOVERY, RELAXATION, SEMICONDUCTOR LASERS, SPECTROSCOPY, TIME, PUMPING(ELECTRONICS).

Subject Categories : Lasers and Masers
      Electrooptical and Optoelectronic Devices
      Solid State Physics

Distribution Statement : APPROVED FOR PUBLIC RELEASE