Title :
Nonlinear gain dynamics in quantum-dot optical amplifiers and its application to optical communication devices
Author :
Akiyama, Tomoyuki ; Kuwatsuka, Haruhiko ; Simoyama, Takashi ; Nakata, Yoshiaki ; Mukai, Kohki ; Sugawara, Mitsuru ; Wada, Osamu ; Ishikawa, Hiroshi
Author_Institution :
Fujitsu Labs. Ltd., Atsugi, Japan
fDate :
8/1/2001 12:00:00 AM
Abstract :
Ultrafast gain dynamics in quantum-dot (QD) optical amplifiers has been studied. It was found that there are at least three nonlinear processes, which are attributed to carrier relaxation to the ground states, phonon scattering, and carrier capture from the wetting layers into the QDs. The relevant time constants were evaluated to be ~90 fs, ~260 fs, and ~3 ps, respectively, under a 50-mA bias condition. The dephasing time was evaluated to be ~85 fs. The third-order optical susceptibility (χ(3)) has been evaluated by means of both nonlinear transmission and four-wave mixing experiments. The results show that the nonlinearity expressed by χ(3)/g0 is quite similar to that of bulk and quantum wells, which can be explained by similar relaxation times. Applications to optical communication devices are also discussed
Keywords :
III-V semiconductors; carrier relaxation time; electron-phonon interactions; indium compounds; multiwave mixing; nonlinear optical susceptibility; optical communication equipment; optical saturable absorption; quantum well lasers; semiconductor optical amplifiers; semiconductor quantum dots; 260 fs; 3 ps; 50 mA; 85 fs; 90 fs; InAs; InAs QDs; all-optical gate operation; carrier capture; carrier relaxation; dephasing time; four-wave mixing; ground states; nonlinear gain dynamics; nonlinear processes; nonlinear transmission; optical communication devices; phonon scattering; quantum-dot optical amplifiers; relaxation times; third-order optical susceptibility; time constants; ultrafast gain dynamics; wetting layers; Nonlinear optics; Optical amplifiers; Optical mixing; Optical scattering; Phonons; Quantum dots; Semiconductor optical amplifiers; Stationary state; Stimulated emission; Ultrafast optics;
Journal_Title :
Quantum Electronics, IEEE Journal of
